ZCZC MIATCDAT1 ALLTTAA00 KNHC DDHHMMTROPICAL DEPRESSION ONE SPECIAL DISCUSSION NUMBER 1NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010600 PM EDT FRI JUN 25 2010THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING THEDISTURBANCE IN THE WESTERN CARIBBEAN SEA HAS FOUND A WELL-DEFINEDCIRCULATION CENTER WITH A MINIMUM CENTRAL PRESSURE OF AROUND 1004MB. BASED ON DATA FROM THE AIRCRAFT...ADVISORIES ARE BEINGINITIATED ON TROPICAL DEPRESSION ONE AT THIS TIME. THE INITIALINTENSITY IS SET AT 30 KT BASED ON A BLEND OF WIND DATA FROM THEAIRCRAFT AND SURROUNDING OBSERVATIONS.THE DEPRESSION IS VERY CLOSE TO TROPICAL STORM STRENGTH...ANDCONDITIONS APPEAR FAVORABLE FOR SOME INTENSIFICATION BEFORE ITREACHES THE YUCATAN PENINSULA IN A DAY OR SO. AFTER WEAKENING OVERLAND...THE CYCLONE COULD REGAIN SOME STRENGTH WHEN IT ENTERS THESOUTHERN GULF OF MEXICO. THE OFFICIAL INTENSITY FORECAST IS CLOSETO THE DECAY SHIPS MODEL...WHICH INCLUDES THE EFFECTS OFINTERACTION WITH THE YUCATAN PENINSULA.THE INITIAL MOTION IS RATHER UNCERTAIN BUT THE BEST ESTIMATE IS300/09. A MID-LEVEL RIDGE IS FORECAST TO PERSIST OVER THE GULF OFMEXICO FOR THE NEXT 48 TO 72 HOURS...THEREFORE A GENERALWEST-NORTHWESTWARD MOTION IS EXPECTED DURING THAT TIME...WHICHSHOULD BRING THE CYCLONE ACROSS THE YUCATAN PENINSULA AND INTO THESOUTHERN GULF OF MEXICO. AFTER 72 HOURS THE TRACK MODEL GUIDANCEDIVERGES...WITH ONE GROUP...INCLUDING THE HWRF AND GFDL...TAKINGTHE SYSTEM ON A MORE NORTHERLY OR NORTHEASTERLY TRACK. A SECONDGROUP OF GUIDANCE...INCLUDING THE GFS...ECMWF AND NOGAPS KEEPS THESYSTEM ON A MORE WESTERLY TRACK OVER THE SOUTHERN GULF OF MEXICO. THE OFFICIAL FORECAST IS A BLEND OF THESE TWO.A TROPICAL STORM WARNING IS REQUIRED FOR THE EAST COAST OF THEYUCATAN PENINSULA AT THIS TIME. IF THE CYCLONE MOVES SOUTH OF THEOFFICIAL FORECAST TRACK...A TROPICAL STORM WARNING FOR BELIZE MAYBE REQUIRED LATER THIS EVENING. FORECAST POSITIONS AND MAX WINDSINITIAL 25/2200Z 16.5N 83.5W 30 KT 12HR VT 26/0600Z 17.4N 84.7W 35 KT 24HR VT 26/1800Z 18.5N 86.5W 40 KT 36HR VT 27/0600Z 19.5N 88.0W 45 KT...INLAND 48HR VT 27/1800Z 21.0N 89.5W 25 KT...INLAND 72HR VT 28/1800Z 23.0N 91.5W 30 KT 96HR VT 29/1800Z 24.0N 92.5W 35 KT120HR VT 30/1800Z 25.0N 93.5W 40 KT$$FORECASTER AVILA/BRENNANNNNN
000WTNT41 KNHC 260847TCDAT1TROPICAL STORM ALEX DISCUSSION NUMBER 3NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010500 AM EDT SAT JUN 26 2010AN AIR FORCE RESERVE HURRICANE HUNTER INVESTIGATING TROPICALDEPRESSION ONE REPORTED 925 MB FLIGHT-LEVEL WINDS OF 46 KT ABOUT 90NM EAST OF THE CENTER...WHICH SUGGEST SURFACE WINDS OF NEAR 35 KT. THE STEPPED FREQUENCY MICROWAVE RADIOMETER ON THE AIRCRAFT SHOWED ALARGE AREA OF WINDS NEAR 35 KT THAT DID NOT APPEAR TO BE RAIN-CONTAMINATED. BASED ON THIS...THE DEPRESSION IS UPGRADED TOTROPICAL STORM ALEX WITH AN INITIAL INTENSITY OF 35 KT. THEAIRCRAFT DATA SUGGESTS THAT THE CIRCULATION OF ALEX REMAINSBROAD...AND THAT THE RECENTLY REPORTED CENTRAL PRESSURE OF 1004 MBMAY HAVE BEEN MEASURED IN A MESOSCALE LOW PRESSURE AREA. IT SHOULDBE NOTED THAT THE AIRCRAFT REPORTED SFMR WINDS IN EXCESS OF 40 KTWHICH APPEAR SUSPECT DUE TO RAIN CONTAMINATION.THE INITIAL MOTION REMAINS UNCERTAIN...WITH THE BEST ESTIMATE OF285/7. FOR THE NEXT 24 TO 48 HOURS ALEX IS EXPECTED TO MOVEWEST-NORTHWESTWARD OR NORTHWESTWARD TO THE SOUTH OF A LOW/MID-LEVELRIDGE CENTERED OVER THE EASTERN UNITED STATES. AFTER THAT...THELARGE-SCALE MODELS FORECAST THE RIDGE TO WEAKEN AS A DEEP-LAYERTROUGH MOVES INTO THE EASTERN U. S. THERE REMAINS A SIGNIFICANTSPREAD IN THE MODEL GUIDANCE ON HOW THIS EVOLUTION WILL AFFECTALEX. THE GFS...GFS ENSEMBLE MEAN...AND THE GFDL SHOW ENOUGH OF ABREAK IN THE RIDGE TO STEER ALEX NORTHWARD TOWARD THE NORTHWESTERNGULF COAST. THE ECMWF...NOGAPS...AND UKMET SHOW THE RIDGE REMAININGSTRONG ENOUGH TO STEER ALEX GENERALLY WESTWARD INTO NORTHEASTERNMEXICO. THE HWRF AND THE CANADIAN MODELS ARE BETWEEN THESEEXTREMES. OVERALL...THE GUIDANCE ENVELOPE HAS SHIFTED WESTWARDSINCE THE LAST ADVISORY...SO THE NEW FORECAST TRACK WILL BE NUDGEDWESTWARD AS WELL. HOWEVER...THE NEW TRACK IS STILL A LITTLE TO THERIGHT OF THE CENTER OF THE GUIDANCE ENVELOPE AND THE VARIOUSCONSENSUS MODELS. IT IS IN BEST OVERALL AGREEMENT WITH THE HWRF.THE LARGE-SCALE MODELS FORECAST ALEX TO BE NEAR OR UNDER A LARGEUPPER-LEVEL ANTICYCLONE THROUGH THE FORECAST PERIOD...WHICH SHOULDCAUSE AN ENVIRONMENT OF LIGHT VERTICAL WIND SHEAR. AS A RESULT...ALEX IS FORECAST TO INTENSIFY AS LONG AS IT REMAINS OVER WATER. THE NEW INTENSITY FORECAST CALLS FOR A 50 KT INTENSITY AS THECENTER REACHES THE COAST OF BELIZE OR THE YUCATAN PENINSULA...FOLLOWED BY WEAKENING OVER LAND. THE GFDL...SHIPS...AND LGEMMODELS FORECAST ALEX TO BE A HURRICANE OVER THE GULF OF MEXICO. THE INTENSITY FORECAST WILL NOT YET DO THAT...BUT WILL CALL FORMORE STRENGTHENING OVER THE GULF THAN THE PREVIOUS FORECAST.FORECAST POSITIONS AND MAX WINDSINITIAL 26/0900Z 16.9N 84.9W 35 KT 12HR VT 26/1800Z 17.4N 86.3W 45 KT 24HR VT 27/0600Z 18.4N 88.0W 50 KT 36HR VT 27/1800Z 19.4N 89.5W 35 KT...INLAND 48HR VT 28/0600Z 20.5N 90.5W 30 KT...OVER WATER 72HR VT 29/0600Z 22.5N 92.5W 35 KT 96HR VT 30/0600Z 24.0N 94.0W 45 KT120HR VT 01/0600Z 24.5N 95.5W 60 KT$$FORECASTER BEVEN