000 AXNT20 KNHC 212351 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT APR 21 2012 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 2315 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE NRN COAST OF SIERRA LEONE AT 9N13W TO 6N15W. THE ITCZ CONTINUES FROM 6N15W ALONG 3N20W 1N30W CROSSING THE EQUATOR AT 32W TO THE COAST OF BRAZIL AT 3S40W. WIDELY SCATTERED MODERATE/STRONG CONVECTION IS FROM EQ-4N BETWEEN 11W-20W. SIMILAR ACTIVITY EQ-3N BETWEEN 31W-34W. ...DISCUSSION... GULF OF MEXICO... A NEARLY CUT-OFF UPPER LEVEL LOW IS MOVING ACROSS THE NRN GULF CURRENTLY CENTERED NEAR 29N89W. THIS UPPER LOW SUPPORTS A COMPLEX SURFACE LOW PRESSURE SYSTEM THAT CONTINUES TO IMPACT MUCH OF THE ERN HALF OF THE BASIN. AS OF 2100 UTC...A 1001 MB LOW IS CENTERED JUST S OF THE FLORIDA PANHANDLE NEAR 30N86W. A WARM FRONT EXTENDS SE FROM THE LOW CENTER ACROSS THE PENINSULA ALONG 28N83W 30N81W. A COLD FRONT EXTENDS TOWARDS THE S ALONG 24N87W 21N92W. A SECONDARY COLD FRONT EXTENDS SW FROM THE LOW CENTER ALONG 28N89W 26N94W. THERE DOESN'T APPEAR TO BE MUCH OF A TEMPERATURE GRADIENT ALONG THIS SECONDARY FRONT AND IT MAY BE TRANSITIONED INTO A SURFACE TROUGH ON THE NEXT ANALYSIS. MODEL GUIDANCE INDICATES ANOTHER FRONT WILL FORM ALONG THE NE GULF COAST LATER TONIGHT AND WILL SWEEP ACROSS THE ERN BASIN TOMORROW. WATER VAPOR IMAGERY ALONG WITH TOTAL PRECIPITABLE WATER INDICATES A VERY MOIST AIRMASS COVERS THE FAR ERN GULF WHERE WIDESPREAD SHOWERS/THUNDERSTORMS ARE PRESENT. CURRENTLY STRONG SHOWERS/THUNDERSTORMS COVER THE FLORIDA STRAITS AND WRN CUBA WITHIN 100 NM SE OF A LINE FROM 25N80W TO 22N86W. SCATTERED SHOWERS ARE ACROSS MUCH OF THE FLORIDA PENINSULA E OF 84W. A LINE OF THUNDERSTORMS IS BETWEEN THE WARM AND COLD FRONT FROM 26N85W TO 28N85W. STRONG SHOWERS/THUNDERSTORMS ALSO COVER MUCH OF NRN FLORIDA AND THE PANHANDLE. A LINE EXTENDS ALONG THE NE FLORIDA COAST FROM 29N81W TO 31N83W AND INTO GEORGIA. A SECOND LINE EXTENDS FROM ALABAMA NEAR 31N86W TO 29N89W. OVER WATER....SCATTERED SHOWERS/THUNDERSTORMS ARE NEAR THE LOW CENTER AND TO THE W FROM 26N-30N BETWEEN 86W-91W. A SLIGHT RISK OF SEVERE WEATHER IS ALSO PRESENT ACROSS THE ERN GULF THROUGH TOMORROW MORNING. DRY AIR ALOFT WRAPPING AROUND THE WRN SIDE OF THE UPPER LOW IS PROVIDING FAIR CONDITIONS ACROSS THE REMAINDER OF THE WRN GULF. EXPECT THE FIRST FRONT TO MOVE THROUGH THE AREA TONIGHT WITH A SECOND FRONT SWEEPING OVER THE AREA BY MONDAY. STRONG SHOWERS/THUNDERSTORMS WITH THE RISK OF FLOODING WILL REMAIN ACROSS THE ERN GULF WITH 20-25 KT NE WINDS SPREADING ACROSS THE AREA IN THE WAKE OF THE BOUNDARIES. CARIBBEAN SEA... COMPARED THE GULF OF MEXICO THE CARIBBEAN IS QUITE TRANQUIL THIS EVENING DUE TO DRY AIR ALOFT AROUND A BROAD UPPER LEVEL RIDGE OVER VENEZUELA. HOWEVER...STRONG SHOWERS/THUNDERSTORMS HAVE BEGUN TO IMPACT WRN CUBA ASSOCIATED WITH THE LOW PRESSURE SYSTEM OVER THE GULF. CLUSTERS OF SHOWERS/THUNDERSTORMS HAVE ALSO POPPED UP OVER PORTIONS OF CENTRAL AMERICA...COLOMBIA...AND VENEZUELA. TRADEWIND FLOW OF 10-15 KTS IS ACROSS MUCH OF THE BASIN WITH SOME EMBEDDED LOW-LEVEL SHOWERS. MORE SCATTERED ACTIVITY IS ACROSS THE NE CARIBBEAN ISLANDS ASSOCIATED WITH A SURFACE TROUGH IN THE CENTRAL ATLC. THE FIRST FRONT OVER THE GULF OF MEXICO WITH REACH THE NW CARIBBEAN SHORTLY WITH SHOWERS/THUNDERSTORMS LIKELY ALONG WITH NE WINDS OF 20-25 KTS. THE REMAINDER OF THE BASIN WILL REMAIN UNDER FAIR CONDITIONS. ATLANTIC OCEAN... SHOWERS/THUNDERSTORMS ASSOCIATED WITH THE LOW PRESSURE SYSTEM IN THE GULF ARE ALREADY BEGINNING TO SPREAD OVER THE WRN ATLC. SCATTERED SHOWERS ARE MAINLY W OF 76W WITH STRONG THUNDERSTORMS EMERGING FROM THE FLORIDA STRAITS TO 77W INCLUDING ANDROS ISLAND. THE REMAINDER OF THE W ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1021 MB HIGH NEAR 36N59W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 70W. AN UPPER LEVEL TROUGH N OF THE AREA IS CONTROLLING THE CENTRAL ATLC SUPPORTING A DISSIPATING COLD FRONT ALONG 30N44W TO 24N51W. POSSIBLE ISOLATED SHOWERS ARE ALONG THE AXIS. A SURFACE TROUGH IS FARTHER E ALONG 27N44W 22N49W 18N63W. SCATTERED SHOWERS ARE WITHIN 115 NM EITHER SIDE OF THE AXIS. A SECOND WEAK SURFACE TROUGH IS W OF THE FRONTAL BOUNDARY EXTENDING FROM A 1015 MB LOW NEAR 31N51W TO 27N53W. POSSIBLE ISOLATED SHOWERS ARE NEAR THE LOW CENTER. AN UPPER LEVEL RIDGE ALONG 30W SUPPORTS A 1027 MB HIGH NEAR THE AZORES ISLANDS AT 36N28W PROVIDING FAIR CONDITIONS ACROSS THE REMAINDER OF THE E ATLC. EXPECT THE FIRST FRONTAL BOUNDARY IN THE GULF OF MEXICO TO REACH THE W ATLC BY TOMORROW. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON