000 AXNT20 KNHC 120604 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU SEP 12 2013 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... HURRICANE HUMBERTO IS CENTERED NEAR 19.1N 29.0W AT 12/0300 UTC OR ABOUT 345 NM NW OF THE CAPE VERDE ISLANDS MOVING N AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. SCATTERED STRONG CONVECTION IS FROM 18N-20N BETWEEN 28W-30W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE REMAINDER OF THE AREA FROM 16N-23N BETWEEN 23W-32W. TROPICAL STORM GABRIELLE WAS DOWNGRADED TO TROPICAL DEPRESSION AT 12/0300 UTC. TROPICAL DEPRESSION GABRIELLE IS CENTERED NEAR 33.0N 67.0W AT 12/0300 UTC OR ABOUT 120 NM W-NW OF BERMUDA AND ABOUT 520 NM S-SE OF NANTUCKET MASSACHUSETTS MOVING W-NW AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. A SMALL AREA OF SCATTERED MODERATE CONVECTION IS WELL THE E OF THE LOW CENTER WITHIN 30 NM OF 33N BETWEEN 64W-66W. A BROAD AREA OF LOW PRESSURE OVER THE YUCATAN PENINSULA IS ANALYZED AS A SURFACE TROUGH THAT EXTENDS FROM THE S GULF OF MEXICO NEAR 24N87W OVER THE THE YUCATAN PENINSULA ALONG 21N89W TO A 1007 MB LOW NEAR 18N90W. ALTHOUGH SHOWERS/THUNDERSTORMS ARE CURRENTLY DISORGANIZED SURFACE PRESSURES ARE FALLING ACROSS THIS REGION AND THE LOW IS EXPECTED TO ENTER THE BAY OF CAMPECHE LATER TODAY WHERE ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR DEVELOPMENT. THIS DISTURBANCE IS LIKELY TO BECOME A TROPICAL CYCLONE DURING THE NEXT COUPLE OF DAYS AS LONG AS IT REMAINS FAR ENOUGH OFFSHORE. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. AN UPPER TROUGH OVER THE GULF OF MEXICO AND AN UPPER RIDGE OVER THE CARIBBEAN ARE CREATING A BROAD AREA OF INSTABILITY WITH CLUSTERS OF SCATTERED TO HEAVY SHOWERS WITH EMBEDDED THUNDERSTORMS COVERING THE AREA S OF 25N BETWEEN 80W-91W INCLUDING PORTIONS OF W CUBA...THE CAYMAN ISLANDS...YUCATAN PENINSULA...AND CENTRAL AMERICA. ...TROPICAL WAVES... NONE. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA TO THE COAST SENEGAL THEN RESUMES SW OF HURRICANE HUMBERTO NEAR 14N33W TO 9N46W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 8N51W INTO SOUTH AMERICA NEAR 6N54W. THE MONSOON TROUGH CONTINUES TO BE DISRUPTED BY HURRICANE HUMBERTO. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 6N-12N BETWEEN 14W-20W INCLUDING THE COAST OF GUINEA AND GUINEA BISSAU. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 6N-9N BETWEEN 38W-48W. A WEAK 1009 MB LOW IS CENTERED NEAR 17N52W WITH SCATTERED MODERATE STRONG CONVECTION WITHIN 75 NM OF THE CENTER IN THE SE QUADRANT. A SURFACE TROUGH IS NE OF THE LEEWARD ISLANDS EXTENDING FROM 23N64W 18N62W TO 15N56W. ISOLATED SHOWERS ARE WITHIN 90 NM EITHER SIDE OF THE TROUGH INCLUDING THE LEEWARD AND PORTION OF THE VIRGIN ISLANDS. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH EXTENDS OVER THE W GULF FROM AN UPPER LOW OVER TEXAS ALONG 26N94W TO OVER THE BAY OF CAMPECHE. AN UPPER LOW IS ALONG THE COAST OF GEORGIA AND EXTENDS AN UPPER TROUGH ACROSS THE NE GULF N OF 26N E OF 88W. AN UPPER RIDGE ANCHORED OVER THE W CARIBBEAN COVERS THE REMAINDER OF THE SE GULF. THIS IS CREATING A VERY DIFFLUENT ENVIRONMENT MAINLY FOR THE S GULF. THE SURFACE TROUGH OVER THE YUCATAN AND THE ASSOCIATED WEATHER ARE DISCUSSED IN THE SPECIAL FEATURES ABOVE. IN ADDITION...SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE IN THE BAY OF CAMPECHE S OF 21N BETWEEN MERIDA AND TUXPAN. REMNANT MOISTURE AND ACCOMPANYING SURFACE TROUGH FROM THE W ATLC EXTENDS ACROSS FLORIDA FROM BOCA RATON TO FORT MYERS TO 25N85W IN THE E GULF. SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS ARE S OF THE SURFACE TROUGH E OF 85W ACROSS FLORIDA AND THROUGH THE STRAITS OF FLORIDA. A SURFACE RIDGE EXTENDS FROM A 1021 MB HIGH OVER WESTERN NORTH CAROLINA TO OVER THE N GULF. SURFACE RIDGE WILL PERSIST THROUGH THU. THE SURFACE TROUGH/LOW IN THE SPECIAL FEATURES ABOVE IS FORECAST TO ENTER THE BAY OF CAMPECHE LATER THIS MORNING AND MOVE VERY SLOWLY W-NW AND POSSIBLY DEVELOP INTO A TROPICAL CYCLONE. CARIBBEAN SEA... AN UPPER RIDGE IS ANCHORED OVER THE NW CARIBBEAN NEAR 20N83W COVERING THE AREA W OF 77W ACROSS CUBA INTO THE SE GULF OF MEXICO. SEE THE SPECIAL FEATURES ABOVE FOR THE ACTIVITY OVER THE W CARIBBEAN ASSOCIATED WITH THE SURFACE TROUGH/LOW. AN UPPER LOW DOMINATES THE REMAINDER OF THE CARIBBEAN CENTERED NEAR 15N72W. CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS DOT THE AREA FROM 17N-20N BETWEEN 75W-79W AND FROM 11N-14N BETWEEN 60W- 70W INCLUDING THE N COAST OF COLOMBIA AND THE GULF OF VENEZUELA. A SURFACE TROUGH DISCUSSED IN THE MONSOON TROUGH/ITCZ SECTION ABOVE IS APPROACHING THE NE CARIBBEAN. MODERATE TO FRESH TRADE WINDS WILL CONTINUE ACROSS THE CENTRAL AND E CARIBBEAN THROUGH THU WHILE MODERATE SE WINDS WILL PREVAIL ACROSS THE W CARIBBEAN BEHIND THE TROUGH OVER THE YUCATAN PENINSULA. HISPANIOLA... SOME ISOLATED SHOWERS ARE POSSIBLE ACROSS THE ISLAND TONIGHT BUT LITTLE SIGN OF ANY THUNDERSTORMS OR HEAVY SHOWERS. THE UPPER TROUGH CURRENTLY COVERING THE CARIBBEAN WILL SHIFT W. SOUTHERLY SURFACE FLOW WILL THEN DOMINATE THE ISLAND BY FRI MORNING. THE WEAK SURFACE TROUGH CURRENTLY E OF THE LEEWARD ISLANDS WILL CONTINUE W CROSSING THE ISLAND ON SAT. THIS COULD INCREASE THE CHANCES OF HEAVIER SHOWERS AND THUNDERSTORMS TO HISPANIOLA LATE FRI INTO SAT. AFTERNOON HEATING COULD STILL BRING POTENTIAL SCATTERED THUNDERSTORMS THROUGH THE REMAINDER OF THE WEEKEND. ATLANTIC OCEAN... THE PRIMARY CONCERNS FOR THE ATLC BASIN TONIGHT ARE TROPICAL DEPRESSION GABRIELLE IN THE W ATLC AND HURRICANE HUMBERTO IN THE E ATLC. SEE SPECIAL FEATURES ABOVE. AN UPPER LOW IS CENTERED ALONG THE COAST OF GEORGIA WITH AN UPPER TROUGH COVERING THE W ATLC N OF 27N W OF 75W. A SURFACE TROUGH IS ALONG THE PERIPHERY FROM 30N75W 27N77W ACROSS FLORIDA INTO THE GULF OF MEXICO NEAR BOCA RATON. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 180 NM S OF THE TROUGH FROM THE BAHAMA ISLANDS TO OVER FLORIDA. CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS DOT THE REMAINDER OF THE W ATLC N OF 27N BETWEEN 74W-80W. AN LARGE ELONGATED UPPER LOW REMAINS IN THE E/CENTRAL ATLC CENTERED NEAR 23N44W BUT IS NOT PRODUCING ANY SIGNIFICANT WEATHER. THE REMAINDER OF THE ATLC IS DOMINATED BY A WEAK SURFACE RIDGE ANCHORED BY HIGHS WELL N OF THE AZORES. A WEAK PRESSURE PATTERN WILL PREVAIL ACROSS THE MOST OF THE ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW