000 AXNT20 KNHC 040004 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED JUL 03 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 21N20W TO 10N23W AND IS MOVING W-NW AT 10 KT. THE WAVE IS NO LONGER INTERACTING WITH THE ITCZ AXIS AND TOTAL PRECIPITABLE WATER IMAGERY INDICATE THIS WAVE IS EMBEDDED IN A LOW TO MODERATE MOIST ENVIRONMENT AT THE LOWER LEVELS. THE METEOSAT-9 SAL TRACKING PRODUCT SHOW THIS WAVE IS EMBEDDED IN SAL DRY AIR WHICH IS HINDERING CONVECTION. TROPICAL WAVE IS EMBEDDED WITHIN THE ITCZ AXIS EXTENDING FROM 14N36W TO A 1011 MB LOW NEAR 06N45W...MOVING W-NW NEAR 10 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED IN A HIGH MOIST ENVIRONMENT AT THE LOWER LEVELS. ISOLATED SHOWERS ARE WITHIN 100 NM WEST OF THE AXIS. CONVECTION ASSOCIATED WITH THIS WAVE IS LIMITED AT THE MOMENT DUE TO UNFAVORABLE CONDITIONS AT THE UPPER LEVELS AND SAL DRY AIR CLOSELY ENGULFING THE WAVE ENVIRONMENT. TROPICAL WAVE MOVING ACROSS THE EASTERN CARIBBEAN EXTENDING FROM 22N61W TO 13N64W...MOVING W-NW NEAR 10 KT. BOTH TOTAL PRECIPITABLE WATER IMAGERY AND THE METEOSAT-9 SAL TRACKING PRODUCT AGREE ON A DRY LOWER TO MIDDLE LEVELS WAVE ENVIRONMENT. SLIGHT RAINSHOWERS WERE REPORTED DURING THE LAST COUPLE OF HOURS ASSOCIATED TO THE PASSAGE OF THIS WAVE THROUGHOUT THE LESSER ANTILLES. CURRENTLY NO CONVECTIVE ACTIVITY IS ASSOCIATED TO THIS WAVE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST NEAR 10N15W TO 07N23W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N23W TO 08N30W TO 11N38W. IT RESUMES WEST OF A TROPICAL WAVE NEAR 05N46W TO NORTHERN BRAZIL NEAR 03N51W. SCATTERED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF THE AXIS BETWEEN 17W-26W. BESIDES THE CONVECTION ASSOCIATED WITH THE WAVE MENTIONED ABOVE...SCATTERED SHOWERS ARE OCCURRING WITHIN 80 NM WEST OF THE ITCZ AXIS WEST OF 48W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER LEVEL TROUGH CENTERED OVER THE CENTRAL U.S. CONTINUE DIPPING INTO THE GULF WEST OF 86W. THIS TROUGH IS SUPPORTING A FRONTAL SYSTEM N OF THE AREA WHICH TRANSITIONS TO A SURFACE TROUGH FROM 30N88W TO A 1013 MB LOW NEAR 27N90W TO 22N93W. THE UPPER LEVEL TROUGH ALSO SUPPORTS ANOTHER SURFACE TROUGH THAT EXTENDS FROM 27N87W TO THE YUCATAN PENINSULA NEAR 21N89W TO THE BAY OF CAMPECHE NEAR 18N91W. IMAGERY FROM RADAR AND A GOES IR ENHANCEMENT SHOW SCATTERED MODERATE/ISOLATED STRONG CONVECTION AND ISOLATED THUNDERSTORMS EAST OF 88W. THE STRONGEST CONVECTION LIES WITHIN 170 NM EAST OF THE EASTERNMOST SURFACE TROUGH. NUMEROUS STRONG CONVECTION ASSOCIATED WITH THIS SURFACE TROUGH IS OCCURRING OVER THE YUCATAN PENINSULA AND EXTENDS WITHIN 70 NM OFF THE PENINSULA WEST COASTLINE. THE CONVECTION OVER THE EASTERN GULF CONTINUES TO BE ENHANCED BY THE LOWER LEVELS MOIST AIR THAT HAVE BEEN ADVECTED TO THE GULF FROM THE WEST CARIBBEAN AND UPPER LEVEL DIFFLUENCE FROM A RIDGE EXTENDING ALONG FLORIDA TO THE YUCATAN PENINSULA. WINDS ACROSS THE BASIN RANGE FROM 5-15 KT WITH HIGHER WINDS OF 20 KT EAST OF THE EASTERNMOST TROUGH. CONVECTIVE ACTIVITY OVER THE EASTERN GULF IS LIKELY TO CONTINUE THROUGH AT LEAST EARLY FRIDAY AS THE UPPER LEVEL SYNOPTIC FEATURES NEARLY STAY IN PLACE...HIGH MOISTURE WILL PERSIST AS WELL AS SURFACE TROUGHING. WITHIN THAT PERIOD...THE LOW IS FORECAST TO DRIFT NORTHEASTWARD. CARIBBEAN SEA... EXCEPT FOR THE WESTERN CARIBBEAN W OF 85W...THE CENTRAL CARIBBEAN S OF LA HISPANIOLA AND THE SOUTHERN CARIBBEAN S OF 12N...TOTAL PRECIPITABLE WATER IMAGERY SHOW VERY DRY AIR AT THE LOWER LEVELS WHICH IS FAVORING FAIR WEATHER ACROSS MOST OF THE BASIN. WATER VAPOR IMAGERY SHOW VERY DRY AIR AT THE MIDDLE LEVELS WHICH REINFORCE A CONVECTIVE FREE ENVIRONMENT. A TROPICAL WAVE IS MOVING ACROSS THE EASTERN CARIBBEAN JUST EAST OF PUERTO RICO BUT AS MENTIONED IN THE WAVES DISCUSSION...NO CONVECTION IS ASSOCIATED WITH IT. SCATTERED SHOWERS ASSOCIATED WITH THE CONVECTIVE ACTIVITY OVER THE EASTERN GULF ARE N OF 19N W OF 81W. SCATTERED MODERATE CONVECTION IS OCCURRING FROM 18N-21N BETWEEN 75W-79W. OTHERWISE...15-20 KT TRADEWINDS FLOW ACROSS THE BASIN WITH THE HIGHEST WINDS MAINLY CENTERED AT THE BASIN. THE TROPICAL WAVE IS EXPECTED TO MOVE OFF THE WESTERN COAST OF PUERTO RICO EARLY ON THURSDAY SLIGHT TO NONE CONVECTIVE ACTIVITY ASSOCIATED WITH IT. NO MAJOR CHANGES ARE EXPECTED FOR THE REST OF THE BASIN. HISPANIOLA... A LOW TO MODERATE MOIST ENVIRONMENT IS ACROSS THE ISLAND AT THE LOWER LEVELS AT THIS TIME. DIFFLUENT FLOW FROM AN UPPER LEVEL RIDGE EXTENDING FROM THE EASTERN GULF TO THE CENTRAL CARIBBEAN AND AN ELONGATED CYCLONIC CIRCULATION N OF THE WINDWARD PASSAGE IS GENERATING ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE ISLAND. A TROPICAL WAVE IS EXPECTED TO ENTER THE DOMINICAN REPUBLIC THURSDAY MORNING INCREASING THE CHANCES OF SHOWERS...ESPECIALLY AS THE AFTERNOON AND EVENING PROGRESS AS DAYTIME HEATING PEAKS WITH MAXIMUM INSTABILITY. ATLANTIC OCEAN... BESIDES THE TROPICAL WAVES ALREADY MENTIONED ABOVE...BROAD SURFACE RIDGING COVERS THE ATLC WATERS ANCHORED BY A 1030 MB HIGH NEAR 35N65W AND THE 1027 MB AZORES HIGH NEAR 36N30W. TOTAL PRECIPITABLE WATER IMAGERY SHOW VERY DRY AIR ACROSS THE REGION AT THE LOWER LEVELS WHICH IS SUPPRESSING CONVECTIVE ACTIVITY. 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