Jeb Posted December 29, 2004 Report Share Posted December 29, 2004 http://www.wrh.noaa.gov/total_forecast/get...sid=rev&pil=afd AREA FORECAST DISCUSSION FXUS65 KREV 281203 AFDREV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RENO NV 400 AM PST TUE DEC 28 2004 .SHORT TERM... LITTLE CHANGE IN PREVIOUS FORECAST. STILL LOOKS LIKE A SIGNIFICANT WINTER STORM WILL AFFECT THE SIERRA FROM MID TO LATE WEEK. SATELLITE IMAGERY DEPICTS BROAD CLOSED LOW CIRCULATION OFF THE WEST COAST. MODELS CONTINUE TO BE CONSISTENT WITH SYSTEM MOVING INLAND TUESDAY NIGHT AND WEDNESDAY. IN THE MEANTIME...MOIST AND DEEP SOUTHERLY FLOW AND DYNAMICS ASSOCIATED WITH THIS LOW WILL CONTINUE TO PRODUCE SNOW IN THE SIERRA. DIFFLUENCE IN NORTHEAST QUAD OF LOW WILL PRODUCE AT LEAST ADVISORY SNOWS IN THE SIERRA DOWN SOUTH IN MONO COUNTY. SNOW WILL ALSO BE EXPECTED FURTHER NORTH IN THE TAHOE AREA AND HIGHER ELEVATIONS IN LASSEN COUNTY. SNOW WILL MAINLY BE SHOWERY DUE TO CONVECTIVE NATURE. SNOW LEVELS AROUND 5500 FEET EARLY THIS MORNING WILL DROP TO BETWEEN 5000 FEET LATER TODAY. A TOTAL OF 6 TO 12 INCHES OF SNOW IS POSSIBLE AT ELEVATIONS ABOVE 7000 FEET IN MONO COUNTY WHICH IS HANDLED WELL BY SNOW ADVISORY. ALSO ADDED A LOWER END SNOW ADVISORY TO THE TAHOE AREA AS LIGHT SNOW SHOWERS WILL CONTINUE TO FALL THROUGH THE DAY. ONCE THIS SYSTEM MOVES EAST THERE WILL BE A BRIEF BREAK IN THE WEATHER BEFORE A STRONG STORM MOVES IN. A LOW IN THE GULF OF ALASKA WILL MOVE SOUTH TO OFF THE PAC NW COAST BY THURSDAY. 120+ KT JET CARVING OUT THE BASE OF THE TROUGH WILL MOVE ACROSS THE TAHOE AREA WEDNESDAY NIGHT THROUGH FRIDAY MORNING. WEST-SOUTHWEST FLOW AROUND 60 KTS WILL CONTINUE TO BRING PACIFIC MOISTURE INTO REGION. GOOD UPSLOPE TRAJECTORY WILL HELP TO FOCUS SNOWFALL ALONG WEST SLOPES OF THE SIERRA. HOWEVER...INSTABILITY IS EXPECTED TO OVERCOME DOWNSLOPE FLOW WITH SPILLOVER INTO WRN NV VALLEYS LIKELY BY THURSDAY. PRECIP WILL LIKELY BE ALL SNOW DOWN TO VALLEY FLOORS IN THE RENO AREA ON THURSDAY. GUSTY WINDS ARE ALSO EXPECTED OVER WRN NV ON THURSDAY...WITH RIDGE WINDS UP TO 100 MPH IN THE SIERRA. OVER 2 FEET OF SNOW IS POSSIBLE IN THE HIGHER ELEVATIONS OF THE SIERRA LATE WEDNESDAY THROUGH FRIDAY. WINTER STORM WATCH WILL BE CONTINUED FOR WEDNESDAY NIGHT THROUGH FRIDAY IN THE SIERRA...A WINTER STORM WATCH OR SNOW ADVISORY MAY ALSO BE NEEDED IN PORTIONS OF WRN NV BY LATER SHIFTS. BENINATO .LONG TERM...FRIDAY THROUGH MONDAY... LONG WAVE TROUGH OVER THE WESTERN U.S. WILL KEEP A COLD AND UNSETTLED AIRMASS OVER THE CWA. A COUPLE SHORT WAVES WILL MOVE THROUGH THE TROUGH DURING THE PERIOD. THE FIRST ONE MOVES THROUGH NORTHERN CA AND NORTHERN NV FRIDAY ADDING TO THE SNOWFALL EXPECTED ON THURSDAY. WINTER STORM WATCHES HAVE BEEN ISSUED FOR THIS TIME PERIOD. THERE WILL BE A RELATIVE BREAK IN THE WEATHER SATURDAY AS FRIDAYS SHORTWAVE MOVES ACROSS THE ROCKIES AND A STRONG CLOSED LOW MOVES TO THE PAC NW COAST. THE GFS...CANADIAN AND ECMWF MODELS TAKE THIS LOW TO THE CENTRAL OREGON COAST BY SUNDAY AFTERNOON WHILE THE UKMET AND NOGAPS ARE MUCH WEAKER AND FARTHER NORTH AND EAST WITH THE LOW. WILL USE THE GFS/ECMWF SOLUTION AS THEY HAVE SHOWN GOOD CONSISTENCY FROM RUN TO RUN AND THIS IS NOT A PROGRESSIVE PATTERN WITH A HIGH AMPLITUDE RIDGE OVER THE GULF OF ALASKA AROUND 145 WEST. THIS SOLUTION WOULD BRING ANOTHER DECENT SHOT OF PRECIP TO THE SIERRA AND WESTERN NV SUNDAY AND SUNDAY NIGHT...WITH A COLDER AND UNSTABLE AIRMASS IN PLACE MONDAY AS THE LOW DROPS INTO SOUTHERN OREGON OR NORTHERN CA. TEMPERATURES NEAR NORMAL FRIDAY BUT COLDER SUNDAY AND MONDAY WITH HIGHS IN THE 30S IN WESTERN NV VALLEYS AND 20S IN THE MOUNTAINS. RC && .REV WATCHES/WARNINGS/ADVISORIES... .NV...SNOW ADVISORY UNTIL 5 AM WEDNESDAY NVZ002. .NV...WINTER STORM WATCH WED NIGHT THRU FRIDAY NVZ002. .CA...SNOW ADVISORY UNTIL 5 AM WEDNESDAY CAZ073. WINTER STORM WATCH WED NIGHT THRU FRIDAY CAZ071<073. && Quote Link to comment Share on other sites More sharing options...
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