000 AXNT20 KNHC 280004 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE FEB 27 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 2345 UTC. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N10W 3N20W...CROSSING THE EQUATOR AT 31W...INTO NORTHEASTERN BRAZIL NEAR 4S43W. ISOLATED CLUSTERS OF MODERATE CONVECTION ARE WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 12W-23W. SCATTERED MODERATE IS FROM 4S-3N BETWEEN 34W-47W. ...DISCUSSION... THE GULF OF MEXICO... VERY COMPLEX FRONTAL PATTERN DOMINATES THE N AND E GULF THIS EVENING. THE SYNOPTIC SIGNAL HAS BECOME QUITE BLURRY WITH NUMEROUS BOUNDARIES EVIDENT FROM SEA BREEZES...OLD FRONTS...AND THE CONVECTION IN THE SE GULF AND S FLORIDA. THE VERY WEAK SFC PRES GRADIENT OVER THE E GULF IS NOT HELPING TO SORT THINGS OUT. HOWEVER...IN THE MIDST OF THE CONFUSION AS OF 27/2100 UTC MY BEST HYPOTHESIS TO WHAT IS GOING ON ENTAILS THIS...A 1011 MB SFC LOW HAS FORMED OVER NE FLORIDA THAT HAS A STATIONARY FRONT RIDING THE GULF COAST THEN CUTTING INLAND THROUGH MISSISSIPPI AND LOUISIANA. THIS BOUNDARY IS SEPARATING A STRONG DEWPOINT GRADIENT WELL BUT NOT AS MUCH WITH TEMPS...WITH PLENTY OF CLEAR SKIES AND SUNSHINE HEATING UP THE SE U.S. SFC OBS AND THE LAST FEW VISIBLE PICTURES THIS EVENING CLEARLY SHOW A TROUGH EXTENDING FROM JUST NORTH OF LAKE OKEECHOBEE TO A PSN IN THE SE GULF NEAR 25N88W. SCATTERED SHOWERS WITH EMBEDDED TSTMS ARE WITHIN 90 NM OF THIS TROUGH...MAINLY TO THE S AND E OF THE AXIS...AND ARE AFFECTING SRN FLORIDA AND ADJACENT WATERS. ELSEWHERE AT THE SFC...A 1014 MB HIGH IS JUST OFFSHORE SE LOUISIANA. ALOFT...ZONAL FLOW IS DOMINATING WITH VERY DRY AIR SEEN IN WV IMAGERY N OF 27N AND JUST OFFSHORE MEXICO. THE STRONG WLY FLOW IS PUSHING THE MOISTURE OVER THE AFOREMENTIONED CONVECTION QUICKLY TO THE E INTO THE SW N ATLC. SFC HI PRES N OF THE AREA WILL PUSH E WED IN ADVANCE OF THE NEXT FRONT TO PUSH OFF THE TX COAST DURING THU. RETURN FLOW WILL GRADUALLY INCREASE IN ADVANCE OF THE FRONT...SEE OFFSHORE WATERS FORECAST UNDER HEADER MIAOFFNT4 FOR DETAILS. THE CARIBBEAN SEA... ABUNDANT WLY UPPER LEVEL FLOW AND DRY AIR/SUBSIDENCE CONTINUE TO AFFECT THE CARIBBEAN BASIN. EXCEPTION IS SLIGHTLY INCREASING UPPER MOISTURE IN THE FAR NW PORTION DOWNSTREAM FROM CONVECTION IN THE SE GULF. MODERATE TO STRONG TRADES CONTINUE E OF 80W...WITH A GALE WARNING NOW IN EFFECT FOR ELY FLOW NEAR THE COLOMBIAN COAST. WINDS ARE A BIT LIGHTER W OF 80W...AND BEND NE S OF 16N AROUND THE COLOMBIAN LOW...AND MORE SE TO THE N OF 16N ON THE SW PORTION OF AN ATLC RIDGE AND AHEAD OF THE TROF IN THE GULF. SPEED CONFLUENCE ASSOCIATED WITH THIS IS GENERATING A REGION OF SCATTERED LOW TO MID CLOUDS WITH POSSIBLE EMBEDDED LIGHT SHOWERS OFFSHORE NICARAGUA. HIGH PRES N OF THE AREA WILL MAINTAIN MODERATE TO STRONG TRADES THROUGHOUT MUCH OF THE CARIBBEAN WITH GALE CONDITIONS OVER THE SW PORTION THROUGH WED MORNING. THE ATLANTIC OCEAN... COMPLEX FRONTAL PATTERN AS DESCRIBED IN GULF SECTION ALSO AFFECTING THE SW N ATLC. A STATIONARY FRONT THAT SEEMS TO MARK A DEWPOINT BOUNDARY THE BEST EXTENDS E FROM THE LOW OVER N FLORIDA TO 32N72W. A TROUGH AHEAD OF THIS IS ALONG 29N69W 26N76W. THE UNSTABLE ENVIRONMENT IN THE WRN ATLC HAS NUMEROUS MODERATE CONVECTION N OF 24N BETWEEN 67W-76W. THIS IS ALSO BEING SUPPORTING BY UPPER DIFFLUENCE BETWEEN A SMALL SHORTWAVE TROUGH ZIPPING E AWAY FROM FLORIDA...AND THE RIDGING EXTENDING NE THROUGH THE CENTRAL ATLC FROM THE CARIBBEAN. OVERALL THOUGH...LARGE SCALE UPPER FLOW IN THE W AND CENTRAL ATLC IS ZONAL. THIS IS ADVECTING THE MOISTURE OVER THE AFOREMENTIONED CONVECTION N OF 24N EWARD TO NEAR 40W. A DISSIPATING COLD FRONT/TROUGH ENTERS THE AREA NEAR 32N30W AND EXTENDS SW TO 24N50W. IT APPEARS AS IF THE 1033 MB HIGH PRES N OF MADEIRA ISLAND IS BUSTING THROUGH THIS BOUNDARY...SO LOOK FOR THIS OLD BOUNDARY TO CONTINUE DISSIPATING. THE HIGH IS PRODUCING MODERATE TO STRONG NE TO E WINDS AND FAIR WEATHER OVER MUCH OF THE E ATLC...AND THIS IS EXPECTED TO PERSIST OVER THE NEXT COUPLE OF DAYS. UPPER PATTERN OVER THE E ATLC GENERALLY DOMINATED BY LARGE SCALE RIDGING...THOUGH A MID LEVEL TROUGH IS JUST OFFSHORE AFRICA FROM 15N-25N E OF 25W THAT IS SURROUNDED BY VERY DRY AIR. $$ WILLIS