HOME	ARCHIVES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP4 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   9
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT THU JUL 11 2002
 
TROPICAL DEPRESSION FOUR-E HAS CONTINUED ITS PAST TREND OF 
DEVELOPING DEEP CONVECTION AT NIGHT AND THEN LOSING IT DURING THE 
DAYLIGHT HOURS. NEW CONVECTION HAS DEVELOPED AROUND THE ALLEGED 
CENTER...BUT NORTHERLY UPPER-LEVEL SHEAR IS MAKING IT DIFFICULT TO 
LOCATE THE LOW-LEVEL CIRCULATION CENTER.  SHIP MZFK4 HAS BEEN 
TRAVERSING THE CENTER OF THE DEPRESSION THE PAST 12 HOURS OR SO AND 
HAS PROVIDED VALUABLE DATA TO HELP BETTER ASCERTAIN WHERE THE CENTER 
OF THE NORTH-SOUTH ELONGATED CIRCULATION IS LOCATED. HOWEVER...THE 
INITIAL POSITION IS BASED MAINLY ON PERSISTENCE AND CONTINUITY WITH 
THE PREVIOUS FORECAST TRACK UNTIL VISIBLE IMAGERY BECOMES AVAILABLE. 
THE INITIAL INTENSITY IS MAINTAINED AT 25 KT BASED ON TAFB AND SAB 
SATELLITE ESTIMATES.
 
THE INITIAL MOTION ESTIMATE IS 285/10.  THERE REMAINS CONSIDERABLE
UNCERTAINTY IN THE EXACT LOCATION OF THE LOW-LEVEL CENTER AND A NEW
CENTER MAY FORM FARTHER SOUTH AND CLOSER TO THE DEEPER CONVECTION.
HOWEVER...THE OVERALL TREND SHOULD BE FOR THE CYCLONE TO TRACK
WESTWARD FOR THE NEXT 24 TO 36 HOURS AND THEN TURN MORE TOWARD THE
WEST-NORTHWEST OR NORTHWEST AFTER THAT AS THE SYSTEM ROUNDS THE
SOUTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE.  WITH THE EXCEPTION OF
THE MORE NORTHERLY NOGAPS AND THE GFDN MODELS...THE REST OF THE NHC
MODEL GUIDANCE IS NOW TIGHTLY CLUSTERED AROUND THE PREVIOUS NHC
FORECAST TRACKS THROUGH 36 HOURS.  THE OFFICIAL TRACK IS CLOSE TO
THE GFDL-AVN-UKMET CONSENSUS THROUGH 48 HOURS...AND THEN FOLLOWS THE
AVN AND GFDL SCENARIO OF TAKING A RAPIDLY WEAKENING SYSTEM MORE
WESTWARD AFTER THAT. 

NONE OF THE GLOBAL OR REGIONAL MODELS HAVE HANDLED THE UPPER-LEVEL 
FLOW VERY WELL. NORTHERLY SHEAR IS EXPECTED TO REMAIN ON THE SYSTEM 
THROUGH AT LEAST THE NEXT 24 HOURS AND THEN BECOME MORE EASTERLY 
AFTER THAT. MID-LEVEL DRY AIR INTRUSION SHOULD ALSO CONTINUE FOR THE 
NEXT 24 HOURS OR SO. BY THE TIME THE CYCLONE MOVES INTO A MORE 
FAVORABLE UPPER-LEVEL ENVIRONMENT IN 36 TO 48 HOURS...IT MAY BE 
APPROACHING COOLER SSTS. IF THE DEPRESSION TAKES A MORE WESTERLY 
TRACK THAN THE OFFICIAL FORECAST IS INDICATING...THEN IT WOULD 
REMAIN OVER WARMER WATER A LITTLE LONGER AND THE SYSTEM COULD STILL 
BECOME A HURRICANE IN 48 TO 72 HOURS.
 
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     11/1500Z 14.5N 111.0W    25 KTS
12HR VT     12/0000Z 14.7N 112.5W    30 KTS
24HR VT     12/1200Z 15.0N 114.1W    35 KTS
36HR VT     13/0000Z 15.7N 115.5W    45 KTS
48HR VT     13/1200Z 16.7N 117.0W    55 KTS
72HR VT     14/1200Z 18.0N 118.5W    55 KTS
 
 
NNNN