000 AXNT20 KNHC 311750 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI MAY 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 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE HAS BEEN ADDED ALONG 13N38W TO 5N43W MOVING WEST AT 15-20 KT. THE WAVE IS ON THE LEADING EDGE OF A SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. IT ALSO IS AHEAD OF A LARGE AREA OF DUST THAT HAS EMERGED OFF THE COAST OF AFRICA. MODEL POTENTIAL VORTICITY FIELDS AT THE 315 KELVIN LEVEL ALSO INDICATE A TROUGH AXIS IN THIS AREA THAT IS EXPECTED TO TRACK WESTWARD FOR AT LEAST THE NEXT 48 HOURS BEFORE MOVING NORTHWEST AROUND A RIDGE. DEEP CONVECTION IS LIMITED TO THE ITCZ REGION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM A 1009 MB LOW ALONG THE COAST OF SENEGAL NEAR 14N17W AND CONTINUES ACROSS THE EASTERN TROPICAL ATLC ALONG 8N24W 6N30W. THE LOW IS ASSOCIATED WITH THE NEXT TROPICAL WAVE THAT WILL LIKELY EMERGE OFF AFRICA WITHIN THE NEXT 24 HOURS. THE ITCZ BEGINS NEAR 6N30W AND CONTINUES ALONG 7N41W 5N50W 6N59W. A LARGE CLUSTER OF NUMEROUS STRONG CONVECTION IS FROM 5N-11N BETWEEN 14W-21W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-7N BETWEEN 21W-32W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N BETWEEN 41W- 60W. ...DISCUSSION... GULF OF MEXICO... A WEAK SURFACE TROUGH REMAINS IN THE SW GULF OF MEXICO ALONG 22N94W TO 18N95W. ISOLATED SHOWERS ARE FROM 18N-22N BETWEEN 92W- 97W. SURFACE RIDGING DOMINATES THE REMAINDER OF THE BASIN EXTENDING FROM A HIGH CENTER IN THE WEST ATLC. THIS PATTERN IS PROVIDING MAINLY SOUTHEAST RETURN FLOW THROUGHOUT THE AREA RANGING FROM 10-15 KT. ALOFT...AN UPPER LEVEL RIDGE CENTERED IN THE NW CARIBBEAN SUPPORTS THE SURFACE RIDGING. A WEAK SHORTWAVE UPPER TROUGH IS TO THE WEST OVER THE SW GULF PROVIDING MOIST SOUTHWESTERLY FLOW OVER THE CENTRAL GULF. RADAR IMAGERY SHOWS LIGHT SCATTERED SHOWERS ARE THROUGHOUT THE FLORIDA PENINSULA INDICATING THAT MOISTURE CONTINUES TO STREAM OVER THE STATE FROM THE WEST ATLC WHERE A BROAD AREA OF SHOWERS/ISOLATED THUNDERSTORMS ARE PRESENT. SURFACE RIDGING WILL DOMINATE FOR THE NEXT 24-48 HOURS BEFORE WEAK AND BROAD LOW PRESSURE FORMS IN THE SW GULF BY THE END OF THE WEEKEND. CARIBBEAN SEA... ABUNDANT DEEP LAYER MOISTURE IS THROUGHOUT THE WESTERN CARIBBEAN EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. THIS IS DUE TO DIFFLUENCE ALOFT AROUND AN UPPER LEVEL HIGH CENTER NEAR 18N81W. A LARGE BURST OF HEAVY SHOWERS AND SCATTERED THUNDERSTORMS IS FROM 15N-21N BETWEEN 78W-84W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN FROM 9N-13N BETWEEN 75W-80W ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS THROUGH NORTHERN CENTRAL AMERICA AND ALONG 11N/12N. THE CENTRAL AND EASTERN CARIBBEAN ARE MOSTLY DRY AT THIS TIME WITH ONLY A FEW ISOLATED SHOWERS EMBEDDED WITHIN TRADEWIND FLOW OF 15-20 KT. STATIONS IN THE LESSER ANTILLES ARE ALSO REPORTING DUST. A SHORTWAVE UPPER TROUGH NORTH OF THE MONA PASSAGE IS STILL PROVIDING AN UNSTABLE ENVIRONMENT OVER EASTERN HISPANIOLA AND PUERTO RICO. SAN JUAN PUERTO RICO REPORTED ALMOST 2 INCHES OF RAIN OVER THE PAST 24 HOURS AS OF 1200 UTC THIS MORNING. RADAR IMAGERY INDICATES ISOLATED SHOWERS/THUNDERSTORMS ARE CURRENTLY ACROSS THE ISLAND AND TO THE SOUTH. MORE ACTIVITY WILL LIKELY BUILD UP OVER THE AFTERNOON HOURS AS DAYTIME HEATING REACHES A MAXIMUM. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS WITH SIGNIFICANT MOISTURE EXPECTED TO REMAIN OVER THE WESTERN CARIBBEAN. HISPANIOLA... A SHORTWAVE UPPER TROUGH IS MAINLY NORTH OF THE ISLAND ALONG 70W...WHICH CONTINUES TO PROVIDE AN UNSTABLE ENVIRONMENT MAINLY OVER THE FAR EASTERN PORTION OF HISPANIOLA. A COUPLE ISOLATED THUNDERSTORMS HAVE ALREADY POPPED UP NEAR THE CENTER OF THE ISLAND AND OVER THE EASTERN PORTION. ACTIVITY IS LIKELY TO INCREASE THROUGHOUT THE DAY AS DAYTIME HEATING REACHES A MAXIMUM. THE UPPER TROUGH SHOULD MOVE EAST OF THE ISLAND SHORTLY. HOWEVER...A LONGWAVE UPPER TROUGH WILL REMAIN OVER THE WEST ATLC NORTH OF THE AREA. ATLANTIC OCEAN... SURFACE RIDGING IS THE DOMINATE SURFACE FEATURE ACROSS THE WEST ATLC EXTENDING FROM A 1028 MB HIGH NEAR 33N60W. HOWEVER...AN UPPER LEVEL TROUGH OVER THE AREA NEAR 70W IS PROVIDING A LARGE AREA OF DIFFLUENCE ALOFT...WHICH IS SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 20N-30N BETWEEN 64W-77W. A WEAK SURFACE TROUGH EXTENDS INTO THE RIDGE ALONG 31N55W TO 26N59W. ISOLATED SHOWERS ARE WITHIN 100 NM EITHER SIDE OF THE AXIS. THE REMAINDER OF THE BASIN IS ALSO DOMINATED BY SURFACE RIDGING EXTENDING FROM A 1035 MB HIGH NEAR 43N23W WHICH IS PROVIDING FAIR CONDITIONS THROUGHOUT THE AREA. VISIBLE SATELLITE IMAGERY ALSO INDICATES AN AREA OF SAHARAN DUST THAT EXTENDS FROM THE COAST OF AFRICA TO NEAR 40W. ALOFT...BROAD UPPER TROUGHING COVERS THE CENTRAL ATLC NEAR 50W WITH UPPER RIDGING COVERING THE EASTERN ATLC CENTERED NEAR 16N26W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON