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TROPICAL STORM ALMA DISCUSSION NUMBER  14
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT MON MAY 27 2002
 
THE LOW-LEVEL CIRCULATION CENTER REMAINS DIFFICULT TO LOCATE AS 
INDICATED BY THE LARGE SPREAD BETWEEN FIX POSITIONS FROM THE VARIOUS 
SATELLITE AGENCIES. THEREFORE...THE INITIAL POSITION IS BASED ON 
PERSISTENCE...EXTRAPOLATION...AND CONTINUITY WITH THE PREVIOUS 
FORECAST TRACK...WHICH PLACES THE CENTER JUST NORTH OF WHAT APPEARS 
TO BE A SMALL CDO FEATURE DEVELOPING. THE INITIAL INTENSITY OF 50 KT 
IS BASED ON DVORAK SATELLITE INTENSITY ESTIMATES OF T3.5...55 KT... 
FROM BOTH TAFB AND SAB...BUT WAS KEPT SLIGHTLY LOWER DUE TO THE 
UNCERTAINTY IN THE EXACT LOCATION OF THE LOW-LEVEL CENTER.
 
THE INITIAL MOTION ESTIMATE IS 285/8. ALMA IS EXPECTED TO CONTINUE 
TRACKING IN A GENERAL WEST-NORTHWESTWARD DIRECTION AROUND THE 
PERIPHERY OF THE MEXICAN SUBTROPICAL RIDGE. ONCE THE CYCLONE REACHES 
ABOUT 115W LONGITUDE...THE RIDGE TO THE NORTH IS FORECAST TO WEAKEN 
AS ALLUDED TO IN THE PREVIOUS FORECAST DISCUSSIONS. THE 18Z AVN/GFS 
AND GFDL MODEL RUNS ARE STILL INDICATING THAT THIS WILL OCCUR AS A 
MID- TO UPPER-LEVEL TROUGH/LOW DEVELOPS JUST WEST OF BAJA 
CALIFORNIA.  THE UKMET SCENARIO IS SIMILAR...BUT MUCH FASTER AND 
TAKES ALMA ALMOST DUE NORTH IN 12 HOURS. THE UKMET SOLUTION SEEMS 
EXCESSIVE GIVEN THE STRONG RIDGE TO THE NORTH AND WAS THEREFORE 
REJECTED. THE GFDL IS A LITTLE EAST OF THE AVN AND AVN ENSEMBLE 
SOLUTIONS...BUT SHOWS THE SAME GRADUAL RECURVATURE TREND AFTER 48 
HOURS. THE OFFICIAL FORECAST TRACK IS A TAD TO THE LEFT OF THE 
PREVIOUS FORECAST TRACK...BUT TO THE RIGHT OF THE AVN TRACK.

BANDING FEATURES HAVE CONTINUED TO IMPROVE DURING THE DAY AND A 
SMALL CDO FEATURE MAY BE DEVELOPING. OUTFLOW REMAINS GOOD IN THE 
WESTERN SEMICIRCLE AND IS IMPROVING TO THE EAST. GRADUAL 
INTENSIFICATION TO 75 KT IN 36 HOURS IS FORECAST BY THE SHIPS 
INTENSITY MODEL...WHILE THE GFDL RAPIDLY STRENGTHENS THE CYCLONE TO 
95 KT IN 24 HOURS. THE GFDL SOLUTION SEEMS EXCESSIVE GIVEN THE LACK 
OF ANY PERSISTENT CENTRAL DEEP CONVECTION DURING THE PAST 48 HOURS. 
HOWEVER...ALMA IS EXPECTED TO REMAIN IN A LOW SHEAR ENVIRONMENT AND 
OVER 28-29C SSTS FOR THE NEXT 24 TO 36 HOURS...SO AT LEAST STEADY 
INTENSIFICATION SEEMS LIKELY AND ALMA IS FORECAST TO BECOME A 
HURRICANE WITHIN 24 HOURS. BY 48 HOURS...THE CYCLONE IS EXPECTED TO 
BE MOVING OVER COOLER SSTS AND ENCOUNTER INCREASING SOUTHWESTERLY 
UPPER-LEVEL SHEAR...WHICH SHOULD ACT TO CAP THE INTENSIFICATION 
PROCESS AND BRING ABOUT GRADUAL WEAKENING BY 72 HOURS. HOWEVER...IF 
A CDO DOES DEVELOP DURING THE NEXT 6 TO 12 HOURS...THEN THE 
INTENSITY FORECAST THROUGH 48 HOURS WILL PROBABLY BE TOO LOW.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     28/0300Z 11.6N 110.7W    50 KTS
12HR VT     28/1200Z 12.0N 111.8W    60 KTS
24HR VT     29/0000Z 12.6N 113.1W    70 KTS
36HR VT     29/1200Z 13.4N 114.4W    80 KTS
48HR VT     30/0000Z 14.7N 115.3W    80 KTS
72HR VT     31/0000Z 18.0N 115.0W    70 KTS
 
 
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