HOME	ARCHIVES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ALMA DISCUSSION NUMBER  15
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT TUE MAY 28 2002

ALMA HAS BECOME BETTER ORGANIZED OVER THE PAST SEVERAL HOURS.
THE SYSTEM HAS DEVELOPED A -80C CDO WITH A VIGOROUS OUTER
CONVECTIVE BAND OVER THE WESTERN SEMICIRCLE.  A RECENT SSM/I
OVERPASS SUGGESTED THAT CONVECTION IS WRAPPING AROUND THE EASTERN
SIDE OF THE CENTER...ALTHOUGH THERE WAS NO EVIDENCE OF AN EYE
FORMING.  THE INTENSITY ESTIMATES FROM TAFB AND SAB ARE 65 KT AND
55 KT RESPECTIVELY...SO THE MAXIMUM WINDS ARE INCREASED TO 55 KT.
 
THE BEST ESTIMATE OF THE INITIAL MOTION REMAINS 285/8.  WATER
VAPOR IMAGERY INDICATES THAT STRONG MID/UPPER LEVEL WESTERLIES
COVER THE PACIFIC NORTH OF A PUERTO VALLARTA-20N120W-11N130W
LINE...WITH RIDGING BETWEEN ALMA AND THE WESTERLIES.  LARGE-SCALE
MODELS INDICATE THAT A MID/UPPER LEVEL LOW SHOULD FORM NEAR
SOUTHERN CALIFORNIA IN THE NEXT 24-36 HR...AND A SHORTWAVE TROUGH
CURRENTLY APPROACHING THE AREA MAY BE THE FIRST SIGNS OF THAT
DEVELOPMENT.  ALL GUIDANCE INDICATES THIS LOW WILL BE STRONG
ENOUGH AND FAR ENOUGH SOUTH TO TURN ALMA NORTHWARD OR PERHAPS
NORTHEASTWARD BY 72 HR.  THE MODEL TRENDS OBSERVED LAST NIGHT
CONTINUE TONIGHT...WITH THE GFS...BAM MODELS...AND NHC91 CALLING
FOR MORE WESTWARD MOTION BEFORE THE TURN...WHILE THE NOGAPS...
GFDL...AND UKMET CALL FOR A SHARPER RECURVATURE.  THE OFFICIAL
FORECAST WILL SPLIT THE DIFFERENCE BETWEEN THE TWO EXTREMES AND
IS BASICALLY AN UPDATE OF THE PREVIOUS PACKAGE.

ALMA REMAINS IN A LOW-SHEAR DIVERGENT ENVIRONMENT...AND LARGE-SCALE
MODELS FORECAST THIS TO CONTINUE FOR THE NEXT 24-36 HR.  THUS...
THE INTENSITY FORECAST CALLS FOR CONTINUED STRENGTHENING DURING
THAT TIME.  AFTER THAT...A COMBINATION OF INCREASING SHEAR AND
DECREASING SEA SURFACE TEMPERATURES SHOULD HALT DEVELOPMENT AND
BEGIN A WEAKENING TREND.  IT SHOULD BE NOTED THAT ALMA HAS
GENERATED -80C OR COLDER CONVECTIVE TOPS ALMOST CONTINUOUSLY FOR
MORE THAN 24 HR.  THIS SUGGESTS A PERIOD OF RAPID INTENSIFICATION
COULD OCCUR IF THE CENTRAL CONVECTION ORGANIZES INTO AN EYEWALL
BEFORE THE CYCLONE ENCOUNTERS THE SHEAR AND COOLER WATERS. 

  
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     28/0900Z 11.7N 111.5W    55 KTS
12HR VT     28/1800Z 12.1N 112.6W    65 KTS
24HR VT     29/0600Z 12.7N 113.7W    75 KTS
36HR VT     29/1800Z 13.7N 114.8W    80 KTS
48HR VT     30/0600Z 15.3N 115.5W    75 KTS
72HR VT     31/0600Z 18.5N 115.0W    65 KTS
 
 
NNNN