000 AXNT20 KNHC 270604 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE OCT 27 2009 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC FOR GOES-12 IMAGES...AND THROUGH 0515 UTC FOR METEOSAT-8 IMAGES. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 16N23W ON TOP OF THE CAPE VERDE ISLANDS...TO 12N25W TO 8N25W...MOVING WESTWARD 10 KT. SHOWERS ARE POSSIBLE FROM THE AREA OF POSSIBLY-ITCZ-RELATED PRECIPITATION NEAR 7N TO 17N BETWEEN 20W AND 27W. AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 56W/57W TO THE SOUTH OF 17N MOVING WESTWARD 15 KT. AN UPPER LEVEL CYCLONIC CIRCULATION CENTER HAS BEEN MOVING ACROSS THE VIRGIN ISLANDS TO PUERTO RICO DURING THE LAST SIX HOURS. CYCLONIC FLOW AROUND THIS CENTER COVERS THE CARIBBEAN SEA AND THE ATLANTIC OCEAN FROM 10N TO 25N BETWEEN 53W AND HAITI. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS COVER THE AREA FROM 14N TO 17N BETWEEN 57W AND 61W. OTHER ISOLATED MODERATE SHOWERS ARE FROM 10N TO 21N BETWEEN 50W AND 57W. ...ITCZ... FROM AFRICA NEAR 11N15W TO 12N24W TO 9N40W TO 9N55W. STRONG SHOWERS AND THUNDERSTORMS ARE ALONG THE AFRICA COAST WITHIN A 30 NM RADIUS OF 8N13W...AND IN CLUSTERS FROM 10N TO 12N BETWEEN AFRICA AND 20W. SHOWERS ARE ELSEWHERE FROM 7N TO 13N BETWEEN AFRICA AND 20W...FROM 7N TO 11N BETWEEN 30W AND 40W... AND FROM THE EQUATOR TO 12N BETWEEN 40W AND 50W. ...DISCUSSION... THE GULF OF MEXICO... A DEEP LAYER TROUGH THAT IS MOVING THROUGH CENTRAL TEXAS AND NORTHERN MEXICO SUPPORTS THE CURRENT COLD FRONT THAT PASSES THROUGH SOUTHWESTERN LOUISIANA TO THE MEXICO GULF COAST NEAR 23N98W. A LARGE-SCALE UPPER LEVEL RIDGE IS IN THE CENTRAL GULF OF MEXICO. MOSTLY UPPER LEVEL SOUTHWESTERLY WINDS ALSO COVER THE AREA TO THE EAST OF THE APPROACHING TEXAS TROUGH. A SURFACE TROUGH GOES FROM 28N86W INTO THE NORTHEASTERN YUCATAN PENINSULA. IT IS POSSIBLE THAT THIS TROUGH IS A REMNANT OF THE DISSIPATED FRONT FROM THE LAST FEW DAYS. A TROUGH REMAINS FROM THAT FEATURE...FROM 31N79W TO 29N81W ALONG THE NORTHEASTERN FLORIDA ATLANTIC OCEAN COAST. BROKEN TO OVERCAST MULTILAYERED CLOUDS HAVE BEEN FORMING TO THE SOUTH OF 28N TO THE EAST OF 86W FOR THE LAST FEW HOURS. PRECIPITATION IS POSSIBLE IN THIS AREA OF CLOUDS. THE CARIBBEAN SEA... AN UPPER LEVEL RIDGE IS CENTERED OVER GUATEMALA NEAR 17N91W AND CONTINUES TO PROVIDE DRY AIR AND SUBSIDENCE ALOFT OVER THE NW CARIBBEAN W OF 84W AND OVER PORTIONS OF CENTRAL AMERICA. HOWEVER...UPPER LEVEL DIFFLUENCE ON THE EASTERN PERIPHERY OF THE UPPER LEVEL RIDGE IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 14N BETWEEN 78W-84W AND ACROSS PORTIONS OF CUBA. THIS ACTIVITY EXTENDS S-SW ACROSS INTERIOR EASTERN HONDURAS... NICARAGUA AND NORTHERN COSTA RICA. E OF 76W...AN UPPER LEVEL TROUGH EXTENDS WESTWARD FROM AN UPPER LEVEL LOW CENTERED OVER THE LEEWARD ISLANDS NEAR 17N60W. PRIMARILY DRY AIR ALOFT IS NOTED ACROSS THE EASTERN CARIBBEAN ON WATER VAPOR IMAGERY. MODERATE TRADE WINDS CONTINUE TO USHER IN ISOLATED LOW-LEVEL SHOWERS E OF 74W THIS EVENING. ELSEWHERE...THE ITCZ AXIS EXTENDS ACROSS PANAMA ALONG 8N AND IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 10N BETWEEN 77W-81W. THE ATLANTIC OCEAN... LARGE-SCALE UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA TO THE NORTH OF 20N TO THE WEST OF 35W. THIS ANTICYCLONIC FLOW IS ON TOP OF THE CYCLONIC FLOW THAT IS NEAR PUERTO RICO AND THE VIRGIN ISLANDS...THAT ALSO COVERS PARTS OF THE ATLANTIC OCEAN. ONE AREA OF A 700 MB-TO-500 MB VORTICITY MAXIMUM COVERS THE AREA ALONG 68W/69W NEAR 27N. CLOUDS ARE FROM 25N TO 29N BETWEEN 66W AND 71W. A SECOND AREA OF 700 MB-TO-500 MB VORTICITY MAXIMUM IS NEAR 27N54W. THIS FEATURE IS SPREADING CLOUDS FROM 25N TO 29N BETWEEN 50W AND 59W. AN EASTERN ATLANTIC OCEAN DEEP LAYER TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTER THAT IS NEAR 31N27W TO 26N29W TO 21N35W. A SHEAR AXIS CONTINUES FROM 21N35W TO 21N42W AND 22N53W. THIS AXIS EVENTUALLY FEEDS INTO THE COMPARATIVELY LARGER AREA OF CYCLONIC FLOW THAT IS MOVING AROUND THE VIRGIN ISLANDS TO PUERTO RICO DURING THE LAST SIX HOURS. A DISSIPATING COLD FRONT GOES FROM 32N21W TO 25N26W. POSSIBLE SHOWERS FROM 31N TO 32N BETWEEN 22W AND 23W. A SURFACE RIDGE IS ALONG 25N32W TO A 1023 MB HIGH PRESSURE CENTER THAT IS NEAR 31N49W... TO A SECOND 1023 MB HIGH PRESSURE CENTER THAT IS NEAR 30N64W... TO 29N73W. $$ MT