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HURRICANE ALMA DISCUSSION NUMBER  19
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT WED MAY 29 2002

ALMA HAS SPUTTERED A BIT DURING THE PAST SEVERAL HOURS...WITH
THE EYE TEMPORARILY DISAPPEARING IN IR IMAGERY AROUND 02Z-03Z.
ADDITIONALLY...SSM/I IMAGERY AT 0355Z INDICATED THAT THE EYEWALL
HAD OPENED TO THE NORTHEAST.  SINCE THAT TIME...THE EYE HAS
RE-APPEARED AND THE EYEWALL CONVECTION HAS BECOME SOMEWHAT MORE
SYMMETRIC IN IR IMAGERY.  INTENSITY ESTIMATES FROM TAFB AND SAB
REMAIN 77 KT AND 65 KT...SO THE INITIAL INTENSITY REMAINS 75 KT.
 
ALMA HAS TURNED TO THE RIGHT DURING THE PAST 6 HR WITH THE INITIAL
MOTION NOW 310/7...AND THE SHORT-TERM MOTION MAY BE A LITTLE
FASTER.  WATER VAPOR IMAGERY INDICATES A WELL-DEFINED MID/UPPER
LEVEL LOW NEAR 28N120W DROPPING SOUTHWARD...WITH SOUTHWESTERLY
FLOW BETWEEN IT AND ALMA.  LARGE-SCALE MODELS INDICATE THIS LOW
SHOULD REMAIN IN PLACE FOR 36-48 HR BEFORE LIFTING NORTHWARD.
THIS PATTERN SUGGESTS THAT ALMA SHOULD RECURVE NORTHEASTWARD DURING
THE FORECAST PERIOD...AND THIS IS REFLECTED IN THE NHC GUIDANCE.
THE BIG QUESTION IS HOW FAST WILL ALMA MOVE?  THE GUIDANCE DIVERGES
ON THIS ISSUE...WITH THE BAMM...BAMD...AND LBAR CALLING FOR A
FASTER MOTION WHILE THE GFS...UKMET...NOGAPS...GFDL...AND NHC91
CALL FOR A SLOW MOTION.  THE OFFICIAL FORECAST WILL LEAN TOWARD
THE SLOWER SOLUTION...WITH ALMA MOVING A LITTLE TO THE EAST OF
THE PREVIOUS FORECAST AT ABOUT 5-7 KT.  THERE IS A POSSIBILITY THE
FASTER MODELS COULD BE RIGHT...AND ALMA COULD MOVE MORE QUICKLY
NORTHWARD THAN CURRENTLY FORECAST BEFORE THE MID/UPPER LEVEL LOW
LIFTS OUT. 
 
ALMA REMAINS IN A FAVORABLE LOW SHEAR ENVIRONMENT...AND THERE
IS NO OBVIOUS REASON FOR THE OBSERVED SPUTTERING.  THE MORE
NORTHWARD MOTION SHOULD MOVE ALMA MORE QUICKLY INTO THE COOLER
WATER TO THE NORTH...SO THE HURRICANE SHOULD PEAK DURING THE NEXT
12-24 HR FOLLOWED BY WEAKENING.  THE LIFTING OUT OF THE UPPER LOW
WILL LIKELY DECREASE THE SOUTHWESTERLY FLOW IN THE PATH OF ALMA. 
THIS MEANS SHEAR MAY NOT BE AS MUCH OF A FACTOR IN ALMA'S WEAKENING
AS WAS EXPECTED 24 HR AGO.

FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     29/0900Z 13.4N 114.6W    75 KTS
12HR VT     29/1800Z 14.1N 115.4W    85 KTS
24HR VT     30/0600Z 15.3N 115.9W    85 KTS
36HR VT     30/1800Z 16.3N 116.0W    75 KTS
48HR VT     31/0600Z 17.3N 115.7W    65 KTS
72HR VT     01/0600Z 19.0N 114.5W    50 KTS
 
 
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