Tropical Storm ERNESTO

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TROPICAL STORM ERNESTO DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL052006
500 AM EDT SUN AUG 27 2006
 
BIG CHANGES IN BOTH THE INITIAL INTENSITY AND FORECAST TRACK WERE
REQUIRED...UNFORTUNATELY...FOR THIS ADVISORY. LATEST RECON DATA
INDICATE ERNESTO IS LIKELY UNDERGOING RAPID INTENSIFICATION. AN EYE
IS FORMING AND MAXIMUM 850 MB FLIGHT-LEVEL WINDS OF 78 KT WERE
RECENTLY OBSERVED IN THE NORTHEAST QUADRANT...WHICH EQUALS ABOUT 62
KT SURFACE WINDS...SO ERNESTO IS VERY NEAR HURRICANE STRENGTH. THE
EYE IS SO SMALL...HOWEVER...THAT THE FLIGHT CREW HAVE BEEN UNABLE
TO PROPERLY ASSESS THE MINIMUM SURFACE PRESSURE. THE SATELLITE
APPEARANCE HAS BECOME QUITE IMPRESSIVE WITH LITTLE OR NO VERTICAL
SHEAR NOTED ON THE SYSTEM NOW...AND CIRRUS OUTFLOW EXPANDING
OUTWARD IN ALL QUADRANTS.
 
THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 295/08...BASED ON A
12-HOUR AVERAGE MOTION. THE CENTER HAS BEEN REFORMING CLOSER TO THE
STRONG CONVECTIVE BURSTS WITH CLOUD TOPS AS COLD AS -85C. IT IS
POSSIBLE THAT ADDITIONAL REFORMATION OF THE LOW-LEVEL CENTER CLOSER
TO THE CENTER OF THE ROUND CONVECTIVE CLOUD MASS COULD BRING
ERNESTO OVER OR VERY CLOSE TO THE SOUTHWESTERN TIP OF HAITI LATER
TODAY. FOR THAT REASON...A HURRICANE WARNING HAS BEEN ISSUED FOR
SOUTHWESTERN HAITI. NOW FOR THE REST OF THE BAD NEWS...THE OFFICIAL
FORECAST TRACK HAS BEEN SHIFTED SIGNIFICANTLY TO THE RIGHT OR EAST
OF THE PREVIOUS TRACK...ESPECIALLY AT 96 AND 120 HOURS..AND NOW
TAKES ERNESTO ACROSS THE FLORIDA PENINSULA. THE CONSENSUS OF THE
AVAILABLE MODEL GUIDANCE NOW INDICATES THAT A STRONG SHORTWAVE
TROUGH CURRENTLY OVER THE CENTRAL AND SOUTHERN ROCKIES WILL DIG
EAST-SOUTHEASTWARD INTO THE WESTERN AND CENTRAL GULF OF MEXICO...
CAUSING THE SUBTROPICAL RIDGE SITUATED OVER FLORIDA AND THE
SOUTHEASTERN U.S. TO GRADUALLY ERODE EASTWARD. THE GFS AND NOGAPS
MODELS APPEAR TO BE ERODING THE RIDGE TO QUICKLY AND HAVE ERNESTO
OVER SOUTHEASTERN FLORIDA IN 84 HOURS. THE REST OF THE MODEL
GUIDANCE TAKES THE CYCLONE FARTHER WESTWARD OVER OR WEST OF THE
LOWER FLORIDA KEYS. HOWEVER...ALL OF THE GLOBAL AND REGIONAL MODELS
NOW AGREE ON RECURVATURE OVER THE EASTERN GULF OF MEXICO AROUND 96
HOURS...AND TAKE ERNESTO NORTHEASTWARD ACROSS THE CENTRAL OR
NORTHERN FLORIDA PENINSULA BY 120 HOURS. THE OFFICIAL TRACK IS
SIMILAR TO BUT A LITTLE WEST OF THE CONSENSUS MODELS.

THE INTENSITY FORECAST WAS AS EQUALLY DIFFICULT TO PREPARE AS THE
TRACK FORECAST WAS...AND IT HIGHLY DEPENDENT ON THE EXACT TRACK
THAT ERNESTO TAKES DUE TO LAND INTERACTION WITH HAITI AND CUBA.
EXCLUDING LAND INTERACTION...THE ENVIRONMENTAL AND OCEAN CONDITIONS
CURRENT AND FORECAST TO BE AFFECTING ERNESTO ARE HIGHLY CONDUCIVE
FOR RAPID INTENSIFICATION IN THE NEAR TERM...AND FOR THE POTENTIAL
DEVELOPMENT OF A MAJOR HURRICANE IN THE LONGER TERM. WATER VAPOR
IMAGERY AND 00Z UPPER-AIR DATA INDICATE THE VERTICAL SHEAR IS
RAPIDLY DECREASING WHILE THE OUTFLOW IS RAPIDLY EXPANDING. IN FACT
...OUTFLOW CHANNELS HAVE NOW DEVELOPED TO THE NORTH AND SOUTH OF
ERNESTO...WITH A THIRD CHANNEL POSSIBLY DEVELOPING TO THE WEST AND
INTO AN UPPER-LOW MOVING RAPIDLY WESTWARD TOWARD THE YUCATAN. THIS
VERY FAVORABLE LOW-SHEAR AND ENHANCED OUTFLOW PATTERN IS FORECAST
BY ALL OF THE GLOBAL MODELS TO PERSIST RIGHT UP UNTIL LANDFALL
ALONG THE FLORIDA WEST COAST. IF ERNESTO DOESN'T LINGER OVER CUBA
FOR MORE THAN 24 HOURS...THEN MAJOR HURRICANE STRENGTH SEEMS LIKELY
BY 96-108 HOURS. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO BUT
HIGHER THAN THE SHIPS...GFDL...AND FSU SUPERENSEMBLE INTENSITY
MODEL FORECASTS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/0900Z 17.0N  73.1W    60 KT
 12HR VT     27/1800Z 17.8N  74.5W    70 KT
 24HR VT     28/0600Z 19.3N  76.3W    85 KT
 36HR VT     28/1800Z 20.6N  78.1W    85 KT
 48HR VT     29/0600Z 22.1N  80.2W    70 KT...INLAND
 72HR VT     30/0600Z 24.4N  83.1W    80 KT
 96HR VT     31/0600Z 26.5N  84.0W   100 KT
120HR VT     01/0600Z 30.0N  81.5W    70 KT...INLAND
 
$$
FORECASTER STEWART
 
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