000 AXNT20 KNHC 082341 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN MAR 08 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N10W 1N20W CROSSING THE EQUATOR NEAR 22W EXTENDING TO 1S40W AND INTO NE BRAZIL NEAR 2S45W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR 4N8W. ISOLATED MODERATE CONVECTION IS S OF 2N BETWEEN 8W-13W. SIMILAR CONVECTION IS NOTED ALONG THE EQUATOR BETWEEN 14W-20W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE WITH AXIS FROM THE BAY OF CAMPECHE TO THE FLORIDA PANHANDLE DOMINATES MUCH OF THE GULF AND SE CONUS. THIS UPPER-LEVEL FEATURE IS PRODUCING MODERATE TO STRONG SUBSIDENCE SE OF A LINE FROM NEW ORLEANS LOUISIANA TO JUST SOUTH OF BROWNSVILLE TEXAS. STRONG SWLY UPPER-LEVEL WINDS ARE ADVECTING MID/UPPER LEVEL MOISTURE FROM THE EPAC REGION INTO NORTHERN MEXICO AND THE NORTH GULF STATES INCLUDING ALSO THE NW CORNER OF THE GULF. SOUTHEASTERLY SURFACE RETURN FLOW OF 15-20 KT RESIDES ON THE WRN PERIPHERY OF A SURFACE RIDGE THAT EXTENDS FROM A 1028 MB HIGH IN THE W ATLC NEAR 28N72W. FRESH E-SE WINDS CONTINUE TO FILTER THROUGH THE STRAITS OF FLORIDA AND INTO THE FAR SE GULF. THESE WINDS ARE TRANSPORTING PATCHES OF LOW-LEVEL CLOUDS WITH POSSIBLE ISOLATED SHOWERS. THE SURFACE HIGH IS FORECAST TO REMAIN NEARLY STATIONARY WHILE GRADUALLY WEAKENING. AS A RESULT...THE OVERALL WEATHER PATTERN ACROSS THE GULF WILL CHANGE LITTLE THROUGH MID-WEEK. LOOKING AHEAD...THE NEXT COLD FRONT IS EXPECTED TO MOVE INTO THE EXTREME NW GULF LATE EARLY THU MORNING THEN STALL THROUGH FRI. CARIBBEAN SEA... FRESH TO STRONG WINDS ASSOCIATED WITH A 1028 MB SURFACE HIGH CENTERED IN THE W ATLC NEAR 28N72W ARE ADVECTING POCKETS OF SHALLOW MOISTURE WITH EMBEDDED ISOLATED LIGHT SHOWERS ACROSS THE GREATER ANTILLES AND MUCH OF THE CARIBBEAN SEA. AN EARLIER ASCAT PASS SHOWED E-NE WINDS OF 20-30 KT OVER MUCH OF THE CENTRAL CARIBBEAN. THE STRONGEST WINDS OF 30-35 KT ARE OCCURRING OFF THE COAST OF COLOMBIA WHERE A GALE WARNING REMAINS IN EFFECT. THESE STRONG WINDS ARE THE RESULT OF A TIGHT SURFACE PRESSURE GRADIENT BETWEEN THE AFOREMENTIONED HIGH OVER THE W ATLC AND LOWER PRESSURE OVER NRN SOUTH AMERICA. ALOFT...STRONG SUBSIDENCE IS RESULTING FROM CONFLUENCE IN WESTERLY UPPER LEVEL FLOW... MAXIMIZED OVER THE ERN CARIBBEAN...AND IT IS THIS UPPER LEVEL REGIME THAT CONTINUES TO LIMIT ANY DEEP CONVECTION ACROSS THE BASIN. ATLANTIC OCEAN... A DEEP LAYERED LOW PRES SYSTEM PERSISTS OVER THE CENTRAL ATLC WITH A 1004 MB OCCLUDED SURFACE LOW CENTERED NEAR 26N51W. THE ATTENDANT COLD FRONT EXTENDS FROM 29N46W ALONG 20N44W SW TO 10N52W. SCATTERED SHOWERS ARE WITHIN 90 NM OF THE COLD FRONT WHILE UPPER LEVEL DIFFLUENCE TO THE NE OF THE LOW IS AIDING IN GENERATING SCATTERED MODERATE CONVECTION WITHIN 300 NM NE OF THE FRONT N OF 24N. THIS LOW PRES SYSTEM IS PRODUCING GALE FORCE WINDS PARTICULARLY TO THE W AND N SEMICIRCLES OF THE LOW CENTER. SEE THE HIGH SEAS FORECAST FOR DETAILS. ACROSS THE W ATLC...A RELATIVELY COOLER AND DRIER AIRMASS REMAINS IN PLACE COURTESY OF A 1028 MB SURFACE HIGH CENTERED NEAR 28N72W. BROKEN COLD AIR STRATOCUMULUS CLOUDS ARE STILL NOTED ON SATELLITE IMAGERY ACROSS THE W ATLC INTO THE BAHAMAS AND CUBA UNDER THE PREVAILING E-NE WIND FLOW. FARTHER TO THE EAST...AN UPPER-LEVEL LOW CONTINUES TO SPIN OVER THE E ATLC JUST NORTH OF THE CANARY ISLANDS. A WEAK 1013 MB SURFACE LOW IS CENTERED NEAR 30N15N WITH A SURFACE TROUGH ANALYZED FROM THE LOW ALONG 26N12W 21N13W TO 18N13W. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS FEATURE IS SUPPORTING AN AREA OF SCATTERED SHOWERS OVER SRN MOROCCO. ACROSS THE TROPICAL ATLC...A BROAD UPPER-LEVEL RIDGE CENTERED NEAR 6N17W IS ENHANCING CONVECTION ALONG THE ITCZ AXIS...NE BRAZIL AND THE GUYANAS. $$ GR