000 AXNT20 KNHC 021802 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI AUG 02 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. ...SPECIAL FEATURES... A 1014 MB LOW IS NOW ASSOCIATED WITH THE SURFACE TROUGH LOCATED BETWEEN THE NORTHWESTERN BAHAMAS AND THE FLORIDA EAST COAST OR THE REMNANTS OF DORIAN. CURRENTLY...SCATTERED MODERATE CONVECTION WITH ISOLATED TSTMS IS FROM 24N-29N W OF 76W. RAINSHOWER ACTIVITY ASSOCIATED WITH THE LOW REMAINS DISORGANIZED...AND IS MAINLY LOCATED WELL SOUTHEAST OF THE CENTER. CONDITIONS ARE FAVORABLE FOR SLIGHT DEVELOPMENT TODAY AND EARLY SATURDAY AS THE SYSTEM MOVES NORTHWARD NEAR THE FLORIDA EAST COAST. AFTER THAT...DEVELOPMENT IS NOT EXPECTED AS THE LOW MOVES NORTH-NORTHEASTWARD AND BECOMES ASSOCIATED WITH A FRONTAL TROUGH OFFSHORE OF THE EASTERN UNITED STATES. THERE IS A MEDIUM CHANCE...30 PERCENT...FOR THIS SYSTEM TO BECOME A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. HOWEVER...THIS DISTURBANCE WILL CONTINUE TO BRING CLOUDINESS AND SHOWERS TO PORTIONS OF THE NORTHWESTERN BAHAMAS AS WELL AS THE COASTAL WATERS OF CENTRAL AND SOUTHEASTERN FLORIDA TODAY. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE TROPICAL E ATLC ASSOCIATED WITH A 1011 MB LOW NEAR 18N24W. THE WAVE AXIS EXTENDS FROM 22N24W TO 11N24W AND THE SYSTEM IS MOVING WEST NEAR 5 KT. THE SYSTEM IS EMBEDDED WITHIN THE MONSOON TROUGH AXIS AS WELL AS VERY DRY AIR AND DUST FROM THE SAHARAN AIR LAYER. ISOLATED SHOWERS LYE WITHIN 140 NM EITHER SIDE OF THE WAVE AXIS S OF THE SOUTHERNMOST CAPE VERDE ISLAND. OTHERWISE...CONVECTION IN THE WAVE ENVIRONMENT IS BEING HINDERED BY THE SAL DRY AIRMASS. THE WAVE AND ASSOCIATED LOW ARE EXPECTED TO MOVE W-SW IN THE NEXT 24 HOURS. A TROPICAL WAVE HAS ENTERED THE SW GULF WITH AXIS EXTENDING FROM 25N90W TO 17N92W MOVING W-NW NEAR 7 KT. THE WAVE IS EMBEDDED WITHIN A MODERATE TO HIGH MOIST ENVIRONMENT E OF 95W AND CURRENTLY STRONG WIND SHEAR IS LIMITING CONVECTIVE ACTIVITY. ISOLATED SHOWERS ARE WITHIN 60 NM EAST OF ITS AXIS FROM 22N-24N. THE WAVE HAVE A CLEAR AXIS AT THE 700 MB AND MODEL GUIDANCE SUGGEST IT WILL CONTINUE MOVING WESTWARD OVER THE SW GULF UNTIL EARLY SATURDAY THAT IT MOVES NW OVER MEXICO. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 17N16W AND CONTINUES ALONG 18N24W TO 10N30W 08N41W. THE ITCZ BEGINS NEAR 08N41W AND CONTINUES ALONG 08N50W 08N59W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALREADY DISCUSSED...SCATTERED SHOWERS ARE FROM 09N-18N E OF 21W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 07N-11N BETWEEN 20W-31W. SCATTERED MODERATE CONVECTION IS ALSO WITHIN 150 NM S OF THE MONSOON TROUGH AXIS BETWEEN 31W-40W. OTHERWISE...ISOLATED SHOWERS ARE WITHIN 100 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 45W-50W AS WELL AS W OF 57W. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...A 1020 MB HIGH IS LOCATED OVER THE NORTHERN CENTRAL GULF NEAR 27N88W SUPPORTED BY A BROAD UPPER LEVEL RIDGE CENTERED OVER WESTERN TEXAS WHICH EXTENDS ACROSS MOST OF THE GULF. A WEAK SURFACE TROUGH IS N OF THE HIGH EXTENDING FROM THE FLORIDA PANHANDLE TO 30N87W 29N89W 28N91W. RADAR IMAGERY SHOW ISOLATED SHOWERS AND TSTMS WITHIN 30 NM SE OF THE AXIS BETWEEN 89W-91W. ANOTHER SURFACE TROUGH MOVES ACROSS NORTHERN FLORIDA INTO THE GULF NEAR 29N83W TO 27N85W. THIS TROUGH IS BEING SUPPORTED BY AN UPPER LEVEL TROUGH ALONG THE EASTERN CONUS AND RADAR IMAGERY IS SHOWING RAINSHOWERS FROM 28N-29N E OF 84W. A TROPICAL WAVE IS MOVING ACROSS THE SW GULF WITH AXIS EXTENDING FROM 25N90W TO 17N92W. THE WAVE IS EMBEDDED WITHIN A MODERATE TO HIGH MOIST ENVIRONMENT E OF 95W AND CURRENTLY STRONG WIND SHEAR IS LIMITING CONVECTIVE ACTIVITY. ISOLATED SHOWERS ARE WITHIN 60 NM EAST OF ITS AXIS FROM 22N-24N. VERY LIGHT WINDS IN THE RANGE OF 5-10 KT SPREAD ACROSS THE BASIN. STRONG WIND SHEAR ALOFT AS WELL AS SUBSIDENCE OF DRY AIR FROM THE MIDDLE LEVELS IS SUPPORTING CLEAR SKIES ACROSS MOST OF THE BASIN. MODEL GUIDANCE SUGGEST THE TROPICAL WAVE WILL CONTINUE TO MOVE WESTWARD OVER THE SW GULF UNTIL EARLY SATURDAY WHEN IT MOVES NW OVER MEXICO. THE SURFACE TROUGH MOVING ACROSS NORTHERN FLORIDA IS EXPECTED TO MOVE NE TONIGHT AS THE HIGH PRESSURE CONTINUES TO DRIFT EASTWARD OVER THE NORTHERN GULF. CARIBBEAN SEA... AS OF 1500 UTC...A SURFACE TROUGH IS MOVING ACROSS LA HISPANIOLA FROM 21N71W TO 17N73W ENHANCING ISOLATED SHOWERS/TSTMS. EASTERLY TRADEWINDS UP TO 25 KT SPREAD ACROSS THE BASIN BEING THE STRONGEST WINDS OVER THE CENTRAL-SOUTHERN CARIBBEAN DUE TO A SLIGHTLY TIGHTER PRESSURE GRADIENT. HIGH MOISTURE IS OVER THE SOUTHERN CARIBBEAN S OF 13N WHERE NUMEROUS MODERATE/ISOLATED STRONG CONVECTION AND TSTMS ARE BEING ENHANCED BY A 1010 MB LOW NEAR 11N82W AND THE MONSOON TROUGH AXIS WHICH MOVES ACROSS COSTA RICA TO A 1011 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 WILL CONTINUE TO SUPPORT NEAR GALE FORCE WINDS ACROSS THE CENTRAL-SOUTHERN BASIN. THE SURFACE TROUGH IS EXPECTED TO MOVE OFF THE HISPANIOLA LATE THIS AFTERNOON. HISPANIOLA... AS OF 1500 UTC...A SURFACE TROUGH IS MOVING ACROSS LA HISPANIOLA FROM 21N71W TO 17N73W ENHANCING ISOLATED SHOWERS/TSTMS. OVERALL...DRY AIR IS ACROSS THE ISLAND AND IS EXPECTED TO CONTINUE AS A VERY DRY SAHARAN AIRMASS MOVES WESTWARD ACROSS THE CARIBBEAN THIS WEEKEND. HOWEVER...AN UPPER TROUGH OVER THE E CARIBBEAN WILL CONTINUE TO DRIFT W TO OVER HISPANIOLA WHICH MAY INCREASE THE CHANCES OF AFTERNOON/EARLY EVENING SHOWERS AND THUNDERSTORMS. ATLANTIC OCEAN... A 1014 MB LOW NEAR 27N79W IS NOW ASSOCIATED WITH THE SURFACE TROUGH LOCATED BETWEEN THE NORTHWESTERN BAHAMAS AND THE FLORIDA EAST COAST OR THE REMNANTS OF DORIAN. CURRENTLY...SCATTERED MODERATE CONVECTION WITH ISOLATED TSTMS IS FROM 24N-29N W OF 76W. THIS DISTURBANCE WILL CONTINUE TO BRING CLOUDINESS AND SHOWERS TO PORTIONS OF THE NORTHWESTERN BAHAMAS AS WELL AS THE COASTAL WATERS OF CENTRAL AND SOUTHEASTERN FLORIDA TODAY. SEE THE SPECIAL FEATURES SECTION FOR MORE INFORMATION ABOUT THIS SYSTEM. ISOLATED SHOWERS ARE OVER THE REMAINDER BAHAMAS FROM 20N- 26N W OF 70W. BESIDES THE CONVECTION ALREADY DISCUSSED ASSOCIATED WITH THE REMNANTS OF DORIAN...THE SURFACE TROUGH ACROSS HISPANIOLA AND THE TROPICAL WAVE IN THE E ATLC...A SURFACE TROUGH EXTENDS FROM 27N32W TO 23N30W WITH NO CONVECTION ASSOCIATED WITH IT. OTHERWISE...SURFACE RIDGING DOMINATES THE BASIN N OF 14N ANCHORED BY THE AZORES HIGH. FAIR WEATHER IS ACROSS THE REMAINDER ATLC SUPPORTED BY VERY DRY AIR FROM A SAL OUTBREAK THAT SPREADS OVER THE E ATLC AND IS ENTERING THE CARIBBEAN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS