000 AXNT20 KNHC 191747 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU SEP 19 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION HUMBERTO IS CENTERED NEAR 32.8N 43.3W AT 19/1500 UTC OR ABOUT 855 NM W-SW OF THE AZORES MOVING N-NE AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. PLEASE SEE LATEST PUBLIC ADVISORIES UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 AND THE FULL FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/ WTNT24 FOR MORE DETAILS. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 75/90 NM OF LINE FROM 28N44W TO 33N39W. AN AREA OF LOW PRESSURE IN THE SW GULF OF MEXICO IS ANALYZED AS A SURFACE TROUGH THAT EXTENDS FROM 25N95W THROUGH A 1004 MB LOW NEAR 21N94W TO THE COAST OF MEXICO NEAR 18N93W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 26N TO INLAND OVER S MEXICO W OF 91W TO THE COAST OF MEXICO. ALTHOUGH THE ACTIVITY HAS DIMINISHED TODAY...CONDITIONS STILL APPEAR SOMEWHAT CONDUCIVE FOR THE FORMATION OF A TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO WHILE THE SYSTEM MOVES TOWARD THE W-NW TO NW AT 5 TO 10 KT. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS DISTURBANCE COULD SPREAD LOCALLY HEAVY RAINS OVER PORTIONS OF E AND S MEXICO DURING THE NEXT FEW DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS W OF THE CAPE VERDE ISLANDS EXTENDING FROM 23N29W TO 13N31W MOVING W 5-10 KT. WAVE IS ALONG THE LEADING EDGE OF SURGE OF DEEP MOISTURE WITH A SLOT OF DRIER AIR UNDERCUTTING THE N PORTION OF THE WAVE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 15N-20N BETWEEN 23W-29W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 12N16W AND CONTINUES ALONG 10N23W TO 11N30W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 9N39W TO 11N46W. CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE FROM 10N- 13N BETWEEN 20W-28W...FROM 7N-12N BETWEEN 30W-37W...FROM 8N-11N BETWEEN 39W-44W...FROM 11N-14N BETWEEN 46W-50W...AND FROM 9N-12N BETWEEN 56W-59W. A SURFACE TROUGH EXTENDS FROM 19N51W TO 12N54W WITH CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 60 NM OF THE TROUGH BETWEEN 12N-17N. ...DISCUSSION... GULF OF MEXICO... FEATURE TO WATCH THIS AFTERNOON IS THE LOW/SURFACE TROUGH IN THE SPECIAL FEATURES ABOVE. A BROAD UPPER RIDGE IS ANCHORED OVER MEXICO COVERING THE GULF W OF 89W. BROAD UPPER TROUGH COVERS THE REMAINDER OF THE GULF INTO THE W ATLC. REMNANT MOISTURE OVER THE NE GULF IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 45 NM OF LINE FROM 27N85W TO INLAND OVER THE N GULF COAST NEAR THE MISSISSIPPI/LOUISIANA BORDER. ISOLATED SHOWERS WITH POSSIBLE ISOLATED THUNDERSTORMS DOT THE REMAINDER OF THE GULF THIS AFTERNOON. THE LOW/SURFACE TROUGH IS FORECAST TO MOVE W-NW ...POSSIBLY AS A TROPICAL CYCLONE...THROUGH SAT. A COLD FRONT WILL ENTER THE N CENTRAL GULF ON SAT STALLING ACROSS THE N GULF THROUGH MON. THE LOW CURRENTLY IN THE SW GULF IS FORECAST TO MERGE WITH THE FRONT OR DISSIPATE NEAR THE NE COAST OF MEXICO ON SUN. CARIBBEAN SEA... AN UPPER RIDGE COVERS THE W CARIBBEAN W OF 70W ANCHORED NEAR 16N82W AND PROVIDING A DIFFLUENT ENVIRONMENT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 16N-20N W OF 83W TO INLAND OVER THE YUCATAN PENINSULA AND S OF 15N W OF 80W TO INLAND OVER CENTRAL AMERICA. A MID LEVEL CYCLONIC CIRCULATION IS IN THE CENTRAL CARIBBEAN NEAR 13N76W WITH SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS FROM 9N-17N TO INLAND OVER COLOMBIA BETWEEN 72W-77W. AN UPPER TROUGH EXTENDS ACROSS PUERTO RICO/MONA PASSAGE INTO THE E CARIBBEAN TO THE ABC ISLANDS. AN E/W UPPER RIDGE ANCHORED IN THE TROPICAL ATLC EXTENDS OVER THE REMAINDER OF THE CARIBBEAN E OF 65W. THIS UPPER RIDGE IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 13N-18N E OF 65W TO OVER THE LESSER ANTILLES. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN WITH FAIR WEATHER THIS AFTERNOON. FRESH TO STRONG WINDS ACROSS THE NW CARIBBEAN WATERS WILL DIMINISH TO MODERATE ON FRI. GENTLE TO MODERATE EASTERLY TRADES WILL CONTINUE ACROSS THE REMAINDER OF AREA THROUGH THE FORECAST PERIOD...EXCEPT INCREASING TO FRESH TO STRONG IN THE CENTRAL CARIBBEAN SUN AND MON AS HIGH PRES BUILDS NE OF THE AREA. HISPANIOLA... DAYTIME HEATING IS DEVELOPING ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE ISLAND. AN UPPER LEVEL TROUGH AXIS IS JUST TO THE E OF HISPANIOLA AND WILL REMAIN IN PLACE THROUGH EARLY SAT. THE UPPER FLOW WILL BECOME WESTERLY AT THE BASE OF ANOTHER UPPER TROUGH THAT MOVES IN FROM THE N. AFTERNOON SHOWERS/THUNDERSTORMS COULD DEVELOP DAILY WITH THE DAYTIME HEATING THROUGH MON. ATLANTIC OCEAN... TROPICAL DEPRESSION HUMBERTO IS IN THE N/CENTRAL ATLC. SEE SPECIAL FEATURES ABOVE. BROAD UPPER TROUGH COVERS THE W ATLC N OF 23N W OF 65W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N53W EXTENDING TO 29N60W WHERE IT BECOMES STATIONARY ALONG 29N67W TO 29N73W THEN DISSIPATES TO 28N79W. A SURFACE TROUGH IS S OF THE FRONT EXTENDING FROM 28N67W ALONG 25N72W TO 22N77W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 26N TO THE FRONT BETWEEN 56W-71W AND FROM 22N TO THE SURFACE TROUGH BETWEEN 66W-72W. A SURFACE RIDGE COVERS THE E ATLC E OF T.D. HUMBERTO ANCHORED BY A 1028 MB HIGH NE OF THE AZORES. WEAKENING STATIONARY FRONT OVER THE W ATLC WILL DISSIPATE BY TONIGHT. A BROAD SURFACE TROUGH S OF THIS FRONT WILL PERSIST ACROSS THE CENTRAL ATLC THROUGH SAT WITH THE POSSIBILITY OF A SURFACE LOW FORMING ALONG THE TROUGH. THIS TROUGH WILL FINALLY MOVE THROUGH THE CENTRAL ATLC ON SUN. HIGH PRESSURE WILL BUILD ACROSS THE SW ATLC LATE SUN INTO MON WHILE A COLD FRONT MAY MOVE INTO THE NW PORTION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW