000 AXNT20 KNHC 181747 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST THU JAN 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 7N11W 5N25W 2N35W EQ. ISOLATED MODERATE CONVECTION ARE WITHIN 80-100 NM OF THE AXIS BETWEEN 20W-24W AND BETWEEN 29W-32W. SIMILAR CONVECTION IS ALSO SEEN BETWEEN 40W-44W. ...DISCUSSION... GULF OF MEXICO... A SUBTROPICAL JETSTREAM CONTINUES TO SPREAD ABUNDANT MID TO UPPER LEVEL MOISTURE FROM THE EPAC ACROSS NRN MEXICO AND TEXAS INTO THE SE U.S....CLIPPING THE NRN GULF WATERS. MUCH DRIER AIR IS PRESENT SE OF A LINE FROM TAMPICO MEXICO TO TAMPA FLORIDA. AN UPPER RIDGE DOMINATES THE AREA. BROKEN TO OVERCAST LOW CLOUDS ARE BEHIND THE LINGERING SFC FRONTAL BOUNDARY...WHICH AS OF 1500 UTC EXTENDS FROM SW FLORIDA WWD ALONG 25N90W 26N95W THEN CURVES SWD TO THE CENTRAL BAY OF CAMPECHE. LIGHT RAIN IS OCCURRING ALONG THE MEXICAN GULF COAST. NLY WINDS OF 20-25 KT ARE ALSO FOUND BEHIND THE FRONTAL BOUNDARY OVER THE FAR WEST GULF AND THE W PORTION OF THE BAY OF CAMPECHE. WINDS AND SEAS WILL CONTINUE TO RELAX ACROSS THE GULF THIS AFTERNOON AND TONIGHT AS A 1032 MB SFC HIGH OVER NE MEXICO WEAKENS. WINDS AND SEAS WILL INCREASE AGAIN IN THE NW CORNER OF THE GULF ON FRIDAY AS LINGERING TROUGH INTERACTS WITH REINFORCING CONTINENTAL HIGH PRESSURE. THE NEXT COLD FRONT IS EXPECTED TO ENTER THE NW GULF SAT NIGHT. CARIBBEAN SEA... VERY DRY AIR...RESULTING IN MODERATE TO STRONG SUBSIDENCE COVERS THE ENTIRE BASIN UNDER THE INFLUENCE OF A MID/UPPER RIDGE. MODERATE TO STRONG TRADE WINDS ALSO CONTINUE OVER THE CARIBBEAN SEA WITH THE MAXIMA REMAINING JUST OFF OF THE COLOMBIAN COAST AROUND 25 KT. THE TRADES ARE ADVECTING TYPICAL PATCHES OF LOW LEVEL MOISTURE WITH EMBEDDED SHOWERS ACROSS THE AREA. SOME OF THESE POCKETS OF MOISTURE ARE AFFECTING CENTRAL AMERICA... PARTICULARLY THE CARIBBEAN PLAINS OF NICARAGUA AND COSTA RICA. SIMILAR CONDITIONS ARE FOUND OVER PUERTO RICO AND THE VIRGIN ISLANDS WHERE DOPPLER RADAR IS SHOWING SCATTERED TO NUMEROUS SHOWERS WITH ISOLATED TSTMS. NO MAJOR CHANGES ARE EXPECTED ON THE WEATHER PATTERN ACROSS THE REGION THROUGH THE WEEKEND AS HIGH PRES REMAINS NORTH OF THE AREA. ATLANTIC OCEAN... A WEAK SFC LOW IS DEVELOPING JUST EAST OF THE NE FLORIDA COAST. AS OF 1500 UTC...A 1022 MB SFC LOW IS ANALYZED NEAR 28.5N80.5W. VIS SATELLITE IMAGERY AND DOPPLER RADAR INDICATE SOME SLIGHT TURNING IN THE CLOUD PATTERN WITH MOST OF THE CONVECTIVE ACTIVITY OBSERVED TO THE E AND SE OF THE LOW CENTER. THIS SFC LOW IS FORECAST TO MOVE NE ALONG THE EASTERN SEABOARD DEEPENING. AN UPPER RIDGE IS BUILDING INTO THE SW N ATLC. HIGH CLOUDS AND MOISTURE ARE BEING ADVECTED EWD FROM THE SE U.S. COAST INTO THE ATLC WATERS N OF 26N W OF 60W. SIGNIFICANT DRY UPPER AIR IS OVER THE REMAINDER OF THE W ATLC. STRONG SFC HIGH PRESSURE REMAINS OVER THE W ATLC BEHIND THE COLD FRONT THAT ENTERS THE AREA AT 32N48W AND CONTINUES SW TO 25N74W. NE TO E WINDS OF 20-25 KT ARE BEHIND THE FRONT. A BAND OF BROKEN LOW CLOUDS/LIGHT RAIN IS ASSOCIATED WITH THE FRONT. A 1018 MB SFC LOW IS OVER THE CENTRAL ATLC NEAR 24N51W. A SFC TROUGH ASSOCIATED WITH IT EXTENDS FROM 30N50W TO 15N50W...AND IS A REFLECTION OF THE UPPER TROUGH EXTENDING THROUGH THE AREA. SCATTERED MODERATE CONVECTION IS MAINLY E OF THE LOW/TROUGH FROM 19N-25N BETWEEN 45W-51W. AN UPPER HIGH LOCATED OVER NE BRAZIL DOMINATES N SOUTH AMERICA. ABUNDANT MOISTURE/HIGH CLOUDS WITH POSSIBLE SCATTERED SHOWERS ARE ON THE NORTHERN PERIPHERY OF THE HIGH OVER THE TROPICS EAST OF 60W. ANOTHER UPPER LOW IS OVER THE E ATLC NEAR 23N27W...THAT ALSO HAS SIGNIFICANT MOISTURE WITH EMBEDDED SHOWERS MAINLY TO ITS N AND E FROM 13N-28N BETWEEN AFRICA AND 27W. A SFC TROUGH... WEAK REFLECTION OF THIS IS ALSO ANALYZED FROM 28N14W TO 21N24W. A 1035 MB SFC HIGH NEAR THE COAST OF PORTUGAL EXTENDS A RIDGE OVER THE E ATLC GENERATING MODERATE E TO NE WINDS. $$ GR