000 AXNT20 KNHC 302343 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU AUG 30 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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 NEAR 29W S OF 21N MOVING W ABOUT 10 KT WITH A 1011 MB LOW NEAR 14N29.5W. THIS WAVE STILL APPEARS TO BE INTO FAR ATLANTIC MONSOON CYCLONIC GYRE THAT IS OBSERVED FROM 10N-18N BETWEEN 27W-34W. CONVECTION REMAINS VERY MINIMAL WITH ONLY ISOLATED SHOWERS AND TSTMS WITHIN 150 NM NW OF THE LOW. BROKEN LOW AND MID CLOUDS WITH ISOLATED SHOWERS ARE SEEN WITHIN 300 NM W OF THE WAVE. TROPICAL WAVE IS ALONG 52W/53W S OF 18W MOVING W 15 KT WITH A 1010 MB LOW ON THE WAVE AXIS NEAR 11N53W. RECENT SATELLITE IMAGERY SHOWS THAT THE OVERALL CLOUD STRUCTURE OF THIS WAVE HAS BECOME BETTER DEFINED WITH MORE REPRESENTATION OF CYCLONIC TURNING NOTED IN THE LOW CLOUDS SWIRLING INTO THE LOW. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM NE OF THE LOW. ISOLATED SHOWERS AND TSTMS ARE ELSEWHERE WITHIN 180 NM W OF THE WAVE FROM 11N-14N. THE CIMSS 850 MB WAVETRACKER CONTINUES TO VERY WELL DISPLAY 850 MB VORTICITY ASSOCIATED WITH THE LOW AS IN PREVIOUS DAYS. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION OVER THE NEXT COUPLE OF DAYS AS IT NEARS THE EASTERN CARIBBEAN SEA. TROPICAL WAVE IS ALONG 75W/76W S OF 23N MOVING W 10-15 KT. LAST VISIBLE SATELLITE IMAGERY SHOWED SOMEWHAT OF A GRADUAL INVERTED V SHAPE PATTERN TO THE LOW CLOUD FIELD ASSOCIATED WITH THE WAVE N OF 13N BETWEEN 74W-77W WHICH WAS DIFFICULT TO SEE 24 HOURS AGO. THE NORTHERN PART OF THE WAVE CONTINUES TO BE MASKED BY THE UPPER LEVEL TROUGH NNE OF HISPANIOLA. SCATTERED MODERATE CONVECTION IS SEEN WITHIN 120 NM W OF THE WAVE AXIS FROM 14N-16N...WHILE ISOLATED SHOWERS AND TSTMS ARE ELSEWHERE WITHIN 180 NM W OF THE WAVE S OF 17N. THE TROPICAL WAVE THAT MOVED ACROSS THE BAY OF CAMPECHE THE PAST 18-24 HRS IS NOW ANALYZED AS A 1012 MB LOW JUST INLAND THE MEXICAN COAST NEAR 20N96W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM NE OF THE LOW. LOW LEVEL CLOUDS MOVING NW ARE SEEN FEEDING INTO THIS SYSTEM OFF THE WESTERN YUCATAN PENINSULA. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 15N16W 14N28W 9N35W 10N45W 11N53W TO INLAND S AMERICA NEAR 9N63W. IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 33W-37W. ISOLATED SHOWERS AND TSTMS ARE WITHIN 120 NM S OF THE AXIS BETWEEN 45W-50W. DISCUSSION... GULF OF MEXICO... UNSETTLED WEATHER COVERS MUCH OF THE SW AND S/CENTRAL PORTIONS OF THE GULF PRIMARILY DUE TO THE AFOREMENTIONED 1012 MB LOW NEAR 20N96W AND AND ABUNDANT MID/UPPER LEVEL TROPICAL MOISTURE BEING CHANNELED ENE TO THE EAST OF THE LOW UNDER A WEAK UPPER DIFFLUENT PATTERN ASSOCIATED WITH MID/UPPER LEVEL TROUGHING THAT STRETCHES FROM NEAR SE LOUISIANA SOUTHWESTWARD TO 23N96W. ASSOCIATED CONVECTION IS DESCRIBED ABOVE UNDER TROPICAL WAVES WITH 1012 MB LOW. WEAK ANTICYCLONIC FLOW COVERS THE GULF TO THE W OF THE MID/UPPER LEVEL TROUGH. LIGHT TO MODERATE WINDS WITH THE RIDGE ARE SPREADING UPPER LEVEL DEBRIS CLOUDINESS FROM SCATTERED MODERATE CONVECTION OCCURRING ALONG AND INLAND THE TEXAS COAST SOUTHWESTWARD TOWARDS SOUTHERN TEXAS AND NORTHERN MEXICO. BROKEN TO SCATTERED LOW AND MID LEVEL CLOUDS WITH SCATTERED SHOWERS AND ISOLATED TSTMS ARE ELSEWHERE S OF 26N AND WEST OF 85W. SCATTERED LOW CLOUDS WITH ISOLATED SHOWERS AND TSTMS ARE OVER THE REMAINDER OF THE GULF W OF 84W. PRECIP POTENTIAL GUIDANCE INDICATES THAT UNSETTLED WEATHER CAN BE EXPECTED FOR THE MUCH OF THE WESTERN GULF DURING THE NEXT 2-3 DAYS AS TROPICAL MOISTURE ATTENDING THE TROPICAL WAVE AND UPPER LEVEL DIFFLUENT FLOW TO THE E OF THE WAVE CONTINUE TO PRODUCE SCATTERED SHOWERS AND TSTMS OVER THIS PART OF THE GULF. CARIBBEAN SEA... BROAD MID/UPPER LEVEL RIDGING COVERS THE NORTHWEST PORTION OF THE CARIBBEAN W OF LINE FROM WESTERN CUBA TO HONDURAS. THE SOUTHERN EXTENSION OF AN ATLANTIC MID/UPPER LEVEL TROUGH STRETCHES SOUTHWESTWARD INTO THE CARIBBEAN ACROSS HISPANIOLA TO 15N75W. ASSOCIATED BROAD CYCLONIC FLOW COVERS THE AREA S OF 18N BETWEEN 70W-79W. THE MID/UPPER FLOW IS GENERALLY CONFLUENT BETWEEN THE ANTICYCLONE AND THE TROUGH ADVECTING A NLY SURGE OF SOMEWHAT DRIER WSW OVER THE WESTERN CARIBBEAN. AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER VENEZUELA NEAR 8N65W EXTENDS A RIDGE NORTHWESTWARD THROUGH 10N69W TO 13N72.5W. MID/UPPER SATELLITE-DERIVED WINDS INDICATE THAT UPPER LEVEL NLY WINDS ARE PRETTY LIGHT OVER THE THE CARIBBEAN...EXCEPT FOR THE WESTERN PORTION W OF 82W WHERE UPPER NLY WINDS ARE STRONGER AS WELL AS OVER THE FAR SW PORTION OF THE SEA. MOST OF THE EASTERN AND REMAINDER OF THE CENTRAL CARIBBEAN ARE UNDER RATHER DRY AIR AS AMPLE MODERATE TO STRONG SUBSIDENCE SPREADS INTO THE SEA FROM THE ATLANTIC BASIN. ONLY SCATTERED LOW CLOUDS MOVING WESTWARD ABOUT 15 KT WITH ISOLATED SHOWERS ARE FOUND THROUGHOUT THIS PART OF THE CARIBBEAN...WITH THE EXCEPTION OF S OF 14N WHERE AMPLE UPPER LEVEL DEBRIS MOISTURE FROM CONVECTION OVER THE NORTHERN PORTION OF S AMERICA IS SPREADING NORTH-NORTHEASTWARD IN ANTICYCLONIC DUE TO THE RIDGE OVER S AMERICA. ATLANTIC OCEAN... MID/UPPER LEVEL TROUGH EXTENDS FROM 32N55W SOUTHWESTWARD TO 25N61W WHERE IT IS THEN IDENTIFIED AS MID/UPPER LEVEL SHEAR AXIS SOUTHWESTWARD THROUGH 23N63W TO SMALL AND WEAK MID/UPPER LEVEL CYCLONIC CIRCULATION NEAR 21N65W...AND CONTINUES SOUTHWESTWARD FROM THERE TO HISPANIOLA. TO THE W OF THE TROUGH...THE MID/UPPER FLOW BECOMES ANTICYCLONIC FLOW WESTWARD TO THE BAHAMAS AND FLORIDA...EXCEPT FOR THE AREA N OF 25N BETWEEN 70W-75W WHERE WEAK MID/UPPER LEVEL TROUGHING IS FOUND. A 1010 MB NEARLY STATIONARY SURFACE LOW MOVING SSE 10 KT IS NEAR 30.5N 76W WITH AN ATTENDED TROUGH SW TO THE WESTERN BAHAMAS. ISOLATED MODERATE CONVECTION IS NOTED WITHIN 180 NM TO THE E AND SE OF THE LOW AND TROUGH. SCATTERED LOW CLOUDS WITH ISOLATED SHOWERS AND TSTMS MOVING S ARE N OF THE BAHAMAS...WHILE SIMILAR CLOUDS ALSO WITH ISOLATED SHOWERS AND TSTMS ARE SEEN MOVING N TO THE E OF THE BAHAMAS TO 60W. THE LOW IS FORECAST TO BEGIN TO MORE MORE E AND ENE OVER THE NEXT 3-4 DAYS. THE MID/UPPER LEVEL FLOW BECOMES ANTICYCLONIC TO THE EAST OF THE TROUGH N OF 15N BETWEEN THE TROUGH AND 48W WITH AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 23.5N53W. MODERATE SUBSIDENCE AND ASSOCIATED DRY AIR IS FOUND HERE WITH SURFACE HIGH PRES NOTED N OF 16N AND E OF 66W. A WEAK UPPER LEVEL TROUGH EXTENDS SSW INTO THE AREA THROUGH 32N39W...AND EXTENDS SW THROUGH 25N43W TO NEAR 20N48W. PATCHES OF LOW AND MID LEVEL CLOUDS MOVING WESTWARD WITH EMBEDDED ISOLATED SHOWERS ARE SEEN N OF 19N E OF 50W. BROAD MID/UPPER LEVEL RIDGING COVERS THE FAR EASTERN PORTION OF THE ATLANTIC EAST OF ABOUT 40W. A WEAK UPPER ANTICYCLONE MOVING WESTWARD IS SEEN ON SATELLITE WATER VAPOR IMAGERY TO BE NEAR 13N43W. DEEP TROPICAL MOISTURE...MOSTLY IN THE FORM OF MID AND HIGH CLOUDS...ORIGINATING FROM AFRICA IS SEEN ADVECTING WESTWARD IN DEEP EASTERLY FLOW OFF THE COAST OF AFRICA AND TO FAR EASTERN ATLANTIC. NEXT POSSIBLE TROPICAL WAVE TO EMERGE OFF THE AFRICAN COAST SHOULD TAKE PLACE IN ABOUT 2 DAYS. $$ AGUIRRE