000 AXNT20 KNHC 210546 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI SEP 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... TROPICAL STORM NADINE IS CENTERED NEAR 35.3N 27.5W AT 21/0600 UTC OR ABOUT 175 NM SSW OF THE AZORES MOVING ESE AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 981 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SCATTERED MODERATE CONVECTION IS FROM 34N-40N BETWEEN 27W-32W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/ WTNT34 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. AN UPPER LEVEL LOW IS CENTERED NEAR 32N55W AND SUPPORTS A 1006 MB SURFACE LOW COLLOCATED WITH THE UPPER LEVEL LOW. LATEST SATELLITE IMAGERY INDICATES THE CIRCULATION OF THE LOW PRESSURE AREA REMAINS BROAD AS IT CONTINUES TO ORGANIZE. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS. WIDELY SCATTERED MODERATE CONVECTION IS FROM 28N-36N BETWEEN 51W-58W. ISOLATED MODERATE CONVECTION IS ELSEWHERE FROM 35N-38N BETWEEN 48W-54W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 12N35W TO 19N34W MOVING W AT 15 KT. GLOBAL MODEL DATA INDICATES THE WAVE AXIS COINCIDES WITH A 700 MB TROUGH ALONG 35W AND REMAINS WITHIN AN AREA OF MAXIMUM TOTAL PRECIPITABLE WATER FROM 14N-18N BETWEEN 28W-41W. ISOLATED MODERATE CONVECTION IS FROM 14N-17N BETWEEN 36W-41W. TROPICAL WAVE EXTENDS FROM 14N59W TO 20N53W MOVING W AT 15 KT. THE WAVE CONTINUES TO STRETCH IN A NE TO SW ORIENTATION DUE TO AN UPPER LEVEL LOW AND TROUGH ACROSS THE CENTRAL ATLC BETWEEN 53W-62W. THIS AREA IS RICH IN DEEP LAYER MOISTURE AS NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION IS FROM 16N-18N BETWEEN 54W-57W. TROPICAL WAVE EXTENDS FROM 14N82W TO 22N80W MOVING W AT 10-15 KT. OVER THE PAST 24 HOURS...THE WAVE HAS MOVED INTO CLOSER PROXIMITY OF AN UPPER LEVEL TROUGH ACROSS THE GULF OF MEXICO AND HAS INCREASED DEEP LAYER MOISTURE ACROSS THE NW CARIBBEAN SEA AND PORTIONS OF THE THE SE GULF OF MEXICO PER TOTAL PRECIPITABLE WATER IMAGERY. LOW-LEVEL CYCLONIC FLOW IS EVIDENT AND GLOBAL MODEL DATA INDICATES A WEAK 700 MB TROUGH ALONG 83W ON THE SOUTHERN PERIPHERY OF A MIDDLE TO UPPER LEVEL RIDGE CENTERED OVER THE SW NORTH ATLC REGION. SCATTERED MODERATE CONVECTION IS FROM 17N-23N BETWEEN 80W-86W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 19N16W TO 12N21W TO 08N32W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N32W TO 06N54W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 05N-09N BETWEEN 11W-21W...AND FROM 04N-08N BETWEEN 24W-34W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE GREAT LAKES REGION SOUTHWARD TO THE SE CONUS AND OVER MUCH OF THE GULF. AS OF 21/0300 UTC...THE TROUGHING SUPPORTS A STATIONARY FRONT ANALYZED ACROSS THE CENTRAL FLORIDA PENINSULA TO NEAR THE TAMPA BAY REGION. WHILE THE SURFACE FRONT HAS BECOME MORE AND MORE DIFFUSE OVER THE GULF WATERS THIS EVENING...LOW-LEVEL MOISTURE CONTENT REMAINS ELEVATED S OF 29N E OF A SURFACE TROUGH ANALYZED FROM 28N94W TO 20N93W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING MAINLY S OF 28N E OF 92W...WITH THE MOST INTENSE ACTIVITY LOCATED IN THE VICINITY OF THE FLORIDA KEYS AND YUCATAN CHANNEL. MOST OF THIS CONVECTION IS LIKELY ENHANCED DUE TO MAXIMIZED MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL TROUGH AXIS WHICH LIES ALONG 92W. WATER VAPOR IMAGERY INDICATES THAT DRY AIR ALOFT N OF 21N W OF 92W IS PREVENTING THE DEVELOPMENT OF ANY SIGNIFICANT DEEP CONVECTION. LOOKING TO THE WEEKEND...THE SURFACE TROUGH IS EXPECTED TO REMAIN ACROSS PORTIONS OF THE WESTERN GULF WITH SURFACE RIDGING ESTABLISHING ITSELF OVER THE NORTHERN GULF WATERS WITH AXIS ALONG 29N. CARIBBEAN SEA... WHILE A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE GULF OF MEXICO...AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NORTH OF EASTERN CUBA NEAR 21N76W AND PROVIDES INFLUENCE SOUTHWARD ACROSS MUCH OF THE WESTERN CARIBBEAN. WHILE MOSTLY FAIR CONDITIONS ARE FOUND ACROSS PORTIONS OF THE CENTRAL CARIBBEAN BETWEEN 68W-76W...MIDDLE TO UPPER LEVEL DIFFLUENCE IS MAXIMIZED BETWEEN THE TROUGH AND RIDGE GENERATING SCATTERED SHOWERS AND TSTMS N OF 16N W OF 76W. ADDING THE LOW-LEVEL MOISTURE CONVERGENCE ASSOCIATED WITH THE TROPICAL WAVE ALONG 81W...CONVECTION REMAINS ENHANCED OVER THE NW CARIBBEAN FROM 17N-23N BETWEEN 80W-87W THIS EVENING. FINALLY...EAST OF THE UPPER LEVEL ANTICYCLONE...AN UPPER LEVEL LOW IS CENTERED NEAR 15N60W AND IS PROVIDING THE EASTERN CARIBBEAN WITH DRIER AND MORE STABLE AIR ALOFT E OF 72W. HOWEVER...A FEW ISOLATED LOW- TOPPED SHOWERS ARE OCCURRING SOUTH OF PUERTO RICO FROM 14N-18N BETWEEN 65W-69W. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH IS ACROSS THE EASTERN CONUS AND SUPPORTS A STATIONARY FRONT ANALYZED FROM 32N74W TO THE CENTRAL FLORIDA PENINSULA NEAR 28N81W. WATER VAPOR IMAGERY INDICATES DEEP LAYERED MOISTURE ADVECTION FROM THE NORTHWESTERN CARIBBEAN SEA NORTH-NORTHEASTWARD TO THE CANADIAN MARITIMES OF NOVA SCOTIA AND NEWFOUNDLAND THAT SUPPORTS SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS WEST OF 74W. FARTHER EAST OVER THE CENTRAL ATLC...THE SPECIAL FEATURES LOW CONTINUES TO INFLUENCE THE AREA N OF 20N BETWEEN 47W-64W. WIDELY SCATTERED SHOWERS AND TSTMS ARE OCCURRING WELL SE OF THE SPECIAL FEATURES LOW FROM 20N-28N BETWEEN 47W-56W. ALSO...CYCLONIC WINDS AND CONVECTION ASSOCIATED WITH TROPICAL STORM NADINE ARE LOCATED N OF 28N BETWEEN 16W-35W IMPACTING THE AZORES. ELSEWHERE THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH CENTERED NEAR 24N39W. THE SURFACE RIDGE AXIS EXTENDS FROM THE HIGH CENTER NORTHWARD TO BEYOND 32N42W AND EASTWARD TO THE CANARY ISLANDS NEAR 28N16W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN