000 AXNT20 KNHC 211802 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI MAR 21 2014 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. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC NEAR 7N12W SW TO 5N20W. ISOLATED SHOWERS AND TSTMS ARE WITHIN 80 NM EITHER SIDE OF THE TROUGH AXIS. THE ITCZ AXIS EXTENDS ALONG 5N21W TO 2N32W TO 2N43W TO 0N49W. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 3S-2N WEST OF 33W. ...DISCUSSION... GULF OF MEXICO... A BROAD SURFACE RIDGE ANCHORED BY A 1021 MB HIGH OVER SOUTH CAROLINA EXTENDS INTO THE GULF TO COVER MUCH OF THE BASIN AND PROVIDE RETURN FLOW OF 10-15 KT. OVER THE SW GULF...A SURFACE TROUGH EXTENDS FROM 23N93W TO 20N94W TO 17N93W. TRADE WINDS ACROSS THE NW CARIBBEAN HAVE BEEN ADVECTING REMNANT MOISTURE ASSOCIATED WITH A FRONTAL BOUNDARY BACK TO THE WESTERN GULF TO SUPPORT LOW CLOUDINESS WITH POSSIBLE ISOLATED SHOWERS S OF 26N W OF 88W. A SECOND SURFACE TROUGH HAS BEEN MOVING WESTWARD ACROSS CENTRAL-SOUTHERN FLORIDA THIS MORNING. AT 1500 UTC THE AXIS OF THIS SURFACE TROUGH EXTENDS ALONG THE SOUTHERN WESTERN COAST OF FLORIDA FROM 27N82W TO 25N80W AND ENHANCES SHOWERS ON THE SW ATLC WATERS BETWEEN WEST PALM BEACH AND FREEPORT. ELSEWHERE IN THE GULF...FAIR WEATHER IS BEING SUPPORTED BY UPPER LEVEL RIDGING AND DRY AIR SUBSIDENCE. LOOKING AHEAD...THE RIDGE IS FORECAST TO WEAKEN ON SAT IN RESPONSE TO A COLD FRONT FORECAST TO MOVE INTO THE NW GULF WATERS LATE ON SUN. CARIBBEAN... A BROAD UPPER RIDGE COVERS THE WESTERN AND CENTRAL CARIBBEAN WHILE A TROUGH COVERS THE REMAINDER BASIN. SATELLITE WATER VAPOR IMAGERY SHOWS DRY STABLE AIR AT THE MID AND UPPER LEVELS ACROSS THE ENTIRE BASIN WHICH IS SUPPRESSING THE DEVELOPMENT OF DEEP CONVECTION. PATCHES OF RESIDUAL SURFACE TO LOW-LEVEL MOISTURE ASSOCIATED WITH A STATIONARY FRONT CURRENTLY OVER THE SW N ATLC LINGER OVER THE NW CARIBBEAN AND PORTIONS OF HISPANIOLA. THIS MOISTURE IS SUPPORTING LOW LEVEL CLOUDINESS ACROSS CENTRAL CUBA AND HISPANIOLA WITH POSSIBLE ISOLATED SHOWERS. A MODERATE MOIST AIRMASS IS MOVING ACROSS THE EASTERN CARIBBEAN WHICH MAY ENHANCE ISOLATED SHOWERS OVER WESTERN PUERTO RICO LATER THIS AFTERNOON. OTHERWISE...TRADES OF 15-20 KT ARE ACROSS THE CENTRAL AND EASTERN CARIBBEAN WITH WINDS REACHING UP TO 25 KT ALONG THE COAST OF COLOMBIA. IN THE NW CARIBBEAN...LIGHTER TRADES OF 10 KT DOMINATE. EXPECT LITTLE CHANGES OVER THE NEXT 48 HOURS. HISPANIOLA... SATELLITE IMAGERY CONTINUE TO SHOW SCATTERED LOW CLOUDS ACROSS THE ISLAND WITH POSSIBLE ISOLATED SHOWERS IN SOME LOCATIONS. CLOUDINESS IS BEING SUPPORTED BY LINGERING MOISTURE ASSOCIATED WITH A FORMER FRONT THAT MOVED ACROSS CUBA. WITH AMPLE DRY AIR ALOFT AS SEEN IN THE VAPOR IMAGERY...LOW-LEVEL MOISTURE IS FORECAST TO REMAIN AT A MINIMUM THROUGH THE NEXT 24-48 HRS WITH THE EXCEPTION OF SHOWER ACTIVITY THAT FORMS WITH AFTERNOON HEATING. ATLANTIC... A MIDDLE TO UPPER LEVEL TROUGH EXTENDS ALONG THE WESTERN ATLC AND SUPPORTS A WARM FRONT THAT EXTENDS FROM 30N53W TO 31N59W TO 30N63W WHERE IT TRANSITIONS TO A STATIONARY FRONT ALONG 25N69W TO 21N75W. SCATTERED MODERATE CONVECTION IS OBSERVED IN SATELLITE IMAGERY WITHIN 100 NM EITHER SIDE OF THE FRONT. WEST OF THE FRONTAL BOUNDARY...A SURFACE TROUGH EXTENDS FROM 28N72W TO 24N73W WITH POSSIBLE ISOLATED SHOWERS WITHIN 30 NM EITHER SIDE OF THE AXIS. OTHERWISE...THE REMAINDER OF THE ATLC E OF 68W IS DOMINATED BY A BROAD SURFACE RIDGE ANCHORED BY A 1029 MB HIGH JUST N OF THE AREA NEAR 32N30W. WEAKER HIGH PRES IS PRESENT W OF 65W ANCHORED BY A 1021 MB HIGH NEAR 34N82W. LOOKING AHEAD...THE FRONTAL BOUNDARY OVER THE SW N ATLC IS FORECAST TO DISSIPATE LATER TODAY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR