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TROPICAL STORM ALMA DISCUSSION NUMBER  12
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT MON MAY 27 2002

THE LOW LEVEL CENTER CONTINUES TO BE DIFFICULT TO LOCATE IN BOTH
INFRARED AND VISIBLE IMAGERY AND IS STILL ASSUMED TO BE ON THE
SOUTHEASTERN OR EASTERN EDGE OF THE CONVECTION.  ALTHOUGH SOME
WARMING HAS TAKEN PLACE IN THE THE CLOUD TOP TEMPERATURES THE
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN AT 45 AND 35
KT RESPECTIVELY.  THE INITIAL INTENSITY REMAINS 35 KT DUE TO THE
UNCERTAINTY ABOUT HOW CLOSE THE CENTER ACTUALLY IS TO THE
CONVECTION.

THE INITIAL MOTION IS ESTIMATED AT 270/7.  ALMA REMAINS SOUTH OF A
MID/UPPER-LEVEL RIDGE WHICH IS STEERING THE CYCLONE WESTWARD.
LARGE-SCALE MODELS 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.  HOWEVER...THE MODELS ARE DIVIDED INTO TWO CAMPS.  THE
AVN...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 ALMOST IDENTICAL TO THE PREVIOUS TRACK.

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.  IN FACT...IT MAY BE THAT
THE SHEAR IS BEING PRODUCED BY MID-LEVEL WINDS THAT CANNOT BE
MEASURED.  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.

FORECASTER JARVINEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     27/1500Z 10.8N 108.6W    35 KTS
12HR VT     28/0000Z 10.9N 109.8W    40 KTS
24HR VT     28/1200Z 11.2N 111.4W    45 KTS
36HR VT     29/0000Z 11.7N 112.7W    50 KTS
48HR VT     29/1200Z 12.3N 113.9W    60 KTS
72HR VT     30/1200Z 14.1N 115.6W    65 KTS
 
 
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