000 AXNT20 KNHC 031821 RRA TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUL 03 2014 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 1745 UTC. ...SPECIAL FEATURE... HURRICANE ARTHUR IS CENTERED NEAR 32.4N 78.5W AS OF 03/1500 UTC...OR ABOUT 95 NM S-SW OF CAPE FEAR NORTH CAROLINA... MOVING N-NE AT 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 981 MB. MAXIMUM SUSTAINED WIND SPEED IS 80 KT WITH GUSTS OF 100 KT. A TURN TOWARD THE NORTHEAST WITH AN INCREASE IN FORWARD SPEED IS EXPECTED TODAY...FOLLOWED BY A FURTHER INCREASE IN FORWARD SPEED TONIGHT AND FRIDAY. REGARDING FORECAST TRACK...THE CORE OF ARTHUR IS EXPECTED TO APPROACH THE COAST IN THE HURRICANE WARNING AREA TONIGHT. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS FROM 31N-35N BETWEEN 75W-80W WITH LIGHTING DATA SHOWING TSTMS IN THE E SEMICIRCLE OF THIS CONVECTION. ARTHUR RAINBANDS ARE GENERATING SHOWERS AND TSTMS OVER THE NORTHERN BAHAMAS AND N OF 26N BETWEEN 72W-77W. PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT1/WTNT31 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE HAS COME OFF THE WEST AFRICAN COAST EARLIER THIS MORNING. THE WAVE AXIS EXTENDS FROM 16N17W TO 7N18W AND IS EXPECTED TO MOVE NEAR 15 KT DURING THE NEXT 24 HOURS. THE WAVE IS BEING ENGULFED BY THE SAHARAN AIR LAYER DRY AIR WHILE METEOSAT PSEUDO NATURAL COLOR IMAGERY SHOW DUST ASSOCIATED WITH THIS AIRMASS IN THE WAVE ENVIRONMENT. THERE IS NO CONVECTION ASSOCIATED WITH THIS WAVE. TROPICAL WAVE IS LOCATED OVER THE CENTRAL ATLANTIC WITH AXIS EXTENDING FROM 22N43W TO 11N44W...MOVING W AT 20 KT. THERE IS NO CONVECTION ASSOCIATED WITH THE WAVE AS IT IS EMBEDDED IN THE DRY AND DUSTY SAHARAN AIR LAYER. TROPICAL WAVE IS LOCATED OVER THE EASTERN CARIBBEAN WITH AXIS EXTENDING FROM 19N63W TO 11N69W...MOVING W AT 20 KT. LOW-LEVEL LOW TO MODERATE MOIST AIR ACCOMPANIES THIS WAVE. THIS FACTOR ALONG WITH DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER ENVIRONMENTAL SHEAR ACROSS THE CARIBBEAN ARE INHIBITING THE DEVELOPMENT OF DEEP CONVECTION. SCATTERED SHOWERS ARE ACROSS WESTERN PUERTO RICO WITH ISOLATED SHOWERS EXTENDING TO ADJACENT WATERS. TROPICAL WAVE IS LOCATED OVER THE FAR NW CARIBBEAN WITH AXIS EXTENDING FROM 20N85W TO 13N87W...MOVING W AT 20-25 KT. DEEP LAYER MOISTURE AND LOW ENVIRONMENTAL SHEAR ARE SUPPORTING SCATTERED SHOWERS AND TSTMS AHEAD OF THE WAVE AXIS...INCLUDING NICARAGUA...HONDURAS...BELIZE AND THE EASTERN YUCATAN PENINSULA. TROPICAL WAVE IS LOCATED OVER THE BAY OF CAMPECHE WITH AXIS EXTENDING FROM 22N94W TO 14N95W...MOVING W AT 20-25 KT DURING THE PAST 24 HOURS. AN UPPER LEVEL LOW AND MOISTURE IN THE SW GULF SUPPORT SCATTERED SHOWERS AND TSTMS S OF 25N W OF 92W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF AFRICA NEAR 9N13W TO 7N20W TO 7N28W. THE ITCZ BEGINS NEAR 7N28W AND CONTINUES TO A 1015 MB LOW NEAR 8N36W...THEN ALONG 6N49W TO 6N57W. SCATTERED SHOWERS ARE FROM 4N-6N BETWEEN 20W-28W. ...DISCUSSION... ...THE GULF OF MEXICO... AN ELONGATED UPPER LEVEL CYCLONIC CIRCULATION IS OVER THE WESTERN GULF SUPPORTING A TROPICAL WAVE MOVING ACROSS THE BAY OF CAMPECHE AS WELL AS SHOWERS AND TSTMS IN THE SW GULF. SEE TROPICAL WAVES SECTION FOR MORE INFORMATION ON THE WAVE. MOISTURE ADVECTED TO THE EASTERN BASIN BY NOW HURRICANE ARTHUR ALONG WITH A MID-LEVEL DIVERGENT ENVIRONMENT SUPPORT HEAVY SHOWERS AND TSTMS FROM 25N-29N BETWEEN 84W-91W. A TROPICAL WAVE OVER THE FAR NW CARIBBEAN IS GENERATING SHOWERS AND TSTMS OVER WESTERN CUBA AND THE YUCATAN CHANNEL. A WEAK HIGH PRESSURE CENTER OF 1018 MB IS OVER THE NW GULF CENTERED NEAR 27N95W. WITH NO SUPPORT IN THE MID-UPPER LEVELS...THIS HIGH IS EXPECTED TO DISSIPATE DURING THE NEXT 24 HOURS. OTHERWISE...VARIABLE WINDS OF 5-10 KT ARE ACROSS THE GULF WATERS. A FRONTAL BOUNDARY IS EXPECTED TO LINGER ALONG THE NORTHERN GULF COASTLINE THROUGH SUNDAY...THUS INCREASING THE CHANCES OF RAIN IN THIS ZONE AND ADJACENT WATERS. ...THE CARIBBEAN SEA... TWO TROPICAL WAVES ARE MOVING ACROSS THE CARIBBEAN WATERS. ONE OF THE WAVES IS OVER THE FAR NW BASIN GENERATING SHOWERS AND TSTMS W OF OF 81W...INCLUDING WESTERN CUBA...THE E YUCATAN PENINSULA...THE YUCATAN CHANNEL...BELIZE AND HONDURAS. A SECOND WAVE IS OVER THE EASTERN CARIBBEAN. LOW-LEVEL LOW TO MODERATE MOIST AIR ACCOMPANIES THIS WAVE. THIS FACTOR ALONG WITH DRY AIR SUBSIDENCE FROM ALOFT AND STRONG DEEP LAYER ENVIRONMENTAL SHEAR ACROSS THE CARIBBEAN ARE INHIBITING THE DEVELOPMENT OF DEEP CONVECTION. SCATTERED SHOWERS ARE ACROSS WESTERN PUERTO RICO WITH ISOLATED SHOWERS EXTENDING TO ADJACENT WATERS. THIS WAVE IS ALSO ENHANCING SHOWERS AND ISOLATED TSTMS OVER THE MONA PASSAGE AND SOUTHERN DOMINICAN REPUBLIC. SEE TROPICAL WAVES SECTION ABOVE FOR MORE DETAILS. OVER THE SW BASIN...THE MONSOON TROUGH IS ENHANCING HEAVY SHOWERS AND TSTMS S OF 12N W OF 80W. BROAD HIGH PRESSURE OVER THE ATLC EXTENDS A RIDGE TO THE NORTHERN CARIBBEAN...THUS TIGHTENING THE PRESSURE GRADIENT AND SUPPORTING EASTERLIES OF 20-25 KT S OF 17N BETWEEN 64W-83W WITH NEAR GALE FORCE WINDS ALONG THE COAST OF COLOMBIA. THE NEXT TROPICAL WAVE WILL ENTER THE EASTERN BASIN BY FRIDAY NIGHT. ...HISPANIOLA... MOSTLY DRY AIR IS ACROSS THE ISLAND WHICH ALONG STRONG WIND SHEAR VALUES IN THE REGION ARE SUPPRESSING THE DEVELOPMENT OF DEEP CONVECTION. HOWEVER...A TROPICAL WAVE TO MOVE ACROSS PUERTO RICO THIS AFTERNOON IS PUSHING SOME MOISTURE WESTWARD THAT IS ENHANCING ISOLATED SHOWERS AND TSTMS ALONG SOUTHERN DOMINICAN REPUBLIC AND ADJACENT WATERS AS WELL AS THE MONA PASSAGE. RAINSHOWERS ACTIVITY WILL INCREASE AS THIS WAVE CONTINUES TO MOVE WESTWARD TOWARDS THE CENTRAL CARIBBEAN. ...THE ATLANTIC OCEAN... SCATTERED SHOWERS AND TSTMS ARE OVER THE SW N ATLC ASSOCIATED WITH THE RAINBANDS OF HURRICANE ARTHUR NOW N OF THE AREA OF DISCUSSION. SEE THE SPECIAL FEATURES SECTION ABOVE FOR MORE INFORMATION ON ARTHUR. FARTHER EAST...A SURFACE TROUGH IS ANALYZED FROM 30N65N TO 26N64W WHICH IS GENERATING ISOLATED SHOWERS WITHIN 100 NM EITHER SIDE OF IT N OF 28N AND SCATTERED MODERATE CONVECTION FROM 25N-28N BETWEEN 63W-66W. REMNANT SCATTERED SHOWERS ASSOCIATED WITH A FORMER FRONTAL BOUNDARY ARE N OF 27N BETWEEN 52W-56W. OTHERWISE...BESIDES THE TROPICAL WAVES DISCUSSED ABOVE...HIGH SURFACE PRESSURE AND RIDGING DOMINATE ELSEWHERE. 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