000 AXNT20 KNHC 311802 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED JUL 31 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 1722 UTC. ...TROPICAL WAVES... TROPICAL WAVE AXIS IN THE TROPICAL ATLC EXTENDS FROM 18N43W TO 13N42W 09N40W MOVING W NEAR 10 KT. WAVE IS EMBEDDED WITHIN A NARROW SURGE OF MODERATE MOISTURE AS DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. THE METEOSAT-9 SAL TRACKING PRODUCT SHOWS THE WAVE IS AT THE LEADING EDGE OF A SAHARAN AIR LAYER OUTBREAK WITH VERY DRY AIR WHICH IS HINDERING CONVECTION. AS OF 1500 UTC...TROPICAL WAVE AXIS EXTENDS FROM 27N80W TO 19N82W MOVING W-NW NEAR 10-15 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT WITH SOME DRIER AIR OVER THE PORTION OF THE WAVE LYING OVER THE FLORIDA PENINSULA. UPPER LEVEL DIFFLUENCE FROM A LOW OVER THE SW N ATLC AND A HIGH OVER SE NEW MEXICO EXTENDING A RIDGE THROUGH THE GULF AND FLORIDA PENINSULA IS ENHANCING SCATTERED RAINSHOWERS AND ISOLATED TSTMS OVER THE SE GULF INCLUDING THE FLORIDA STRAITS...OVER WESTERN CUBA...AS WELL AS WITHIN 170 NM E OF THE WAVE AXIS S OF 22N. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 15N16W AND CONTINUES ALONG 08N28W TO 05N38W. THE ITCZ BEGINS NEAR 05N38W AND CONTINUES ALONG 05N47W 06N57W. SCATTERED MODERATE CONVECTION WITH ISOLATED TSTMS IS SE OF A LINE FROM 17N18W TO 06N22W. A CLUSTER OF MODERATE CONVECTION IS FROM 04N-08N BETWEEN 29W-33W. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...SURFACE RIDGING DOMINATES ACROSS MOST OF THE GULF N OF 21N WITH RETURN FLOW IN THE RANGE OF 5-10 KT MOVING AROUND A 1022 MB HIGH NEAR 27N87W. UPPER LEVEL DIFFLUENCE FROM A LOW OVER THE SW N ATLC AND A HIGH OVER SE NEW MEXICO EXTENDING A RIDGE THROUGH THE GULF AND FLORIDA PENINSULA IS ENHANCING SCATTERED RAINSHOWERS AND ISOLATED TSTMS OVER THE SE GULF INCLUDING THE FLORIDA STRAITS. A PREFRONTAL TROUGH EXTENDS ACROSS NORTHERN FLORIDA INTO THE NE GULF ALONG 29N83W TO 26N85W GENERATING ISOLATED SHOWERS AND TSTMS WITHIN 70 NM EITHER SIDE OF THE AXIS. A WEAK SURFACE TROUGH IS OVER THE BAY OF CAMPECHE FROM 21N92W TO 16N93W WITH NO CONVECTION ASSOCIATED WITH IT. OTHERWISE...DRY AIR IN THE LOWER AND MIDDLE LEVELS IS SUPPORTING FAIR WEATHER OVER THE REMAINDER BASIN W OF 88W. HIGH PRESSURE IS EXPECTED TO CONTINUE OVER THE NORTHERN GULF DURING THE NEXT 48 HOURS. THE TROPICAL WAVE MOVING ACROSS SOUTHERN FLORIDA AND THE WESTERN CARIBBEAN IS EXPECTED TO ENTER THE SE GULF THIS EVENING AND CONTINUE MOVING WESTWARD TOWARDS THE SW GULF THROUGH THURSDAY. RAINSHOWERS ACTIVITY IS EXPECTED DURING THIS PERIOD ACROSS THE SOUTHERN BASIN. CARIBBEAN SEA... AS OF 1500 UTC...A TROPICAL WAVE IS MOVING ACROSS THE SOUTHERN FLORIDA PENINSULA AND WESTERN CARIBBEAN ENHANCING ISOLATED SHOWERS AND TSTMS N OF 18N W OF 78W. A SURFACE TROUGH IS NOW ANALYZED FROM 26N72W TO 18N75W ASSOCIATED WITH REMNANT CONVECTION FROM DORIAN. SCATTERED MODERATE CONVECTION AND TSTMS ARE AFFECTING THE SOUTHERN BAHAMAS AS WELL...CENTRAL AND EASTERN CUBA...THE WINDWARD PASSAGE AND NORTHERN HISPANIOLA. ANOTHER SURFACE TROUGH IS ANALYZED FROM 20N63W TO 16N66W JUST E OF PUERTO RICO. SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH THIS TROUGH ARE FROM 17N-20N BETWEEN 61W-66W. THE LEEWARD ISLANDS HAVE BEEN REPORTING RAINSHOWERS AND RADAR IMAGERY FROM PUERTO RICO SHOW SIMILAR ACTIVITY ACROSS THE SOUTHERN PART OF THE ISLAND. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE OVER THE SOUTHERN GULF S OF 14N W OF 80W ASSOCIATED WITH THE MONSOON TROUGH WHICH AXIS MOVES ACROSS COSTA RICA AND PANAMA. TRADEWINDS OF 10-15 KT SPREAD OVER MOST OF THE BASIN WITH HIGHER WINDS UP TO 25 KT NEAR THE COAST OF COLOMBIA. OTHERWISE...DRY AIR IN THE LOWER AND MIDDLE LEVELS IS SUPPORTING FAIR WEATHER IN THE REMAINDER BASIN. THE TROPICAL WAVE MOVING ACROSS SOUTHERN FLORIDA AND THE WESTERN CARIBBEAN IS EXPECTED TO ENTER THE SE GULF THIS EVENING AND CONTINUE MOVING WESTWARD TOWARDS THE SW GULF THROUGH THURSDAY. THE TROUGH AND REMNANT CONVECTION ASSOCIATED WITH DORIAN WILL CONTINUE TO MOVE WESTWARD ACROSS THE BAHAMAS IN THE NEXT 24 HOURS AND RAINSHOWERS ARE EXPECTED TO CONTINUE AFFECT CUBA THROUGH EARLY THURSDAY. THE SURFACE TROUGH E OF PUERTO RICO WILL MOVE ACROSS THE ISLAND TODAY WITH MOST OF ITS CONVECTION STAYING OFFSHORE N OF THE ISLAND. HISPANIOLA... ISOLATED RAINSHOWERS AND TSTMS ARE OCCURRING ACROSS NORTHERN HISPANIOLA ASSOCIATED WITH A SURFACE TROUGH AND REMNANT CONVECTION FROM DORIAN. SHOWERS ARE EXPECTED TO CONTINUE OVERNIGHT. CONDITIONS IMPROVE THURSDAY MORNING BUT DETERIORATE IN THE AFTERNOON AS THE SURFACE TROUGH CURRENTLY E OF PUERTO RICO MOVES ACROSS THE ISLAND. ATLANTIC OCEAN... BESIDES THE CONVECTION ALREADY DISCUSSED ASSOCIATED WITH THE REMNANTS OF DORIAN...THE SURFACE TROUGH E OF PUERTO RICO AND THE TROPICAL WAVE...A SURFACE TROUGH EXTENDS FROM 30N53W TO 29N59W 27N65W WITH ISOLATED SHOWERS AND TSTMS WITHIN 100 NM EITHER SIDE OF ITS AXIS. ANOTHER SURFACE TROUGH EXTENDS ALONG 28N50W TO 16N52W WITH NO CONVECTION ASSOCIATED WITH IT. OTHERWISE...A 1025 MB HIGH IS NEAR 29N39W. FAIR WEATHER IS ACROSS THE EASTERN ATLC AS OF VERY DRY AIR FROM A SAL OUTBREAK SPREADS ACROSS THAT PART OF THE BASIN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS