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Tropical Storm BILL


ZCZC MIATCDAT3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM BILL DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 AM EDT SUN JUN 29 2003

VISIBLE SATELLITE IMAGES SHOW THAT A LOW CLOUD CIRCULATION CENTER
HAS FORMED OVERNIGHT TO GO ALONG WITH THE DEEP CONVECTION THAT HAS
PERSISTED FOR A SEVERAL DAYS.  THE SHIP H3GQ REPORTED 38 KNOTS IN
THE DEEP CONVECTION AT 12Z.  THE SHIP IS LOCATED ABOUT 150 N MI
NORTHEAST OF THE CENTER.  WITH THE CONVECTION AND STRONGEST WINDS
LOCATED RATHER FAR FROM THE CENTER...THIS CYCLONE MIGHT BE
CLASSIFIED AS SUBTROPICAL...BUT SINCE THE ORIGINS OF THE WEATHER
WERE TROPICAL...A TROPICAL DESIGNATION IS USED.  

THE INITIAL MOTION ESTIMATE IS 320/14 ALTHOUGH THIS IS HIGHLY
UNCERTAIN SINCE THERE IS NO GOOD HISTORY TO THE LOW LEVEL CENTER. 
THE GUIDANCE IS IN GOOD AGREEMENT ON A TRACK TURNING NORTHWARD
AROUND THE WESTERN PERIPHERY OF A MID LEVEL HIGH PRESSURE RIDGE
THAT EXTENDS EASTWARD FROM THE EASTERN GULF OF MEXICO.  THE
GUIDANCE IS ALSO IN GOOD AGREEMENT ABOUT A SLOWER FORWARD SPEED
THAT THE 14 KNOTS USED FOR THE INITIAL MOTION AND THE FORECAST
TRACK FOLLOWS THIS.

THE OFFICIAL WIND SPEED IS 35 KNOTS BASED ON THE SHIP REPORT
MENTIONED ABOVE.  WITH WEAK VERTICAL SHEAR AND WARM SSTS...THE
SHIPS MODEL BRINGS THE WIND SPEED TO 55 KNOTS IN 48 HOURS.  THE
OFFICIAL FORECAST BACKS OFF A LITTLE TO 50 KNOTS SINCE NONE OF THE
GLOBAL MODELS SHOW ANY STRENGTHENING BEFORE LANDFALL. 
 
FORECASTER LAWRENCE
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/1500Z 23.5N  91.5W    35 KT
 12HR VT     30/0000Z 24.9N  92.8W    40 KT
 24HR VT     30/1200Z 26.8N  93.8W    45 KT
 36HR VT     01/0000Z 28.7N  94.2W    50 KT
 48HR VT     01/1200Z 30.2N  94.2W    30 KT...INLAND
 72HR VT     02/1200Z 31.3N  93.3W    25 KT...INLAND
 96HR VT     03/1200Z 32.3N  90.8W    20 KT...INLAND
120HR VT     04/1200Z...DISSIPATED INLAND
 
 
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