000 AXNT20 KNHC 151758 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...TROPICAL WAVE... THE FIRST TROPICAL WAVE HAS BEEN IDENTIFIED IN THE EASTERN TROPICAL ATLC EMBEDDED IN THE ITCZ ...OFF THE COASTAL WATERS OF NE BRAZIL WITH AXIS ANALYZED FROM 7N38W TO 2N42W. THE WAVE IS DRIFTING WEST AT ABOUT 5 KT. THIS WAVE SHOWS UP WELL AS A LOW AMPLITUDE MOISTURE SURGE ON TOTAL PRECIPITABLE WATER IMAGE AND SATELLITE DERIVED WINDS...AND HAS GOOD CONTINUITY ON SATELLITE DATA WITH THE WAVE EMERGING FROM WEST AFRICA ON MAY 12. THE MOST RECENT WINDSAT PASS REVEALS THIS WAVE LACKS OF CYCLONIC CURVATURE...WITH NE WINDS UP TO 20 KT SURROUNDING THE WAVE AXIS. VERY WEAK CONVECTION ASSOCIATED TO THIS SYSTEM CONTINUES TO BE EMBEDDED IN THE ITCZ. ...ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE COAST OF SIERRA LEONE NEAR 7N12W WESTWARD ALONG 3N20W 3N30W 5N40W TO NE BRAZIL ALONG 3N51W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 120 NM ON EITHER SIDE OF THE ITCZ E OF 30W. AN EMBEDDED SURFACE TROUGH FOUND WITHIN THIS AREA OF CONVECTION EXTENDING FROM 5N21W TO 1N23W. OTHERWISE...SCATTERED MODERATE CONVECTION IS WITHIN 70 NM EITHER SIDE OF THE ITCZ W OF 42W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL SHORT WAVE/TROUGH MOVES ACROSS THE FAR EASTERN GULF INTO THE WEST ATLC. THIS UPPER FEATURE CONTINUES TO SUPPORT THE COLD FRONT MOVING ACROSS THE SE GULF INTO THE STRAITS OF FLORIDA. THE FRONT IS ANALYZED ALONG 26N82W TO 25N83W DISSIPATING TO 22N86W. DOPPLER RADAR IMAGERY INDICATES SCATTERED MODERATE TO HEAVY SHOWERS AND ISOLATED THUNDERSTORM IMPACTING THE COASTAL WATERS OF SOUTHERN FLORIDA INCLUDING THE KEYS AND THE STRAITS N OF 24N. STRONG DRY AIR AND SUBSIDENCE COVER THE BASIN BEHIND THE UPPER TROUGH SUPPRESSING CONVECTION AND SUPPORTING FAIR WEATHER ACROSS THE REMAINDER OF THE AREA. EXPECT THE FRONT TO MOVE OUT OF THE AREA OVER THE NEXT 6 HOURS WITH A FEW ISOLATED SHOWERS LINGERING IN THE FAR EAST BASIN. CARIBBEAN SEA... AN UPPER LEVEL TROUGH MOVES ACROSS THE CARIBBEAN THIS AFTERNOON. DRY AIR ALOFT ACCOMPANIES THE TROUGHING W OF 70W. THIS PATTERN IS PROVIDING FAIR CONDITIONS ACROSS THE ENTIRE NW AND CENTRAL PORTIONS OF THE BASIN. THE UPPER LEVEL TROUGH IS INDUCING BROAD CYCLONIC TURNING COVERING THE EASTERN AND CENTRAL BASIN E OF 74W. THIS SCENARIO IS SUPPORTING A BROAD AREA OF SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS E OF 70W INCLUDING THE LESSER ANTILLES AND PUERTO RICO. WITHIN THIS AREA OF CONVECTION...A SURFACE TROUGH IS ANALYZED FROM THE ATLC BASIN ACROSS THE US/UK VIRGIN ISLANDS ALONG 18N65W...EXTENDING SW INTO NE VENEZUELA NEAR 11N70W. ATMOSPHERIC 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... AN UPPER LEVEL TROUGH/CUT OFF LOW IS OVER THE EASTERN CONUS SUPPORTING A COLD FRONT EMERGING OFF THE EASTERN SEABOARD FROM NORTH CAROLINA NEAR 34N78W INTO OUR AREA ALONG 30N79W CONTINUING SW ACROSS THE SOUTHERN FLORIDA PENINSULA ALONG 26N80W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 70 NM AHEAD OF THE FRONT. FARTHER EAST...A BROAD/ELONGATED UPPER LOW IS OVER THE CENTRAL ATLC ROTATING AROUND 35N50W. THIS SYSTEM SUPPORTS A SURFACE TROUGH AXIS DEPICTING THE MAIN WIND SHIFT ACROSS THE CENTRAL ATLC ALONG 32N45W 25N46W 22N56W INTO THE CARIBBEAN SEA ALONG 18N65W. A BROAD AREA OF WIDELY SCATTERED SHOWERS AND THUNDERSTORMS IS FOUND WITHIN 150 NM ON EITHER SIDE OF THE TROUGH. AN AREA OF DIFFLUENCE FLOW ALOFT ASSOCIATED TO A FAIRLY STRONG 70 KT UPPER LEVEL JET STREAK FURTHER SUPPORTS THE CONVECTION IN THIS REGION. SURFACE RIDGING COVERS THE REMAINDER OF THE EASTERN ATLC E OF 40W PROVIDING FAIR WEATHER CONDITIONS ACROSS THIS AREA. AN UPPER LEVEL LOW CONTINUES TO SPIN NE OF THE CANARY ISLANDS SUPPORTING A WEAK SURFACE TROUGH ANALYZED FROM 34N18W TO 29N19W. MINIMAL ACTIVE WEATHER IS ASSOCIATED WITH THIS TROUGH. EXPECT CONVECTIVE WEATHER TO REMAIN ACROSS THE CENTRAL ATLC WITH ACTIVITY INCREASING OVER THE W ATLC AS A COLD FRONT PROGRESSES EWD INTO THE W ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA