Tropical Storm LISA Discussion 31 11PM EDT

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Tropical Storm LISA

 

 

000

WTNT43 KNHC 270259

TCDAT3

TROPICAL STORM LISA DISCUSSION NUMBER 31

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

11 PM EDT SUN SEP 26 2004

 

LISA CONTINUES TO PRODUCE SPORADIC BURSTS OF DEEP CONVECTION ON THE

NORTHEAST SIDE OF AN OCCASIONALLY-EXPOSED LOW-LEVEL CENTER. A 2337

UTC SSMI MICROWAVE PASS SHOWED THAT THE CYCLONE IS A LITTLE FARTHER

SOUTH THAN THOUGHT AND HAS BEEN MOVING RATHER SLOWLY. DVORAK

INTENSITY ESTIMATES HAVE NOT CHANGED WITH A SHEARED TROPICAL

CYCLONE PATTERN PRESENT SO THE INITIAL INTENSITY REMAINS 45 KT.

 

MICROWAVE FIXES INDICATE THE STORM HAS BEEN MOVING GENERALLY TO THE

NORTH AROUND 5 KT FOR THE PAST 6-12 HOURS. THE OFFICIAL FORECAST IS

SHIFTED A LITTLE TO THE RIGHT IN THE NEAR-TERM TO ACCOUNT FOR THE

SLOWER AND MORE NORTHERLY MOTION.A MORE NORTHWESTERLY OR

NORTH-NORTHWESTERLY MOTION SHOULD COMMENCE SOON DUE TO A MIDDLE-

LEVEL RIDGE BUILDING TO THE NORTH AND NORTHEAST OF LISA. THE

FORECAST BEYOND 2 DAYS IS RATHER UNCERTAIN WITH CONSIDERABLE SPREAD

IN MODEL GUIDANCE. THERE SEEMS TO BE TWO CLUSTERS OF SOLUTIONS

EMERGING. THE UKMET/GFS MODELS WANT TO RECURVE LISA THRU A BREAK IN

THE SUBTROPICAL RIDGE ALONG 50W. THE OTHER CLUSTER COMPOSED OF THE

NOGAPS/GFDN/GFDL SUGGESTS THAT THE STORM WILL NOT RECURVE AND WILL

INSTEAD TAKE A WESTERLY TURN UNDER A BUILDING RIDGE OVER THE

WEST-CENTRAL ATLANTIC. IF THE CURRENT SLOW MOTION CONTINUES THE

MORE WESTERLY MOTION COULD BE CORRECT AS THE RIDGE WOULD HAVE MORE

TIME TO BUILD TO THE NORTH OF LISA. WITH SO MUCH UNCERTAINTY...THE

OFFICIAL FORECAST WILL SLOW THE MOTION CONSIDERABLY IN THE MEDIUM-

RANGE BETWEEN THE TWO CLUSTERS.

 

IN ADDITION TO ABOUT 15-20 KT OF SOUTHWESTERLY SHEAR...LISA HAS BEEN

MOVING OVER THE COOL WAKE OF KARL...FURTHER HINDERING ITS

DEVELOPMENT. LITTLE CHANGE IN STRENGTH IS LIKELY UNTIL AFTER 24

HOURS WHEN THE STORM MOVES OVER WARMER WATER WITH ABOUT THE SAME

AMOUNT OF SHEAR. GLOBAL MODEL GUIDANCE SUGGESTS THAT THE SHEAR WILL

DECREASE IN TWO OR THREE DAYS AS AN UPPER TROUGH CUTS OFF FROM THE

MID-LATITUDES WEST OF LISA. THIS PATTERN WOULD BE SLIGHTLY MORE

FAVORABLE FOR INTENSIFICATION OVER WARM WATER NEAR 28C BUT THERE IS

CONSIDERABLY UNCERTAINTY ON WHERE THE STORM WILL BE AT THAT POINT.

WITH SO MUCH AMBUIGUITY PRESENT THERE IS NO CHANGE TO THE PREVIOUS

INTENSITY FORECAST.

 

FORECASTER BLAKE/STEWART

 

FORECAST POSITIONS AND MAX WINDS

 

INITIAL 27/0300Z 19.7N 46.1W 45 KT

12HR VT 27/1200Z 20.8N 46.4W 45 KT

24HR VT 28/0000Z 22.4N 47.4W 45 KT

36HR VT 28/1200Z 24.0N 48.4W 50 KT

48HR VT 29/0000Z 25.4N 49.1W 55 KT

72HR VT 30/0000Z 27.5N 50.0W 65 KT

96HR VT 01/0000Z 29.0N 50.5W 65 KT

120HR VT 02/0000Z 31.0N 51.0W 65 KT

 

 

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