000 AXNT20 KNHC 150004 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 14 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... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 26W/27W SOUTH OF 18N MOVING WEST 10 TO 15 KT. THIS WAVE CONTINUES TO EXHIBIT A RATHER CLASSIC APPEARANCE IN SATELLITE IMAGERY WITH AN INVERTED V PATTERN AND CLEAR CYCLONIC TURNING NOTED IN THE LOW CLOUD FIELD. SHOWER AND TSTM ACTIVITY REMAINS DISORGANIZED WITH SW SHEAR OVER THE AREA N OF 10N. THE MOST CONCENTRATED AREA OF SCATTERED TSTM ACTIVITY IS WITHIN 90NM EITHER SIDE OF THE AXIS N OF 13N. SCATTERED SHOWERS AND TSTMS ARE ELSEWHERE WITHIN 250NM EITHER SIDE OF THE AXIS S OF 10N. AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 46W SOUTH OF 16N MOVING WEST 10 TO 15 KT. WHILE NOT AS WELL DEFINED AS THE WAVE FURTHER E...A LOW AMPLITUDE CYCLONIC SWIRL REMAINS EVIDENT FROM 9N-14N WITHIN 120NM EITHER SIDE OF THE AXIS. SCATTERED SHOWERS AND TSTMS ARE WITHIN 90 NM EITHER SIDE OF THE AXIS FROM 10N-12N...WITH MINIMAL ACTIVITY NOTED ELSEWHERE NEAR THE WAVE. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W...WITH A 1006 MB LOW PRESSURE CENTER ALONG IT NEAR 13N MOVING W NEAR 10 KT. THE CIRCULATION ASSOCIATED WITH THE LOW IS FAIRLY WELL DEFINED...THOUGH THE SURROUNDING SHOWER AND TSTM ACTIVITY REMAINS DISORGANIZED. SCATTERED MODERATE TO STRONG CONVECTION IS DISPLACED WITHIN 250 NM W OF THE AXIS FROM 11N-17N...DUE TO STRONG E/NE SHEAR OVER THE AREA. THIS ACTIVITY IS APPROACHING THE COAST OF NICARAGUA. THIS SYSTEM IS EXPECTED TO CONTINUE MOVING WESTWARD WITHOUT SIGNIFICANT DEVELOPMENT DUE TO THE STRONG UPPER-LEVEL WINDS. ...THE ITCZ... AXIS CENTERED ALONG 6N11W 7N25W 8N44W 11N56W 10N63W. BESIDES FOR THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS WITHIN 90 NM S OF THE AXIS BETWEEN 13W-21W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ALSO AFFECTING THE WATERS NEAR TRINIDAD AND NE VENEZUELA FROM 7N-12N W OF 58W. DISCUSSION... THE GULF OF MEXICO... THE GULF REMAINS TRANQUIL OVERALL THIS EVENING WITH DEEP CONVECTION AT A MINIMUM DUE TO A PERSISTENT MID TO UPPER LEVEL CAP. WV IMAGERY SHOWS VERY DRY/STABLE AIR OVER THE ENTIRE GULF EXCEPT FOR THE FAR SE PORTION AND NEAR THE YUCATAN CHANNEL. THE SFC TROUGHING EXTENDING N FROM THE LOW IN THE NW CARIBBEAN IS GENERATING SCATTERED SHOWERS/ISOLATED TSTMS BETWEEN THE NRN YUCATAN PENINSULA AND THE FLORIDA KEYS. OTHER MOSTLY SHALLOW...SCATTERED SHOWER ACTIVITY NOTED IN LOW LEVEL CONFLUENT FLOW WITHIN 30NM OF THE LINE FROM THE BAY OF CAMPECHE AT 18N93W TO CORPUS CHRISTI. SIMILAR ACTIVITY NOTED ABOUT 150NM S OF MOBILE. THE LARGE SCALE SFC PATTERN REMAINS DOMINATED BY THE SRN PORTION OF HIGH PRES OVER THE OHIO RIVER VALLEY. THE INTERACTION BETWEEN THE HIGH AND THE LOW PRES OVER THE NW CARIB IS PRODUCING MODERATE NE TO E WINDS FOR THE ERN GULF THAT BEND MORE SE IN THE WRN PORTION. SCATTERED SHOWER ACTIVITY EXPECTED TO SPREAD NW INTO THE MIDDLE GULF FROM THE CARIBBEAN OVER THE NEXT DAY OR SO. THE CARIBBEAN SEA... A PERSISTENT SFC LOW REMAINS JUST OFF THE YUCATAN PENINSULA...ANALYZED 1007 MB NEAR 18N86W AT 1800 UTC. THIS IS SPREADING SCATTERED SHOWERS AND TSTMS INLAND AND OVER THE GULF OF HONDURAS FROM 15N-21N MAINLY W OF 85W. THIS SYSTEM IS EXPECTED TO MOVE OVER THE YUCATAN PENINSULA TONIGHT AND TOMORROW WITH LITTLE DEVELOPMENT. HOWEVER...LOCALLY HEAVY RAINS ARE STILL POSSIBLE OVER PORTIONS OF CENTRAL AMERICA AND SOUTHEASTERN MEXICO TONIGHT AND TOMORROW. ANOTHER SFC LOW IS NEAR 13N77W ASSOCIATED WITH A TROPICAL WAVE...AND IS SPREADING SHOWERS AND TSTMS WWD TOWARDS NICARAGUA. SEE TROPICAL WAVE SECTION ABOVE FOR DETAILS. AN UPPER-LEVEL LOW IS LOCATED NEAR THE ABC ISLANDS...AND IS SUPPORTING ISOLATED TSTMS FROM 12N-18N BETWEEN 66W-71W. A FAIRLY SIGNIFICANT PLUME OF MOISTURE WITH ADDITIONAL SHOWER ACTIVITY IS IN THE UPPER DIFFLUENT ZONE TO THE E OF THE UPPER LOW...AFFECTING THE SE CARIBBEAN...TRINIDAD...NE VENEZUELA...AND THE WINDWARD ISLANDS. BASED ON SOME OF THE RECENT RAOB DATA FROM THIS AREA...THERE MAY ALSO BE A LOW AMPLITUDE TROPICAL WAVE OR SFC TROUGH IN THE VICINITY SUPPORTING THE WEATHER OVER THE SE CARIBBEAN. HOWEVER...I CURRENTLY HAVE LOW CONFIDENCE IN THIS SO WILL PROBABLY HOLD OFF ON ADDING ANOTHER WAVE TO THE 15/0000 UTC MAP AT THIS POINT. THE ATLANTIC OCEAN... A SLOW MOVING FRONTAL BOUNDARY ENTERS THE REGION NEAR 32N59W AND EXTENDS SW TOWARD THE CENTRAL BAHAMAS AND STRAITS OF FLORIDA TO 24N79W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE GENERALLY WITHIN 120 NM OF THE BOUNDARY. DIFFLUENT FLOW ALOFT BETWEEN TROUGHING JUST OFF THE EAST COAST AND AN UPPER HIGH NEAR 27N56W IS ALSO SUPPORTING THIS ACTIVITY. THE COMBINATION OF LOW-LEVEL CONVERGENCE AND A PLENTIFUL AMOUNT OF UPPER MOISTURE...ADVECTED BY STRONG SWLY FLOW...IS PRODUCING ABUNDANT CLOUDINESS ELSEWHERE BETWEEN THE SE BAHAMAS AND BERMUDA. THE TIGHTENED PRES GRADIENT BETWEEN THE FRONT...LOW PRES IN THE CARIB AND HIGH PRES OVER THE OHIO RIVER VALLEY IS PRODUCING MODERATE TO FRESH NE-E WINDS ACROSS PORTIONS OF THE SW NORTH ATLC...NW BAHAMAS AND S FLORIDA. THESE WINDS GENERALLY EXPECTED TO PERSIST THROUGH MON. CONDITIONS ARE FAIRLY TRANQUIL ACROSS MUCH OF THE REMAINDER OF THE CENTRAL AND E ATLC. THE SFC PATTERN IS CONTROLLED BY RIDGING EXTENDING S/SW FROM A 1023 MB HIGH SITUATED OVER THE AZORES NEAR 39N28W. THIS IS PRODUCING MOSTLY LIGHT WINDS OVER THE SUBTROPICAL E AND CENTRAL ATLC...WHILE MODERATE TRADES PERSIST IN THE TROPICS. THE UPPER PATTERN OVER THE E ATLC CONSISTS OF A LARGE SCALE UPPER TROUGH. A SWLY JET BRANCH ORIGINATES JUST AHEAD OF THE BASE OF THE TROUGH OVER THE TROPICAL ATLC AND EXTENDS NE TO AFRICA NEAR 22N17W. THIS JET IS SHEARING THE TROPICAL WAVES ALONG 27W AND 46W AND SPREADING HIGH LEVEL CLOUDINESS ACROSS THE TROPICAL E ATLC. $$ WILLIS