000 AXNT20 KNHC 091748 RRA TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU MAY 09 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. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF SENEGAL TO NEAR 6N25W...THEN TRANSITIONS TO ITCZ...CONTINUING ON TO 3N30W TO THE COAST OF BRAZIL AT 1S48W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED N OF THE EQUATOR TO THE COAST OF AFRICA BETWEEN THE PRIME MERIDIAM AND 12W. SIMILAR CONVECTION IS FROM 2N TO 6N BETWEEN 12W AND 25W. ISOLATED TO SCATTERED MODERATE CONVECTION IS SEEN WITHIN 210 NM N OF ITCZ AXIS W OF 30W. ...DISCUSSION... GULF OF MEXICO... A 1021 MB HIGH CENTERED OVER THE NE GULF NEAR 28N85W EXTENDS A RIDGE SW TO THE BAY OF CAMPECHE. THIS SYSTEM ALSO DOMINATES THE STATE OF FLORIDA WHERE MAINLY FAIR WEATHER PREVAILS. UNDER THE INFLUENCE OF THIS FEATURE...E-SE WINDS OF 10-15 KT ARE NOTED OVER THE EASTERN GULF WHILE SE FLOW HAS INCREASED TO 15-20 KT OVER THE WESTERN GULF. THESE WINDS ARE TRANSPORTING SOME LOW LEVEL MOISTURE INTO TEXAS. THE HIGH WILL MOVE LITTLE THROUGH TONIGHT AND DISSIPATE. THEN...THE ATLC RIDGE WILL EXTEND WESTWARD MAINLY ALONG 28N E OF 90W DURING THE NEXT COUPLE OF DAYS. THE NEXT COLD FRONT IS FORECAST TO MOVE OFF THE LOUISIANA AND TEXAS COAST EARLY ON SAT. IN THE UPPER LEVELS...A RIDGE DOMINATES THE MAJORITY OF THE REGION WITH THE RIDGE AXIS EXTENDING FROM A BROAD ANTICYCLONE IN THE EPAC THROUGH THE BAY OF CAMPECHE ACROSS THE WESTERN GULF TO BEYOND LOUISIANA. A TROUGH IS NOTED OVER THE FAR EAST GULF AND FLORIDA WHERE THE LIKELIHOOD OF SHOWERS AND TSTMS IS ON INCREASE. CARIBBEAN SEA... A SURFACE TROUGH EXTENDS FROM 25N72W THROUGH THE WINDWARD PASSAGE TO HAITI NEAR 18N74W. THIS TROUGH PRODUCED LOCALLY HEAVY RAIN OVER HISPANIOLA DURING THE PAST 24 HOURS. THE DOMINICAN REPUBLIC WEATHER SERVICE...ONAMET...REPORTED RAINFALL AMOUNTS OF 4 TO 5 INCHES IN SOME LOCALES DURING THE PAST 24 HOURS. THE GREATEST TOTAL RAINFALL AMOUNT WAS REPORTED IN BONAO WITH NEAR 6 INCHES...142.7 MM. A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH AN UPPER LEVEL TROUGH THAT CURRENTLY EXTENDS ACROSS FLORIDA AND WEST-CENTRAL CUBA TO NEAR PANAMA IS HELPING TO INDUCE THE CONVECTIVE ACTIVITY ASSOCIATED WITH THIS TROUGH. CURRENTLY... CONVECTION IS FLARE UP AHEAD OF THE TROUGH AXIS BETWEEN CUBA AND THE NW BAHAMAS. SHOWERS AND TSMTS ARE ALSO DEVELOPING BETWEEN JAMAICA AND EASTERN CUBA AS WELL AS ACROSS THE WINDWARD PASSAGE AND NEAR THE NORTHERN END OF THE TROUGH. LOCALIZED FLOODING IS STILL POSSIBLE OVER HISPANIOLA AS THE TROUGH DRIFTS WESTWARD. FURTHER E...THE TAIL END OF A SHEARLINE IS OVER THE NORTHERN LEEWARD AND THE VIRGIN ISLANDS CROSSING JUST N OF PUERTO RICO. NE WINDS OF 20 KT ARE NOTED N OF THE SHEAR LINE BY SCATTEROMETER DATA. THIS FEATURE IS PRODUCING SOME SHOWER ACTIVITY ACROSS THE NE CARIBBEAN AND COINCIDES WITH A WELL DEFINED BAND OF MOISTURE AS DEPICTED IN THE TPW PRODUCT. IN FACT...SAN JUAN REPORTED 3.42 INCHES OF RAIN OVER THE PAST 24 HOURS ENDING THIS MORNING AT 8 AM. LOW LEVEL MOISTURE AND UPPER LEVEL DYNAMIC ASSOCIATED WITH THE ABOVE MENTIONED TROUGH WILL COMBINE WITH LOCAL EFFECTS AND DIURNAL HEATING TO PRODUCE SHOWER AND THUNDERSTORM ACTIVITY ACROSS PARTS OF PUERTO RICO...HISPANIOLA...MAINLY EASTERN CUBA AND THE BAHAMAS. ANOTHER SURFACE TROUGH IS OVER THE CARIBBEAN SEA AND EXTENDS FROM 18N79W TO A 1010 MB LOW PRES NEAR 9N76W. SCATTERED MODERATE TO STRONG CONVECTION IS ASSOCIATED WITH THIS SYSTEM OVER THE SW CARIBBEAN. TRADEWIND FLOW OF 15-20 KT IS PRESENT ACROSS THE EAST AND CENTRAL CARIBBEAN JUST E OF THE SURFACE TROUGH. IN THE UPPER LEVELS...A RIDGE DOMINATES MUCH OF CENTRAL AMERICA. THE WESTERN PORTION OF ANTICYCLONE LOCATED NEAR 10N55W IS OVER THE REMAINDER OF THE CARIBBEAN PRODUCING SW UPPER LEVEL FLOW. UPPER LEVEL SUBSIDENCE IS OVER THE W CARIBBEAN AND CENTRAL AMERICA W OF 80W. ABUNDANT MID/UPPER LEVEL MOISTURE IS NOTED AHEAD OF THE AFOREMENTIONED UPPER LEVEL TROUGH. ATLANTIC OCEAN... AS PREVIOUSLY MENTIONED...A SURFACE TROUGH IS OVER THE SOUTHERN BAHAMAS AND THE WINDWARD PASSAGE WITH SCATTERED SHOWERS AND TSTMS. SEE THE CARIBBEAN SEA SECTION FOR MORE DETAILS. A 1031 MB HIGH PRES LOCATED N OF AREA NEAR 35N55W EXTENDS A RIDGE OVER THE WESTERN AND CENTRAL ATLC. A SURFACE TROUGH IS OVER THE E ATLC FROM 31N22W TO 23N27W. A SHEARLINE CONTINUES FROM THIS POINT TO 18N40W TO 14N55W TO 18N62W TO 19N67W. A WELL DEFINED BAND OF MAINLY LOW LEVEL CLOUDS IS ASSOCIATED WITH THE SHEARLINE. A 1017 MB LOW PRES IS NEAR 31N30W WITH A TROUGH EXTENDING SW TO NEAR 26N37W. ALOFT...A TROUGH/RIDGE/TROUGH PATTERN DOMINATES THE REGION. EXPECT THE PORTION OF THE SHEARLINE W OF 55W TO REMAIN ACTIVE WITH SHOWERS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE AT THE REQUEST OF METEO-FRANCE AND THE METEOROLOGICAL SERVICES OF HAITI AND THE DOMINICAN REPUBLIC...THE TROPICAL ANALYSIS AND FORECAST BRANCH (TAFB) WILL BEGIN PROVIDING...ON A TEMPORARY BASIS...A SEPARATE DETAILED SECTION WITHIN THE ATLANTIC TROPICAL WEATHER DISCUSSION (TWDAT). IT WILL COVER BOTH HAITI AND THE DOMINICAN REPUBLIC DUE TO THE SHARED GEOGRAPHY OF BOTH COUNTRIES ON THE ISLAND OF HISPANIOLA. THE SECTION BEGINS ON MAY 15 2013 AT 1800 UTC...2 PM EDT. IT WILL PROVIDE GUIDANCE FOR SIGNIFICANT WEATHER EVENTS THAT ARE EXPECTED TO IMPACT THE REGION THROUGH 48 HOURS...WITH THE FOCUS ON ASSESSING THE POTENTIAL FOR HEAVY RAINFALL. $$ GR