000 AXNT20 KNHC 041743 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SUN MAR 04 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. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 8N20W 3N30W EQ40W 5N51W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 120-180 NM EITHER SIDE OF THE AXIS BETWEEN 20W AND 40W...AND WITHIN 120-150 NM OF THE AXIS W OF 40W TO THE COAST OF BRAZIL. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT IS MOVING SLOWLY ACROSS THE FLORIDA STRAITS AND THE SE PORTION OF THE GULF. A LINE OF WIDELY SCATTERED SHOWERS OVER THE STRAITS OF FLORIDA DEFINES THE LEADING EDGE OF THE FRONT WHILE A SURGE OF COLD AIR AND EXTENSIVE AREA OF LOW AND SOME MID LEVEL CLOUDS ARE FOUND BEHIND THIS FRONTAL SYSTEM. A BROAD POSITIVELY TILTED MID-UPPER LEVEL TROUGH WHICH EXTENDS FROM THE CANADIAN MARITIMES SOUTHWESTWARD THROUGH THE OHIO VALLEY TO EASTERN TEXAS SUPPORTS THIS FRONTAL BOUNDARY. VERY STRONG UPPER LEVEL WINDS ASSOCIATED WITH A SUBTROPICAL JETSTREAM AHEAD OF THE TROUGH ARE TRANSPORTING A NARROW BAND OF UPPER LEVEL MOISTURE FROM THE EPAC ACROSS N MEXICO AND THE NORTH GULF STATES INTO THE W ATLC. DRY AIR/STRONG SUBSIDENCE IS NOTED OVER THE GULF S OF THE STRONG JET/27N...WITH SATELLITE DERIVED WINDS INDICATING CORE SPEEDS OF 125-140 KT. AT THE SURFACE BUILDING HIGH PRESSURE OVER TEXAS AND THE NW CORNER OF THE GULF CONTINUES TO PUSH THE ABOVE MENTIONED COLD FRONT SLOWLY SEWD. THIS FEATURE IS EXPECTED TO BUILD FURTHER INTO THE W GULF TODAY WITH STRONG NORTHERLY WINDS OF GALE FORCE OCCURRING OVER THE SW GULF. BROKEN TO OVERCAST LOW LEVEL CLOUDS WITH LIGHT RAIN/DRIZZLE ARE BANKED UP ALONG THE E SLOPE OF THE SIERRA MADRE MOUNTAINS AND A STATIONARY FRONT IS INDICATED THERE. CARIBBEAN... AN EXPANSIVE MID/UPPER LEVEL HIGH IS CENTERED OVER E CUBA WITH THE ASSOCIATED RIDGE AXIS EXTENDING ENE INTO THE SW ATLC. THIS FEATURE COVERS THE ENTIRE CARIBBEAN AND IS ACCOMPANIED BY VERY STRONG SUBSIDENCE/DRY AIR ESPECIALLY OVER THE E CARIBBEAN IN THE VICINITY OF AN UPPER LEVEL TROUGH AXIS WHICH IS UNDERCUTTING THE RIDGE AXIS AND EXTENDS THROUGH 14N61W TO THE NORTH COAST OF COLOMBIA. PRESSURE GRADIENT BETWEEN THE SURFACE RIDGE OVER THE ATLC AND THE 1005 MB SFC LOW PRESSURE LOCATED OVER N COLOMBIA IS GENERATING STRONG EASTERLY TRADE WINDS ACROSS THE AREA. PATCHES OF LOW LEVEL MOISTURE WITH EMBEDDED SHOWERS DRIVEN BY THESE WINDS ARE MOVING WWD FROM THE TROPICAL N ATLC INTO THE CARIBBEAN E OF 70W. SOME OF THESE SHOWERS HAVE SPREAD OVER PUERTO RICO AND HISPANIOLA AS WELL AS JAMAICA AND PARTS OF CUBA. THE ATLC RIDGE WILL CONTINUE TO MOVE EWD AND THE COLD FRONT CURRENTLY OVER THE SE GULF WILL REACH THE NW CARIB/W CUBA TONIGHT FOLLOWED BY STRONG GUSTY N WINDS OVER THE YUCATAN CHANNEL. ATLANTIC... STRONG ZONAL FLOW BETWEEN THE RIDGE OVER E CUBA AND THE BROAD TROUGH OVER THE E CONUS IS SWEEPING OVER THE ATLC N OF 26N W OF 60W. THE AXIS OF THE UPPER RIDGE EXTENDS FROM THE CARIBBEAN INTO THE W AND CENTRAL ATLC TO BEYOND 32N45W COVERING THE AREA N OF 15N W OF 45W. STRONG SUBSIDENCE AND VERY DRY UPPER AIR DOMINATE THE REGION S OF 23N W OF 45W LIMITING SHOWER ACTIVITY E OF A COLD FRONT THAT ENTERS THE FORECAST AREA NEAR 31N66W AND CROSSES THE BAHAMAS NEAR ANDROS ISLAND INTO THE FLORIDA STRAITS. A SURFACE RIDGE EXTENDS FROM A 1030 MB HIGH LOCATED NEAR 33N35W SOUTHWEST TO NEAR 22N72W. A SHEARED MID/UPPER LEVEL TROUGH EXTENDS FROM THE CANARY ISLANDS SW TO A DEVELOPING CYCLONIC CIRCULATION NEAR 18N46W. THE TAIL END OF THE ASSOCIATED COLD FRONT CLIPS THE REGION THROUGH 31N18W TO 27.5N30W. A WEAKENING SURFACE TROUGH CROSSING THE WINDWARD ISLANDS. IT LIES ALONG 61W FROM 12N-20N. ONLY ISOLATED LOW TOP SHOWERS ARE OCCURRING WITH THIS TROUGH. AN UPPER RIDGE IS DOMINATING THE FAR E ATLC. WV AND INFRARED IMAGERY REVEALS A BROAD BAND OF TRANSVERSE HIGH CLOUDS AND POSSIBLE UPPER LEVEL TURBULENCE ASSOCIATED WITH A TROPICAL JETSTREAM OVER THE DEEP TROPICS E OF 50W CROSSING S OF THE CAPE VERDE ISLANDS. $$ COBB