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TROPICAL STORM JERRY DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT SUN OCT 07 2001
 
AIR FORCE RESERVE RECON DATA AND NEARBY SURFACE OBSERVATIONS
INDICATE THAT A LOW-LEVEL CENTER HAS RE-DEVELOPED FARTHER NORTH ON
THE NORTH SIDE OF THE CONVECTIVE CLOUD MASS.  THE PREVIOUS INTENSITY
OF 45 KT IS MAINTAINED BASED ON DVORAK SATELLITE INTENSITY ESTIMATES
OF 55 KT...T3.5...FROM TAFB AND 35 KT...T2.5...FROM SAB.
UPPER-LEVEL OUTFLOW IS FAIR TO THE EAST AND POOR ELSEWHERE.

THE INITIAL MOTION ESTIMATE IS NOW 290/12...  BASED ON THE
ASSUMPTION THAT JERRY WILL RESUME A BASE WEST-NORTHWEST MOTION.
DURING PAST 6 HOURS...THE LOW-LEVEL CENTER HAS REFORMED ON THE NORTH
SIDE OF THE DEEP CONVECTION...WHICH HAS YIELDED A TRANSLATIONAL
MOTION OF 320/12.  HOWEVER...LATEST SATELLITE IMAGERY AND SURFACE
OBSERVATIONS FROM THE WINDWARD ISLANDS SUGGEST THAT JERRY MAY
ALREADY HAVE RESUMED A WEST-NORTHWEST TRACK.  GIVEN THE STRENGTH OF
THE 500 MB RIDGE TO THE NORTH...AS INDICATED BY 5900 METER HEIGHTS
AT SAN JUAN...IT IS UNLIKELY THAT JERRY COULD MAINTAIN A NORTHWEST
MOTION FOR MUCH LONGER.  THERE IS CONSIDERABLE DIVERGENCE AMONG THE
NHC MODEL GUIDANCE.  THE AVN IS THE NORTHERNMOST MODEL AND BRINGS
THE CYCLONE ACROSS PUERTO RICO IN 36 TO 48 HOURS...WHILE THE
SOUTHERNMOST MODELS ARE THE GFDN AND THE GFDL WHICH TAKE JERRY
RAPIDLY WESTWARD INTO CENTRAL AMERICA IN 72 HOURS.  THE UKMET AND
NOGAPS MODELS HAVE BEEN THE MOST CONSISTENT AND CONTINUE TO TAKE
JERRY TOWARD JAMAICA IN 72 HOURS.  THE OFFICIAL FORECAST IS SLIGHTLY
SLOWER AND TO THE RIGHT OF THE PREVIOUS FORECAST AND CLOSE TO A
UKMET-NOGAPS-DEEP BAM CONSENSUS FOR THE FORWARD SPEED.

UPPER-LEVEL WESTERLY WINDS...ABOVE 200 MB...HAVE BEEN DISRUPTING THE
CONVECTIVE ORGANIZATION.  THESE WINDS ARE FORECAST BY ALL OF THE
GLOBAL MODELS TO BECOME EASTERLY IN 24 TO 36 HOURS...WHICH SHOULD
FAVOR MORE INTENSIFICATION.  THE GFDL AND SHIPS MODELS BRING JERRY
UP TO 72 KT AND 76 KT IN 72 HOURS...RESPECTIVELY.  HOWEVER...THE
OFFICIAL INTENSITY FORECAST WILL REMAIN CONSERVATIVE UNTIL A
WELL-DEFINED CENTER AND A PERISTENT CONVECTIVE PATTERN DEVELOPS.

FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     08/0300Z 13.3N  60.6W    45 KTS
12HR VT     08/1200Z 14.0N  62.7W    50 KTS
24HR VT     09/0000Z 14.8N  65.1W    55 KTS
36HR VT     09/1200Z 15.5N  67.5W    60 KTS
48HR VT     10/0000Z 16.2N  69.8W    65 KTS
72HR VT     11/0000Z 17.5N  74.0W    70 KTS
 
 
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