000 AXNT20 KNHC 300552 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU MAY 30 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 12N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 12N19W TO 05N40W TO 05N49W. SCATTERED MODERATE CONVECTION IS WITHIN 60 NM EITHER SIDE OF A LINE FROM 04N AND THE PRIME MERIDIAN TO 05N06W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 04N-08N BETWEEN 25W-39W. ISOLATED MODERATE CONVECTION IS FROM 05N-08N BETWEEN 40W-55W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE AXIS EXTENDS ALONG 88W BETWEEN TWO AREAS OF TROUGHING ON EITHER SIDE OF THE RIDGE OVER THE GULF THIS EVENING. ONE MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE FLORIDA PENINSULA THAT CONTINUES TO GENERATING ISOLATED SHOWERS ACROSS THE SOUTHERN FLORIDA PENINSULA AND FAR SE GULF S OF 26N E OF 82W. THE OTHER MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS FROM THE NORTHERN ROCKIES SE TO OVER THE TEXAS GULF COAST NEAR 28N94W. MOST CONVECTION ASSOCIATED WITH THIS TROUGH REMAINS WELL NORTH OF THE BASIN OVER THE CENTRAL AND NORTHERN U.S. PLAINS THIS EVENING. THE MOST INFLUENTAL FEATURE IS A SURFACE RIDGE ANCHORED IN THE SW NORTH ATLC WITH AXIS EXTENDING ACROSS NORTHERN FLORIDA TO THE WEST- CENTRAL GULF NEAR 23N96W. E-SE WINDS CONTINUE IN THE RANGE OF 15 TO 25 KT AND THIS OVERALL SYNOPTIC PATTERN IS EXPECTED TO PERSIST THROUGH EARLY SATURDAY. MOIST SOUTHERLY RETURN FLOW ALONG WITH MARGINAL LOW-LEVEL CONVERGENCE IS GENERATING A FEW AREAS OF ISOLATED SHOWERS...ONE FROM 25N-28N BETWEEN 82W- 87W...AND THE SECOND FROM 22N-26N BETWEEN 88W-94W. THE CIRCULATION ASSOCIATED WITH TROPICAL STORM BARBARA LOCATED JUST NORTH OF THE GULF OF TEHUANTEPEC IN THE EAST PACIFIC REGION IS PROVIDING FOR SCATTERED SHOWERS AND TSTMS ACTIVITY OVER THE YUCATAN PENINSULA THIS EVENING AND THE ADJACENT COASTAL WATERS IN THE SW GULF S OF 21N. BARBARA IS EXPECTED TO CONTINUE ON A WEAKENING TREND AS IT TRACKS SLOWLY NORTHWARD AND ITS REMNANTS BECOME EMBEDDED WITHIN THE SE RETURN FLOW DESCRIBED ABOVE. CARIBBEAN SEA... A WEAK MIDDLE TO UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE FLORIDA PENINSULA WITH THE BASE OF THIS TROUGH DIPPING SOUTHWARD OVER WESTERN CUBA. A CONSIDERABLE AMOUNT OF MIDDLE TO UPPER LEVEL DIFFLUENCE IS LOCATED OVER THE WESTERN CARIBBEAN W OF 62W AS AN UPPER LEVEL RIDGE EXTENDS EASTWARD FROM OVER CENTRAL AMERICA NEAR 15N87W TO 15N64W. THESE UPPER LEVEL LIFTING DYNAMICS ALONG WITH LOW-LEVEL MOISTURE CONVERGENCE AT THE SURFACE DUE TO PERSISTENT E-SE TRADES ARE GENERATING SCATTERED SHOWERS AND TSTMS N OF 16N BETWEEN 68W-80W...INCLUDING PORTIONS OF HISPANIOLA...JAMAICA...EASTERN CUBA...AND THE WINDWARD PASSAGE. ANOTHER AREA OF SCATTERED SHOWERS AND TSTMS IS LOCATED PRIMARILY OVER INLAND AREAS OF CENTRAL AMERICA STRETCHING FROM COSTA RICA N-NW TO THE YUCATAN PENINSULA AND SOUTHERN MEXICO WHERE A WEAKENING TROPICAL STORM BARBARA IS CENTERED. ISOLATED SHOWERS AND TSTMS ARE POSSIBLE ACROSS THE NW CARIBBEAN BETWEEN 80W-88W AND AREAS OF THE SW CARIBBEAN S OF 13N W OF 72W DUE TO CLOSE PROXIMITY OF THE MONSOON TROUGH ANALYZED AWLONG 10N/11N. MOIST SOUTHWESTERLY FLOW ALOFT IS NOTED WEST OF THE LESSER ANTILLES...HOWEVER LINGERING WESTWARD MOVING LOW- LEVEL MOISTURE IS GENERATING ISOLATED SHOWERS E OF 70W. THE OVERALL SYNOPTIC PATTERN OF E-SE TRADES IS EXPECTED TO PERSIST THROUGH EARLY NEXT WEEK AS HIGH PRESSURE REMAINS ANCHORED TO THE NORTH IN THE SW NORTH ATLC. HISPANIOLA... HISPANIOLA REMAINS UNDER THE INFLUENCE OF MAXIMUM MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH NOTED ON WATER VAPOR IMAGERY WITH AXIS ALONG 80W. THE DIFFLUENCE ALOFT COUPLED WITH PERSISTENT MOIST LOW-LEVEL SOUTHEASTERLY FLOW IS CONTINUING TO SUPPORT SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS ACROSS THE ISLAND THROUGH THE OVERNIGHT HOURS AND AREAS TO THE WEST...INCLUDING THE WINDWARD PASSAGE AND ALL APPROACHES. LOOKING AHEAD...WITH THE UPPER LEVEL TROUGH SLOW TO MOVE EASTWARD...SUPPORTING DYNAMICS ALOFT WILL REMAIN OVER HISPANIOLA THURSDAY WITH SCATTERED SHOWERS AND TSTMS EXPECTED...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS DUE TO PEAK DAYTIME HEATING AND INSTABILITY. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH OVER THE FLORIDA PENINSULA HAS BEEN SLOW TO MOVE INTO THE SW NORTH ATLC AND CONTINUES AMPLIFYING AN UPPER LEVEL RIDGE EXTENDING FROM OVER THE NORTH-CENTRAL CARIBBEAN SEA NEAR 18N73W TO BEYOND 32N68W. MIDDLE TO UPPER LEVEL DIFFLUENCE BETWEEN THE TROUGHING AND RIDGE CONTINUES TO GENERATE SCATTERED SHOWERS AND TSTMS ACROSS A LARGE AREA FROM 18N-29N BETWEEN 70W- 80W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC OUTSIDE OF THE CONVECTIVE ACTIVITY IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH CENTERED NEAR 36N62W. BRIDGING THIS RIDGE AND A STRONGER SURFACE RIDGE OVER THE EASTERN ATLC... IS A FRONTAL TROUGH HIGHLIGHTED BY A STATIONARY FRONT ANALYZED FROM 32N52W TO 30N53W WHERE IT BECOMES A SURFACE TROUGH TO 26N55W. ISOLATED SHOWERS ARE OCCURRING WITHIN 180 NM EITHER SIDE OF THE BOUNDARY. FINALLY...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1035 MB HIGH CENTERED N OF THE AZORES NEAR 41N28W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN