Tropical Storm GIL

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TROPICAL STORM GIL DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP102007
800 AM PDT FRI AUG 31 2007
 
ANIMATED INFRARED IMAGERY INDICATES THAT GIL IS EXHIBITING A STRONG
DIURNAL CYCLE IN CONVECTIVE ACTIVITY. AFTER DEEP CONVECTION NEARLY
DISAPPEARED BETWEEN 0600 AND 1200 UTC...MOST RECENT IMAGERY SHOWS
ANOTHER BURST OF THUNDERSTORMS DEVELOPING NEAR THE CENTER. A TRMM
MICROWAVE PASS AT 1117Z INDICATES THE LOW LEVEL CENTER OF GIL
STILL REMAINS DISPLACED EAST OF THE CONVECTION...A RESULT OF
PERSISTENT UPPER LEVEL EASTERLY SHEAR. SATELLITE INTENSITY
ESTIMATES AT 12Z REMAIN AT 35 KT...SO THERE IS NO CHANGE TO THE
INITIAL INTENSITY. A QUIKSCAT PASS AT 31/0154Z SHOWED A SMALL AREA
OF TROPICAL STORM FORCE WINDS AROUND THE CENTER...AND WAS USED TO
FORMULATE THE WIND RADII ESTIMATES.
 
THE ENVIRONMENTAL FACTORS AFFECTING THE INTENSITY OF GIL ARE NOT
EXPECTED TO CHANGE MUCH OVER THE NEXT 24 TO 48 HOURS.  VERTICAL WIND
SHEAR IS FORECAST TO RELAX A BIT...BUT SHOULD STILL PREVENT
PERSISTENT DEEP CONVECTION TO REMAIN OVER THE CENTER FOR ANY
SIGNIFICANT LENGTH OF TIME. THE FORECAST TRACK NEARLY PARALLELS THE
27C SST ISOTHERM...SO OCEAN TEMPERATURES WILL REMAIN A NEUTRAL
INFLUENCE FOR SEVERAL DAYS. GIL IS ENTRAINING STABLE STRATOCUMULUS
AIR FROM ITS NORTHWEST SEMICIRCLE INTO ITS CORE...WHICH IN TURN
WILL PROBABLY KEEP A LID ON ANY FUTURE DEVELOPMENT. ALL INDICATIONS
ARE THAT GIL WILL MAINTAIN ITS CURRENT INTENSITY OR WEAKEN SLIGHTLY
OVER THE NEXT 3 DAYS. THE OFFICIAL INTENSITY FORECAST IS SLIGHTLY
LOWER THAN SHIPS AND IS CONSISTENT WITH THE PREVIOUS ADVISORY.
 
THE INITIAL MOTION OF 270/9 IS VIRTUALLY UNCHANGED FROM THE PREVIOUS
ADVISORY...AS IS THE TRACK FORECAST PHILOSOPHY. TRACK GUIDANCE IS IN
VERY GOOD AGREEMENT...AND CONFIDENCE IN THE FORECAST POSITIONS IS
FAIRLY HIGH. GIL WILL CONTINUE ALONG A WESTWARD TRACK FOR THE NEXT
24 HOURS FOLLOWED BY A SLIGHT TURN TO THE WEST-NORTHWEST AS IT
NEARS THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE TO ITS
NORTHEAST. THE GFS MODEL IS SHOWING A WEAKNESS IN THE SUBTROPICAL
RIDGE BETWEEN 130W AND 140W IN THE 72-96 HOUR TIME FRAME...BUT NONE
OF THE FORECAST AIDS ARE HINTING AT A RECURVATURE TRACK. ONCE GIL
WEAKENS TO A REMNANT LOW OVER COOLER WATERS...IT WILL BE STEERED
BACK TOWARD THE WEST IN RESPONSE TO THE LOW-LEVEL EASTERLY FLOW AND
PROBABLY NOT FEEL THE WEAKNESS IN THE RIDGE AT LONG-RANGE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/1500Z 19.1N 117.4W    35 KT
 12HR VT     01/0000Z 19.2N 119.1W    35 KT
 24HR VT     01/1200Z 19.4N 121.3W    35 KT
 36HR VT     02/0000Z 19.9N 123.6W    35 KT
 48HR VT     02/1200Z 20.4N 125.8W    35 KT
 72HR VT     03/1200Z 20.7N 130.3W    30 KT
 96HR VT     04/1200Z 21.0N 134.5W    25 KT...REMNANT LOW
120HR VT     05/1200Z 21.0N 138.5W    25 KT...REMNANT LOW
 
$$
FORECASTER MUNDELL/BLAKE
 
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