Subject: Pacific-EN: Tropical Storm Hilda Discussion Number 14

From: SIU Weather Processor <[email-masked]>
Date: Wed, 13 Aug 1997 03:29:47 +1900

496
WTPZ45 KNHC 130829
TCDEP5
TROPICAL STORM HILDA DISCUSSION NUMBER  14
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT WED AUG 13 1997

ANOTHER LARGE BURST OF VERY DEEP CONVECTION HAS OCCURRED...BUT THERE
ARE STILL NO IDENTIFIABLE CENTRAL FEATURES OR BANDING FEATURES
EVIDENT IN SATELLITE IMAGERY.  INITIAL INTENSITY REMAINS 45
KNOTS...IN AGREEMENT WITH SAB...AFGWC...AND TAFB DVORAK ESTIMATES.
WATER VAPOR IMAGERY CLEARLY SHOWS THE MID/UPPER-LEVEL LOW TO THE
WEST OF HILDA...MOVING WESTWARD A LITTLE BIT FASTER THAN OUR
TROPICAL CYCLONE.  OUR INTENSITY FORECAST IS BASED ON THE ASSUMPTION
THAT THE MID/UPPER-LEVEL LOW WILL CONTINUE TO MOVE A LITTLE FASTER
THAN HILDA...MEANING THAT THE UPPER-LEVEL ENVIRONMENT COULD BECOME
MORE FAVORABLE AND ALLOW THE TROPICAL CYCLONE TO STRENGTHEN.  THIS
STRENGTHENING SHOULD LEVEL OFF LATER IN THE FORECAST PERIOD AS HILDA
MOVES OVER COOLER WATER. HOWEVER... IF HILDA MOVES CLOSER TO THE
MID/UPPER-LEVEL LOW...INCREASED SHEAR SHOULD INHIBIT ANY SIGNIFICANT
STRENGTHENING.  OUR INTENSITY FORECAST IS IN BEST AGREEMENT WITH
SHIPS GUIDANCE.  SHIFOR AND THE GFDI INTENSITY SCHEMES DO NOT SHOW
AS MUCH STRENGTHENING.

GIVEN THE UNCERTAINTY IN THE INITIAL POSITION...IT IS BEST TO LEAVE
THE INITIAL MOTION UNCHANGED AT 290/10.  IF THE MID/UPPER-LEVEL LOW
KEEPS ITS DISTANCE AS INDICATED BY THE AVIATION MODEL...THERE SHOULD
BE ENOUGH OF A MID-LEVEL RIDGE TO THE NORTH AND NORTHEAST OF HILDA
TO ALLOW THE GENERAL WEST-NORTHWESTWARD MOTION TO CONTINUE.  OUR
CURRENT TRACK IS AN UPDATE OF THE PREVIOUS PACKAGE AND IS IN BEST
AGREEMENT WITH THE NHC90.  THE AVIATION AND NOGAPS MODELS ARE TO THE
LEFT OF OUR TRACK...WHILE THE GFDL AND LBAR ARE TO THE RIGHT.

MAYFIELD

FORECAST POSITIONS AND MAX WINDS

INITIAL     13/0900Z 14.2N 122.7W    45 KTS
12HR VT     13/1800Z 14.7N 124.2W    50 KTS
24HR VT     14/0600Z 15.4N 126.3W    55 KTS
36HR VT     14/1800Z 16.2N 128.4W    60 KTS
48HR VT     15/0600Z 16.9N 130.5W    60 KTS
72HR VT     16/0600Z 18.5N 135.0W    60 KTS

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