297 
 WTPZ44 KNHC 250843
 TCDEP4
 TROPICAL STORM FRANK DISCUSSION NUMBER  15
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092010
 200 AM PDT WED AUG 25 2010
  
 CONVENTIONAL SATELLITE IMAGERY AND A RECENT AMSU-B OVERPASS INDICATE
 THAT FRANK HAS BECOME BETTER ORGANIZED THIS MORNING.  THE IMAGERY
 REVEALS A WELL DEVELOPED BANDING FEATURE WITH -80C CLOUD TOPS
 EXTENDING OVER THE WESTERN HALF OVER THE CYCLONE...AND A STRONG
 BURST OF DEEP CONVECTION OVER THE CIRCULATION CENTER.  BASED ON THE
 SATELLITE INTENSITY ESTIMATES OF 55 KT FROM BOTH TAFB AND SAB...AND
 RECENT TRENDS ASSOCIATED WITH THE DEVELOPING STRONG CONVECTIVE
 BAND...THE INITIAL INTENSITY IS ADJUSTED UP TO 60 KT.  THE UW-CIMSS
 SHEAR PRODUCT SUGGESTS THAT SOME EASTERLY SHEAR IS IMPACTING THE
 CLOUD PATTERN...HOWEVER...THE UPPER FLOW IS QUITE DIFFLUENT...
 PARTICULARLY OVER THE WESTERN PORTION OF THE SYSTEM WHERE THE
 STRONG BAND RESIDES.  THE OFFICIAL FORECAST CONTINUES TO CALL FOR
 FRANK TO STRENGTHEN INTO A HURRICANE...BUT SOONER THAN SHOWN IN THE
 PREVIOUS NHC FORECAST.  THIS IS CONSISTENT WITH THE LATEST RUNS OF
 THE SHIPS AND LGEM INTENSITY MODELS.  BEYOND THE 36 HOUR PERIOD...A
 GRADUAL WEAKENING IS FORECAST TO OCCUR AS AS THE CYCLONE TRAVERSES
 COOLER SEA SURFACE TEMPERATURES AND MOVES INTO A MORE STABLE AIR
 MASS.
  
 THE INITIAL MOTION IS A STEADY 285/8.  FRANK IS MOVING WITHIN THE
 DEEP-LAYER EAST-SOUTHEASTERLY FLOW TO THE SOUTH OF A RIDGE OVER THE
 SOUTHWESTERN U.S. AND NORTHERN MEXICO.  THIS GENERAL WEST-
 NORTHWESTWARD MOTION IS EXPECTED TO CONTINUE DURING THE NEXT 3
 DAYS.  AFTERWARD...THE AFOREMENTIONED RIDGE IS FORECAST TO WEAKEN
 IN RESPONSE TO A MID- TO UPPER-LEVEL TROUGH AMPLIFYING ALONG THE
 WEST COAST OF THE U.S.  THIS CHANGE IN THE SYNOPTIC PATTERN SHOULD
 CAUSE FRANK TO DECREASE IN FORWARD SPEED AND TURN TOWARD THE
 NORTHWEST...AND THEN NORTHWARD INTO THE WEAKNESS BY DAY 5.  THE
 TIGHTLY CLUSTERED DYNAMICAL MODELS HAVE AGAIN SHIFTED TO THE SOUTH
 OR LEFT OF THE PREVIOUS ADVISORY.  CONSEQUENTLY...THE NHC OFFICIAL
 FORECAST FOLLOWS SUIT AND IS CLOSE TO THE MULTI-MODEL CONSENSUS...
 TVCN...AND THE ECMWF GUIDANCE.
   
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      25/0900Z 16.2N 103.6W    60 KT
  12HR VT     25/1800Z 16.6N 105.0W    65 KT
  24HR VT     26/0600Z 17.1N 106.8W    65 KT
  36HR VT     26/1800Z 17.7N 108.7W    65 KT
  48HR VT     27/0600Z 18.3N 110.3W    60 KT
  72HR VT     28/0600Z 19.5N 112.5W    55 KT
  96HR VT     29/0600Z 20.5N 113.5W    45 KT
 120HR VT     30/0600Z 21.5N 113.5W    35 KT
  
 $$
 FORECASTER ROBERTS/PASCH