HOME	PRODUCTS	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ALETTA DISCUSSION NUMBER  19
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT FRI MAY 26 2000

ALTHOUGH SATELLITE INTENSITY ESTIMATES FROM TAFB...SAB...AND AFWA
ARE 77 KT...65 KT...AND 55 KT RESPECTIVELY...SATELLITE IMAGERY
INDICATES THE CENTER OF ALETTA HAS BECOME EXPOSED NORTHEAST OF THE
CONVECTION DURING THE AFTERNOON. THUS THE CYCLONE IS DOWNGRADED TO A
60 KT TROPICAL STORM.

THE CENTER IS A LITTLE FURTHER EAST THAN IN THE PREVIOUS ADVISORY.
IT IS UNCLEAR WHETHER THIS IS MOVEMENT OR A BETTER CENTER POSITION.
THE INITIAL MOTION IS THUS STATIONARY. WATER VAPOR IMAGERY INDICATES
A MID/UPPER LEVEL TROUGH HAS FORMED NORTH OF ALETTA...WHICH HAS
COLLAPSED THE STEERING CURRENTS. THE AVN...UKMET...AND NOGAPS MODELS
HAVE A GOOD HANDLE ON THE TROUGH...AND SUGGEST IT SHOULD BE REPLACED
BY A RIDGE IN 36-48 HR. THIS WOULD ALLOW A FASTER MOTION TOWARD THE
WEST OR NORTHWEST. NHC TRACK GUIDANCE REMAINS DIVERGENT...ALTHOUGH
THE UKMET AND NOGAPS GENERALLY AGREE WITH THIS SCENARIO. THE GFDL
TRACKS ALETTA SLOWLY TOWARD THE NORTHEAST...WHICH LOOKS UNLIKELY
GIVEN THE DEVELOPING SYNOPTIC PATTERN. THE OFFICIAL FORECAST IS
SHIFTED A LITTLE TO THE RIGHT OF THE PREVIOUS FORECAST DUE TO
CURRENT INITIAL POSITION.

THE SHEARING UPPER LEVEL EASTERLIES ARE NOT WELL HANDLED IN THE
MODELS...WITH THE AVN...NOGAPS...AND UKMET SHOWING LESS FLOW
AFFECTING ALETTA THAN INDICATED BY SATELLITE IMAGERY. THESE MODELS
INDICATE THE SHEAR SHOULD WEAKEN OVER THE NEXT 24-36 HR... WHICH
WOULD ALLOW ALETTA TO MAINTAIN ITSELF OR PERHAPS RE-INTENSIFY.  THE
AVN-BASED SHIPS MODEL FOLLOWS THIS IDEA AND SHOWS LITTLE CHANGE IN
STRENGTH FOR 48 HR. THE INTENSITY FORECAST INDICATES LITTLE CHANGE
THROUGH 24 HR...FOLLOWED BY WEAKENING AS ALETTA MOVES OVER COOLER
WATERS. IT IS NOTABLE THAT THE AVN MERGES ALETTA WITH A NEW CYCLONE
FORMING TO THE EAST. WHILE THIS COULD HAPPEN EVENTUALLY...THE
DISTURBED WEATHER SOUTH OF THE GULF OF TEHUANTEPEC IS STILL POORLY
ORGANIZED.


FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     27/0300Z 15.0N 107.7W    60 KTS
12HR VT     27/1200Z 15.4N 107.9W    60 KTS
24HR VT     28/0000Z 15.7N 108.1W    60 KTS
36HR VT     28/1200Z 16.0N 108.3W    55 KTS
48HR VT     29/0000Z 16.5N 109.0W    50 KTS
72HR VT     30/0000Z 17.0N 111.0W    40 KTS
 
 
NNNN