[Tropical] Tropical Cyclone Discussion

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WTNT45 KNHC 040852
TCDAT5

TROPICAL STORM ERNESTO DISCUSSION NUMBER  11...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
500 AM AST SAT AUG 04 2012

CORRECTED TIME OF AMSU PASS IN FIRST PARAGRAPH

THE SATELLITE PRESENTATION OF ERNESTO HAS BEEN GRADUALLY IMPROVING
OVERNIGHT. THE COVERAGE OF COLD TOPS HAS INCREASED WHILE CONVECTIVE
BANDING FEATURES HAVE BECOME MORE APPARENT AND THE OUTFLOW HAS
EXPANDED IN THE NORTHERN SEMICIRCLE. IN ADDITION...AN AMSU PASS
FROM 0549 UTC SHOWED A LITTLE BETTER STRUCTURE IN THE INNER CORE.
THE INITIAL INTENSITY IS RAISED TO 50 KT BASED ON A BLEND OF THE
LATEST DVORAK ESTIMATES FROM TAFB AND SAB.

THE LOW-SHEAR ENVIRONMENT AND IMPROVED STRUCTURE OF THE CYCLONE
SUGGEST AT LEAST STEADY INTENSIFICATION OVER THE NEXT COUPLE OF
DAYS. HOWEVER...THE DISAGREEMENT IN THE INTENSITY GUIDANCE
CONTINUES. THE SHIPS AND LGEM STILL SHOW A FASTER PACE OF
INTENSIFICATION...WHILE THE DYNAMICAL MODELS SHOW STRENGTHENING AT A
MUCH SLOWER RATE. GIVEN THE CURRENT TRENDS...THE OFFICIAL FORECAST
HAS BEEN ADJUSTED UPWARD AND SHOWS ERNESTO BECOMING A HURRICANE IN
36 HOURS...BUT REMAINS BELOW THE STATISTICAL-DYNAMICAL GUIDANCE.
LATER IN THE PERIOD...THE GFDL SHOWS MORE INTENSIFICATION THAN
EARLIER RUNS...BUT THE HWRF AND MUCH OF THE HFIP GUIDANCE REMAIN
WEAKER. AT DAYS 3 THROUGH 5 THE NEW NHC FORECAST HAS BEEN ADJUSTED
UPWARD SLIGHTLY...AND IS CLOSE TO THE IV15 CONSENSUS AND THE
FLORIDA STATE SUPERENSEMBLE. NEEDLESS TO SAY...THERE IS LOW
CONFIDENCE IN THE INTENSITY FORECAST THROUGH THE PERIOD.

THE INITIAL MOTION ESTIMATE IS 275/16 AS ERNESTO IS SITUATED SOUTH
OF THE SUBTROPICAL RIDGE. THE TRACK MODEL GUIDANCE IS IN GOOD
AGREEMENT THROUGH 48 HOURS IN SHOWING A CONTINUED WESTWARD MOTION
AS THE RIDGE BUILDS WESTWARD TO NORTH OF THE CYCLONE. THROUGH THIS
TIME THE NHC FORECAST IS SIMPLY AN UPDATE OF THE PREVIOUS ONE. AT
DAYS 3 THROUGH 5 THERE CONTINUES TO BE LARGE SPREAD IN THE MODEL
GUIDANCE. THE BIGGEST CHANGE THIS CYCLE IS A SOUTHWARD SHIFT IN THE
UKMET...WHICH NOW JOINS THE GFS AND ECMWF IN SHOWING THAT ERNESTO
WILL REMAIN TOO FAR SOUTH TO MOVE INTO A WEAKNESS IN THE
SUBTROPICAL RIDGE THAT DEVELOPS OVER THE EASTERN GULF OF MEXICO IN
4 TO 5 DAYS. HOWEVER...THE GFDL...HWRF...AND SEVERAL OF THE HFIP
MODELS CONTINUE TO SHOW ERNESTO GAINING MORE LATITUDE IN THE SECOND
HALF OF THE FORECAST PERIOD. THE NHC FORECAST HAS BEEN ADJUSTED A
LITTLE TO THE SOUTH TOWARD THE NEW MULTI-MODEL CONSENSUS AT DAYS 3
THROUGH 5...BUT STILL LIES TO THE RIGHT OF THE CENTER OF THE
GUIDANCE ENVELOPE.

INTERESTS IN JAMAICA SHOULD MONITOR THE PROGRESS OF ERNESTO...AS A
TROPICAL STORM WATCH OR WARNING COULD BE REQUIRED FOR PORTIONS OF
THAT ISLAND LATER TODAY.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0900Z 14.1N  67.2W   50 KT  60 MPH
 12H  04/1800Z 14.5N  69.7W   55 KT  65 MPH
 24H  05/0600Z 15.1N  73.1W   60 KT  70 MPH
 36H  05/1800Z 15.7N  76.4W   65 KT  75 MPH
 48H  06/0600Z 16.3N  79.1W   70 KT  80 MPH
 72H  07/0600Z 17.5N  83.0W   75 KT  85 MPH
 96H  08/0600Z 19.5N  86.5W   80 KT  90 MPH
120H  09/0600Z 21.5N  90.0W   70 KT  80 MPH

$$
FORECASTER BRENNAN



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