000 AXNT20 KNHC 291759 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON JUL 29 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 1725 UTC. ...SPECIAL FEATURES... A TROUGH OF LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF DORIAN EXTENDS FROM 24N63W TO 17N66W WITH AXIS MOVING W-NW NEAR 13-17 KT. THIS TROUGH IS EMBEDDED IN A HIGH MOIST ENVIRONMENT AT THE LOWER AND MIDDLE LEVELS WHICH IS SUPPORTING NUMEROUS MODERATE CONVECTION AND TSTMS FROM 19N-25N BETWEEN 62W-67W. THIS DISTURBANCE STILL DOES NOT APPEAR TO HAVE A CLOSED LOW-LEVEL CIRCULATION...AND SURFACE PRESSURES REMAIN HIGH ACROSS THE AREA. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE ONLY MARGINALLY CONDUCIVE FOR REGENERATION TO OCCUR AND AT THE MOMENT THERE IS A MEDIUM CHANCE...40 PERCENT...FOR IT TO BECOME A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THE DISTURBANCE IS EXPECTED TO CONTINUE PASSING WELL TO THE NORTH OF PUERTO RICO TODAY...AND MOVE ACROSS THE TURKS AND CAICOS ISLANDS AND THE BAHAMAS ON TUESDAY AND WEDNESDAY. ...TROPICAL WAVES... A TROPICAL WAVE EXTENDS FROM 16N33W TO 04N33W MOVING W NEAR 5 KT. AS NOTED IN THE METEOSAT-9 SAL TRACKING PRODUCT...SAHARAN DRY AIR SPREADS OVER THE WAVE ENVIRONMENT N OF THE MONSOON TROUGH AXIS WHICH IS HINDERING CONVECTION IN THIS REGION. ISOLATED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE WAVE AXIS S OF 08N ASSOCIATED WITH THE MONSOON TROUGH. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 09N13W TO 08N30W 05N42W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N42W TO 05N50W 05N56W. BESIDES THE CONVECTION FROM THE TROPICAL WAVE ALREADY DISCUSSED...A CLUSTER OF MODERATE/ISOLATED STRONG CONVECTION WITH TSTMS IS OFF THE W COAST OF AFRICA FROM 05N-11N BETWEEN 13W-20W. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM S OF THE MONSOON TROUGH BETWEEN 38W- 41W. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...SURFACE RIDGING AND RETURN FLOW IN THE RANGE OF 5-15 KT ANCHORED BY A 1020 MB HIGH NEAR 25N85W DOMINATE MOST OF THE GULF. IN THE MIDDLE TO UPPER LEVELS...A BROAD TROUGH EXTENDING ALONG THE EASTERN CONUS AND OFFSHORE OVER THE W ATLC SUPPORTS A PAIR OF TROUGHS OVER THE EASTERN BASIN. THE FIRST TROUGH EXTENDS FROM THE FLORIDA PANHANDLE TO 28N88W 27N91W WITH ISOLATED SHOWERS WITHIN 90 NM EITHER SIDE OF THE AXIS. THE SECOND TROUGH EXTENDS FROM THE W ATLC NEAR 30N78W TO 25N80W...ACROSS SOUTHERN FLORIDA TO 24N82W IN THE SE GULF. ISOLATED SHOWERS AND TSTMS ARE WITHIN 30 NM EITHER SIDE OF THE AXIS. OVER THE REMAINDER GULF...A TONGUE OF DRY AIR IN THE LOWER AND MIDDLE LEVELS SUPPORTS FAIR WEATHER. SURFACE RIDGING IS EXPECTED TO CONTINUE ACROSS MOST OF THE BASIN DURING THE NEXT 48 HOURS AS WELL AS THE CENTER OF HIGH PRESSURE. THE SURFACE TROUGH OVER THE N-NE GULF IS EXPECTED TO DRIFT NORTHWARD AND THE ONE OVER THE W ATLC TO MOVE COMPLETELY OVER THE FLORIDA PENINSULA ENHANCING SHOWERS. SHOWERS ARE ALSO POSSIBLE OVER THE FAR EASTERN GULF ASSOCIATED WITH THIS TROUGH. CARIBBEAN SEA... STRONG TRADEWINDS UP TO 25 KT SPREAD OVER THE CENTRAL CARIBBEAN WHICH ARE BANKING HIGH LOW LEVEL MOISTURE ALONG THE COASTLINES OF EASTERN HONDURAS AND NICARAGUA ENHANCING SURFACE CONVERGENCE. THIS COMBINED WITH UPPER LEVEL DIFFLUENCE AND PROXIMITY TO THE MONSOON TROUGH AXIS IS SUPPORTING SCATTERED MODERATE CONVECTION AND TSTMS S OF 17N W OF 81W AS WELL AS WITHIN 62 NM N OF THE COAST OF PANAMA W OF 78W. A TROUGH OF LOW PRESSURE ASSOCIATED WITH THE REMNANTS OF DORIAN IS NEAR 80 NM N-NE OF PUERTO RICO AND AT THE MOMENT THERE IS NO CONVECTION AFFECTING EITHER PUERTO RICO OR HISPANIOLA. MIDDLE TO UPPER LEVEL DIFFLUENCE IS SUPPORTING A SMALL CLUSTER OF MODERATE CONVECTION BETWEEN SE CUBA AND JAMAICA. OTHERWISE...LOWER AND MIDDLE LEVEL DRY AIR SUPPORTS FAIR WEATHER OVER THE REMAINDER BASIN. THE DISTURBANCE IS EXPECTED TO CONTINUE PASSING WELL TO THE NORTH OF PUERTO RICO TODAY...AND MOVE ACROSS THE TURKS AND CAICOS ISLANDS AND THE BAHAMAS ON TUESDAY AND WEDNESDAY. AS IT CONTINUES A W-NW TRACK IS EXPECTED TO ADVECT SOME MOISTURE WHICH WILL ENHANCE RAINSHOWERS STARTING TONIGHT UNTIL VERY EARLY TUESDAY. HISPANIOLA... CURRENTLY VERY DRY AIR IN THE LOWER AND MIDDLE LEVELS ARE SUPPORTING FAIR WEATHER ACROSS THE HISPANIOLA. HOWEVER...WEATHER CONDITIONS ARE EXPECTED TO DETERIORATE AS SOON AS LATE THIS AFTERNOON/EARLY EVENING. MOISTURE ADVECTION FROM THE REMNANTS OF DORIAN COMBINED WITH AN UPPER LEVEL TROUGH ARE LIKELY TO SUPPORT CONVECTIVE ACTIVITY POSSIBLY UNTIL LATE TUESDAY. ATLANTIC OCEAN... BESIDES THE SPECIAL FEATURES ALREADY DISCUSSED...A MIDDLE TO UPPER LEVEL BROAD TROUGH EXTENDING ALONG THE EASTERN CONUS AND OFFSHORE OVER THE W ATLC SUPPORTS A SURFACE TROUGH ALONG 30N78W TO 25N80W...ACROSS SOUTHERN FLORIDA TO 24N82W IN THE SE GULF. ISOLATED SHOWERS AND TSTMS ARE WITHIN 30 NM EITHER SIDE OF ITS AXIS. SCATTERED SHOWERS AND TSTMS ARE ACROSS THE WESTERN BAHAMAS TO NORTHERN CUBA BEING ENHANCED BY MIDDLE TO UPPER LEVEL DIVERGENT FLOW. A SURFACE TROUGH EXTENDS FROM 30N50W TO 27N55W WITH NO CONVECTION ASSOCIATED WITH IT. SIMILARLY...ANOTHER SURFACE TROUGH EXTENDS FROM 30N26W TO 25N34W 20N42W WITH NO CONVECTION ASSOCIATED WITH IT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR