000 AXNT20 KNHC 190601 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... HUMBERTO WEAKENED TO A TROPICAL DEPRESSION AT 19/0300 UTC. ITS CENTER IS NEAR 32.5N 43.4W OR ABOUT 867 NM W-SW OF THE AZORES. PRESENT MOVEMENT IS N AT 8 KNOTS AND THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 30 KNOTS WITH GUSTS TO 40 KNOTS. PLEASE READ THE PUBLIC ADVISORIES ABOUT HUMBERTO THAT ARE ISSUED UNDER WMO HEADER WTNT34 KNHC AND UNDER AWIPS HEADER MIATCPAT4... AND THE FORECAST/ADVISORIES THAT ARE ISSUED UNDER WMO HEADER WTNT24 KNHC AND UNDER AWIPS HEADER MIATCMAT4. WIDELY SCATTERED MODERATE CONVECTION IS FROM 27N-31N BETWEEN 39W-44W. A 1005 MB LOW PRESSURE CENTER IS OVER THE BAY OF CAMPECHE NEAR 20N92W WITH AN ASSOCIATED TROUGH EXTENDING FROM 22N91W TO 17N92W. PRESENTLY...SCATTERED MODERATE CONVECTION IS S OF 22N E OF 94W. HOWEVER...HEAVIER CONVECTION IS INLAND S-SE MEXICO AND IN GUATEMALA. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR THE FORMATION OF A TROPICAL DEPRESSION ON THURSDAY. THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS WHILE IT MOVES TO THE WEST-NORTHWEST. THIS DISTURBANCE WILL LIKELY SPREAD HEAVY RAIN OVER PORTIONS OF EASTERN AND SOUTHERN MEXICO AND COULD CAUSE LIFE-THREATENING FLOODS AND MUDSLIDES OVER AREAS ALREADY IMPACTED BY TORRENTIAL RAIN DURING THE PAST SEVERAL DAYS. ...TROPICAL WAVES... THE AXIS OF A TROPICAL WAVE IS WEST OF THE CAPE VERDE ISLANDS ALONG 21N27W TO 08N29W AND IS MOVING W NEAR 10 KNOTS. METEOSAT SATELLITE IMAGERY CONTINUE TO SHOW DRY AIR INTRUSION TO THE NORTHERN SECTOR OF THE WAVE WHICH IS HINDERING CONVECTION. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH PASSES THROUGH COASTAL WEST AFRICA NEAR 12N16W TO 10N25W. THE ITCZ CONTINUES FROM 10N25W TO 09N40W TO 11N56W. SCATTERED MODERATE CONVECTION IS FROM 04N-09N BETWEEN 23W-33W...FROM 06N-10N BETWEEN 34W-43W AND FROM 07N-13N BETWEEN 44W-51W. ...DISCUSSION... THE GULF OF MEXICO... A VERY MOIST ENVIRONMENT AT THE LOWER AND MIDDLE LEVELS DOMINATE THE GULF WATERS AS DEPICTED IN IMAGERY OF TOTAL PRECIPITABLE WATER AND WATER VAPOR. HOWEVER...STRONG NORTHWESTERLY WIND SHEAR IS INHIBITING IN PART CONVECTIVE ACTIVITY ACROSS GREAT PORTIONS OF THE BASIN. A DISTURBANCE IS BEING ANALYZED IN THE SW GULF. SEE THE SPECIAL FEATURES SECTION. A WEAK UPPER-LEVEL TROUGH OVER THE EASTERN GULF SUPPORTS A DISSIPATING STATIONARY FRONT ACROSS NORTH-CENTRAL FLORIDA TO 28N82W TO 29N86W. ISOLATED SHOWERS ASSOCIATED WITH THIS FRONTAL BOUNDARY ARE N OF 27N E OF 88W. DIFFLUENT FLOW ALOFT FROM THE TROUGH OVER THE EASTERN GULF AND AN UPPER-LEVEL RIDGE COVERING THE WESTERN CARIBBEAN SEA CONTINUES TO SUPPORT SCATTERED SHOWERS IN THE FLORIDA STRAITS AND THE YUCATAN CHANNEL. THERE IS A HIGH CHANCE FOR THE DISTURBANCE TO BECOME A TROPICAL CYCLONE DURING THE NEXT 48. HEAVY RAIN OVER PORTIONS OF EASTERN AND SOUTHERN MEXICO IS EXPECTED. THE CARIBBEAN SEA... A VERY MOIST ENVIRONMENT AT THE LOWER AND MIDDLE LEVELS DOMINATE THE CARIBBEAN WATERS AS DEPICTED IN IMAGERY OF TOTAL PRECIPITABLE WATER AND WATER VAPOR. UPPER-LEVEL DIVERGENCE FROM A BROAD RIDGE COVERING THE BAHAMAS AND THE WESTERN-CENTRAL CARIBBEAN SEA SUPPORTS SCATTERED SHOWERS AND TSTMS N OF 15N W OF 75W...INCLUDING PORTIONS OF CUBA AND JAMAICA. A CUT-OFF LOW IS OVER THE CENTRAL-EASTERN BASIN BETWEEN 66W-70W THUS GENERATING DIFFLUENCE TO SUPPORT SCATTERED MODERATE CONVECTION OVER SOUTHERN HAITI AND ADJACENT WATERS WITHIN 120 NM OF THE COASTLINE. SIMILAR CONVECTION IS OVER NW PUERTO RICO...INCLUDING THE MONA PASSAGE. THIS CUT-OFF LOW IS ALSO GENERATING DIFFLUENCE ALOFT IN THE SOUTHERN BASIN TO SUPPORT NUMEROUS MODERATE/ISOLATED STRONG CONVECTION AND TSTMS S OF 13N BETWEEN 72W-76W. SCATTERED MODERATE CONVECTION AND TSTMS ARE JUST WEST OF THE LEEWARD ISLANDS FROM 14N-17N BETWEEN 61W-65W. A SURFACE TROUGH IS EXPECTED TO ENTER THE EASTERN CARIBBEAN SEA SATURDAY AFTERNOON WHILE AN AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP N OF THE AREA JUST EAST OF THE BAHAMAS. THESE FEATURES MAY GENERATE SHOWERS POSSIBLY AFFECTING THE GREATER AND LESSER ANTILLES. HISPANIOLA... UPPER-LEVEL DIFFLUENCE FROM AN UPPER-LEVEL RIDGE COVERING THE BAHAMAS AS WELL AS THE WESTERN-CENTRAL CARIBBEAN AND A CUT-OFF LOW OVER THE CENTRAL-EASTERN BASIN IS SUPPORTING ISOLATED SHOWERS AND TSTMS ACROSS THE ISLAND AND ADJACENT WATERS. BESIDES THE TYPICAL AFTERNOON/EARLY EVENING SHOWERS ACTIVITY DUE TO SURFACE HEATING...EXPECT LITTLE CHANGES IN THE NEXT 48 HOURS. THE ATLANTIC OCEAN... THE MAIN FEATURE IN THE ATLC IS TROPICAL DEPRESSION HUMBERTO WHICH INFORMATION IS PROVIDED IN THE SPECIAL FEATURES SECTION. A WEAK UPPER-LEVEL TROUGH IN THE W ATLC SUPPORTS A FRONTAL SYSTEM THAT ENTERS THE DISCUSSION AREA AS A STATIONARY FRONT FROM 30N66W TO 28N74W WHERE IT TRANSITIONS TO A DISSIPATING STATIONARY FRONT TO THE EASTERN COAST OF FLORIDA NEAR 28N80W. A PRE-FRONTAL SURFACE TROUGH EXTENDS FROM 26N67W TO 24N73W. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ASSOCIATED WITH THE FRONT AND THE TROUGH ARE FROM 24N-30N BETWEEN 60W-76W. DIFFLUENT FLOW ALOFT FROM THE UPPER-LEVEL TROUGH AND A RIDGE COVERING THE BAHAMAS AND THE WESTERN-CENTRAL CARIBBEAN SUPPORTS SCATTERED SHOWERS IN THE BAHAMAS AND N OF CUBA BETWEEN 75W-83W. FURTHER EAST...A 1017 MB HIGH PRESSURE CENTER IS NEAR 25N54W WHICH IS EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS. A PAIR OF SURFACE TROUGHS ARE OVER THE TROPICAL CENTRAL ATLC...HOWEVER WITH NO CONVECTION ASSOCIATED WITH IT. ONE SURFACE TROUGH EXTENDS FROM 20N33W TO 12N33W...JUST W OF A TROPICAL WAVE. THE SECOND TROUGH IS ALONG 18N48W TO 11N50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR