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| #355503 (Received by flhurricane at: 4:37 PM 27.Jun.2010) TCDAT1 TROPICAL DEPRESSION ALEX DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010 400 PM CDT SUN JUN 27 2010 SATELLITE IMAGES SHOW THAT ALEX CONTINUES TO HAVE A LARGE AND WELL-DEFINED CIRCULATION WITH PLENTY OF BANDING FEATURES. NEAR THE CENTER...HOWEVER...CONVECTION HAS DECREASED...PROBABLY DUE TO THE INFLUENCE OF LAND. THE MEXICAN NAVY SURFACE STATION AT ISLA PEREZ RECENTLY REPORTED 30 KT WINDS...SO THE INITIAL WIND SPEED IS KEPT AT 30 KT. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE ALEX THIS EVENING AFTER THE CENTER MOVES OFFSHORE. THE INITIAL MOTION OF ALEX IS A LITTLE SLOWER...WITH A 12-HR AVERAGE YIELDING AN ESTIMATE OF 300/8. THE PIVOTAL QUESTION FOR THE LONG-TERM FORECAST TRACK OF THE TROPICAL CYCLONE APPEARS TO HINGE ON THE STRENGTH OF MID-LEVEL RIDGING OVER THE NORTHERN GULF COAST. THE MODELS THAT SHOW A WEAKER RIDGE...SUCH AS THE CMC/GFS/HWRF... ALLOW THE TROPICAL CYCLONE TO TURN TOWARD THE NORTH-NORTHWEST AND NORTH AND APPROACH THE NORTHWESTERN GULF COAST IN SEVERAL DAYS. OTHER MODELS...SUCH AS THE ECMWF/UKMET/NOGAPS...HAVE A STRONGER RIDGE AND KEEP ALEX MOVING TO THE NORTHWEST OR WEST-NORTHWEST INTO MEXICO. OVERALL THE MODEL GUIDANCE HAS SHIFTED SLIGHTLY TO THE NORTH...AND THE OFFICIAL FORECAST IS A LITTLE TO THE RIGHT OF THE PREVIOUS ONE. SINCE THERE IS CONSIDERABLE MODEL SPREAD...THIS TRACK FORECAST IS THOUGHT TO BE OF BELOW-AVERAGE CONFIDENCE. WHILE THERE IS A LARGE DISAGREEMENT ON THE TRACK OF ALEX...THE GLOBAL MODELS ARE IN MUCH BETTER AGREEMENT WITH THE LARGE-SCALE ENVIRONMENT. THESE MODELS SHOW AN UPPER-RIDGE AXIS SITTING VERY NEAR THE TROPICAL CYCLONE FOR THE NEXT SEVERAL DAYS...IN A FAVORABLE POSITION FOR INTENSIFICATION. COMBINED WITH THE WARM WATERS OF THE GULF OF MEXICO...STRENGTHENING IS LIKELY...ESPECIALLY AFTER ALEX MOVES FARTHER AWAY FROM THE YUCATAN PENINSULA. GIVEN THE OVERALL ENVIRONMENTAL CONDITIONS...IT IS SURPRISING THAT THE GFDL/HWRF DO NOT SHOW MORE INTENSIFICATION...LEAVING THE SYSTEM AS A TROPICAL STORM FOR MANY DAYS. THE STATISTICAL GUIDANCE SEEMS MORE REASONABLE AND THE NHC FORECAST IS CLOSE TO THE SHIPS MODEL...AND IS NOT TOO DISSIMILAR FROM THE PREVIOUS FORECAST. FORECAST POSITIONS AND MAX WINDS INITIAL 27/2100Z 19.2N 90.9W 30 KT 12HR VT 28/0600Z 19.9N 91.8W 35 KT 24HR VT 28/1800Z 20.6N 92.6W 45 KT 36HR VT 29/0600Z 21.5N 93.3W 55 KT 48HR VT 29/1800Z 22.3N 94.2W 65 KT 72HR VT 30/1800Z 23.2N 96.3W 80 KT 96HR VT 01/1800Z 24.0N 98.5W 55 KT...INLAND 120HR VT 02/1800Z 24.5N 100.5W 20 KT...DISSIPATING INLAND $$ FORECASTER BLAKE |
