000 AXNT20 KNHC 271803 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT JUL 27 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 1730 UTC. ...SPECIAL FEATURE... TROPICAL STORM DORIAN IS CENTERED NEAR 18.5N 52.1W AT 27/1500 UTC OR ABOUT 626 NM E OF THE NORTHERN LEEWARD ISLANDS MOVING W AT 20 KT. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. MINIMUM CENTRAL PRESSURE IS 1011 MB. PLEASE SEE THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. SCATTERED MODERATE CONVECTION IS FROM 17N- 20N BETWEEN 50W-55W. ...TROPICAL WAVES... TROPICAL WAVE IS OVER THE EASTERN TRPCL ATLC WITH AXIS EXTENDING FROM 17N24W TO 05N27W AND MOVING W-NW NEAR 10 KT. SMALL CLUSTERS OF MODERATE CONVECTION WITH ISOLATED TSTMS ARE IN THE SOUTHERN PART OF THE WAVE EMBEDDED WITHIN THE MONSOON TROUGH FROM 06N-09N BETWEEN 25W-29W. THE REMAINDER WAVE IS EMBEDDED WITHIN A DRY ENVIRONMENT AS SAL DRY AIR SPREADS OVER IT HINDERING CONVECTION. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 16N16W AND CONTINUES ALONG 09N24W TO 05N34W. THE ITCZ AXIS BEGINS NEAR 05N34W AND CONTINUES ALONG 04N44W TO 05N52W. BESIDES THE CONVECTION ALREADY DISCUSSED ASSOCIATED WITH THE TRPCL WAVE...SCATTERED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 15W-24W. ISOLATED SHOWERS ARE WITHIN 140 NM N OF THE AXES BETWEEN 32W-35W. ...DISCUSSION... GULF OF MEXICO... AN UPPER RIDGE EXTENDS ACROSS TEXAS INTO THE GULF THEN TO OVER SOUTHERN FLORIDA PROVIDING MOST OF THE GULF NORTHERLY FLOW ALOFT. AN UPPER LEVEL CYCLONIC CIRCULATION OVER THE UPPER GREAT LAKES EXTENDS A BROAD TROUGH ACROSS THE CENTRAL AND EASTERN CONUS. THIS TROUGH IS SUPPORTING A FRONTAL SYSTEM INLAND FROM ALABAMA TO LOUISIANA TO TEXAS. AS OF 1600 UTC...A PREFRONTAL SURFACE TROUGH EXTENDS FROM MISSISSIPPI TO SE LOUISIANA TO 27N95W IN THE GULF. RADAR IMAGERY SHOW RAINSHOWERS AND ISOLATED TSTMS N OF 29N BETWEEN 91W-94W. SURFACE RIDGING AND ANTICYCLONIC FLOW IN THE RANGE OF 5-15 KT DOMINATES THE REMAINING GULF ANCHORED BY A 1017 MB HIGH NEAR 24N88W. WATER VAPOR AND TOTAL PRECIPITABLE WATER IMAGERY SHOW DRY AIR ACROSS THE BASIN WHICH IS SUPPORTING FAIR WEATHER. SURFACE RIDGING WILL PREVAIL ACROSS THE GULF WITHIN THE NEXT 48 HOURS. THE FRONTAL SYSTEM INLAND IS EXPECTED TO MOVE OVER THE NORTHERN GULF CAUSING RAINSHOWERS ON SUNDAY WHICH WILL CONCENTRATE OVER THE NE GULF MONDAY AS THE FRONT MOVES EASTWARD. CARIBBEAN SEA... A BROAD AND ELONGATED UPPER LEVEL LOW IS CENTERED OVER THE W ATLC NEAR 21N68W AND EXTENDS INTO THE EASTERN CARIBBEAN SUPPORTING SCATTERED RAINSHOWERS N OF 11N BETWEEN 64W-68W. CLUSTERS OF MODERATE CONVECTION WITH EMBEDDED TSTMS ARE OVER THE SOUTHERN CARIBBEAN S OF 12N INCLUDING COSTA RICA AND PANAMA AND ASSOCIATED WITH THE MONSOON TROUGH. EXCEPT THE WESTERN CARIBBEAN W OF 80W...EASTERLY TRADEWINDS UP TO 25 KT ARE ACROSS THE BASIN WITH THE STRONGEST WINDS BEING OVER THE CENTRAL-SOUTHERN CARIBBEAN. EXCEPT FOR THE AREAS ALREADY MENTIONED...FAIR WEATHER CONTINUES OVER THE REMAINDER BASIN BEING SUPPORTED BY DRY AIR IN THE LOWER AND MIDDLE LEVELS. TROPICAL STORM DORIAN IS EXPECTED TO WEAKEN INTO A TROPICAL DEPRESSION LATER TODAY AND PASS AS A REMNANT LOW N OF THE EASTERN CARIBBEAN ON MONDAY. HISPANIOLA... CLEAR SKIES ARE ACROSS THE HISPANIOLA WITH THE EXCEPTION OF THE NE DOMINICAN REPUBLIC WHERE ISOLATED SHOWERS/TSTMS ARE CONTINUING ENHANCED BY AN UPPER LEVEL ELONGATED LOW THAT EXTENDS FROM THE W ATLC OVER THE E CARIBBEAN. AFTERNOON RAINSHOWERS/TSTMS ARE EXPECTED ACROSS THE ISLAND ASSOCIATED WITH DAYTIME HEATING AND THE LOW ALOFT. TROPICAL STORM DORIAN IS EXPECTED TO WEAKEN INTO A TROPICAL DEPRESSION LATER TODAY AND PASS AS A REMNANT LOW/TRPCL WAVE N OF ISLAND EARLY ON MONDAY. PRECIPITATION COULD INCREASE AS THE REMNANTS OF THE STORM APPROACHES THE ISLAND. ATLANTIC OCEAN... OVER THE W ATLC...A BROAD UPPER LEVEL TROUGH IS SUPPORTING A FRONTAL SYSTEM THAT EXTENDS AS A STATIONARY FRONT FROM 30N74W TO A 1015 MB LOW NEAR 28N78W. A COLD FRONT EXTENDS SW FROM THE LOW TO 25N79W 23N81W. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE OCCURRING N OF 24N W OF 75W. AN ELONGATED UPPER LEVEL LOW IS SUPPORTING SIMILAR CONVECTION FROM 18N-27N BETWEEN 60W- 67W. OVER THE EASTERN ATLC...A SURFACE TROUGH EXTENDS FROM 30N21W TO 25N28W WITH NO CONVECTION ASSOCIATED WITH IT. OTHERWISE...BESIDES THE SPECIAL FEATURES ALREADY DISCUSSED...SURFACE RIDGING AND FAIR WEATHER DOMINATES THE REMAINDER BASIN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR