000 AXNT20 KNHC 030002 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU OCT 02 2008 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. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 43W S OF 18N MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A REGION OF ENHANCED DEEP LAYER MOISTURE BASED ON TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. COMPUTER MODEL GUIDANCE DEPICTS BROAD AREA OF LOW LEVEL COUNTERCLOCKWISE CIRCULATION NEAR WAVE AXIS...CONSISTENT WITH CLOUD MOTION FROM SATELLITE IMAGERY. ISOLATED SHOWERS ARE OCCURRING WITHIN 150 NM E AND W OF THE WAVE AXIS N OF 13N. TROPICAL WAVE IS ALONG 54W S OF 18N MOVING W 10-15 KT. COUNTERCLOCKWISE MOTION OF CLOUD FIELD HAS BEEN NOTED IN SATELLITE IMAGERY ALONG THE WAVE AXIS. THIS CIRCULATION COINCIDES WITH A MAXIMUM IN CIMSS WAVETRACK DERIVED LOW LEVEL CIRCULATION. ADDITIONALLY...DEEP LAYER MOISTURE IS DISTINCTLY MAXIMIZED ALONG THIS WAVE. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM E AND W OF THE WAVE AXIS S OF 12N. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 10N13W 7N25W 9N42W 11N51W 8N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS AFFECTING W AFRICA FROM 6N-14N BETWEEN 9W-17W...INCLUDING GUINEA-BISSAU... GAMBIA...AND S SENEGAL. ISOLATED MODERATE CONVECTION IS WITHIN 240 NM N AND S OF THE AXIS FROM THE W AFRICAN COAST WESTWARD TO 33W. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM N AND S OF THE AXIS BETWEEN 46W-51W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF THE ITCZ AXIS FROM 57W WESTWARD TO THE SOUTH AMERICAN COAST...IMPACTING NE VENEZUELA. ...DISCUSSION... GULF OF MEXICO... A DEEP UPPER TROUGH CONTINUES TO AFFECT THE E CONUS AND GULF REGION. STABLE AND DRY AIR IN THE BASE OF THE TROUGH...COMBINED WITH SUBSIDENCE UPSTREAM OF THE TROUGH AXIS...CONTINUE TO RESULT IN FAIR WEATHER CONDITIONS ACROSS MUCH OF THE GULF. THIS DEEP TROUGH CONTINUES TO SUPPORT A SURFACE COLD FRONT THAT EXTENDS FROM S FLORIDA NEAR 25N81W TO THE SE GULF NEAR 22N88W TO THE BAY OF CAMPECHE NEAR 19N95W. SURFACE CONVERGENCE IN THE VICINITY OF THE FRONT IS SUPPORTING BANDS OF SCATTERED LOW CLOUDS AND POSSIBLY A SHOWER WITHIN 90 NM N AND S OF THE FRONT. CARIBBEAN SEA... THE DEEP TROUGH OVER THE GULF IS BRINGING MOIST SW FLOW ALOFT TO THE NW CARIBBEAN. ALSO...A SURFACE TROUGH EXTENDS FROM CENTRAL HONDURAS NEAR 15N87W NORTHWARD TO A 1011 MB SURFACE LOW NEAR 17N85W TO CENTRAL CUBA NEAR 22N79W NORTHEASTWARD INTO THE SW ATLC. DEEP ATMOSPHERIC LIFT FROM THE COMBINATION OF THESE FEATURES IS RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS WITHIN 240 NM EITHER SIDE OF THE SURFACE TROUGH N OF 19N. ISOLATED SHOWERS AND THUNDERSTORMS ARE OCCURRING WITHIN 180 NM EITHER SIDE OF THE SURFACE TROUGH S OF 19N...IMPACTING BELIZE AND HONDURAS. FURTHER TO THE E...UPPER DIFFLUENCE IS SUPPORTING ISOLATED MODERATE CONVECTION FROM 13N-16N BETWEEN 72W-79W. OVER THE NE CARIBBEAN...AN UPPER RIDGE IS PRESENT...ANCHORED BY AN UPPER HIGHER IN THE SW ATLC NEAR 28N62W. ALSO...OVER THE SE CARIBBEAN...AN UPPER TROUGH IS PRESENT...ANCHORED BY AN UPPER LOW IN THE TROPICAL N ATLC NEAR 17N56W. BETWEEN THE UPPER RIDGE AND UPPER TROUGH...DRY EASTERLY UPPER FLOW COVERS MUCH OF THE E CARIBBEAN INCLUDING THE LESSER ANTILLES...WHERE FAIR WEATHER IS OCCURRING. SCATTERED MODERATE CONVECTION THAT FORMED OVER NW VENEZUELA...N COLOMBIA...AND PANAMA FROM LOW LEVEL CONVERGENCE CONTINUES TO PROPAGATE OVER ADJACENT LAND AREAS IN THE S CARIBBEAN. ATLANTIC OCEAN... STRONG SW FLOW ALOFT AHEAD OF A DEEP TROUGH OVER THE E CONUS CONTINUES TO IMPACT PORTIONS OF THE SW ATLC...WITH A COLD FRONT EXTENDING FROM SE FLORIDA NEAR 25N80W NORTHEASTWARD TO 28N76W TO 32N71W. DRY AND STABLE AIR IN THE BASE OF THE TROUGH CONTINUES TO SPREAD OVER THE SW ATLC TO THE NW OF THE COLD FRONT...WITH LINGERING MOISTURE TO THE SE OF THE COLD FRONT. ABOUT 150 NM TO THE SE OF THE COLD FRONT...A SURFACE TROUGH EXTENDS FROM CENTRAL CUBA NEAR 22N79W NORTHEASTWARD TO 26N75W TO 30N68W. SURFACE CONVERGENCE IS MAXIMIZED IN THE VICINITY OF THE SURFACE TROUGH...WHERE THE DEEP UPPER TROUGH IS PROVIDING ADDED UPPER SUPPORT FOR SHOWERS AND THUNDERSTORMS. SCATTERED SHOWERS AND THUNDERSTORMS ARE WITHIN 180 NM EITHER SIDE OF THE SURFACE TROUGH S OF 25N...WITH ISOLATED SHOWERS WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH N OF 25N. FURTHER TO THE E...AN UPPER HIGH IS CENTERED NEAR 28N62W...WITH ITS ASSOCIATED UPPER RIDGE EXTENDING TO THE SW NEAR HISPANIOLA...PROVIDING DRY AND STABLE ATMOSPHERIC CONDITIONS TO MUCH OF THE CENTRAL ATLC. FURTHER TO THE E...A DEEP LOW IS CENTERED NEAR 27N42W...AND IS PROVIDING SUPPORT FOR A SURFACE TROUGH THAT EXTENDS FROM 25N41W TO 27N39W TO 31N38W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH S OF 25N. TO THE E OF THE UPPER TROUGH...A BROAD UPPER TROUGH IS N OF 28N E OF 28W TO THE AFRICAN COAST. OVER THE TROPICAL ATLC...A BROAD E/W UPPER RIDGE EXTENDS FROM AFRICA ALONG 14N TO 48W DOMINATING THE E TROPICAL ATLC. TO THE W OF THIS UPPER RIDGE...AN UPPER LOW IS CENTERED NEAR 17N56W...WITH MAINLY DRY AIR SURROUNDING THIS LOW. $$ COHEN