000 AXNT20 KNHC 121805 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON MAR 12 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 1745 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N13W 3N25W 1N40W CROSSING THE EQ NEAR 47W AND INTO NE BRAZIL NEAR 1S51W. FAIRLY ACTIVE CONVECTION ALONG THE AXIS THIS AFTERNOON...WITH CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 150 NM OF THE AXIS BETWEEN 22W-40W. ISOLATED TSTMS ARE WITHIN 180 NM OF AXIS W OF 40W. ...DISCUSSION... GULF OF MEXICO... IMPRESSIVE SQUALL LINE MOVED OFF THE TEXAS COAST EARLIER THIS MORNING. DOPPLER RADAR CURRENTLY SHOWS NUMEROUS HEAVY SHOWERS AND TSTMS IN THE NW GULF N OF 26N W OF 93W. THIS ACTIVITY IS ASSOCIATED WITH INSTABILITY AHEAD OF A COLD FRONT CURRENTLY PUSHING THROUGH ERN TEXAS AND NE MEXICO. IN ADDITION TO THE SFC FRONT...DEEP LAYER MOISTURE AND DIFFLUENCE AHEAD OF THE MID TO UPPER LOW OVER WRN TEXAS IS SUPPORTING THE CONVECTION. OTHERWISE THE UPPER FLOW OVER THE GULF IS SLIGHTLY ANTICYCLONIC AROUND RIDGING. ELSEWHERE AT THE SFC...CONDITIONS ARE MORE TRANQUIL WITH 10-20 KT E TO SE WINDS AROUND RIDGING EXTENDING INTO THE AREA FROM THE NE. THE SW PORTION OF THE ATLC RIDGE WILL CONTINUE TO DOMINATE MUCH OF THE GULF OVER THE NEXT COUPLE OF DAYS...THOUGH SHOWERS AND TSTMS AHEAD OF THE SLOW MOVING MID TO UPPER LOW OVER W TX WILL LINGER IN THE NW PORTION. CARIBBEAN... BROAD UPPER RIDGE COVERS MUCH OF THE CARIBBEAN EXCEPT FOR A SMALL EMBEDDED TROUGH IN THE FAR SW PORTION...WHICH IS ADVECTING A NARROW BAND OF HIGH CLOUDS/MOISTURE BETWEEN PANAMA AND SW PUERTO RICO. SIMILAR MOISTURE IS BEING ADVECTED INTO THE FAR NW PORTION/YUCATAN CHANNEL DOWNSTREAM FROM THE EPAC. VERY DRY/STABLE AIR NOTED ELSEWHERE IN THIS AFTEROONS WV IMAGERY. AT THE SFC...MODERATE TO FRESH TRADES DOMINATE EXCEPT FOR MORE VARIABLE FLOW NEAR PUERTO RICO AND LEEWARD ISLANDS...AHEAD OF THE FRONTAL TROUGH EXTENDING INTO THE MONA PASSAGE. WITH THE TROUGH...BROKEN TO OVERCAST LOW AND MID CLOUDS WITH EMBEDDED SHOWERS ARE AFFECTING WRN PUERTO RICO...THE MONA PASSAGE...ERN HISPANIOLA AND THE ADJACENT WATERS. HIGH PRES OVER THE SE U.S. AND W ATLC KEEP STRONG TRADES OVER THE CENTRAL AND WRN CARIBBEAN THROUGH WED. THE SFC TROUGH THROUGH THE MONA PASSAGE WILL MOVE SE AND EXTEND FROM 22N60W 18N63W TONIGHT AND TUE...22N57W 18N60W WED...THEN E OF THE AREA THU. ATLANTIC... DEEP LAYERED TROUGH COVERS THE W ATLC FROM 55W-80W WITH THE ASSOCIATED COLD FRONT EXTENDING INTO THE AREA ALONG 32N57W TO 24N61W THEN CONTINUING AS A SURFACE TROUGH TO THE MONA PASSAGE. BROKEN/OVERCAST LOW AND CLOUDS WITH EMBEDDED SHOWERS ARE WITHIN 30 NM OF THE BOUNDARY. THE DEEPEST MOISTURE/POSSIBLE TSTMS ARE MAINLY N OF 30N NOW BETWEEN 50W-55W...IN THE UPPER DIFLUENT ZONE AHEAD OF THE UPPER TROUGH. A REINFORCING...DISSIPATING COLD FRONT IS MOVING INTO THE AREA ALONG 30N BETWEEN 67W-77W. THIS BOUNDARY IS MARKED BY A RAGGED AREA OF BROKEN LOW CLOUDS WITH POSSIBLE ISOLATED SHOWERS WITHIN 30 NM. FAIR WEATHER AND MODERATE TO STRONG TRADES CONTINUE TO DOMINATE MUCH OF THE E ATLC E OF 45W...WITH THE SRN PERIPHERY OF STRONG SFC HIGH PRESSURE DOMINATING. BROAD RIDGING GENERALLY DOMINATES THE UPPER LEVELS OVER THE E ATLC TOO...EXCEPT FOR A WEAK UPPER TROUGH EMBEDDED ALONG 41W N OF 17N. ANOTHER UPPER TROUGH IS OVER THE FAR NE PORTION THAT HAS AN ASSOCIATED COLD FRONT JUST NORTH OF THE AREA AND JUST NW OF MADEIRA ISLAND. SFC HIGH PRES WILL DOMINATE THE WRN AND ERN ATLC THROUGH MID WEEK. CONFLUENCE BETWEEN THESE TWO HIGHS WILL CONTINUE TO SUPPORT THE FRONTAL TROUGH IN THE CENTRAL ATLC...WHICH IS FORECAST TO DRIFT SLOWLY E OVER THE NEXT COUPLE OF DAYS. $$ WALLACE