000 AXNT20 KNHC 210541 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT MAR 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 3N20W CROSSING THE EQUATOR ALONG 30W EXTENDING TO 1S40W INTO NE BRAZIL NEAR 2S45W. ISOLATED MODERATE CONVECTION IS WITHIN 50 NM EITHER SIDE OF AXIS BETWEEN 30W AND 42W. ...DISCUSSION... GULF OF MEXICO... HIGH PRES CENTERED OVER THE NE CONUS EXTENDS A RIDGE ACROSS THE EASTERN U.S. AND THE GULF OF MEXICO WHERE A 1020 MB HIGH IS ALSO ANALYZED NEAR 23N96W. THERE ARE MOSTLY CLEAR SKIES OVER THE GULF WATERS...EXCEPT FOR A FEW BROKEN CLOUDS AND ISOLATED SHOWERS NEAR 24N ASSOCIATED WITH A SMALL REGION OF WEAK INSTABILITY. SIMILAR CLOUDINESS IS NOTED OVER THE YUCATAN PENINSULA AND COASTAL WATERS. A WEAKENING COLD FRONT IS CURRENTLY MOVING ACROSS CENTRAL FLORIDA REACHING THE LAKE OKEECHOBEE AREA. THE MOSAIC DOPPLER RADAR FROM THE SE U.S. SHOWS ISOLATED SHOWERS ALONG THE FRONTAL BOUNDARY WHILE SCATTERED SHOWERS ARE NOTED JUST OFFSHORE THE EAST COAST OF FLORIDA AND ALSO ACROSS THE STRAITS OF FLORIDA. THE FRONT IS EXPECTED TO MOVE ACROSS SOUTH FLORIDA THIS AFTERNOON PRODUCING SCATTERED FAST MOVING SHOWERS AND INCREASING NE WINDS. A QSCAT PASS FROM AROUND 2330 UTC SHOWED NE WINDS OF 20 TO 25 KT BEHIND THE FRONT OVER THE FAR W ATLC. IN THE UPPER LEVELS...A WEAK UPPER LEVEL TROUGH OVER THE CENTRAL GULF IS DROPPING SE INTO THE E GULF...DOWNSTREAM OF AN AMPLIFYING UPPER RIDGE ALONG 100W. MODERATE TO STRONG SUBSIDENCE/DRY AIR ALOFT COVERS THE GULF W OF 90W...MAINLY BEHIND THE TROUGH AXIS. CARIBBEAN SEA... AN EARLIER QSCAT PASS AND SFC DATA INDICATED PREDOMINATELY NE TO E WINDS OVER THE BASIN...WITH WINDS OF 20 KT ALONG THE COLOMBIAN COAST...DECREASING TO 5-10 KT IN THE NW CARIBBEAN SEA. TYPICAL PATCHES OF LOW LEVEL CLOUDS WITH EMBEDDED LIGHT TO MODERATE SHOWERS ARE OBSERVED ACROSS THE AREA PARTICULARLY JUST OFFSHORE THE COAST OF COLOMBIA...AS CYCLONIC TURNING AROUND THE LOW OVER COLOMBIA NEAR 9N75W HAS CREATED CONVERGENT FLOW IN THE AREA. THE TRADE WINDS ARE ALSO ADVECTING LOW LEVEL MOISTURE ACROSS WESTERN PANAMA AND COSTA RICA. AT THE UPPER LEVELS...WATER VAPOR IMAGERY INDICATES SUBSIDENCE ACROSS THE CARIBBEAN. SUBTROPICAL JET STREAK IS OVER THE YUCATAN PENINSULA TO CUBA WITH CORE SPEEDS OF 80-90 KT. THIS IN COMBINATION WITH LIFT AHEAD OF AN UPPER LEVEL TROUGH SWEEPING SE OVER THE GULF IS CAUSING BROKEN HIGH CLOUDS OVER THE NW CARIBBEAN AND THE STRAITS OF FLORIDA. A SFC TROUGH IS OVER THE WINDWARD PASSAGE. LOW LEVEL CONVERGENCE NEAR THE TROUGH AXIS IS SUPPORTING PATCHES OF LOW LEVEL CLOUDS OVER EASTERN CUBA AND HISPANIOLA. ATLANTIC OCEAN... STRONG QUASI-STATIONARY LOW PRESSURE IS CURRENTLY WELL N OF THE DISCUSSION AREA NEAR 37N41W. A COLD FRONT EXTENDS INTO THE AREA FROM THE LOW TO 32N36W TO 24N45W THEN CONTINUES AS A STATIONARY FRONT TO 24N60W...AND AS A WARM FRONT TO A 1012 MB LOW NEAR 26N69W. A LOW PRES TROUGH EXTENDS SW FROM THE LOW TO THE WINDWARD PASSAGE. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 80 NM AHEAD OF THE TROUGH N OF 22N. THIS CONVECTION IS PART OF A MUCH LARGER AREA OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS WHICH COVERED THE AREA N OF 22N BETWEEN 60W AND 70W. WIDELY SCATTERED LOW TOPPED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE COLD FRONT...AND WITHIN 90 NM N OF THE STATIONARY FRONT. THE LOW PRESSURE IS FORECAST TO MOVE NE AND AWAY FROM THE FORECAST AREA TO NEAR 33N58W BY 24 HOURS. ELSEWHERE...A 1023 MB HIGH PRESSURE N OF THE AREA NEAR 36N55W IS CURRENTLY EXTENDING A RIDGE INTO THE REGION BEHIND THE COLD FRONT. OTHERWISE...MAINLY CLEAR SKIES WITH A FEW AREA OF BROKEN CLOUDS DOMINATE THE WEATHER OVER THE REMAINDER OF THE ATLC. AT THE UPPER LEVELS...A TROUGH/RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE ENTIRE AREA. A BROAD AREA OF STRONG SUBSIDENCE IS NOTED OVER THE OCEAN WITHIN THE RIDGE GENERALLY FROM 15N TO 23N BETWEEN 30W AND 65W. MOSTLY ZONAL FLOW IS FOUND ACROSS THE DEEP TROPICS. $$ GR