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POTENTIAL HISTORIC SNOWSTORM FOR DCA / N VA


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Area Forecast Discussion

Issued by NWS Sterling, VA

 

http://forecast.weather.gov/product.php?si...p;highlight=off

 

 

 

402AM Dec 17 2009

 

000

FXUS61 KLWX 170828

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

328 AM EST THU DEC 17 2009

 

.SYNOPSIS...

-- Changed Discussion --

HIGH PRESSURE WILL AFFECT THE AREA TODAY...BEFORE MOVING OFF THE

COAST TONIGHT. LOW PRESSURE WILL DEVELOP ALONG THE COASTLINE OF

THE GULF OF MEXICO LATE TONIGHT...AND EMERGE OFF THE COAST OF THE

CAROLINAS FRIDAY NIGHT. THIS STORM WILL THEN TRACK UP THE EASTERN

SEABOARD SATURDAY AND SATURDAY NIGHT. COLD HIGH PRESSURE WILL

BUILD FOR THE FIRST HALF OF NEXT WEEK.

-- End Changed Discussion --

 

 

&&

 

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --

ANOTHER DAY OF QUIET WX...AHEAD OF A POSSIBLE WINTRY SCENARIO FOR

THE COMING WEEKEND. NOT MUCH ACTIVITY ONGOING ACROSS THE CONUS...

BUT A RELATIVELY SMALL DISTURBANCE JUST OFF THE TX GULF COAST WILL

CONTINUE TO STRENGTHEN OVER THE COURSE OF THE DAY AND INTO TOMORROW.

AN UPPER LOW ROTATING OVER NOVA SCOTIA WILL REMAIN SITUATED IN THAT

GENERAL AREA INTO THE WEEKEND...KEEPING A STEADY STREAM OF NWLY

WINDS AND COLDER-DRIER AIR SLIDING DOWN INTO THE NORTHEAST AND MID

ATLC.

 

HIGHS TODAY WILL BE COMPARABLE TO YESTERDAY...AS ANOTHER PERIOD OF

10-15MPH WINDS PICK-UP DURING THE LATE MRNG-EARLY AFTN HRS AND KEEP

WIND CHILL VALUES ABOUT 10 DEGREES BELOW THE AMBIENT TEMP. SKIES

WILL REMAIN MOSTLY CLEAR THROUGHOUT THE MRNG...THEN A STEADY STREAM

OF UPPER CIRRUS /FOLLOWED BY MID LEVEL STRATUS/ WILL MAKE AN

APPEARANCE DURING THE AFTN-EVNG HRS.

-- End Changed Discussion --

 

&&

 

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...

-- Changed Discussion --

OTHER THAN A FAIRLY SOLID LAYER OF UPPER CIRRUS AND INCREASING

AMOUNTS OF MID CLOUD DECKS...ANOTHER SIMILAR OVERNIGHT PERIOD FOR

THU NIGHT/FRI MRNG. CLOUD COVER WILL KEEP THE STRATIFICATION OF

TEMPS ACROSS THE AREA FAIRLY LOW /EVERYONE RANGING IN THE L-M20S

FROM THE MTNS TO THE BAY/.

-- End Changed Discussion --

 

&&

 

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...

-- Changed Discussion --

MDL GDNC /OP RUNS AND ENSEMBLES/ CNVGG TWD A WKND SNW EVENT ACRS

CWFA. THE MAIN PIECES SEEM TO BE FALLING INTO PLACE-- SRN STREAM

LOPRES CROSSES THE GLFMEX CST PICKING UP AMPLE MSTR FRI AND THEN

TRANSFERS THAT ENERGY TO THE CAROLINA COAST AS IT INTERACTS W/ H5

TROF AXIS. STORM SUBSEQUENTLY ATTAINS NEG TILTING AS IT DEEPENS

AND TRACKS TWD NEW ENGLND SUNDAY. SFC LOW PROGGED TO BE CLS ENUF

TO COAST TO PROVIDE DECENT PCPN FM NOT JUST THE GLFMEX CONNECTION

BUT ALSO ACCESSING ATLC MSTR...BUT TRACK WL STILL BE S OF CWFA. H8

LOW ALSO PROGGED TO BE S OF CWFA. THUS...MDL SNDGS AND CRIT TKNS

VALUES ALL SUGGEST IT WL BE PLENTY COLD FOR JUST SNW. THOSE SIGNS

ALL SUGGEST THAT CWFA WL BE W/IN BAND OF HVYR QPF. BUT...DO XPCT A

THERMAL GRADIENT WHICH LKLY WL CLIP SERN CRNR OF CWFA...MAINLY SRN

MD...MEANING THERE WL BE A RA/SN LINE TO DEAL WITH.

 

HAVING SAID THAT...THERE ARE SMALL DIFFS IN MDL GDNC WHICH WL HV

BIG RAMIFICATIONS IN THE END FCST. /FOR ONE THING...ITS STILL WAY

TOO ELY TO PIN DOWN QPF./ SINCE THERE IS THAT ASPECT OF UNCERTAINTY

AND STORM WL BE IN FCST PDS 4-6...WON/T BE ISSUING A WATCH JUST YET.

/DAYSHIFT MAY NEED TO IF 06Z-12Z GDNC PAINTS A SIMLR PICTURE./

BUT...WL BUMP UP POPS SIGNIFICANTLY /LKLY-CAT/ FRI NGT-SAT NGT W/

THIS CYCLE. WL MAKE CORRESPONDING ADJUSTMENTS TO TEMPS AS WELL...

SPCLY MAXT SAT-SUN...SINCE TEMPS WL STRUGGLE TO RISE IN LIGHT OF

POTL SNWFL.

 

ONCE H5 TROF SWINGS THRU...FLOODGATES OPEN FOR MORE COLD AIR FOR THE

1ST HALF OF NXT WEEK. THAT ALSO SHUD EQUATE TO UPSLP SHSN FOR OUR

WRN TIER.

-- End Changed Discussion --

 

&&

 

.AVIATION /09Z THURSDAY THROUGH MONDAY/...

-- Changed Discussion --

HIGH PRESSURE WILL KEEP CONDITIONS QUIET INTO NEXT WEEKEND. BREEZY

NWLY WINDS WILL AGAIN PICK-UP THIS MRNG...LINGERING THRU THE AFTN

THEN DECREASING TO NEAR CALM BY LATE TONIGHT. A LOW PRESSURE SYSTEM

GATHERING OVER THE TX GULF COAST WILL BEGIN TO AFFECT THE REGION BY

LATE FRI...BUT LITTLE CONCERN WX-WISE TILL THEN.

 

CONDS DETERIORATE FRI AFTN-NGT AS LOPRES FM GLFMEX CST TRANSFERS

ENERGY OFF THE CAROLINA COAST AND TRACKS NEWD. MAIN PTYPE WL BE SNW.

IFR OR LWR SEEMS PLAUSIBLE LT FRI NGT/ELY SAT MRNG INTO SAT EVE.

SOME DETAILS /TIMING/AMTS/ STILL NEED TO BE WORKED OUT...SO WON/T BE

GETTING TOO SPECIFIC ATTM.

 

CONDS WL BE IMPVG BY SUN. CUD BE A FEW MVFR PDS...BUT VFR SHUD

PREVAIL.

-- End Changed Discussion --

 

&&

 

.MARINE...

-- Changed Discussion --

SCA THRU LATE THIS AFTN. WINDS ARE NOTICEABLY STRONGER CLOSER TO

/AND OVER/ THE MD CHESAPEAKE. A TIGHTENING PRESSURE GRADIENT HELPING

TO KEEP 15-20 KT GUSTS OVER THE WATERS...W/ INTERMITTENT GUSTS NEAR

25 KT. THIS WILL LINGER THRU THE LATE MRNG AND INTO THE MID

AFTN...GRADUALLY TAPERING OFF BY EVNG.

 

LOPRES ALNG GLFMEX CST FRI WL TRANSFER OFF CAROLINA CST SAT...AND

TRACK TO NEW ENGLND SUN. STORM WL BE STRENGTHENING WHILE IN WRN

ATLC...AND LTST GDNC PAINTS A STRONGER STORM CLSR TO THE CST. GIVEN

SUCH A LRG CONTINUITY SHIFT...AM HESITANT TO OFFER UP GALES ATTM...

BUT IT CERTAINLY SEEMS PLAUSIBLE BASED ON LTST PROGS. WL CAP WNDS AT

30KT IN THE GRIDS LT FRI NGT/ELY SAT MRNG THRU ELY SUN...MAINLY

IMPACTING LWR PTMC AND MID BAY. SCA CONDS SHUD CONT PAST SUN.

 

WL ALSO BE VSBY RESTRICTIONS AS PCPN /RASN XCPT SNW UPR REACHES BAY

AND MOST OF PTMC/ MVS IN FRI EVE AND CONTS THRU SAT. ONCE STORM MVS

N OF DELMARVA /RIGHT NOW THAT APPEARS TO BE SAT EVE/...COLD AIR WL

RUSH IN CHGG ALL PCPN TO SNW.

-- End Changed Discussion --

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

-- Changed Discussion --

DC...NONE.

MD...NONE.

VA...NONE.

WV...NONE.

MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR

ANZ530>534-537>543.

-- End Changed Discussion --

 

 

&&

 

$$

SYNOPSIS...HTS

NEAR TERM...GMS

SHORT TERM...GMS

LONG TERM...HTS

AVIATION...GMS/HTS

MARINE...GMS/HTS

 

 

 

 

 

------------------------

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Area Forecast Discussion

Issued by NWS Sterling, VA

 

http://forecast.weather.gov/product.php?si...p;highlight=off

 

 

000

FXUS61 KLWX 180849

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

349 AM EST FRI DEC 18 2009

 

.SYNOPSIS...

-- Changed Discussion --

HIGH PRESSURE WILL MOVE EAST OF THE AREA TODAY. LOW PRESSURE

ALONG THE GULF COAST WILL EMERGE OFF THE COAST OF THE CAROLINAS

TONIGHT. THIS STORM WILL THEN TRACK ALONG THE EAST COAST

SATURDAY THROUGH SUNDAY MORNING. A WEAK DISTURBANCE TO CROSS THE

MID- ATLANTIC REGION EARLY NEXT WEEK BEFORE HIGH PRESSURE BUILDS

IN FOR THE MIDDLE PART OF THE WEEK.

-- End Changed Discussion --

 

 

&&

 

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --

LITTLE TO SPEAK OF WX-WISE THRU MIDDAY FRI. THE APPROACHING STORM

SYSTEM THAT IS EXPECTED TO BE A SNOW-MAKER FROM SOUTHERN

APPALACHIANS TO THE NEW ENGLAND IS CURRENTLY STRENGTHENING OVER

THE GULF COAST STATES. A REGIONAL-SCALE FETCH OF LOW LEVEL

MOISTURE STREAMING UP THE SOUTHEAST...FROM LA TO SC. THE LEADING

EDGE OF THE PRECIP WILL BE EXPANDING UP THE ERN SEABOARD THRU THE

DAYTIME HRS.

 

TEMPS WILL GRADUALLY RISE CLOSE TO FREEZING BY LATE MRNG AS THE

STORM SYSTEM IS STILL WELL TO THE SOUTH...AND ONLY BANDS OF MID-

HIGH CLOUDS WILL BE STREAMING INTO THE MID ATLC. HIGHS NOT

EXPECTED TO RISE MUCH MORE THAN THAT...LIKELY STILL IN THE L-M30S

BY MID AFTN...MODERATING FROM THERE AS MORE SOLID CLOUD COVER

PUSHES IN FROM THE SW AND FROM A WEAK ELY ONSHORE FLOW AS A WEAK

SFC HIGH OVER SRN QUEBEC HELPS TO REINFORCE THE RELATIVELY COLDER

AIR IN THE LOW LEVELS.

-- End Changed Discussion --

 

&&

 

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...

-- Changed Discussion --

AS THE LEADING EDGE OF PRECIP BEGINS TO WORK THRU THE DRIER REGIME

BY LATE FRI AFTN-EARLY EVENING...A FEW SNOW FLAKES WILL BEGIN TO

FALL ACROSS THE SOUTHERNMOST PORTIONS OF THE CWA JUST AFTER

SUNSET. PCPN WILL LIKELY BE VERY LIGHT FOR THE FIRST FEW HRS W/

LITTLE-NO ACCUMULATION EXPECTED UNTIL LATER IN THE EVENING.

 

THIS COMPLEX STORM SYSTEM HAS TWO MAIN PHASES. THE FIRST PHASE

AFFECTS THE MID ATLC MAINLY FOR THE LATE NIGHT-OVERNIGHT HRS ON

FRI...INTO EARLY SAT. A DYNAMIC MESOSCALE REGION OF MODERATE

SNOW...W/ EMBEDDED AREAS OF HEAVY SNOW...WILL BE SETTING UP

ACROSS THE LEE OF THE SRN-CNTRL APPALACHIANS...AN EFFECT OF THE

PROXIMITY OF THE SHORTWAVE ACROSS THE MID MISSISSIPPI VLY AND THE

COASTAL LOW OFF THE CAROLINAS. AS THE COASTAL LOW STRENGTHENS OFF

THE SC/NC COAST /MYRTLE BEACH-WILMINGTON/ LATE FRI NIGHT...THIS

MESOSCALE AREA OF HEAVIER PRECIP WILL BE MAXIMIZED IN BETWEEN I-81

AND I-95 OF SRN VA TOWARD THE LATE NIGHT HRS. AN EVEN STRONGER

COASTAL LOW DEPICTED FROM THE LATEST NAM SUGGESTS THAT THIS

CORRIDOR OF PRECIP /WHICH WOULD BE ALL SNOW ONCE IT ENTERS OUR

CWA/ WILL BE FAIRLY WELL MAINTAINED AS IT PUSHES NORTH-

NORTHEASTWARD INTO THE OVERNIGHT HRS.

 

THE AREA HIGHLIGHTED FOR ACCUMULATING SNOWS WILL BE TO THE SOUTH

OF THE I-66 CORRIDOR W/ THE HIGHEST AMOUNTS OVER EXTREME W CNTRL

VA...INTO THE NEARBY BLUE RIDGE AND FOOTHILLS. WHILE THE HEAVIEST

CORRIDOR OF SNOW BANDING WILL BE PROPAGATING UP THE VA/MD PIEDMONT

INTO THE PRE-DAWN HRS SAT...SNOW WILL CONTINUE TO FALL OVER THE

CNTRL-SRN SHENANDOAH VLY...ADDING TO THEIR OVERNIGHT ACCUMULATIONS.

THE FOCUS WILL THEN SHIFT TOWARD THE METRO AREAS.

-- End Changed Discussion --

 

 

&&

 

.LONG TERM /SATURDAY THROUGH THURSDAY/...

-- Changed Discussion --

MDL GDNC REMAINS QUITE CONSISTENT ON A BIG EAST COAST NOREASTER SAT-

SAT NGT. THE QSTNS RIGHT NOW HOVER ARND HOW MUCH AND WHEN...NOT

IF. GFS SEEMS A BIT FLAT CONSIDERING THE POTL. ON THE OTR HAND...

NAM QPF GROSSLY OVERDONE. THEREIN LIES THE UNCERTAINTY.

 

ON SAT...CSTL LOW PASSES JUST E OF CWFA...AND INTERACTS W/ H5 TROF.

STORM THEN LIFTS NE OF CWFA SAT NGT. EVEN IF FULL PHASING DOES NOT

OCCUR...THE DEFORMATION AXIS WL BE ACRS CWFA...SUPPORTING A SWATH OF

MDT-HVY SNW-- NOT EVEN SPEAKING OF LCL BANDING. WHILE SNW WL START

ERLR...ACCUM PCPN WL SPREAD IN EARNEST INTO METROS ON SAT...W/ MAX

IMPACT LKLY SAT AFTN-EVE INVOF DEF AXIS. CYCLONE PLENTY JUICED FM

GLFMEX...AND WL IMPORT ADDTL MSTR FM ATLC. THERMALLY... COLUMN

COLD ENUF FOR ALL SNW ACRS ENTIRE CWFA. ENUF INGREDIENTS TO RAISE

WRNG.

 

PLEASE NOTE...TTL ACCUMS WL NEED TO BE FINE TUNED IN THE CYCLES TO

COME. SUFFICE IT TO SAY...THE WRNG THRESHOLD WL BE SURPASSED.

THERE/S ALWAYS A BIT OF UNCERTAINTY IN FCSTG EXTREME EVENTS...AND HV

ATTEMPTED TO STRIKE A BALANCE CONVEYING THE THREAT IN A RESERVED

MANNER.

 

IN ADDITION...LOOKING FOR WNDS TO PICK UP TOO AS THE P-GRAD INCR...

ADDING BLOWING/DRIFTING CONCERNS.

 

PCPN LKLY TO WIND DOWN SUN MRNG AS LOW DEPARTS. THE UPSLP EVENT THEN

WL UNFOLD. LATER FCSTRS WL NEED TO ADDRESS THAT CONCERN. IT/LL BE

PLENTY COLD FOR THE WK AHD.

-- End Changed Discussion --

 

&&

 

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...

-- Changed Discussion --

VFR CONDITIONS THRU MUCH OF THE CURRENT TAF PERIOD...BUT A LOW

PRESSURE SYSTEM WILL BE FAST APPROACHING THE MID ATLC BY LATE IN THE

DAY ON FRIDAY. SNOW WILL BEGIN TO FALL AT LOCALES SUCH AS KCHO BY

FRI EVENING...AND MOVE INTO THE DC/BALT METRO AREAS INTO THE LATE

NIGHT HRS /AND INCREASING IN INTENSITY OVERNIGHT/. BY THE PRE-DAWN

HRS...MOST OF THE AREA TAF SITES WILL BE IN STEADILY FALLING

SNOW...W/ THE HEAVIEST ACTIVITY ALONG THE I-95 CORRIDOR GOING INTO

THE MORNING HRS ON SAT. LESSER INTENSITIES AND DURATIONS ACROSS THE

NRN SHENANDOAH VLY...LIKE KMRB/KHGR.

 

POOR FLYING CONDS SAT-SAT NGT /AOB IFR VSBYS/CIGS/ IN SNW. IMPVMNT

COMES SUN.

-- End Changed Discussion --

 

&&

 

.MARINE...

-- Changed Discussion --

WINDS NEAR CALM AROUND THE REGION...W/ WEAK NLY SURGES CLOSER TO 10

KT INTO THE EARLY MRNG HRS. FOR MUCH OF TODAY...WINDS WILL REMAIN

RELATIVELY LIGHT...CHANGING TO MORE ELY BY THIS AFTN...THEN NELY

INTO THE LATE EVENING. A LOW PRESSURE SYSTEM JUST OFF THE CAROLINA

COAST WILL BEGIN TO AFFECT THE REGION BY SPREADING SNOW ACROSS THE

MID ATLC AND A MIX OF RAIN-SNOW CLOSER TO THE BAY...CHANGING MAINLY

TO ALL SNOW INTO THE OVERNIGHT HRS FRI. AS THE COASTAL LOW

STRENGTHENS INTO EARLY SAT AND GETS CLOSER TO THE TIDEWATER

REGION...SO WILL WINDS ACROSS THE BAY. SCA CONDITIONS WILL BE

APPARENT BY EARLY SAT.

 

CYCLONE DEEPENS OFF DELMARVA SAT-SAT NGT...MAKING GLW A VERY REAL

PSBLTY. HV UPGRADED TO GLW FOR MOST OF BAY/LWR PTMC...STRONG SCA

ELSW. WL LET LATER FCSTRS HANDLE THE ENDING OF THE EVENT.

-- End Changed Discussion --

 

&&

 

.TIDES/COASTAL FLOODING...

-- Changed Discussion --

LOW PRESSURE WILL INTENSIFY OFF THE CAROLINA COAST TONIGHT...MOVING

NEAR THE MOUTH OF THE BAY LATE TONIGHT AND INTO SATURDAY. PROLONGED

NORTHEASTERLY FLOW WILL BUILD EXCESS WATER INTO THE BAY...BRINGING

POSITIVE TIDAL DEPARTURES TONIGHT AND SATURDAY. THERE WILL BE

POTENTIAL FOR MINOR COASTAL FLOODING WITH THIS SYSTEM. STRONG

NORTHERLY FLOW SATURDAY WILL REMOVE EXCESS WATER FROM THE BAY

THROUGH SUNDAY NIGHT.

-- End Changed Discussion --

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

-- Changed Discussion --

DC...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR DCZ001.

MD...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR MDZ003>007-009>011-013-014-016>018-501-502.

VA...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR VAZ028-031-042-052>054.

WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR VAZ021-025>027-029-030-036>041-050-051-055>057.

WV...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR WVZ050>053-503-504.

WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR WVZ054-055-501-502.

MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST

SATURDAY FOR ANZ531-532-539-540.

GALE WARNING FROM 6 AM TO 10 PM EST SATURDAY FOR ANZ531>534-

537-539>543.

SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EST

SATURDAY FOR ANZ533-534-537-541>543.

SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 10 PM EST

SATURDAY FOR ANZ530-535-536-538.

-- End Changed Discussion --

 

 

&&

 

$$

SYNOPSIS...HTS

NEAR TERM...GMS

SHORT TERM...GMS

LONG TERM...HTS

AVIATION...GMS/HTS

MARINE...GMS/HTS

TIDES/COASTAL FLOODING...HTS

 

 

 

 

 

 

 

 

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Area Forecast Discussion

Issued by NWS Sterling, VA

 

http://forecast.weather.gov/product.php?si...p;highlight=off

 

 

 

000

FXUS61 KLWX 191532

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

1032 AM EST SAT DEC 19 2009

 

.SYNOPSIS...

LOW PRESSURE OFF THE NORTH CAROLINA COAST WILL INTENSIFY AND

MOVE ALONG THE COAST AND OFF THE DELMARVA TONIGHT AND EAST OF LONG

ISLAND SUNDAY MORNING. A WEAK DISTURBANCE WILL CROSS THE MID-ATLANTIC

REGION LATE MONDAY BEFORE HIGH PRESSURE BUILDS IN FOR THE MIDDLE

PART OF THE WEEK. A STRONG UPPER DISTURBANCE IS EXPECTED TO IMPACT

THE MID-ATLANTIC FOR CHRISTMAS.

 

&&

 

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --

LOW PRES INVOF KHSE...989MB...AND WL CONT INTENSIFY AS IT APRCHS

THE DELMARVA LATE THIS AFTN/ERLY EVE. BANDS OF HVIEST RDR RETURN

ACROSS CENTRAL VIRGINIA HAS NE- SW ALIGNMENT. HVIEST SNOWFALL AREA

WL MOVE FM THE CENTRAL SHEN VALLEY UP TOWARDS DC/BALT/NHK...WHERE

IT WL CONT TO SNOW HEAVILY THRUT THE DAY. STORM TOTALS 2 TO 2.5 FT

INVOF CHO WHERE 16.5 WAS REPORTED AT 9 AM...ALONG THE ALLEGHENY

FRONT...AND 1.5 TO 2 FT ALONG THE THE I-95 CORRIDOR.

 

BLIZZARD WARNING EXPANDED TO GREATER I-95 CORRIDOR AND SOUTHERN

MARYLAND. PERIODS AND HEAVY SNOW AND GUSTY WINDS ARE EXPECTED

THROUGH THE AFTERNOON HOURS OF THE BLIZZARD AREA.

 

SNOW IS STARTING TO TAPER OFF FOR SW ZONES...A FEW BANDS TO CROSS

OUT THERE BRINGING A FEW MORE INCHES.

 

MIXED PRECIP FOR LOWER ST MARYS/SOUTHERN CALVERT COUNTY TO TURN TO

ALL SNOW THROUGH MIDDAY.

 

PLEASE CHECK CLIMATE SXN FOR TWO DAY DEC SNOW TOTALS.

-- End Changed Discussion --

 

 

&&

 

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...

BLV SNOW WL BECOME LGT TNGT IN THE SW...BUT XPCTD TO CONT AT A MDT

PACE IN I-95 CORRIDOR DURG THE EVE HRS. TEMPS OVRNGT IN 20S ACROSS

THE CWA - WIND CHILLS IN THE TEENS.

 

&&

 

.LONG TERM /SUNDAY THROUGH FRIDAY/...

SNOW XPCD TO TAPER OFF SUN AS LOPRES MOVES QUICKLY AWAY FROM RGN.

WNWLY LOW-LVL FLOW AND APRCH OF A LOW-AMPLITUDE SHRTWV TROF WILL

PROMOTE UPSLP SNOW SHOWERS ALONG WRN SLOPES OF ALLEGHENY FRONT

THRU MON NGT.

 

COLD AIR RMNS PRESENT THRU MUCH OF NEXT WEEK OWING TO PERSISTENT

SNOW PACK. A STRONG CLOSED UPR LOW XPCD TO FORM OVER SRN PLNS MID

WEEK AND COULD RESULT IN PCPN THU-FRI. ATTM...MODELS SUGGEST A

TRANSITION FROM SNOW INITIALLY TO RAIN AS WARM AIR IS DRAWN INTO

THE SYSTEM.

 

&&

 

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...

-- Changed Discussion --

TAFS CONTINUE TO BE BURIED IN VLIFR CIGS/VSBYS THRUT THE DAYLGT

HRS. SNOW THROUGH THE AFTERNOON PERIODS OF HEAVY SNOW WITH BANDED

PRECIPITATION. ALTHO THERE MAY BE SOME MINOR IMRVMNTS GETTING

IN/OUT OF THE THREE MAJOR AIRPORTS WL BE XTRMLY DIFFICULT THIS

EVENG.

 

MAIN PSBLTY FOR TERMINAL IMPACTS IN EXTENDED PDS IS THU-FRI NEXT

WEEK...WHEN A DEEP CLOSED UPR LOW WILL APRCH APLCNS AND COULD

GENERATE RAIN/SNOW OVER MUCH OF MID-ATLC RGN.

-- End Changed Discussion --

 

 

&&

 

.MARINE...

-- Changed Discussion --

LOW PRESSURE NEAR HATTERAS MOVING NE. GRADIENT HAS

INCREASED...GALES FOR THE WATERS THROUGH TONIGHT. ANY MIXED PRECIP

OVER THE WATER TO CHANGE OVER TO ALL SNOW THIS AFTERNOON. SMALL

CRAFT ADVISORY WILL BE WARRANTED FOR THE WATERS SUNDAY THROUGH

SUNDAY NIGHT. STRONGER NW WINDS CONTINUE THROUGH MONDAY/MONDAY NIGHT AS

HIGH PRESSURE BUILDS ACROSS THE WATERS.

-- End Changed Discussion --

 

 

 

 

&&

 

.TIDES/COASTAL FLOODING...

-- Changed Discussion --

PROLONGED NORTHEASTERLY FLOW HAS BUILT POSITIVE ANOMALIES INTO THE

BAY. ATTM TIDAL LVLS ARE APPROACHING TWO FEET ABOVE PREDICTED FOR

LOWER TIDAL POTOMAC AND LOWER PORTIONS OF THE MD CHES BAY. A

COASTAL FLOOD ADVISORY WILL GO UP FOR CALVERT..ST

MARYS...CHARLES...KING GEORGE COUNTIES SOON. POSITIVE TIDAL

DEPARTURES OF UP TO ONE FOOT ABOVE NORMAL ARE POSSIBLE REST OF THE

WATERS TODAY.

-- End Changed Discussion --

 

 

&&

 

.CLIMATE...

-- Changed Discussion --

MID ATLC LOOKS ON ITS WAY TO RECORD DEC SNOWFALL - TWO DAY DEC RECORDS

FOR MAJOR AIRPORTS:

 

DCA 12.0" 1932

BWI 14.1" 1960

IAD 12.1" 1969

-- End Changed Discussion --

 

 

 

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

-- Changed Discussion --

DC...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR DCZ001.

BLIZZARD WARNING UNTIL 6 PM EST THIS EVENING FOR DCZ001.

MD...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR MDZ006-007-009>011-013-014-016>018.

BLIZZARD WARNING UNTIL 6 PM EST THIS EVENING FOR MDZ006-007-

009>011-013-014-016>018.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MDZ003>005-501-

502.

VA...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR VAZ052>057.

BLIZZARD WARNING UNTIL 6 PM EST THIS EVENING FOR VAZ052>057.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR VAZ021-025>031-

036>042-050-051.

WV...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ050>055-

501>504.

MARINE...GALE WARNING UNTIL 6 AM EST SUNDAY FOR ANZ530>543.

-- End Changed Discussion --

 

 

&&

 

$$

UPDATE...BAJ

PREVIOUS DISCUSSION...ABW/BPP/JRK

 

 

 

 

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000

WWUS41 KLWX 191939

WSWLWX

 

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

239 PM EST SAT DEC 19 2009

 

DCZ001-MDZ006-007-009>011-VAZ052>057-200345-

/O.CAN.KLWX.BZ.W.0001.000000T0000Z-091219T2300Z/

/O.CON.KLWX.WS.W.0008.000000T0000Z-091220T1100Z/

DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD-MONTGOMERY-HOWARD-

SOUTHERN BALTIMORE-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-

ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-

KING GEORGE-

INCLUDING THE CITIES OF...WASHINGTON...GAITHERSBURG...COLUMBIA...

BALTIMORE...MANASSAS...MANASSAS PARK...FAIRFAX...ALEXANDRIA...

FALLS CHURCH...FREDERICKSBURG

239 PM EST SAT DEC 19 2009

 

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY...

...BLIZZARD WARNING IS CANCELLED...

 

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS CANCELLED

THE BLIZZARD WARNING. A WINTER STORM WARNING REMAINS IN EFFECT

UNTIL 6 AM EST SUNDAY.

 

* PRECIPITATION TYPE...SNOW.

 

* ACCUMULATIONS...STORM TOTAL ACCUMULATIONS OF 14 TO 22 INCHES.

 

* TIMING...SNOW WILL BE HEAVIEST THROUGH 9 PM TONIGHT. SNOW WILL

CONTINUE THROUGH EARLY SUNDAY MORNING.

 

* TEMPERATURES...MID TO UPPER 20S.

 

* WINDS...15 TO 20 MPH...WITH GUSTS UP TO 25 MPH.

 

 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW...

SLEET...AND ICE ARE EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO

POSSIBLE. THIS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE.

 

&&

 

$$

 

MDZ013-014-016>018-200345-

/O.CAN.KLWX.BZ.W.0001.000000T0000Z-091219T2300Z/

/O.EXT.KLWX.WS.W.0009.091219T1939Z-091220T1100Z/

PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-

INCLUDING THE CITIES OF...ANNAPOLIS...WALDORF...ST MARYS CITY

239 PM EST SAT DEC 19 2009

 

...WINTER STORM WARNING NOW IN EFFECT UNTIL 6 AM EST SUNDAY...

...BLIZZARD WARNING IS CANCELLED...

 

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS CANCELLED

THE BLIZZARD WARNING. THE WINTER STORM WARNING IS NOW IN EFFECT

UNTIL 6 AM EST SUNDAY.

 

* PRECIPITATION TYPE...SNOW.

 

* ACCUMULATIONS...STORM TOTAL ACCUMULATIONS OF 12 TO 18 INCHES.

 

* TIMING...SNOW WILL BE HEAVIEST THROUGH 7 PM TONIGHT. SNOW WILL

CONTINUE THROUGH EARLY SUNDAY MORNING.

 

* TEMPERATURES...MID TO UPPER 20S.

 

* WINDS...15 TO 25 MPH...WITH GUSTS UP TO 30 MPH AT COASTAL

LOCATIONS.

 

 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW...

SLEET...AND ICE ARE EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO

POSSIBLE. THIS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE.

 

&&

 

$$

 

VAZ021-025-026-036>039-050-WVZ054-200345-

/O.CON.KLWX.WS.W.0008.000000T0000Z-091220T1100Z/

HIGHLAND-AUGUSTA-ROCKINGHAM-NELSON-ALBEMARLE-GREENE-MADISON-

ORANGE-PENDLETON-

INCLUDING THE CITIES OF...STAUNTON...WAYNESBORO...HARRISONBURG...

CHARLOTTESVILLE

239 PM EST SAT DEC 19 2009

 

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY...

 

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY.

 

* PRECIPITATION TYPE...SNOW.

 

* ACCUMULATIONS...STORM TOTAL ACCUMULATIONS OF 14 TO 24 INCHES.

 

* TIMING...SNOW WILL CONTINUE THROUGH TONIGHT.

 

* TEMPERATURES...MID TO UPPER 20S.

 

* WINDS...10 TO 15 MPH WITH GUSTS TO 25 MPH.

 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE

EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO POSSIBLE. CONDITIONS

WILL DETERIORATE VERY RAPIDLY LATE TONIGHT AND WILL MAKE TRAVEL

EXTREMELY TREACHEROUS.

 

&&

 

$$

 

MDZ501-502-VAZ027>031-WVZ050-055-501>504-200345-

/O.CON.KLWX.WS.W.0008.000000T0000Z-091220T1100Z/

EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-SHENANDOAH-

FREDERICK VA-PAGE-WARREN-CLARKE-HAMPSHIRE-HARDY-WESTERN GRANT-

EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-

INCLUDING THE CITIES OF...FROSTBURG...CUMBERLAND...WINCHESTER...

FRONT ROYAL...BAYARD...PETERSBURG...EMORYVILLE...HARTMANSVILLE...

KEYSER...FORT ASHBY

239 PM EST SAT DEC 19 2009

 

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY...

 

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY.

 

* PRECIPITATION TYPE...SNOW.

 

* ACCUMULATIONS...STORM TOTAL ACCUMULATIONS OF 12 TO 24 INCHES.

 

* TIMING...SNOW WILL CONTINUE THROUGH TONIGHT.

 

* TEMPERATURES...LOW TO MID 20S.

 

* WINDS...10 TO 15 MPH...WITH GUSTS TO 25 MPH.

 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE

EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO POSSIBLE. CONDITIONS

WILL DETERIORATE VERY RAPIDLY EARLY TODAY MORNING AND WILL MAKE

TRAVEL EXTREMELY TREACHEROUS.

 

&&

 

$$

 

MDZ003-WVZ051>053-200345-

/O.CON.KLWX.WS.W.0008.000000T0000Z-091220T1100Z/

WASHINGTON-MORGAN-BERKELEY-JEFFERSON-

INCLUDING THE CITIES OF...HAGERSTOWN...MARTINSBURG...CHARLES TOWN

239 PM EST SAT DEC 19 2009

 

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY...

 

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY.

 

* PRECIPITATION TYPE...SNOW.

 

* ACCUMULATIONS...STORM TOTAL ACCUMULATIONS OF 12 TO 24 INCHES.

 

* TIMING...SNOW WILL CONTINUE THROUGH EARLY SUNDAY MORNING.

 

* TEMPERATURES...MID 20S.

 

* WINDS...10 TO 20 MPH.

 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE

EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO POSSIBLE. CONDITIONS

WILL DETERIORATE VERY RAPIDLY TODAY MORNING AND WILL MAKE TRAVEL

EXTREMELY TREACHEROUS.

 

&&

 

$$

 

VAZ040-041-051-200345-

/O.CON.KLWX.WS.W.0008.000000T0000Z-091220T1100Z/

RAPPAHANNOCK-FAUQUIER-CULPEPER-

INCLUDING THE CITIES OF...WASHINGTON...CULPEPER

239 PM EST SAT DEC 19 2009

 

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY...

 

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY.

 

* PRECIPITATION TYPE...SNOW.

 

* ACCUMULATIONS...STORM TOTAL ACCUMULATIONS OF 14 TO 24 INCHES.

 

* TIMING...SNOW WILL CONTINUE THROUGH LATE TONIGHT.

 

* TEMPERATURES...MID 20S.

 

* WINDS...10 TO 15 MPH...WITH GUSTS TO 25 MPH.

 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE

EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO POSSIBLE. CONDITIONS

WILL DETERIORATE VERY RAPIDLY TODAY MORNING AND WILL MAKE TRAVEL

EXTREMELY TREACHEROUS.

 

&&

 

$$

 

MDZ004-005-VAZ042-200345-

/O.CON.KLWX.WS.W.0008.000000T0000Z-091220T1100Z/

FREDERICK MD-CARROLL-LOUDOUN-

INCLUDING THE CITIES OF...FREDERICK...WESTMINSTER...LEESBURG

239 PM EST SAT DEC 19 2009

 

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY...

 

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM EST SUNDAY.

 

* PRECIPITATION TYPE...SNOW.

 

* ACCUMULATIONS...STORM TOTAL ACCUMULATIONS OF 12 TO 24 INCHES.

 

* TIMING...SNOW WILL CONTINUE THROUGH EARLY SUNDAY MORNING.

 

* TEMPERATURES...MID 20S.

 

* WINDS...10 TO 20 MPH WITH GUSTS OF 25 MPH.

 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE

EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO POSSIBLE. CONDITIONS

WILL DETERIORATE VERY RAPIDLY TODAY MORNING AND WILL MAKE TRAVEL

EXTREMELY TREACHEROUS.

 

&&

 

$$

 

BAJ

 

 

 

-------

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000

FXUS61 KLWX 182025

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

325 PM EST FRI DEC 18 2009

 

.SYNOPSIS...

-- Changed Discussion --

LOW PRESSURE OVER THE SOUTHEASTERN STATES WILL INTENSIFY ALONG THE

CAROLINA COAST THIS EVENING. THE STORM WILL INTENSIFY AND MOVE

ALONG THE EAST COAST SATURDAY INTO SUNDAY MORNING. A WEAK

DISTURBANCE WILL CROSS THE MID-ATLANTIC REGION LATE MONDAY BEFORE

HIGH PRESSURE BUILDS IN FOR THE MIDDLE PART OF THE WEEK. A STRONG

UPPER DISTURBANCE IS EXPECTED TO IMPACT THE MID-ATLANTIC FOR

CHRISTMAS.

-- End Changed Discussion --

 

 

&&

 

.NEAR TERM /THROUGH TONIGHT/...

-- Changed Discussion --

ACCUMULATING SNOWFALL BEGINS THIS AFTERNOON. REGIONAL RADAR MOSAIC

DEPICTS THE LEADING BANDS OF SNOW CURRENTLY STRETCHED FROM SOUTHERN

WV TO CAPE HATTERAS...INCLUDING HIGHLAND...AUGUSTA AND NELSON

COUNTIES. A FEW FLAKES MAY REACH DC AND BALTIMORE THIS EVENING...BUT

ACCUMULATING SNOW WILL BE A FEW HOURS LATER GIVEN SURFACE AND AIR

TEMPERATURES IN THE LOW 30S. GENERAL OVERNIGHT ACCUMULATIONS OF

2-4 INCHES WILL BE POSSIBLE IN THE METRO AREAS...5-10 INCHES IN

THE CENTRAL SHENANDOAH VALLEY AND CENTRAL FOOTHILLS.

-- End Changed Discussion --

 

 

&&

 

.SHORT TERM /SATURDAY/...

-- Changed Discussion --

INTENSE SNOWFALL BEGINS THIS EVENING FOR SW ZONES THEN SPREADS

NORTHEAST THROUGH THE NIGHT AS THE CENTER OF THE LOW REACHES THE

GA COAST AND INTENSIFIES AS IT HEADS NE UP THE CAROLINA COAST

TONIGHT. EXPECTING THE STORM TO BE HALF OVER FOR THE SW ZONES BY

TOMORROW MORNING...WHILE JUST GETTING UNDERWAY FOR THE BALTIMORE-

DC METRO AREA. AS THE SYSTEM CROSSES CAPE HATTERAS EARLY SATURDAY...

WRAPAROUND SNOW BANDS SPREAD ACROSS THE CWA...PRIMARILY ALONG AND

EAST OF THE SHENANDOAH VALLEY. A TROWAL WITH EMBEDDED INSTABILITY

EXPECTED TO BE ALONG THE I-95 CORRIDOR THROUGH THE DAY SATURDAY...

PRODUCING INTENSE SNOWFALL. THE TROWAL AXIS PULLS EAST SATURDAY

NIGHT...THOUGH THE RATE AT WHICH IT MOVES EAST REMAINS TO BE SEEN.

HOWEVER...EXPECT SNOWFALL TO TAPER OFF FROM WEST TO EAST SATURDAY

NIGHT...ENDING ALONG THE WESTERN SHORE OF THE BAY SUNDAY MORNING.

 

WINDS OF 15 TO 20 MPH WITH GUSTS TO 25 MPH WILL BLOW THE HEAVY SNOW

AS IT FALLS...FURTHER DECREASING VISIBILITY. TRAVEL WILL BE VERY

TREACHEROUS AND IS GREATLY DISCOURAGED LATE TONIGHT THROUGH

SATURDAY.

-- End Changed Discussion --

 

 

&&

 

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...

-- Changed Discussion --

SNOW XPCD TO TAPER OFF SUN AS LOPRES MOVES QUICKLY AWAY FROM RGN.

WNWLY LOW-LVL FLOW AND APRCH OF A LOW-AMPLITUDE SHRTWV TROF WILL

PROMOTE UPSLP SNOW SHOWERS ALONG WRN SLOPES OF ALLEGHENY FRONT

THRU MON NGT.

 

COLD AIR RMNS PRESENT THRU MUCH OF NEXT WEEK OWING TO PERSISTENT

SNOW PACK. A STRONG CLOSED UPR LOW XPCD TO FORM OVER SRN PLNS MID

WEEK AND COULD RESULT IN PCPN THU-FRI. ATTM...MODELS SUGGEST A

TRANSITION FROM SNOW INITIALLY TO RAIN AS WARM AIR IS DRAWN INTO

THE SYSTEM.

-- End Changed Discussion --

 

 

&&

 

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...

-- Changed Discussion --

VFR CONDITIONS END THIS EVENING AS SNOW SPREADS NORTHEASTWARD. SNOW

INTENSIFIES FROM SW TO NE TONIGHT WITH HEAVY SNOW ALL DAY SATURDAY

BEFORE TAPERING OFF FROM SW TO NE SATURDAY NIGHT. NLY WINDS 15 KT

WITH GUSTS UP TO 25 KT DURING SNOWFALL SATURDAY.

 

MAIN PSBLTY FOR TERMINAL IMPACTS IN EXTENDED PDS IS THU-FRI NEXT

WEEK...WHEN A DEEP CLOSED UPR LOW WILL APRCH APLCNS AND COULD

GENERATE RAIN/SNOW OVER MUCH OF MID-ATLC RGN.

-- End Changed Discussion --

 

 

&&

 

.MARINE...

-- Changed Discussion --

EASTERLY FLOW INCREASES THIS AFTERNOON WITH SCA STARTING SOUTH THIS

EVENING AND EXPANDING TO ALL WATERS BY MIDNIGHT. INTENSIFICATION

CONTINUES THROUGH THE NIGHT WITH GALES EXPECTED ACROSS THE WATERS

EXCEPT THE TIDAL POTOMAC ABOVE COBB ISLAND...THE PATAPSCO...AND

NORTH OF POOLES ISLAND. GALE FORCE GUSTS AND HEAVY SNOW ARE

EXPECTED SATURDAY AND SATURDAY NIGHT BEFORE THE STORM PULLS AWAY

FROM THE BAY SUNDAY MORNING.

-- End Changed Discussion --

 

 

&&

 

.TIDES/COASTAL FLOODING...

-- Changed Discussion --

LOW PRESSURE WILL INTENSIFY OFF THE CAROLINA COAST TONIGHT...MOVING

NEAR THE MOUTH OF THE BAY LATE TONIGHT AND SATURDAY. PROLONGED

NORTHEASTERLY FLOW WILL BUILD EXCESS WATER INTO THE BAY...BRINGING

POSITIVE TIDAL DEPARTURES OF AROUND ONE FOOT TONIGHT AND SATURDAY.

NO COASTAL FLOODING IS EXPECTED.

-- End Changed Discussion --

 

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

DC...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR DCZ001.

MD...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR MDZ003>007-009>011-013-014-018.

WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 AM EST SUNDAY

FOR MDZ016-017-501-502.

VA...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR VAZ042-053-054.

WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR VAZ021-025-026-036>039-050-056.

WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 AM EST SUNDAY

FOR VAZ027>031-040-041-051-052-055-057.

WV...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR WVZ051>053.

WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR WVZ054.

WINTER STORM WARNING FROM 9 PM THIS EVENING TO 6 AM EST SUNDAY

FOR WVZ050-055-501>504.

MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST

SATURDAY FOR ANZ531-532-539-540.

GALE WARNING FROM 6 AM TO 10 PM EST SATURDAY FOR ANZ531>534-

537-539>543.

SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EST

SATURDAY FOR ANZ533-534-537-541>543.

SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 10 PM EST

SATURDAY FOR ANZ530-535-536-538.

 

&&

 

$$

 

BAJ/KRAMAR

 

 

 

 

 

 

 

-----------

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000

FXUS61 KLWX 190139

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

839 PM EST FRI DEC 18 2009

 

.SYNOPSIS...

-- Changed Discussion --

LOW PRESSURE OVER THE SOUTHEASTERN STATES WILL INTENSIFY ALONG THE

CAROLINA COAST OVERNIGHT. THE STORM WILL INTENSIFY AND MOVE ALONG

THE EAST COAST SATURDAY INTO SUNDAY MORNING. A WEAK DISTURBANCE WILL

CROSS THE MID-ATLANTIC REGION LATE MONDAY BEFORE HIGH PRESSURE

BUILDS IN FOR THE MIDDLE PART OF THE WEEK. A STRONG UPPER

DISTURBANCE IS EXPECTED TO IMPACT THE MID-ATLANTIC FOR CHRISTMAS.

-- End Changed Discussion --

 

 

&&

 

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...

-- Changed Discussion --

CURRENT ANALYSIS SHOWS LOW PRESSURE DEVELOPING ALONG THE SOUTH

CAROLINA COAST EARLY THIS EVENING. THIS LOW WILL CONTINUE TO

INTENSIFY AS IT SLOWLY MOVES UP THE MID-ATLANTIC COAST OVERNIGHT. AN

UPPER-LEVEL LOW IS CURRENTLY MOVING THROUGH THE MIDWEST WHILE HIGH

PRESSURE REMAINS OVER NEW ENGLAND PUMPING IN PLENTY OF COLD AIR.

 

SNOW HAS ALREADY BROKE OUT ACROSS THE CENTRAL AND SOUTHERN

CWA THIS EVENING WELL AHEAD OF THE SURFACE LOW. PRECIPITATION WILL

CONTINUE TO SPREAD NORTH THIS EVENING AND SNOW...HEAVY AT TIMES IS

EXPECTED OVERNIGHT ACROSS THE ENTIRE CWA. HAVE BUMPED UP

ACCUMULATIONS OVERNIGHT DUE TO BANDING THAT IS ANTICIPATED WITH THE

PRECIPITATION. ACCUMULATIONS BY MORNING WILL BE AROUND 4 TO 8 INCHES

ACROSS THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS...AND 6 TO 12

INCHES ACROSS THE SHENANDOAH VALLEY INTO CENTRAL VIRGINA INTO THE

VIRGINIA PIEDMONT AND LOWER SOUTHERN MARYLAND.

-- End Changed Discussion --

 

 

&&

 

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...

-- Changed Discussion --

LOW PRESSURE WILL CONTINUE TO INTENSIFY AS IT MOVES UP THE MID-

ATLANTIC COAST SATURDAY. SNOW WILL CONTINUE ACROSS THE ENTIRE

CWA...HEAVY AT TIMES. THE HEAVIEST SNOW WILL FALL DURING THE

MORNING HOURS WEST OF THE BLUE RIDGE MOUNTAINS AND THROUGH THE

AFTERNOON HOURS EAST OF THE BLUE RIDGE MOUNTAINS.

 

WINDS OF 15 TO 20 MPH WITH GUSTS TO 25 MPH WILL BLOW THE HEAVY SNOW

AS IT FALLS...FURTHER DECREASING VISIBILITY. TRAVEL WILL BE VERY

TREACHEROUS AND IS GREATLY DISCOURAGED THROUGH SATURDAY.

-- End Changed Discussion --

 

 

&&

 

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...

SNOW XPCD TO TAPER OFF SUN AS LOPRES MOVES QUICKLY AWAY FROM RGN.

WNWLY LOW-LVL FLOW AND APRCH OF A LOW-AMPLITUDE SHRTWV TROF WILL

PROMOTE UPSLP SNOW SHOWERS ALONG WRN SLOPES OF ALLEGHENY FRONT

THRU MON NGT.

 

COLD AIR RMNS PRESENT THRU MUCH OF NEXT WEEK OWING TO PERSISTENT

SNOW PACK. A STRONG CLOSED UPR LOW XPCD TO FORM OVER SRN PLNS MID

WEEK AND COULD RESULT IN PCPN THU-FRI. ATTM...MODELS SUGGEST A

TRANSITION FROM SNOW INITIALLY TO RAIN AS WARM AIR IS DRAWN INTO

THE SYSTEM.

 

&&

 

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...

-- Changed Discussion --

CIGS AND VSBYS WILL RAPIDLY DETERIORATE ONCE SNOW BEGINS THIS

EVENING. IFR/SUBIFR CIGS AND VSBYS ARE EXPECTED IN SNOW OVERNIGHT

THROUGH SATURDAY. NLY WINDS 15 KT WITH GUSTS UP TO 25 KT DURING

SNOWFALL SATURDAY...ESPECIALLY ACROSS THE EASTERN TERMINALS.

 

MAIN PSBLTY FOR TERMINAL IMPACTS IN EXTENDED PDS IS THU-FRI NEXT

WEEK...WHEN A DEEP CLOSED UPR LOW WILL APRCH APLCNS AND COULD

GENERATE RAIN/SNOW OVER MUCH OF MID-ATLC RGN.

-- End Changed Discussion --

 

 

&&

 

.MARINE...

-- Changed Discussion --

LOW PRESSURE DEVELOPING OFF THE SOUTH CAROLINA COAST THIS EVENING

WILL SLOWLY MOVE NORTHWARD UP THE MID-ATLANTIC COAST AS IT

INTENSIFIES OVERNIGHT AND SATURDAY. THE INCREASING PRESSURE

GRADIENT WILL BRING SCA WINDS OVERNIGHT...WITH THE STRONGEST WINDS

ACROSS THE CHESAPEAKE BAY AND LOWER TIDAL POTOMAC WHERE GUSTS

AROUND 30 KNOTS ARE EXPECTED.

 

AS THE GRADIENT INCREASES...WINDS WILL INCREASE SATURDAY INTO

SATURDAY NIGHT ACROSS THE LOWER TIDAL POTOMAC AND CHESAPEAKE BAY

FROM POOLES ISLAND TO SMITH POINT. WILL CONTINUE WITH A GALE WARNING

ACROSS THESE AREAS...AND SCA CONDITIONS ELSEWHERE. A SMALL CRAFT

ADVISORY WILL LIKELY BE WARRANTED FOR THE WATERS OVERNIGHT SATURDAY

AND SUNDAY.

-- End Changed Discussion --

 

 

&&

 

.TIDES/COASTAL FLOODING...

-- Changed Discussion --

LOW PRESSURE WILL INTENSIFY OFF THE CAROLINA COAST

TONIGHT...MOVING NEAR THE MOUTH OF THE BAY SATURDAY. PROLONGED

NORTHEASTERLY FLOW WILL BUILD EXCESS WATER INTO THE BAY...BRINGING

POSITIVE TIDAL DEPARTURES OF UP TO ONE FOOT ABOVE NORMAL BY

SATURDAY. MINOR COASTAL FLOODING IS POSSIBLE NEAR TIMES OF HIGH

TIDE SATURDAY.

-- End Changed Discussion --

 

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

-- Changed Discussion --

DC...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR DCZ001.

MD...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR MDZ003>007-009>011-013-014-018.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MDZ016-017-501-

502.

VA...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR VAZ042-053-054.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR VAZ021-025-026-

036>039-050-056.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR VAZ027>031-040-

041-051-052-055-057.

WV...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 AM EST SUNDAY

FOR WVZ051>053.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ054.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ050-055-

501>504.

MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST

SATURDAY FOR ANZ531-532-539-540.

GALE WARNING FROM 6 AM TO 10 PM EST SATURDAY FOR ANZ531>534-

537-539>543.

SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR ANZ533-534-

537-541>543.

SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 10 PM EST

SATURDAY FOR ANZ530-535-536-538.

-- End Changed Discussion --

 

 

&&

 

$$

LASORSA/KRAMAR/BAJ

 

 

 

 

 

 

 

 

---------------

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000

FXUS61 KLWX 190858

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

358 AM EST SAT DEC 19 2009

 

.SYNOPSIS...

 

-- Changed Discussion --

LOW PRESSURE OFF THE NORTH CAROLINA COAST WILL INTENSIFY AND

MOVE ALONG THE COAST AND OFF THE DELMARVA TONIGHT AND EAST OF LONG

ISLAND SUNDAY MORNING. A WEAK DISTURBANCE WILL CROSS THE MID-ATLANTIC

REGION LATE MONDAY BEFORE HIGH PRESSURE BUILDS IN FOR THE MIDDLE

PART OF THE WEEK. A STRONG UPPER DISTURBANCE IS EXPECTED TO IMPACT

THE MID-ATLANTIC FOR CHRISTMAS.

-- End Changed Discussion --

 

 

&&

 

.NEAR TERM /TODAY/...

 

-- Changed Discussion --

MID ATLC LOOKS ON ITS WAY TO RECORD DEC SNOWFALL - TWO DAY DEC RECORDS

FOR MAJOR AIRPORTS:

 

DCA 12.0" 1932

BWI 14.1" 1960

IAD 12.1" 1969

 

LOW PRES HAS DEEPENED DRAMATICALLY AT HAT BTWN 04 AND 08Z - FM

1004 TO 990 MB...AND WL CONT INTENSIFY AS IT APRCHS THE DELMARVA

LATE THIS AFTN/ERLY EVE. BAND OF HVIEST RDR RETURN ALREADY SEEN

TO BE PIVOTING TO A MORE NE-SW ALIGNMENT. HVIEST SNOWFALL AREA WL

MOVE FM THE CENTRAL SHEN VALLEY UP TOWARDS DC/BALT/NHK...WHERE IT WL

CONT TO SNOW HEAVILY THRUT THE DAY. TOTALS NEAR 2` PSBL W OF CHO

WHERE 15" WAS REPORTED AT 1 AM...AND BY END OF TNGT NEAR 20" IN

THE I-95 CORRIDOR.

 

BLZRD WRNG SE OF DC WL RMN AS IS. THIS IS A REFLECTION OF STRONGER

WINDS CLOSE TO THE BAY...NOT HEAVIER SNOWFALL.

-- End Changed Discussion --

 

 

&&

 

.SHORT TERM /TONIGHT/...

 

-- Changed Discussion --

BLV SNOW WL BECOME LGT TNGT IN THE SW...BUT XPCTD TO CONT AT A MDT

PACE IN I-95 CORRIDOR DURG THE EVE HRS. TEMPS OVRNGT IN 20S ACROSS

THE CWA - WIND CHILLS IN THE TEENS.

-- End Changed Discussion --

 

 

&&

 

.LONG TERM /SUNDAY THROUGH FRIDAY/...

 

SNOW XPCD TO TAPER OFF SUN AS LOPRES MOVES QUICKLY AWAY FROM RGN.

WNWLY LOW-LVL FLOW AND APRCH OF A LOW-AMPLITUDE SHRTWV TROF WILL

PROMOTE UPSLP SNOW SHOWERS ALONG WRN SLOPES OF ALLEGHENY FRONT

THRU MON NGT.

 

COLD AIR RMNS PRESENT THRU MUCH OF NEXT WEEK OWING TO PERSISTENT

SNOW PACK. A STRONG CLOSED UPR LOW XPCD TO FORM OVER SRN PLNS MID

WEEK AND COULD RESULT IN PCPN THU-FRI. ATTM...MODELS SUGGEST A

TRANSITION FROM SNOW INITIALLY TO RAIN AS WARM AIR IS DRAWN INTO

THE SYSTEM.

 

&&

 

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...

 

-- Changed Discussion --

TAFS HV ESSENTIALLY BEEN BURIED IN VLIFR CIGS/VSBYS THRUT THE

DAYLGT HRS. ALTHO THERE MAY BE SOME MINOR IMRVMNTS GETTING IN/OUT

OF THE THREE MAJOR AIRPORTS WL BE XTRMLY DIFFICULT TDA THRU THIS

EVENG.

 

MAIN PSBLTY FOR TERMINAL IMPACTS IN EXTENDED PDS IS THU-FRI NEXT

WEEK...WHEN A DEEP CLOSED UPR LOW WILL APRCH APLCNS AND COULD

GENERATE RAIN/SNOW OVER MUCH OF MID-ATLC RGN.

-- End Changed Discussion --

 

 

&&

 

.MARINE...

 

LOW PRESSURE NEAR ILM WILL SLOWLY MOVE NORTHWARD UP THE MID-

ATLANTIC COAST AS IT INTENSIFIES OVERNIGHT AND SATURDAY. THE

INCREASING PRESSURE GRADIENT WILL BRING SCA WINDS OVERNIGHT...WITH

THE STRONGEST WINDS ACROSS THE CHESAPEAKE BAY AND LOWER TIDAL

POTOMAC WHERE GUSTS AROUND 30 KNOTS ARE EXPECTED.

 

AS THE GRADIENT INCREASES...WINDS WILL INCREASE SATURDAY INTO

SATURDAY NIGHT ACROSS THE LOWER TIDAL POTOMAC AND CHESAPEAKE BAY

FROM POOLES ISLAND TO SMITH POINT. WILL CONTINUE WITH A GALE WARNING

ACROSS THESE AREAS...AND SCA CONDITIONS ELSEWHERE. A SMALL CRAFT

ADVISORY WILL LIKELY BE WARRANTED FOR THE WATERS OVERNIGHT SATURDAY

AND SUNDAY.

 

&&

 

.TIDES/COASTAL FLOODING...

 

-- Changed Discussion --

PROLONGED NORTHEASTERLY FLOW WILL BUILD EXCESS WATER INTO THE

BAY. ATTM TIDAL LVLS AT DC/BALT/ANNA HAVEN`T BUDGED FM NRML...BUT

POSITIVE TIDAL DEPARTURES OF UP TO ONE FOOT ABOVE NORMAL ARE

POSSIBLE TODAY.

-- End Changed Discussion --

 

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

-- Changed Discussion --

DC...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR DCZ001.

MD...WINTER STORM WARNING UNTIL 6 AM EST EARLY THIS MORNING FOR

MDZ013-014-016>018.

WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR MDZ013-014-016>018.

BLIZZARD WARNING UNTIL 6 PM EST THIS EVENING FOR MDZ013-014-

016>018.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MDZ003>007-

009>011-501-502.

VA...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR VAZ021-025>031-

036>042-050>057.

WV...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ050>055-

501>504.

MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR

ANZ531>534-537-539>543.

GALE WARNING UNTIL 10 PM EST THIS EVENING FOR ANZ531>534-537-

539>543.

SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ530-

535-536-538.

-- End Changed Discussion --

 

 

&&

 

$$

PRODUCTS...WOODY!/JRK/BP

 

 

 

 

 

 

 

 

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000

FXUS61 KLWX 191532

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

1032 AM EST SAT DEC 19 2009

 

.SYNOPSIS...

LOW PRESSURE OFF THE NORTH CAROLINA COAST WILL INTENSIFY AND

MOVE ALONG THE COAST AND OFF THE DELMARVA TONIGHT AND EAST OF LONG

ISLAND SUNDAY MORNING. A WEAK DISTURBANCE WILL CROSS THE MID-ATLANTIC

REGION LATE MONDAY BEFORE HIGH PRESSURE BUILDS IN FOR THE MIDDLE

PART OF THE WEEK. A STRONG UPPER DISTURBANCE IS EXPECTED TO IMPACT

THE MID-ATLANTIC FOR CHRISTMAS.

 

&&

 

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --

LOW PRES INVOF KHSE...989MB...AND WL CONT INTENSIFY AS IT APRCHS

THE DELMARVA LATE THIS AFTN/ERLY EVE. BANDS OF HVIEST RDR RETURN

ACROSS CENTRAL VIRGINIA HAS NE- SW ALIGNMENT. HVIEST SNOWFALL AREA

WL MOVE FM THE CENTRAL SHEN VALLEY UP TOWARDS DC/BALT/NHK...WHERE

IT WL CONT TO SNOW HEAVILY THRUT THE DAY. STORM TOTALS 2 TO 2.5 FT

INVOF CHO WHERE 16.5 WAS REPORTED AT 9 AM...ALONG THE ALLEGHENY

FRONT...AND 1.5 TO 2 FT ALONG THE THE I-95 CORRIDOR.

 

BLIZZARD WARNING EXPANDED TO GREATER I-95 CORRIDOR AND SOUTHERN

MARYLAND. PERIODS AND HEAVY SNOW AND GUSTY WINDS ARE EXPECTED

THROUGH THE AFTERNOON HOURS OF THE BLIZZARD AREA.

 

SNOW IS STARTING TO TAPER OFF FOR SW ZONES...A FEW BANDS TO CROSS

OUT THERE BRINGING A FEW MORE INCHES.

 

MIXED PRECIP FOR LOWER ST MARYS/SOUTHERN CALVERT COUNTY TO TURN TO

ALL SNOW THROUGH MIDDAY.

 

PLEASE CHECK CLIMATE SXN FOR TWO DAY DEC SNOW TOTALS.

-- End Changed Discussion --

 

 

&&

 

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...

BLV SNOW WL BECOME LGT TNGT IN THE SW...BUT XPCTD TO CONT AT A MDT

PACE IN I-95 CORRIDOR DURG THE EVE HRS. TEMPS OVRNGT IN 20S ACROSS

THE CWA - WIND CHILLS IN THE TEENS.

 

&&

 

.LONG TERM /SUNDAY THROUGH FRIDAY/...

SNOW XPCD TO TAPER OFF SUN AS LOPRES MOVES QUICKLY AWAY FROM RGN.

WNWLY LOW-LVL FLOW AND APRCH OF A LOW-AMPLITUDE SHRTWV TROF WILL

PROMOTE UPSLP SNOW SHOWERS ALONG WRN SLOPES OF ALLEGHENY FRONT

THRU MON NGT.

 

COLD AIR RMNS PRESENT THRU MUCH OF NEXT WEEK OWING TO PERSISTENT

SNOW PACK. A STRONG CLOSED UPR LOW XPCD TO FORM OVER SRN PLNS MID

WEEK AND COULD RESULT IN PCPN THU-FRI. ATTM...MODELS SUGGEST A

TRANSITION FROM SNOW INITIALLY TO RAIN AS WARM AIR IS DRAWN INTO

THE SYSTEM.

 

&&

 

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...

-- Changed Discussion --

TAFS CONTINUE TO BE BURIED IN VLIFR CIGS/VSBYS THRUT THE DAYLGT

HRS. SNOW THROUGH THE AFTERNOON PERIODS OF HEAVY SNOW WITH BANDED

PRECIPITATION. ALTHO THERE MAY BE SOME MINOR IMRVMNTS GETTING

IN/OUT OF THE THREE MAJOR AIRPORTS WL BE XTRMLY DIFFICULT THIS

EVENG.

 

MAIN PSBLTY FOR TERMINAL IMPACTS IN EXTENDED PDS IS THU-FRI NEXT

WEEK...WHEN A DEEP CLOSED UPR LOW WILL APRCH APLCNS AND COULD

GENERATE RAIN/SNOW OVER MUCH OF MID-ATLC RGN.

-- End Changed Discussion --

 

 

&&

 

.MARINE...

-- Changed Discussion --

LOW PRESSURE NEAR HATTERAS MOVING NE. GRADIENT HAS

INCREASED...GALES FOR THE WATERS THROUGH TONIGHT. ANY MIXED PRECIP

OVER THE WATER TO CHANGE OVER TO ALL SNOW THIS AFTERNOON. SMALL

CRAFT ADVISORY WILL BE WARRANTED FOR THE WATERS SUNDAY THROUGH

SUNDAY NIGHT. STRONGER NW WINDS CONTINUE THROUGH MONDAY/MONDAY NIGHT AS

HIGH PRESSURE BUILDS ACROSS THE WATERS.

-- End Changed Discussion --

 

 

 

 

&&

 

.TIDES/COASTAL FLOODING...

-- Changed Discussion --

PROLONGED NORTHEASTERLY FLOW HAS BUILT POSITIVE ANOMALIES INTO THE

BAY. ATTM TIDAL LVLS ARE APPROACHING TWO FEET ABOVE PREDICTED FOR

LOWER TIDAL POTOMAC AND LOWER PORTIONS OF THE MD CHES BAY. A

COASTAL FLOOD ADVISORY WILL GO UP FOR CALVERT..ST

MARYS...CHARLES...KING GEORGE COUNTIES SOON. POSITIVE TIDAL

DEPARTURES OF UP TO ONE FOOT ABOVE NORMAL ARE POSSIBLE REST OF THE

WATERS TODAY.

-- End Changed Discussion --

 

 

&&

 

.CLIMATE...

-- Changed Discussion --

MID ATLC LOOKS ON ITS WAY TO RECORD DEC SNOWFALL - TWO DAY DEC RECORDS

FOR MAJOR AIRPORTS:

 

DCA 12.0" 1932

BWI 14.1" 1960

IAD 12.1" 1969

-- End Changed Discussion --

 

 

 

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

-- Changed Discussion --

DC...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR DCZ001.

BLIZZARD WARNING UNTIL 6 PM EST THIS EVENING FOR DCZ001.

MD...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR MDZ006-007-009>011-013-014-016>018.

BLIZZARD WARNING UNTIL 6 PM EST THIS EVENING FOR MDZ006-007-

009>011-013-014-016>018.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR MDZ003>005-501-

502.

VA...WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM EST SUNDAY

FOR VAZ052>057.

BLIZZARD WARNING UNTIL 6 PM EST THIS EVENING FOR VAZ052>057.

WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR VAZ021-025>031-

036>042-050-051.

WV...WINTER STORM WARNING UNTIL 6 AM EST SUNDAY FOR WVZ050>055-

501>504.

MARINE...GALE WARNING UNTIL 6 AM EST SUNDAY FOR ANZ530>543.

-- End Changed Discussion --

 

 

&&

 

$$

UPDATE...BAJ

PREVIOUS DISCUSSION...ABW/BPP/JRK

 

 

 

 

 

 

 

 

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000

FXUS61 KLWX 210840

AFDLWX

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

340 AM EST MON DEC 21 2009

 

.SYNOPSIS...

-- Changed Discussion --

HIGH PRESSURE WILL BUILD ACROSS THE AREA THROUGH WEDNESDAY. LOW

PRESSURE OVER THE LOWER MISSISSIPPI VALLEY WILL MOVE NORTH TOWARDS

THE GREAT LAKES ON THURSDAY. A SECONDARY LOW PRESSURE SYSTEM WILL

DEVELOP OVER THE SOUTHEAST U.S. EARLY CHRISTMAS DAY...BEFORE

MOVING NORTH OF THE REGION ON SATURDAY. THIS SYSTEM WILL BRING A

WINTRY MIX OF PRECIPITATION TO THE REGION ON CHRISTMAS EVE...THEN

LIKELY CHANGE TO ALL RAIN ON CHRISTMAS DAY. HIGH PRESSURE WILL

RETURN NEXT WEEKEND.

-- End Changed Discussion --

 

 

&&

 

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --

MOST TEMPERATURES HAVE DROPPED INTO THE 20S EARLY THIS MORNING

ACROSS THE CWA...WITH A FEW LOCATIONS WHERE THE WIND HAS GONE

LIGHT/CALM REPORTING TEENS AT 07Z. NO MATTER HOW ONE SLICES

IT...TEMPERATURES WERE SUB-FREEZING AND THIS WILL ALLOW ANY SNOW

MELT/SLUSH TO RE-FREEZE AND RESULT IN DANGEROUS ICY CONDITIONS THIS

MORNING. SPS AND HWO ADDRESS THE HAZARD.

 

NEARLY ZONAL /WEST/NORTHWEST/ FLOW ALOFT WILL CONTINUE TODAY. THIS

WILL LEAD TO LOTS OF CLOUDS AND SOME SNOW SHOWERS ACROSS FAVORED

WESTERN FACING SLOPES OF THE HIGHLANDS TODAY. AM FORECASTING AROUND

AN INCH OF SNOW ACCUMULATION. WOULDNT BE SHOCKED FOR A TWO INCH

TOTAL TO BE REPORTED BUT HAVE KEPT AMOUNTS BELOW WINTER WEATHER

ADVISORY CRITERIA. UPSLOPE AMOUNTS WILL BE PALTRY ADDITIONS TO

EXISTING SNOW PACK FROM SATURDAYS SNOW STORM.

 

MAY HAVE CLOUDS AND EVEN SOME FLURRIES PENETRATE EAST OF THE FAVORED

UPSLOPE AREAS INTO WESTERN MARYLAND/EASTERN WEST

VIRGINIA TODAY...ESPECIALLY IN LIGHT OF A WEAK WAVE PROPAGATING IN

ZONAL FLOW. HOWEVER...NO ACCUMULATION IS EXPECTED. CLOUDS AND SOME

SUNSHINE IS EXPECTED EAST OF THE BLUE RIDGE.

 

PREFER THE LOWER SET OF MOS GIVEN SNOW PACK AND SOME CLOUD COVER

TODAY.

-- End Changed Discussion --

 

 

&&

 

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...

-- Changed Discussion --

UPPER FLOW REMAINS NEARLY CONSTANT TONIGHT...AS WEAK HIGH PRESSURE

AT THE SURFACE STARTS TO BUILD ACROSS THE AREA. SNOW SHOWERS WILL

BEGIN TO WANE OVER FAVORED UPSLOPE LOCATIONS. GRADIENT WILL ALSO BE

WEAKER SO WINDS WILL BE LIGHTER AND THIS WILL PAVE THE WAY FOR A

DECENT RADIATION COOLING NIGHT. IN ADDITION...GIVEN THE SNOW PACK

AND ITS ENHANCING EFFECT AT RADIATING LONGWAVE RADIATION...HAVE

UNDERCUT MOS BY A FEW DEGREES. WATCH FOR RE-FREEZING OF SLUSH

AGAIN.

-- End Changed Discussion --

 

 

&&

 

.LONG TERM /TUESDAY THROUGH SUNDAY/...

-- Changed Discussion --

HIPRES RIDGING SWD FROM ONTARIO WILL CONTINUE TO PROVIDE COOL AND

QUIET CONDITIONS FOR THE AREA TUE-WED. LEANED TOWARDS COOLER SIDE OF

GUIDANCE WITH SNOWPACK IN PLACE...WITH DAILY HIGHS IN THE 30S/LOWS

IN THE TEENS TO L20S. PROGRESSIVE FLOW PATTERN MIDWEEK WITH UPPER

LOW E OF NEWFOUNDLAND SLOWLY EXITING AND C CONUS RIDGE BUILDING

TOWARDS THE ERN SEABOARD.

 

LOPRES OVR THE PAC NW IS EXPECTED TO DIVE SWD TOWARDS THE ROCKIES

AND SRN PLAINS BY WED. MODEL GUIDANCE GENERALLY IN AGREEMENT OF THIS

SYSTEM PHASING WITH UPSTREAM ENERGY...WHICH WOULD LIFT CYCLONE NWD

TOWARDS THE MIDWEST AND WELL W OF THE REGION LATE THIS WEEK. 00Z GFS

STILL INDICATES SECONDARY CYCLOGENESIS ALONG THE SE COAST. HIPRES

RIDGING FROM SRN CANADA WOULD CREATE A CAD SETUP AS MOISTURE STREAMS

NWD AHEAD OF THE LOW...WITH THE POTENTIAL FOR WINTRY PRECIP

/PRIMARILY FREEZING RAIN/ AT THE ONSET THU NGT AND FRI MRNG. WITH

THE EXPECTED TRACK OF THE MAIN LOW...PRECIP SHOULD TRANSITION TO

RAIN AS WARM AIR EVENTUALLY INTRUDES THE AREA. STILL TOO FAR OUT TO

PINPOINT QPF AMOUNTS BUT WITH 1-2 INCHES LIQUID EQUIV OF SNOWPACK ON

GROUND AND FROZEN SOIL...WOULD HAVE TO MONITOR ANY FLOODING

POTENTIAL.

 

COLDER TEMPS EXPECTED FOR THE WEEKEND IN WAKE OF FROPA ON SAT.

-- End Changed Discussion --

 

 

&&

 

.AVIATION /08Z MONDAY THROUGH FRIDAY/...

-- Changed Discussion --

WEST/NORTHWEST WIND AT 8-12 KNOTS IS EXPECTED TO PERSIST INTO THE

EVENING HOURS...BEFORE LESSENING TO 4-8 KNOTS OVERNIGHT. EXPECT

SCT-BKN VFR STRATOCU BY AFTERNOON...DISSIPATING AFTER SUNSET.

 

VFR CONDITIONS AND LGT NWLY WINDS THRU THU. A STORM SYSTEM WILL

APPROACH LATE THIS WEEK. WITH A SHALLOW LAYER OF COLD AIR IN

PLACE...WINTRY PRECIP...SPECIFICALLY FZRA...IS POSSIBLE AT THE ONSET

THU NGT AND ERY FRI BEFORE CHANGING TO ALL RA FRI.

-- End Changed Discussion --

 

 

&&

 

.MARINE...

-- Changed Discussion --

WEST/NORTHWEST FLOW EXPECTED TO REACH SCA GUST CRITERIA ACROSS THE

LOWER TIDAL POTOMAC RIVER/CHESAPEAKE BAY TODAY...THEN LIKELY

PERSISTING ACROSS THE MID CHESAPEAKE BAY INTO EARLY TONIGHT.

 

WINDS SHOULD STAY JUST BELOW SCA LVLS FOR MIDWEEK. HOWEVER GUSTS TO

15 KT POSSIBLE DURING THE DAY TUE AND WED. A STORM SYSTEM APPROACHES

LATE IN THE WEEK WITH SCA CONDITIONS POSSIBLE BEGINNING THU NGT.

-- End Changed Discussion --

 

 

&&

 

.CLIMATE...

MULTIPLE SNOWFALL RECORDS WERE BROKEN FROM THIS SNOWSTORM AT

DCA...BWI...IAD. DAILY SNOWFALL RECORDS FOR DEC 19 WERE SMASHED AT

ALL THREE AIRPORTS. THESE DAILY SNOWFALL REPORTS ON DEC 19 ALSO

BROKE RECORDS FOR THE MOST SNOWFALL FOR ANY CALENDAR DAY DURING

THE MONTH OF DEC.

 

DAILY DECEMBER SNOWFALL (IN INCHES)

NEW RECORD OLD RECORD

DCA 15.0 11.5 (1932)

BWI 20.5 11.5 (1932)

IAD 16.0 10.6 (1982)

 

ADDITIONAL CLIMATE TIDBITS FROM THE PAST STORM...

 

DCA...

THE 15.0 INCHES OF SNOW MEASURED YESTERDAY WAS THE THIRD

HIGHEST DAILY SNOWFALL ON ANY CALENDAR DAY AT WASHINGTON DC SINCE

SNOWFALL RECORDS BEGAN IN 1884.

 

THE STORM TOTAL SNOWFALL OF 16.4 INCHES OF SNOWFALL ON DEC 18-19

2009 MARKS THE 6TH HIGHEST TWO-DAY SNOWFALL RECORD FOR WASHINGTON

DC...PUTTING IT JUST BELOW THE PRESIDENT/S DAY STORM IN 2003 AND

AHEAD OF THE JAN 1996 STORM.

 

FOR THE MONTH SO FAR...A TOTAL OF 16.6 INCHES OF SNOW HAS BEEN

RECORDED AT DCA. THIS MAKES IT THE SNOWIEST DECEMBER ON RECORD FOR

WASHINGTON DC (PREVIOUS RECORD WAS 16.2 IN 1962).

 

BWI...

THE 20.5 INCHES OF SNOW MEASURED YESTERDAY WILL GO DOWN AS THE FIFTH

HIGHEST DAILY SNOWFALL ON ANY CALENDAR DAY AT BALTIMORE SINCE

SNOWFALL RECORDS BEGAN IN 1893.

 

THE STORM TOTAL SNOWFALL OF 21.0 INCHES OF SNOWFALL ON DEC 18-19

2009 MARKS THE 6TH HIGHEST TWO-DAY SNOWFALL RECORD FOR BALTIMORE.

 

FOR THE MONTH SO FAR...A TOTAL OF 22.2 INCHES OF SNOW HAS BEEN

RECORDED AT BWI. THIS MAKES IT THE SNOWIEST DECEMBER ON RECORD FOR

BALTIMORE (PREVIOUS RECORD WAS 20.4 INCHES IN 1966).

 

&&

 

.LWX WATCHES/WARNINGS/ADVISORIES...

-- Changed Discussion --

DC...NONE.

MD...NONE.

VA...NONE.

WV...NONE.

MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST TUESDAY FOR ANZ531>534-

538>543.

SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ530-

537.

-- End Changed Discussion --

 

 

&&

 

$$

SYNOPSIS...PELOQUIN/KLEIN

NEAR TERM...PELOQUIN

SHORT TERM...PELOQUIN

LONG TERM...KLEIN

AVIATION...PELOQUIN/KLEIN

MARINE...PELOQUIN/KLEIN

CLIMATE...KLEIN

 

 

 

 

 

 

 

 

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