ZCZC MIATCDAT4 ALLTTAA00 KNHC DDHHMMTROPICAL STORM DENNIS DISCUSSION NUMBER 5NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL11 PM EDT TUE JUL 05 2005 DENNIS HAS CONTINUED TO GET BETTER ORGANIZED AND HAS INTENSIFIEDDURING THE PAST 6 HOURS. A NOAA RECON REPORT AT 650 MB INDICATEDFLIGHT-LEVEL WINDS OF 45 KT IN THE NORTHEAST QUADRANT AT 05/2114ZAND A CENTRAL PRESSURE OF 1001 MB. USING ABOUT 95 PERCENT OF THEFLIGHT-LEVEL WINDS AND A T3.0/45 KT SATELLITE INTENSITY ESTIMATEFROM TAFB AND SAB SUPPORT INCREASING THE INITIAL INTENSITY TO 45KT. UPPER-LEVEL OUTFLOW REMAINS IMPRESSIVE IN ALL QUADRANTS.THE INITIAL MOTION ESTIMATE IS 295/15. DENNIS HAS SLOWED ITS FORWARDSPEED SOMEWHAT...POSSIBLY DUE TO RE-ORGANIZATION OF THE DEEPCONVECTION AROUND THE CENTER. THE NHC MODEL GUIDANCE REMAINSTIGHTLY CLUSTERED ABOUT THE PREVIOUS FORECAST TRACKS AND TAKESDENNIS BETWEEN HAITI AND JAMAICA AND THEN BETWEEN JAMAICA ANDSOUTHEASTERN CUBA THROUGH 72 HOURS AS THE CYCLONE MOVES AROUND THESOUTHWEST PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE THAT LIESEAST-WEST ACROSS THE WESTERN ATLANTIC AND FLORIDA. HOWEVER...AFTERTHAT...THE FORECAST BECOMES A LITTLE MURKY. ALL OF THE MODELSWEAKEN THE WESTERN PORTION OF THE RIDGE OVER FLORIDA AS A SHARPSHORTWAVE TROUGH OVER THE CENTRAL U.S. DIGS SOUTHEASTWARD INTO THECENTRAL GULF OF MEXICO BY DAYS 4 AND 5...BEFORE LIFTING OUT SLOWLYTO THE NORTHEAST AFTER THAT. SINCE DENNIS IS A LARGER THAN AVERAGETROPICAL CYCLONE THAT IS FORECAST TO BECOME A MAJOR HURRICANE INDAYS 3-5...THE LARGE OUTER CIRCULATION COULD ERODE THE RIDGE EVENMORE...RESULTING IN WEAKER STEERING CURRENTS THAN THE 5-8 KT THATTHE MODELS ARE FORECASTING. THE OFFICIAL TRACK IS ALMOST IDENTICALTO THE PREVIOUS FORECAST AND IS ALONG THE EXTREME EASTERN..ORRIGHT...SIDE OF THE MODEL GUIDANCE ENVELOPE. DENNIS IS EXPECTED TO REMAIN IN A VERY LOW SHEAR AND HIGH SSTENVIRONMENT..WHICH UNFORTUNATELY ARE PRIME CONDITIONS FOR PRODUCINGINTENSE HURRICANES. THE OFFICIAL INTENSITY FORECAST IS MUCH HIGHERTHAN THE PREVIOUS FORECASTS...BUT IS LESS THAN THE SHIPS AND GFDLINTENSITY MODELS...WHICH BRING DENNIS TO 108 KT IN 96 HOURS AND 113KT IN 60 HOURS...RESPECTIVELY.FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 06/0300Z 14.6N 69.2W 45 KT 12HR VT 06/1200Z 15.8N 71.3W 55 KT 24HR VT 07/0000Z 17.4N 74.0W 70 KT 36HR VT 07/1200Z 18.8N 76.5W 80 KT 48HR VT 08/0000Z 20.1N 78.8W 90 KT 72HR VT 09/0000Z 22.4N 82.4W 100 KT 96HR VT 10/0000Z 24.5N 84.5W 100 KT120HR VT 11/0000Z 27.0N 86.5W 100 KT $$NNNN
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