000 AXNT20 KNHC 272347 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON SEP 27 2010 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... AN AREA OF BROAD LOW PRESSURE IS LOCATED OVER THE NW CARIBBEAN SEA FOCUSED AROUND A 1004 MB LOW CENTERED OVER NORTHERN BELIZE NEAR 18N88W. A SURFACE TROUGH EXTENDS E-SE FROM THE LOW TO 17N82W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 17N-22N BETWEEN 85W-91W...WHICH INCLUDES A LARGE PORTION OF THE YUCATAN PENINSULA. THIS AREA OF LOWER PRESSURE OVER THE NW CARIBBEAN IS WEDGED IN BETWEEN TWO UPPER LEVEL ANTICYCLONES...ONE CENTERED OVER SOUTHERN MEXICO NEAR 20N98W AND THE OTHER CENTERED OVER THE WESTERN CARIBBEAN SEA NEAR 17N79W. THESE UPPER LEVEL FEATURES ARE PROVIDING AN UPPER DIFFLUENT ENVIRONMENT OVER THE NW CARIBBEAN KEEPING CONDITIONS FAVORABLE FOR GRADUAL DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS AS IT TRACKS N-NE. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 13N16W 09N24W 08N36W THEN RESUMES NEAR 10N40W 10N50W 08N59W. A SURFACE TROUGH IS ANALYZED WITHIN THE ITCZ FROM 09N38W TO 15N35W WITH ISOLATED MODERATE CONVECTION WITHIN 90 NM WEST OF THE SURFACE TROUGH FROM 12N-15N. ELSEWHERE...SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 03N-09N BETWEEN 25W-37W. SCATTERED MODERATE CONVECTION IS ALSO FROM 06N-13N BETWEEN 42W-48W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH IS OVER THE TENNESSEE RIVER AND LOWER MISSISSIPPI RIVER VALLEYS WITH AXIS THAT EXTENDS INTO THE NORTH-CENTRAL GULF WATERS ALONG 16N86W TO 30N86W TO 25N91W. THIS UPPER LEVEL TROUGH SUPPORTS A COLD FRONT THAT ENTERS THE GULF NEAR APALACHEE BAY TO 28N85W THEN SW ALONG 24N94W TO THE MEXICO COAST NEAR TUXPAN. A PRE-FRONTAL TROUGH IS LOCATED SE OF THE COLD FRONT ANALYZED FROM 27N86W TO THE EASTERN BAY OF CAMPECHE NEAR 20N92W. WITH THE MIDDLE TO UPPER LEVEL SUPPORT STRONGEST N OF 26N...SCATTERED SHOWERS AND TSTMS ARE MAINLY CONCENTRATED OVER THE NE GULF AND FLORIDA PENINSULA THIS EVENING N OF 27N EAST OF THE COLD FRONT TO 78W IN THE W ATLC. A FEW SCATTERED SHOWERS AND TSTMS ARE ALSO S OF 27N OVER INTERIOR PORTIONS OF THE FLORIDA PENINSULA. ELSEWHERE S OF THE COLD FRONT OVER THE SW GULF...CONVERGENT LOW-LEVEL WINDS AND A DIFFLUENT UPPER LEVEL ENVIRONMENT ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 23N W OF 93W. IN THE WAKE OF THE COLD FRONT OVER THE NW GULF...STRONG NW TO N SURFACE WINDS PREVAIL SUPPORTED ALOFT BY VERY DRY AND SUBSIDENT NW FLOW. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER SOUTHERN MEXICO NEAR 20N98W THAT EXTENDS AN UPPER LEVEL RIDGE AXIS SOUTHEASTWARD TO ANOTHER UPPER LEVEL ANTICYCLONE CENTERED NEAR 17N79W. AN UPPER LEVEL RIDGE AXIS THEN EXTENDS EASTWARD TO 14N61W OVER THE REMAINDER OF THE CARIBBEAN BASIN. THIS UPPER LEVEL PATTERN IS PROVIDING A DIFFLUENT ENVIRONMENT ALOFT AND IN TURN SUPPORTS THE WIDESPREAD SHOWERS AND SCATTERED TSTMS NOTED ON SATELLITE IMAGERY MOSTLY LOCATED W OF 64W. THE MOST CONCENTRATED AREA OF CONVECTIVE ACTIVITY HOWEVER IS ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE CENTERED OVER NORTHERN BELIZE NEAR 18N88W AS A 1004 MB LOW CENTER. SCATTERED MODERATE TO STRONG CONVECTION IS MOSTLY LOCATED WITHIN 180 NM OF THE CENTER...AND OVER INTERIOR PORTIONS OF THE YUCATAN PENINSULA THIS EVENING. GLOBAL MODEL GUIDANCE IS COMING INTO BETTER AGREEMENT ON FURTHER ORGANIZATION OF THIS BROAD AREA OF LOW PRESSURE OVER THE WESTERN CARIBBEAN. WITH THE APPROACHING UPPER LEVEL TROUGH CURRENTLY IMPACTING THE EASTERN GULF OF MEXICO...CYCLOGENESIS IS FORECAST TO OCCUR OVER THE NW CARIBBEAN AND ANY SURFACE LOW...TROPICAL OR SUBTROPICAL...WILL QUICKLY MOVE N-NE OVER THE FLORIDA STRAITS AND FAR W ATLC WATERS THROUGH THURSDAY MORNING. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS OVER THE EASTERN GULF OF MEXICO PROVIDING THE W ATLC W OF 75W WITH MOIST SW UPPER LEVEL FLOW. THIS ALONG WITH AN APPROACHING COLD FRONT IS GENERATING SCATTERED SHOWERS AND TSTMS OVER THE FLORIDA PENINSULA AND W ATLC WATERS N OF 26N W OF 77W. FARTHER SE...AN UPPER LEVEL RIDGE EXTENDS TO 27N76W FROM AN ANTICYCLONIC CIRCULATION IN THE WESTERN CARIBBEAN SEA CENTERED NEAR 17N79W. THE RIDGE IS PROVIDING AN UPPER LEVEL DIFFLUENT ENVIRONMENT OVER CUBA AND THE FLORIDA STRAITS THAT IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 25N BETWEEN 79W-82W AND WITHIN 60 NM OF THE NORTHERN CUBA AND HISPANIOLA COASTLINES. SCATTERED SHOWERS EXTENDS FARTHER SE OVER THE MONA PASSAGE AND PUERTO RICO REMAINING S OF 21N BETWEEN 63W-70W. A 1015 MB LOW IS ANALYZED IN THE CENTRAL ATLC NEAR 29N60W CONTINUING TO GENERATE SCATTERED SHOWERS WITHIN 120 NM OF THE CENTER. OVER THE EASTERN ATLC...THE REMNANTS OF LISA ARE ANALYZED AS A 1015 MB LOW CENTERED NEAR 28N31W AND A SURFACE TROUGH EXTENDING NE TO 31N29W AND SW TO 25N35W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE LOCATED NORTH OF THE LOW CENTER FROM 29N-32N BETWEEN 28W-32W. OTHERWISE THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF HIGH PRESSURE N OF 18N WITH THE EXCEPTION OF BOTH WEAK LOW PRESSURE AREAS MENTIONED ABOVE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN