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Tropical Depression THREE (Text)

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TROPICAL DEPRESSION THREE DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON JUL 04 2005

TROPICAL DEPRESSION THREE IS SHOWING INTERESTING STRUCTURAL
DEVELOPMENTS THIS MORNING.  A STRONG AND PERSISTENT AREA OF
CONVECTION HAS FORMED NEAR THE LOW LEVEL CENTER OVER THE EAST
CENTRAL YUCATAN PENINSULA...WHICH SUGGESTS THE INNER CORE IS
GETTING BETTER ORGANIZED.  ON THE OTHER HAND...THE OVERALL
CIRCULATION IS BECOMING ELONGATED NORTH-SOUTH...WITH A SECOND
VORTICITY MAXIMUM APPARENT IN SATELLITE IMAGERY ALONG THE NORTHERN
COAST OF YUCATAN.  SATELLITE INTENSITY ESTIMATES ARE 30 KT FROM
TAFB AND 25 KT FROM AFWA...SO THE INITIAL INTENSITY WILL REMAIN 30
KT.
 
THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 310/8.  WATER VAPOR
IMAGERY AND LARGE-SCALE MODEL ANALYSES INDICATE A DEEP LAYER RIDGE
OVER FLORIDA AND THE ADJACENT WESTERN ATLANTIC...WITH A COMPLEX
MID/UPPER-LEVEL TROUGH OVER EASTERN TEXAS AND THE WESTERN GULF OF
MEXICO.  THE MODEL GUIDANCE SHOWS A WIDE RANGE OF POSSIBILITIES IN
RESPONSE TO THIS PATTERN.  THE MODELS THAT FORECAST AN ORGANIZED
TROPICAL CYCLONE...INCLUDING THE NOGAPS...GFDL...AND CANADIAN...
INDICATE THAT THE DEPRESSION SHOULD MOVE NORTHWESTWARD FOR 36-48 HR
FOLLOWED BY A NORTHWARD TURN TOWARD THE LOUISIANA OR UPPER TEXAS
COASTS BETWEEN THE RIDGE TO THE EAST AND THE TROUGH TO THE WEST. 
AN ALTERNATIVE SCENARIO IS THAT THE DEPRESSION CIRCULATION BECOMES
ELONGATED AND DISORGANIZED AS INDICATED BY THE GFS...UKMET...AND
THE BAM MODELS.  THIS WOULD ALLOW FOR A WEAKER SYSTEM TO MOVE
NORTHWESTWARD TOWARD TEXAS OR NORTHEASTERN MEXICO IN THE LOW-LEVEL
FLOW.  THE OFFICIAL FORECAST GOES WITH THE SCENARIO FOR A STRONGER
CYCLONE...CALLING FOR THE NORTHWARD TURN.  THE NEW FORECAST TRACK
IS SHIFTED SOMEWHAT TO THE EAST OF THE PREVIOUS TRACK BASED
PRIMARILY ON THE CURRENT POSITION AND MOTION.

THE INTENSITY FORECAST IS A BIT PROBLEMATIC.  NONE OF THE LARGE
SCALE MODELS FORECAST SIGNIFICANT DEVELOPMENT EVEN THOUGH ALL OF
THEM SHOW FAVORABLE UPPER-LEVEL WINDS ALONG THE FORECAST TRACK. 
THE REASON FOR THIS IS NOT CLEAR...BUT IT MAY BE THAT THE MODELS
ARE RESPONDING TO DRY AIR CURRENTLY SEEN IN WATER VAPOR IMAGERY
OVER THE NORTHWESTERN GULF OF MEXICO...OR TO THE DISTORTION OF THE
LOW-LEVEL CIRCULATION BY THE BUILDING RIDGE TO THE EAST.  ON THE
OTHER HAND...THE SHIPS MODEL FORECASTS THE CYCLONE TO REACH 50 KT
IN 72 HR...WHILE THE GFDL CALLS FOR IT TO BECOME A HURRICANE JUST
BEFORE LANDFALL.  THE INTENSITY FORECAST FOLLOWS THE SCENARIO THAT
THE CYCLONE WILL INTENSIFY OVER THE GULF OF MEXICO AND FORECASTS
THE SYSTEM TO REACH 55 KT BEFORE LANDFALL AS A COMPROMISE BETWEEN
THE GFDL AND SHIPS.  AN ALTERNATIVE SCENARIO IS THAT LITTLE OR NO
DEVELOPMENT WILL OCCUR AS FORECAST BY THE GFS AND UKMET.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/0900Z 19.6N  88.1W    30 KT...INLAND
 12HR VT     04/1800Z 20.5N  89.1W    30 KT...INLAND
 24HR VT     05/0600Z 22.4N  90.7W    30 KT...OVER WATER
 36HR VT     05/1800Z 24.1N  92.1W    40 KT
 48HR VT     06/0600Z 26.2N  93.2W    45 KT
 72HR VT     07/0600Z 29.0N  93.5W    55 KT
 96HR VT     08/0600Z 31.5N  92.5W    35 KT...INLAND
120HR VT     09/0600Z 33.0N  90.0W    25 KT...INLAND DISSIPATING
 
 
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