Tropical Storm FRANK

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TROPICAL STORM FRANK DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092010
200 PM PDT SUN AUG 22 2010
 
EVEN THOUGH CLOUD TOPS HAVE WARMED A BIT OVER THE PAST SEVERAL HOURS
...A CURVED CONVECTIVE BAND CONTINUES TO WRAP INTO THE CENTER
OF FRANK.  THE INITIAL INTENSITY IS RAISED TO 50 KNOTS FOR THIS
PACKAGE...BASED ON A BLEND OF DVORAK ESTIMATES FROM TAFB AND SAB.
DESPITE SHOWING THE SHEAR INCREASING TO 25 KNOTS BY 12 HOURS...THE
STATISTICAL INTENSITY MODELS HAVE TRENDED SHARPLY UPWARD IN THE
FIRST 48 HOURS IN RESPONSE TO THE CURRENT STRENGTHENING AND AN
OTHERWISE FAVORABLE ENVIRONMENT.  THE OFFICIAL FORECAST IS AGAIN
ADJUSTED UPWARD...BUT NOW LIES A LITTLE BELOW THE SHIPS AND LGEM
THROUGH DAY 2 AND CLOSE TO A BLEND OF THOSE MODELS BEYOND THAT
TIME.
 
THE INITIAL MOTION ESTIMATE IS 270/07...AND THE OVERALL SYNOPTIC
REASONING REMAINS UNCHANGED.  THROUGH THE PERIOD FRANK SHOULD BE
STEERED PRIMARILY WESTWARD AND THEN WEST-NORTHWESTWARD BY A
DEEP-LAYER RIDGE CENTERED OVER WESTERN NORTH AMERICA.  WHILE ALL OF
THE GLOBAL MODEL AND ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT WITH
THE SYNOPTIC PATTERN...THE TRACK MODEL GUIDANCE SPREAD HAS INCREASED
...ESPECIALLY IN TERMS OF THE FORWARD SPEED OF THE CYCLONE.  MOST OF
THE GUIDANCE HAS TRENDED FASTER THROUGH 48 HOURS...AND THE OFFICIAL
FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION AND LIES NEAR THE
CENTER OF THE GUIDANCE SUITE.  LATE IN PERIOD THE OFFICIAL FORECAST
IS A LITTLE SLOWER THAN THE MULTI-MODEL CONSENSUS DUE TO THE LARGE
SPREAD IN THE GUIDANCE.
 
GIVEN THE NEW FORECAST TRACK...THE GOVERNMENT OF MEXICO HAS EXTENDED
THE TROPICAL STORM WARNING WESTWARD TO ACAPULCO.  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/2100Z 13.9N  96.0W    50 KT
 12HR VT     23/0600Z 14.0N  97.2W    60 KT
 24HR VT     23/1800Z 14.3N  98.8W    65 KT
 36HR VT     24/0600Z 14.8N 100.4W    70 KT
 48HR VT     24/1800Z 15.4N 101.7W    75 KT
 72HR VT     25/1800Z 16.5N 104.0W    75 KT
 96HR VT     26/1800Z 17.5N 106.5W    70 KT
120HR VT     27/1800Z 18.5N 109.5W    70 KT
 
$$
FORECASTER BRENNAN
 
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