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TROPICAL STORM ALMA DISCUSSION NUMBER  11
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT MON MAY 27 2002

CONVECTION ASSOCIATED WITH ALMA HAS INCREASED MARKEDLY OVER THE
PAST SEVERAL HR...WITH A LARGE AREA OF CLOUD TOPS COLDER THAN
-80C.  HOWEVER...THE LOW LEVEL CENTER IS VERY HARD TO FIND IN
INFRARED IMAGERY AND IS STILL ASSUMED TO BE ON THE SOUTHEASTERN
OR EASTERN EDGE OF THE CONVECTION.  SATELLITE INTENSITY ESTIMATES
FROM TAFB AND SAB ARE 45 AND 35 KT.  THE INITIAL INTENSITY REMAINS
35 KT DUE TO THE UNCERTAINTY ABOUT HOW CLOSE THE CENTER ACTUALLY
IS TO THE CONVECTION.
 
THE BEST ESTIMATE OF THE INITIAL MOTION IS 270/9.  ALMA IS
CURRENTLY SOUTH OF A MID/UPPER-LEVEL RIDGE WHICH IS STEERING
THE CYCLONE WESTWARD.  LARGE-SCALE MODELS UNANIMOUSLY AGREE THAT
THE RIDGE WILL WEAKEN AS A CUT-OFF LOW FORMS NEAR SOUTHERN
CALIFORNIA AND MOVES SOUTHWESTWARD.  THE TRACK GUIDANCE RESPONDS
TO THIS DEVELOPMENT BY TURNING ALMA NORTHWESTWARD OR NORTHWARD.
THE GFS...BAM MODELS...NHC91...AND LBAR CALL FOR A MORE
NORTHWESTWARD MOTION...WHILE THE GFDL...NOGAPS...UKMET...AND
ASSOCIATED  ENSEMBLES TURN THE STORM NORTHWARD NEAR 111W-113W.
THE OFFICIAL FORECAST WILL FOLLOW THE MODEL CLUSTER CALLING FOR
NORTHWESTERLY MOTION...WITH THE TRACK ADJUSTED SLIGHT NORTH OF
THE PREVIOUS TRACK.  A BETTER MOTION ESTIMATE FROM VISIBLE IMAGERY
MAY HELP DETERMINE WHICH CLUSTER OF THE BIFURCATED GUIDANCE IS
CORRECT.
 
SATELLITE PRODUCTS FROM CIMSS AT THE UNIVERSITY OF WISCONSIN
SUGGEST THAT SHEAR HAS WEAKENED OVER ALMA...CREATING A MORE
FAVORABLE ENVIRONMENT FOR INTENSIFICATION.  HOWEVER...IT IS NOT
YET CLEAR IF THE STORM IS ACTUALLY RESPONDING TO IT.  THE INTENSITY
FORECAST WILL THEREFORE BE SIMILAR TO THE PREVIOUS PACKAGE...
CALLING FOR ALMA TO REACH HURRICANE STRENGTH JUST BEFORE MOVING
INTO STRONG WESTERLY SHEAR AT ABOUT THE 72 HR POINT.  ALMA COULD
STRENGTHEN MORE QUICKLY THAN FORECAST IF THE CURRENT COLD
CONVECTIVE TOPS PERSIST AFTER THE DIURNAL CONVECTIVE MAXIMUM...OR
IF THE CENTER IS MORE INVOLVED WITH THE CONVECTION THAN CURRENTLY
INDICATED.
 
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     27/0900Z 10.7N 107.9W    35 KTS
12HR VT     27/1800Z 10.8N 109.2W    40 KTS
24HR VT     28/0600Z 11.0N 110.8W    45 KTS
36HR VT     28/1800Z 11.4N 112.3W    50 KTS
48HR VT     29/0600Z 12.0N 113.5W    60 KTS
72HR VT     30/0600Z 13.5N 115.5W    70 KTS
 
 
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