000 AXNT20 KNHC 232353 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON APR 23 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA... CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA... NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N12W 2N30W 1N40W EQ50W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 60-70 NM N OF AXIS BETWEEN 14W-22W. SIMILAR CONVECTION IS OVER NE BRAZIL. SCATTERED MODERATE CONVECTION IS FROM EQ-4N WEST OF 28W. BETWEEN 26W-29W. ...DISCUSSION... THE GULF OF MEXICO... AS OF 21Z...A 1026 MB HIGH LOCATED NEAR 32N73W EXTENDS A RIDGE SW TO THE BAY OF CAMPECHE...COVERING ALSO THE STATE OF FLORIDA. UNDER THE INFLUENCE OF THIS SYSTEM...MOSTLY FAIR WEATHER PREVAILS. 10-20 KT SELY RETURN FLOW COVERS THE ENTIRE GULF OF MEXICO. ONSHORE FLOW OVER TEXAS AND E MEXICO IS PRODUCING BROKEN LOW CLOUDS WITH EMBEDDED SHOWERS W OF 96W TO THE FOOTHILLS OF THE SIERRA MADRE MOUNTAINS. ALOFT...AN UPPER LEVEL RIDGE DOMINATES THE GULF AND THE FLORIDA PENINSULA. A SUBTROPICAL JET IS TRANSPORTING ABUNDANT UPPER LEVEL MOISTURE FROM THE EPAC INTO N-CENTRAL MEXICO AND TEXAS. HIGH PRES WILL SHIFT E ALLOWING THE RETURN FLOW TO INCREASE TO 25 KT ON WED. THE CARIBBEAN SEA... THE TAIL END OF AN ATLC STATIONARY FRONT EXTENDS SW TO THE VIRGIN ISLANDS. FROM THERE...A SURFACE TROUGH CONTINUES SW TO E PANAMA. THE SAN JUAN DOPPLER RADAR SHOWS SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED TSTMS OVER THE VIRGIN ISLANDS AND PUERTO RICO...WHERE A FLASH FLOOD WATCH IS NOW IN EFFECT UNTIL TUESDAY MORNING. SCATTERED SHOWERS/TSTMS ARE WITHIN 35 NM EITHER SIDE OF THE TROUGH...MAINLY BETWEEN 70W-76W. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE AFFECTING NORTHERN COLOMBIA AND E PANAMA. A DIFFLUENT PATTERN ALOFT IS HELPING THIS CONVECTIVE ACTIVITY. PATCHES OF LOW LEVEL CLOUDS WITH MAINLY LIGHT RAIN/SHOWERS ARE OVER HISPANIOLA AND JAMAICA. EARLIER QUIKSCAT PASS SHOWED 20-25 KT NELY WINDS FLOW THROUGH BOTH THE MONA PASSAGE AND THE WINDWARD PASSAGE. THESE WINDS WILL PERSIST TONIGHT. LIGHTER ELY WINDS ARE OVER THE E CARIBBEAN E OF THE SURFACE TROUGH. IN THE UPPER LEVELS...A POSITIVELY TILTED TROUGH EXTENDS FROM AN UPPER LOW NEAR 31N61W TO CENTRAL CUBA INTO THE NW CARIBBEAN. AN UPPER LEVEL E/W RIDGE AXIS IS OVER NRN SOUTH AMERICA ALONG 10N FROM TRINIDAD/TOBAGO TO COSTA RICA. MOSTLY WLY UPPER LEVEL FLOW COVERS THE CARIBBEAN SEA N OF THE RIDGE AXIS. UPPER DRY AIR...RESULTING IN STRONG SUBSIDENCE COVERS THE BASIN W OF 75W WITH THE DRIEST AIR OVER CENTRAL CUBA. THE SURFACE TROUGH IS FORECAST TO REMAIN NEARLY STATIONARY ENHANCING THE SHOWER ACTIVITY FROM PUERTO RICO AND THE VIRGIN ISLANDS TO PANAMA DURING THE NEXT 24 HOURS. THE ATLANTIC OCEAN... A 1026 MB HIGH IS OVER THE W ATLANTIC NEAR 32N73W. A STATIONARY FRONT ENTERS THE FORECAST AREA NEAR 31N34W THEN CONTINUES SW TO THE VIRGIN ISLANDS. COMPUTER MODEL ANTICIPATES THE DEVELOPMENT OF A WEAK SFC LOW ALONG THE FRONTAL BOUNDARY NEAR 26N55W LATE TONIGHT. THIS LOW WILL MOVE NE EXITING THE DISCUSSION AREA TUE NIGHT. A WIDE BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH THE STATIONARY FRONT. A 1023 MB HIGH IS OVER THE E ATLANTIC NEAR 32N22W. THE UPPER TROUGH MENTIONED ABOVE IN THE CARIBBEAN SECTION SUPPORTS THIS FRONT. AN UPPER RIDGE ANCHORED ON A HIGH NEAR 20N40W IS OVER THE CENTRAL ATLANTIC COVERING N OF 10N BETWEEN 20W-50W. STRONG SWLY WINDS BETWEEN THESE TWO UPPER FEATURES ARE ADVECTING UPPER LEVEL MOISTURE FROM THE NE CARIBBEAN ALL THE WAY NE TO BEYOND 32N40W. AN AREA OF BROKEN TO OVERCAST LOW/MID CLOUDS COVERS FROM 14N-25N BETWEEN 28W-45W. ANOTHER TROUGH IS OVER WEST AFRICA WITH AXIS CROSSING NEAR THE CAPE VERDE ISLANDS. $$ GR