000 AXNT20 KNHC 242354 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAY 24 2012 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... A 1008 MB LOW PRESSURE CENTERED OVER THE UPPER FLORIDA KEYS NEAR 25N80W CONTINUES TO MOVE NORTHEAST THIS EVENING AS AN UPPER LEVEL TROUGH WITH AXIS OVER THE EASTERN GULF OF MEXICO LIFTS EAST-NORTHEASTWARD. SURFACE TROUGHING EXTENDS TO 31N77W NE OF THE LOW AND TO 20N84W SW OF THE LOW. PLENTY OF MIDDLE TO UPPER LEVEL MOISTURE ADVECTION IS NOTED ON WATER VAPOR IMAGERY OVER THE AREA 540 NM EAST OF THE SURFACE TROUGH AXIS WITH SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN TWO AREAS...ONE FROM 20N-24N BETWEEN 76W-81W...INCLUDING PORTIONS OF CENTRAL CUBA... AND THE OTHER FROM 25N-32N BETWEEN 71W-79W OVER THE SW NORTH ATLC...INCLUDING THE NW BAHAMAS. SIGNIFICANT RAINFALL IS EXPECTED WITH THIS CONVECTION OVER LAND AREAS THROUGH THE OVERNIGHT HOURS AND AN INCREASED THREAT FOR FLOODING AND POSSIBLE MUDSLIDES WILL PERSIST ACROSS PORTIONS OF CUBA. WHILE UPPER LEVEL CONDITIONS ARE NOT CURRENTLY CONDUCIVE FOR FURTHER DEVELOPMENT DUE TO STRONG WIND SHEAR...THE WIND SHEAR IS EXPECTED TO LESSEN OVER THE WEEKEND AS THE LOW MEANDERS OFF THE SOUTH CAROLINA AND GEORGIA COAST BY SUNDAY. THERE IS A MEDIUM CHANCE OF THIS SYSTEM DEVELOPING INTO A TROPICAL OR SUBTROPICAL CYCLONE OVER THE NEXT 48 HOURS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 04N40W TO 11N37W MOVING W AT 15-20 KT. THE WAVE REMAINS ON THE LEADING EDGE OF A SURGE OF DEEP LAYER MOISTURE NOTED IN TOTAL PRECIPITABLE WATER IMAGERY BETWEEN 25W-39W. THERE IS A LACK OF DEEP CONVECTION IN THE VICINITY OF THE WAVE LIKELY DUE TO SAHARAN DUST SURROUNDING THE WAVE AXIS. TROPICAL WAVE EXTENDS FROM 08N61W TO 14N60W MOVING W AT 10-15 KT. THE WAVE CONTINUES TO BE EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE IMPACTING THE SE CARIBBEAN SEA S OF 15N BETWEEN 56W-67W. WIDELY SCATTERED SHOWERS AND ISOLATED MODERATE CONVECTION ARE OCCURRING S OF 14N BETWEEN 56W-66W...INCLUDING NE VENEZUELA...THE WINDWARD ISLANDS...AND ADJACENT COASTAL WATERS IN THE SE CARIBBEAN SEA. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N13W TO 02N22W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 02N22W TO 05N32W TO 05N40W TO 02N50W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 01N-08N BETWEEN THE PRIME MERIDIAN AND 18W...AND FROM 08N-12N BETWEEN 12W-16W. ISOLATED MODERATE CONVECTION IS FROM 01N-07N BETWEEN 23W-29W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL TROUGH AXIS EXTENDS FROM THE SE CONUS NEAR 34N83W OVER THE NORTHEASTERN GULF WATERS TO A BASE NEAR 24N90W. WATER VAPOR IMAGERY INDICATES THAT DRY AIR AND SUBSIDENCE COVERS THE BASIN AND THIS DRYNESS ALOFT EXTENDS EASTWARD ACROSS THE FLORIDA PENINSULA. AS A RESULT OF THE OVERALL SUBSIDENT ATMOSPHERE...A SURFACE RIDGE AXIS EXTENDS FROM THE NE GULF TO THE FAR SW GULF IN THE BAY OF CAMPECHE. SKIES REMAIN CLEAR THROUGHOUT WITH LIGHT NE TO E WINDS E OF 90W AND E TO SE WINDS IN THE RANGE OF 15 TO 25 KT W OF 92W. THE RIDGE IS FORECAST TO SLIDE WESTWARD AND WEAKEN THROUGH SUNDAY AS THE SPECIAL FEATURES LOW PRESSURE SYSTEM DRIFTS WESTWARD FROM THE SW NORTH ATLC WATERS INLAND ACROSS NE FLORIDA AND SOUTHERN GEORGIA LATE SUNDAY THROUGH THE EARLY PART OF NEXT WEEK. GENTLE TO MODERATE BREEZE WILL DOMINATE THE GULF OVER THE WEEKEND THROUGH TUESDAY. CARIBBEAN SEA... SOUTHWESTERLY UPPER LEVEL FLOW DOMINATES OVER THE NW CARIBBEAN BETWEEN AN UPPER LEVEL TROUGH ACROSS THE EASTERN GULF OF MEXICO AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NORTH OF HISPANIOLA NEAR 21N72W. MIDDLE TO UPPER LEVEL MOISTURE CONTINUES TO ADVECT NORTHEASTWARD N OF 16N ACROSS CUBA AND INTO THE SW NORTH ATLC IN ASSOCIATION WITH THE SPECIAL FEATURES LOW CENTERED OVER THE UPPER FLORIDA KEYS. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING N OF 17N BETWEEN 74W-82W... INCLUDING PORTIONS OF CENTRAL AND EASTERN CUBA. ANOTHER AREA OF ACTIVE CONVECTION THIS EVENING IN THE FORM OF SCATTERED SHOWERS AND TSTMS IS ACROSS INLAND CENTRAL AMERICA...NAMELY NORTHERN COSTA RICA...NICARAGUA...HONDURAS...AND EL SALVADOR. FARTHER EAST...THE UPPER LEVEL ANTICYCLONE NORTH OF THE BASIN IS PROVIDING MOSTLY EASTERLY FLOW S OF 20N BETWEEN 60W-80W. WATER VAPOR IMAGERY INDICATES MOSTLY DRY AIR...HOWEVER WITH THE APPROACH OF A TROPICAL WAVE ALONG 60W...INCREASED DEEP LAYERED MOISTURE IS ACROSS THE SW CARIBBEAN AND WINDWARD ISLANDS. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING S OF 14N BETWEEN 56W-66W...INCLUDING NE VENEZUELA...THE WINDWARD ISLANDS...AND ADJACENT COASTAL WATERS IN THE SE CARIBBEAN SEA. ATLANTIC OCEAN... DIFFLUENCE ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS AND AN UPPER LEVEL RIDGE WITH AXIS ALONG 21N72W TO BEYOND 32N66W IS SUPPORTING A BROAD AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS CENTRAL AND EASTERN CUBA STRETCHING NE ACROSS MUCH OF THE SW NORTH ATLC W OF 70W. MORE DETAILS ON THIS SYSTEM ARE LOCATED IN THE SPECIAL FEATURES SECTION ABOVE. THE UPPER LEVEL RIDGE CIRCULATION SUPPORTS BROAD SURFACE RIDGING ANCHORED BY A PAIR OF 1027 MB HIGHS CENTERED NEAR 34N45W AND 35N37W THAT COVERS THE REMAINDER OF THE CENTRAL AND EASTERN ATLC E OF 70W. 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