[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 290229
TCDAT3
TROPICAL STORM LISA DISCUSSION NUMBER  39
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT TUE SEP 28 2004

VARIOUS SATELLITE SOURCES INDICATE LISA HAS BECOME A LITTLE BETTER
ORGANIZED AND HAS STRENGTHENED. A 28/1936Z TRMM OVERPASS INDCIATED
A NICE MID-LEVEL EYE FEATURE THAT WAS STILL SHEARED ABOUT 30 NMI TO
THE NORTHEAST OF THE LOW-LEVEL CENTER. A 28/2115Z HI-RES QUIKSCAT
OVERPASS REVEALED A SEVERAL RAINFLAGGED WINDS OF 60-70 KT AND A
28/1708Z CIRA/AMSU OVERPASS PROVIDED A PRESSURE OF 991 MB AND
SURFACE WIND ESTIMATE OF 59 KT. THE INITIAL INTENSITY OF 55 KT IS
BASED ON A COMBINATION OF THE MICROWAVE DATA AND A DVORAK SATELLITE
ESTIMATE OF T3.5...OR 55 KT FROM TAFB.

THE INITIAL MOTION ESTIMATE IS 360/11. LISA IS EXPECTED TO MOVE
NORTH TO NORTHWESTWARD FOR THE NEXT 36 HOURS OR SO AROUND THE
WESTERN PERIPHERY OF A SUBTROPICAL RIDGE LOCATED ALONG 30-32N
LATITUDE. BY 48-72 HOURS...AN APPROACHING MID-LEVEL SHORTWAVE
TROUGH IS EXPECTED TO TURN LISA MORE NORTHEASTWARD AND BRING ABOUT
RECURVATURE AROUND THE NORTH SIDE OF THE RIDGE. IN 96-120 HOURS...
LISA IS EXPECTED TO BE CAPTURED BY THE SHORTWAVE TROUGH AND BECOME
EXTRATROPICAL...OR EVEN MERGE WITH ANOTHER EXTRATROPICAL LOW. THE
NHC MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS EVOLVING SCENARIO.

LISA REMAINS A RATHER TENACIOUS TROPICAL CYCLONE BY DEVELOPING A
NICE MID-LEVEL EYE FEATURE DESPITE RATHER STRONG VERTICAL SHEAR.
THE VERTICAL SHEAR ACROSS LISA HAS BEEN SLOWLY DECREASING AND THE
SHIPS MODEL IS FORECASTING THE SHEAR TO DECREASE TO LESS THAN 5 KT
IN THE 24-72 HOUR PERIOD. LISA IS EXPECTED TO REMAIN OVER 26C OR
HIGHER SSTS THROUGH 36 HOURS...SO SOME SLOW STRENGTHENING IS
FORECAST. AFTER 36 HOURS...LISA IS EXPECTED TO MOVE OVER SUB-25C
SSTS AND SLOW WEAKENING IS FORECAST TO OCCUR. THE OFFICIAL
INTENSITY FORECAST IS SLIGHTLY LOWER THAN THE SHIPS MODEL FORECAST.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      29/0300Z 27.0N  46.5W    55 KT
 12HR VT     29/1200Z 28.7N  46.7W    55 KT
 24HR VT     30/0000Z 30.5N  47.3W    60 KT
 36HR VT     30/1200Z 32.3N  48.2W    65 KT
 48HR VT     01/0000Z 34.0N  48.7W    60 KT
 72HR VT     02/0000Z 38.0N  47.0W    60 KT
 96HR VT     03/0000Z 41.0N  42.0W    55 KT...BECOMING EXTRATROPICAL
120HR VT     04/0000Z 43.5N  32.0W    50 KT...EXTRATROPICAL


$$This weather bulletin was brought to you by:
www.nashvilleweather.net