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#29870 (Received by flhurricane at: 5:26 AM 04.Jul.2005) TCDAT3 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 |