000 AXNT20 KNHC 191043 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN APR 19 2009 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...ITCZ... THE ITCZ IS CENTERED ALONG 5N9W ...CROSSING THE EQUATOR NEAR 15W TO 1S20W 3S30W AND INTO NE BRAZIL NEAR 3S40W. NO SIGNIFICANT CONVECTION IS OBSERVED IN THE DISCUSSION AREA. ...DISCUSSION... GULF OF MEXICO... MOIST WESTERLY FLOW ALOFT IS OBSERVED OVER THE GULF REGION AS A DEEP LAYER TROUGH PROGRESSES ACROSS THE CENTRAL CONUS. THE RETURN FLOW AROUND A 1021 MB SURFACE HIGH CENTERED OVER THE W ATLC NEAR 31N79W IS RESULTING IN SE WINDS OF 15 TO 20 KT ACROSS MUCH OF THE GULF REGION THIS MORNING. THESE WINDS ARE ADVECTING ABUNDANT LOW-LEVEL MOISTURE ACROSS THE GULF REGION...RESULTING IN INCREASED INSTABILITY ACROSS MUCH OF THE NRN GULF. THIS INSTABILITY AND A SURFACE TROUGH ANALYZED FROM ERN TEXAS THROUGH CORPUS CHRISTI TO NE MEXICO IS COMBINING WITH MIDDLE TO UPPER LEVEL ATMOSPHERIC DIFFLUENCE ACROSS THE NW AND N/CENTRAL GULF TO SUPPORT SCATTERED SHOWERS AND TSTMS N OF 26N W OF 88W. ACROSS THE E AND SE GULF...STABLE ATMOSPHERIC CONDITIONS ARE RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. A SURFACE COLD FRONT ASSOCIATED WITH THE CENTRAL CONUS DEEP LAYER TROUGH IS FORECAST TO MOVE OFF THE TEXAS COAST MIDDAY SUNDAY...AND EXTEND FROM THE FLORIDA BIG BEND TO THE BAY OF CAMPECHE BY MONDAY. INCREASED NLY WINDS AND RELATIVELY COOLER AND DRIER CONDITIONS ARE FORECAST ACROSS THE NW GULF WITH THE PASSAGE OF THIS FRONT. CARIBBEAN SEA... A SURFACE RIDGE LOCATED OVER THE W ATLC IS FORECAST TO MAINTAIN FRESH NE TO E TRADE WINDS ACROSS THE CARIBBEAN SEA THROUGH WEDNESDAY. GENERALLY FAIR WEATHER IS PRESENT ACROSS THE CARIBBEAN...WHERE DEEP LAYER DRY AIR AND SUBSIDENCE IS RESULTING FROM CONFLUENT WESTERLY FLOW ALOFT. HOWEVER...LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 90 NM EITHER SIDE OF A WEAKENING SURFACE COLD FRONT IN THE N/CENTRAL CARIBBEAN THAT EXTENDS FROM THE W ATLC N OF THE MONA PASSAGE TO ACROSS SE HISPANIOLA NEAR 19N69W TO 18N72W. SCATTERED SHOWERS ARE N OF 17N BETWEEN 64W-73W...INCLUDING PUERTO RICO AND THE SURROUNDING ADJACENT COASTAL WATERS. ATLANTIC OCEAN... SUBSIDENCE IN NW FLOW ALOFT ACROSS THE W ATLC IS ASSOCIATED WITH A 1021 MB SURFACE HIGH CENTERED NEAR 31N79W. A SURFACE RIDGE EXTENDS S-SE FROM THIS HIGH INTO THE SW NORTH ATLC...WHERE GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT. FARTHER TO THE E...AN UPPER LEVEL TROUGH OVER THE W AND CENTRAL ATLC WITH AXIS ALONG 60W IS ASSOCIATED WITH A SURFACE STATIONARY FRONT THAT EXTENDS FROM NE OF THE DISCUSSION AREA TO 32N50W SW INTO A 1014 MB SURFACE LOW NEAR 26N59W. A COLD FRONT CONTINUES SW FROM THE LOW ALONG 20N65W TO ACROSS SE HISPANIOLA NEAR 19N69W. LOW LEVEL CONVERGENCE AND ATMOSPHERIC INSTABILITY ARE SUPPORTING SCATTERED SHOWERS WITHIN 120 NM EITHER SIDE OF THIS FRONT S OF 26N WITH NUMEROUS SHOWERS AND ISOLATED TSTMS WITHIN 150 NM EITHER SIDE OF THIS FRONT N OF 25N. W OF THE FRONT...A WEAK 1013 MB SURFACE LOW IS CENTERED NEAR 30N57W WITH A COLD FRONT EXTENDING ALONG 28N60W TO 27N64W. LOW LEVEL CONVERGENCE IS SUPPORTING ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE FRONTAL BOUNDARY. ACROSS THE E ATLC...SUBSIDENCE ASSOCIATED WITH A SURFACE RIDGE IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. THIS SURFACE RIDGE IS ANCHORED BY A 1026 MB SURFACE HIGH NEAR 33N27W. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE IS S OF 15N E OF 60W WITH THE UPPER LEVEL HIGH CENTERED NEAR 4N49W. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THIS FEATURE IS ENHANCING CONVECTION...MAINLY SOUTH OF THE EQUATOR...ASSOCIATED WITH THE ITCZ. $$ HUFFMAN