000 AXNT20 KNHC 011805 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU AUG 01 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. ...TROPICAL WAVES... A TROPICAL WAVE CAME OFF THE WEST AFRICAN COAST EARLY TODAY ASSOCIATED WITH A 1011 MB LOW NEAR 19N21W. THE WAVE AXIS EXTENDS FROM 23N21W TO 10N20W. THE WAVE IS EMBEDDED WITHIN THE MONSOON TROUGH AXIS AND IS ALSO BEING ENGULFED BY VERY DRY AIR AND DUST FROM THE SAHARAN AIR LAYER N OF 14N. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 07N-14N BETWEEN 15W-25W. THE WAVE AND ASSOCIATED LOW ARE EXPECTED TO MOVE W-SW IN THE NEXT 24 HOURS. TROPICAL WAVE IS OVER THE FAR WESTERN CARIBBEAN WITH AXIS EXTENDING FROM 24N86W TO 15N86W MOVING W NEAR 5 KT. THE WAVE IS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT N OF 18N WHERE ISOLATED SHOWERS/TSTMS ARE WITHIN 180 NM EAST OF THE AXIS. SIMILAR CONVECTION IS WITHIN 100 NM W OF THE WAVE AXIS N OF 18N. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 21N17W AND CONTINUES ALONG 13N25W TO 08N34W 07N42W. THE ITCZ BEGINS NEAR 07N42W AND CONTINUES ALONG 07N50W 06N57W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALREADY DISCUSSED...SMALL CLUSTERS OF MODERATE CONVECTION ARE WITHIN 120 NM OF THE AXES BETWEEN 37W-48W. SCATTERED MODERATE CONVECTION IS SW OF A LINE FROM 10N56W TO 05N50W. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...A 1017 MB HIGH IS LOCATED OVER THE NW GULF NEAR 27N92W PROVIDING ANTICYCLONIC WIND FLOW IN THE RANGE OF 5-10 KT N OF 22N W OF 90W. A BROAD UPPER LEVEL RIDGE CENTERED OVER TEXAS EXTENDS ACROSS MOST OF THE GULF SUPPORTING THIS SURFACE HIGH. DRY AIR IS PRESENT IN THE LOWER AND MIDDLE LEVELS SUPPORTING FAIR WEATHER IN THIS REGION. OVER THE NE GULF...A SURFACE PRE- FRONTAL TROUGH EXTENDS ACROSS THE FLORIDA PANHANDLE TO 29N85W 29N89W BEING SUPPORTED BY AN UPPER LEVEL TROUGH ALONG THE EASTERN CONUS. RADAR IMAGERY SHOW SCATTERED SHOWERS AND TSTMS WITHIN 70 NM EITHER SIDE OF THE TROUGH AXIS. MODERATE MOIST AIR S OF THE SURFACE TROUGH OVER THE EASTERN BASIN ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE ARE ENHANCING SCATTERED SHOWERS S OF 28N E OF 85W. OTHERWISE...THE NORTHERN PART OF THE TROPICAL WAVE OVER THE FAR WESTERN CARIBBEAN HAS ENTERED THE SE GULF GENERATING ISOLATED SHOWERS/TSTMS WITHIN 180 NM EAST OF ITS AXIS S OF 24N E OF 87W. THE SURFACE TROUGH WILL MOVE OUT OF THE NE GULF TONIGHT WHILE THE HIGH PRESSURE OVER THE NW DRIFTS EASTWARD WHERE IT DISSIPATES FRIDAY AFTERNOON. THE TROPICAL WAVE IS EXPECTED TO BE IN THE SW GULF BY FRIDAY AFTERNOON BRINGING SHOWERS WITH IT. CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE FAR WESTERN CARIBBEAN WITH AXIS EXTENDING FROM 24N86W TO 15N86W. THE WAVE IS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT N OF 18N WHERE ISOLATED SHOWERS/TSTMS ARE OBSERVED WITHIN 180 NM EAST OF THE AXIS AS WELL AS WITHIN 100 NM W OF THE WAVE AXIS. A SURFACE TROUGH CONTINUES TO MOVE OVER PUERTO RICO ENHANCING SHOWERS AND TSTMS ACROSS THE ISLAND AND WITHIN 30 NM S OF ITS COASTLINE. EXCEPT FOR THE WESTERN CARIBBEAN...EASTERLY TRADEWINDS UP TO 25 KT SPREAD ACROSS THE BASIN BEING THE STRONGEST WINDS OVER THE CENTRAL-SOUTHERN CARIBBEAN. HIGH MOISTURE IS OVER THE SOUTHERN CARIBBEAN S OF 12N WHERE SCATTERED MODERATE CONVECTION AND TSTMS ARE BEING ENHANCED BY THE MONSOON TROUGH AXIS WHICH MOVES ACROSS COSTA RICA TO A 1010 MB LOW OVER NORTHERN COLOMBIA. ELSEWHERE...DRY AIR AT THE LOWER AND MIDDLE LEVELS IS FAVORING SUBSIDENCE WHICH IS HINDERING CONVECTIVE ACTIVITY. SURFACE RIDGING WILL CONTINUE ACROSS THE BASIN AND A TIGHT PRESSURE GRADIENT IS EXPECTED TO GENERATE NEAR GALE FORCE WINDS ACROSS THE CENTRAL-SOUTHERN BASIN. THE SURFACE TROUGH IS EXPECTED TO MOVE OFF THE WESTERN COAST OF PUERTO RICO TONIGHT AND GENERATE RAINSHOWERS ACROSS THE MONA PASSAGE AND NE OF THE DOMINICAN REPUBLIC. HISPANIOLA... EXCEPT FOR THE FAR EASTERN HISPANIOLA...DRY AIR SPREADS ACROSS THE ISLAND FAVORING FAIR WEATHER. HOWEVER...CONDITIONS WILL START TO DETERIORATE LATER THIS AFTERNOON AS THE SURFACE TROUGH MOVING ACROSS PUERTO RICO CONTINUES MOVING W-NW CARRYING MOISTURE AND ENHANCING SHOWERS. THESE SHOWERS ARE EXPECTED TO CONTINUE DURING THURSDAY AND POSSIBLY FRIDAY MORNING. ON FRIDAY AFTERNOON A DRY AIRMASS ENTERS THE ISLAND CLEARING THE SKIES. ATLANTIC OCEAN... OVER THE SW N ATLC...CLOUDINESS AND THUNDERSTORMS ASSOCIATED WITH THE REMNANTS OF DORIAN HAVE BECOME MORE CONCENTRATED ALONG A TROUGH OF LOW PRESSURE IN THE CENTRAL AND NORTHWESTERN BAHAMAS EXTENDING FROM 28N75W TO NORTHERN CUBA NEAR 22N78W. CLUSTERS OF MODERATE CONVECTION WITH EMBEDDED TSTMS SURROUNDS THE TROUGH AXIS FROM 22N-27N BETWEEN 74W-79W. BESIDES THE CONVECTION ALREADY DISCUSSED ASSOCIATED WITH THE REMNANTS OF DORIAN...THE SURFACE TROUGH ACROSS PUERTO RICO AND THE TROPICAL WAVE IN THE E ATLC...A COLD FRONT EXTENDS ALONG 30N21W 28N28W 30N37W WITH NO CONVECTION ASSOCIATED WITH IT. OTHERWISE...SURFACE RIDGING DOMINATES THE BASIN N OF 14N ANCHORED BY A PAIR OF SURFACE HIGHS NORTH OF THE AREA OF DISCUSSION. FAIR WEATHER IS ACROSS THE REMAINDER ATLC SUPPORTED BY VERY DRY AIR FROM A SAL OUTBREAK THAT SPREADS E OF 60W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS