Tropical Storm ERIKA

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TROPICAL STORM ERIKA DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT THU AUG 14 2003
 
A RECONNAISSANCE PLANE THIS EVENING FOUND A MUCH BETTER DEFINED
LOW-LEVEL CIRCULATION. MAXIMUM FLIGHT-LEVEL WINDS WERE 47 KT IN THE
NORTHEAST AND NORTHWEST QUADRANTS AT 1500 FT...WHICH EQUATES TO
ABUT 38 KT AT THE SURFACE. HOWEVER...THE CENTRAL CONVECTION HAS
INCREASED MARKEDLY SINCE THE LAST RECON WIND REPORTS...SO THE
INITIAL INTENSITY IS BUMPED UP TO 40 KT FOR THIS ADVISORY.

THE INITIAL MOTION ESTIMATE IS 270/20. THE LOW-LEVEL CENTER HAS
ACTUALLY BEEN PROPAGATING WEST-NORTHWESTWARD DURING THE PAST 6
HOURS...BUT THAT MOTION IS BELIEVED TO BE DUE TO RE-ORGANIZATION OF
THE LOW-LEVEL CENTER WITHIN THE DEVELOPING CENTRAL DENSE OVERCAST
REGION. THERE MAY EVEN BE A SLIGHT SOUTHWARD JOG DURING THE NIGHT
AS THE CONVECTION WRAPS AROUND THE SOUTH SIDE OF THE CENTER...BUT
THE GENERAL MOTION SHOULD BE WESTWARD. AT 500 MB...ALL OF THE
GLOBALS MODELS MAINTAIN THE SAME DISTANCE BETWEEN ERIKA AND A
STRONG HIGH PRESSURE CENTER CURRENTLY OVER NORTHERN MISSISSIPPI AS
BOTH SYSTEMS MOVE WESTWARD IN TANDEM. THE FORECAST TRACK BECOMES A
LITTLE MURKY AFTER 24 HOURS AS ALL THE GLOBAL MODELS AND THE GFDL
WEAKEN ERIKA SIGNIFICANTLY...AND TAKE THE CYCLONE SLOWLY SOUTHWARD
JUST BEFORE IT REACHES THE WESTERN GULF COAST SATURDAY MORNING.
SINCE THE OFFICIAL FORECAST CALLS FOR STRENGTHENING INSTEAD OF
WEAKENING TO OCCUR...ERIKA IS EXPECTED TO REMAIN A VERTICALLY DEEP
SYSTEM AND BE STEERED WESTWARD BY THE DEEP-LAYERED EASTERLY FLOW
ACROSS THE NORTHERN GULF THAT ALL OF THE MODELS ARE MAINTAINING
THROUGHOUT THE PERIOD. THE OFFICIAL FORECAST TRACK IS A LITTLE
FASTER AND SLIGHTLY NORTH OF THE PREVIOUS TRACK DUE TO THE FARTHER
NORTH INITIAL POSITION AND FASTER MOTION. A GRADUAL DECREASE IN
FORWARD SPEED IS EXPECTED AFTER 24 HOURS AS THE LOW-LEVEL STEERING
FLOW WEAKENS ACROSS TEXAS AND LOUISIANA.  THIS TRACK SCENARIO IS
CONSISTENT WITH THE MEDIUM AND DEEP BAM MODELS...AND THE GLOBAL
MODEL'S MID-LEVEL CENTER TRACK POSITIONS. SINCE THE 36 HOUR
FORECAST POSITION IS NEAR BROWNSVILLE TEXAS...A HURRICANE WATCH HAS
BEEN ISSUED FROM PORT O'CONNOR TEXAS SOUTHWARD TO BOCA SANTA MARIA
MEXICO.

ERIKA CONTINUES TO GET BETTER ORGANIZED BASED ON SATELLITE IMAGERY
AND THE LAST RECON REPORTS. HOWEVER...THE CYCLONE IS MOVING QUITE
FAST AND THAT WILL LIMIT THE TIME THAT ERIKA WILL HAVE TO
STRENGTHEN. THE OUTFLOW PATTERN IS VERY IMPRESSIVE FOR SUCH A FAST
MOVING TROPICAL STORM. HOWEVER... THE FAST MOTION IS KEEPING THE
CONVECTION FROM WRAPPING COMPLETELY AROUND THE CENTER FOR MORE THAN
JUST A COUPLE OF HOURS AT A TIME. THIS SHOULD LIMIT INTENSIFICATION
FOR THE NEXT 24 HOURS OR SO UNTIL THE CYCLONE BEGINS TO SLOW DOWN.
AFTER THAT TIME...SOME SIGNIFICANT STRENGTHENING COULD OCCUR RIGHT
UP UNTIL LANDFALL. THE OFFICIAL INTENSITY FORECAST IS LOWER THAN
THE SHIPS INTENSITY MODEL WHICH BRINGS THE CYCLONE UP TO NEAR 70-75
KT AT LANDFALL. THE GFDL MODEL WEAKENS ERIKA TO BELOW TROPICAL
DEPRESSION STRENGTH IN ABOUT 24 HOURS...WHICH SEEMS UNLIKELY AT
THIS TIME.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/0300Z 26.6N  86.5W    40 KT
 12HR VT     15/1200Z 26.5N  89.9W    45 KT
 24HR VT     16/0000Z 26.5N  93.7W    55 KT
 36HR VT     16/1200Z 26.4N  97.0W    65 KT
 48HR VT     17/0000Z 26.3N  99.9W    30 KT...DISSIPATING INLAND
 72HR VT     18/0000Z 26.5N 104.5W    20 KT...DISSIPATING INLAND
 96HR VT     19/0000Z...DISSIPATED INLAND
 
 
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