000 AXNT20 KNHC 160032 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT MAY 15 2011 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC. ...TROPICAL WAVE... POORLY DEFINED TROPICAL WAVE EMBEDDED IN THE ITCZ IS ANALYZED IN THE EASTERN TROPICAL ATLC OFF THE COASTAL WATERS OF NE BRAZIL FROM 7N38W TO 2N42W. THE WAVE IS DRIFTING WEST AT ABOUT 5 KT. BEST DEPICTION OF THE WAVE IS IN WATER VAPOR IMAGERY AS A LOW AMPLITUDE MOISTURE SURGE. CONTINUITY BASED ON OLD SATELLITE DATA SHOWS THE WAVE EMERGING OFF WEST AFRICA AROUND MAY 12. THIS WAVE LACKS CYCLONIC CURVATURE...AND VERY WEAK CONVECTION IS ASSOCIATED WITH THIS SYSTEM. ...ITCZ... ITCZ AXIS IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR 7N12W TO 4N17W TO 3N33W TO 5N41W TO 4N51W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120 NM ON EITHER SIDE OF THE ITCZ E OF 25W. AN EMBEDDED SURFACE TROUGH IS WITHIN THIS AREA OF DEEP CONVECTION FROM 1N TO 5N ALONG 22W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL RIDGING IS BUILDING ACROSS THE REGION AS DEEP UPPER TROUGH ALONG 83W SHIFTS E OVER THE FLORIDA PENINSULA. CLOUDS AND SHOWERS ASSOCIATED WITH DISSIPATING COLD FRONT IN THE SE GULF OF MEXICO HAVE DIMINISHED THIS EVENING AS THE UPPER LEVEL SUPPORT MOVES FURTHER EAST. VISUAL SATELLITE IMAGERY SHOWS A WEAK POST- FRONTAL BOUNDARY IN THE EASTERN GULF ALONG 26N...AND SURFACE OBS SHOW NOTHING MORE THAN A SLIGHT SHIFT IN WIND DIRECTION ALONG THE BOUNDARY. HIGH PRES RIDGE EXTENDS ACROSS THE WESTERN GULF FROM CENTRAL TEXAS TO THE YUCATAN PENINSULA. ANTICYCLONIC WIND FLOW ASSOCIATED WITH THIS RIDGE WILL PERSIST W OF 90W FOR THE NEXT 24 HOURS...THEN SE WINDS WILL PICK UP IN THE NW GULF TO AROUND 15 KT TUE AND WED AS THE RIDGE SHIFTS FURTHER EAST. MODERATE W TO SW WINDS WILL PREVAIL OVER THE EASTERN GULF THROUGH WED. SEAS WILL CONTINUE TO BE 2-4 FT THROUGH MON NIGHT THEN BUILD TO 4-5 FT IN THE NE GULF OF MEXICO TUE. CARIBBEAN SEA... ANIMATED VIS SATELLITE IMAGERY SHOWS A WEAK CYCLONIC CIRCULATION CENTERED NEAR 15N70W. A SURFACE TROUGH EXTENDS FROM THE SW NORTH ATLC ACROSS THE VIRGIN ISLANDS AND PUERTO RICO INTO THE EASTERN CARIBBEAN. DIVERGENCE ASSOCIATED WITH A DEEP UPPER LEVEL TROUGH ALONG 83W IS ENHANCING CONVECTIVE ACTIVITY ALL ALONG THE SURFACE TROUGH AXIS WITH MOST OF THE CLOUDS AND SHOWERS E OF 70W IN A BROAD AREA OF SCATTERED MODERATE SHOWERS AND ISOLATED TSTMS THAT INCLUDES THE LESSER ANTILLES AND PUERTO RICO. LOW LEVEL MOISTURE REMAINS VERY HIGH IN THE REGION OF CONVECTION NOTED ON TOTAL PRECIPITABLE WATER IMAGERY...AND GLOBAL MODEL GUIDANCE INDICATES THIS SYNOPTIC SETUP WILL REMAIN IN PLACE OVER THE NEXT FEW DAYS. THEREFORE EXPECT SURFACE TROUGHING TO REMAIN ACROSS THE ERN CARIBBEAN WITH ENHANCED MOISTURE LEVELS SUPPORTING CONVECTION. ATLANTIC OCEAN... A DEEP UPPER LEVEL TROUGH ALONG 83W AND A CUT OFF LOW SITUATED OVER EASTERN OHIO ARE SUPPORTING A SLOW MOVING COLD FRONT JUST E OF THE EASTERN SEABOARD. WHILE THE COLD FRONT EXTENDS FROM 31N80W TO SOUTHERN FLORIDA...MOST OF THE SHOWERS AND TSTMS ARE WELL E OF THE FRONTAL BOUNDARY IN THE SW NORTH ATLC. A NEW LINE OF TSTMS IS DEVELOPING FROM 31N78W TO 27N80W. LATEST ANALYSIS SHOWS A SURFACE TROUGH AXIS INDICATED BY WIND SHIFT ACROSS THE CENTRAL ATLC ALONG 31N45W TO 25N46W TO PUERTO RICO NEAR 18N65W. SCATTERED MODERATE SHOWERS AND ISOLATED TSTMS ARE FOUND WITHIN 150 NM EITHER SIDE OF THE TROUGH AXIS. A BROAD AREA OF DIVERGENT FLOW ALOFT E OF THE UPPER TROUGH ALONG 83W FURTHER SUPPORTS CONVECTION IN THE REGION. SURFACE RIDGING COVERS THE REMAINDER OF THE EASTERN ATLC E OF 40W PROVIDING FAIR WEATHER CONDITIONS ACROSS THIS AREA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MUNDELL