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TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
10 PM EST TUE OCT 30 2001
 
SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE THAT THE CENTER
OF TROPICAL DEPRESSION FIFTEEN HAS MOVED OR REFORMED FARTHER NORTH
ALONG THE EAST COAST OF NICARAGUA.  THIS MORE NORTHWARD MOTION IS
SUPPORTED BY THE WINDS AT PUERTO CABEZAS STEADILY VEERING AROUND
FROM THE EAST TO THE SOUTHEAST.  ANOTHER BURST OF DEEP CONVECTION
HAS DEVELOPED JUST NORTH OF THE LOW-LEVEL CENTER AND NEARBY SURFACE
OBSERVATIONS INDICATE THE PRESSURE HAS DROPPED ANOTHER 2 MB...WHICH
IS SUPPORTED BY A 2 MB PRESSURE DECREASE IN THE UW-CIMMS AMSU-B
DERIVED PRESSURE VALUES DURING THE PAST 6 HOURS.  THEREFORE...THE
INITIAL INTENSITY IS KEPT AT 30 KT SINCE STRONGER WINDS MAY BE
LOCATED JUST OFFSHORE AS SUGGESTED BY EARLIER SSMI- AND TRMM-DERIVED
SURFACE WIND ESTIMATES.  UPPER-LEVEL OUTFLOW REMAINS EXCELLENT IN
THE NORTHERN SEMICIRCLE AND POOR TO FAIR ELSEWHERE.
 
THE INITIAL MOTION ESTIMATE IS 345/04.  AS WAS THE CASE THIS SAME
TIME LAST NIGHT...THE APPARENT NORTH-NORTHWESTWARD MOTION MAY BE DUE 
PRIMARILY TO REFORMATION OF THE LOW-LEVEL CENTER CLOSER TO THE 
DEEPER CONVECTION. HOWEVER...SURROUNDING UPPER-AIR OBSERVATIONS 
SUGGEST THAT THE MID TO UPPER-LEVEL RIDGE TO THE EAST HAS 
STRENGTHENED...WHICH MAY FINALLY BE INDUCING A NORTHWARD COMPONENT 
OF MOTION TO THE CYCLONE.  THE AVN MODEL HAS MADE A LARGE SHIFT TO 
THE EAST AND IS THE RIGHT-MOST MODEL OF ALL THE NHC FORECAST 
GUIDANCE THROUGH 36 HOURS...AFTER WHICH IT BENDS THE TRACK BACK TO 
THE NORTHWEST AND IS JUST WEST OF THE ISLE OF YOUTH IN 72 HOURS.  
THE REMAINDER OF THE MODEL GUIDANCE FANS OUT FROM BELIZE EASTWARD TO 
CENTRAL CUBA.  THE OFFICIAL FORECAST IS ALMOST ON TOP OF THE 
PREVIOUS FORECAST TRACK...ONLY SLIGHTLY SLOWER...AND IS MIDWAY 
BETWEEN THE GFDL MODEL TO THE WEST AND THE AVN MODEL TO THE EAST.
  
LITTLE CHANGE IN STRENGTH IS EXPECTED WHILE THE CENTER OF THE
DEPRESSION REMAINS OVER OR NEAR LAND.  ONCE THE LOW-LEVEL CENTER
EMERGES OVER THE WARM WATER OF THE NORTHWEST CARIBBEAN SEA NORTH OF
HONDURAS IN ABOUT 36 HOURS...SIGNIFICANT STRENGTHENING COULD OCCUR
SINCE THE LOW-LEVEL CIRCULATION IS ALREADY WELL-DEFINED AND THE
PRESSURE CONTINUES TO DROP EVEN WHILE THE CENTER HAS BEEN OVER LAND.
THE UPPER-LEVEL FLOW PATTERN FORECAST BY ALL OF THE GLOBAL MODELS
SUGGESTS THAT THE CURRENT IMPRESSIVE OUTFLOW PATTERN SHOULD PERSIST
AND POSSIBLY EVEN BECOME BETTER DEFINED.  THE 18Z GFDL RUN "ONLY"
BRINGS THE CYCLONE TO A 114 KT/945 MB CATEGORY 4 HURRICANE IN THE
YUCATAN CHANNEL IN 72 HOURS.  WHILE THIS SEEMS A LITTLE OVERDONE AT
THIS POINT IN TIME...THIS IS STILL LOWER THAN THE PREVIOUS RUN WHICH
TOOK THE SYSTEM TO 121 KT AND 927 MB AT THE SAME TIME AND LOCATION.
THE SHIPS INTENSITY MODEL IS NOT AS ROBUST AS THE GFDL...BUT EVEN IT
TAKES THE SYSTEM UP TO HURRICANE STRENGTH IN 72 HOURS.  THE TRUTH
MAY EVENTUALLY LIE SOMEWHERE BETWEEN THE SHIPS AND GFDL MODELS.

HEAVY RAINFALL AND FLOODING/MUD SLIDES OVER NICARAGUA AND HONDURAS
REMAIN THE IMMEDIATE CONCERN ASSOCIATED WITH THIS TROPICAL CYCLONE.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     31/0300Z 14.1N  83.7W    30 KTS
12HR VT     31/1200Z 14.7N  83.8W    30 KTS...INLAND
24HR VT     01/0000Z 15.6N  84.0W    30 KTS...INLAND
36HR VT     01/1200Z 16.7N  84.3W    35 KTS...OVER WATER
48HR VT     02/0000Z 17.8N  84.4W    45 KTS
72HR VT     03/0000Z 20.0N  84.0W    60 KTS
 
 
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