000 AXNT20 KNHC 081753 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST TUE DEC 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS ALONG 5N9W 3N17W 4N24W 3N30W 4N40W 2N50W. WEAK TO MODERATE CONVECTION IS FOUND FROM 3N AND 7N BETWEEN 26W TO 37W. ANOTHER AREA OF WEAK CONVECTION IS FROM 2N AND 6N BETWEEN 43W TO 50W. ...DISCUSSION... GULF OF MEXICO... A WARM FRONT IS ANALYZED ALONG THE TEXAS COAST TO SOUTH CENTRAL LOUISIANA...BECOMING STATIONARY ACROSS THE FLORIDA PANHANDLE TO THE NW FLORIDA COAST. THIS SYSTEM IS BEING SUPPORTED BY A LONGWAVE UPPER LEVEL TROUGH OVER THE WRN CONUS AND A SHORTWAVE TROUGH EXTENDING OVER THE SOUTHEASTERN US...FURTHER ENHANCING PRECIPITATION IN THIS REGION. THEREFORE...MOST OF THE ASSOCIATED PRECIPITATION IS FOUND NORTH OF THE FRONTAL BOUNDARY. RADAR IMAGERY SHOWS ISOLATED SHOWERS DEVELOPING OVER THE NORTHERN GULF FROM 30N TO 28N BETWEEN 83W AND 90W...AS WELL AS OVER THE SOUTHWESTERN FLORIDA COAST FROM 26N TO 24N BETWEEN 81W AND 83W. ISOLATED THUNDERSTORMS MAY POSSIBLY DEVELOP IN THESE TWO REGIONS. SOUTHERLY FLOW 15-25 KTS OVER THE NORTHEAST BASIN IS BRINGING SUFFICIENT MOISTURE TO THE SOUTHEASTERN US. ZONAL SW FLOW ALOFT OVER THE ENTIRE BASIN WILL CONTINUE OVER THE NEXT 24 HOURS. LOOK FOR THE PRECIPITATION TO PROPAGATE EASTWARD TO THE NW FLORIDA PANHANDLE OVER THE NEXT 24 HOURS. CARIBBEAN SEA... THE CARIBBEAN CONTINUES TO BE MARKED BY MODERATE TO STRONG SUBSIDENCE. TOTAL PRECIPITABLE WATER SATELLITE IMAGERY SHOWS THE AVAILABLE MOISTURE IS INCREASING IN THE CARIBBEAN UNDER EASTERLY FLOW...BUT RELATIVELY TRANQUIL WEATHER CONTINUES TO BE IN PLACE. ISOLATED SHOWERS CAN BE FOUND OVER THE NORTHERN BASIN DUE TO SLIGHT INCREASE IN MOISTURE. AN AREA OF WEAK CONVECTION IS FOUND ALONG THE COAST BETWEEN PANAMA AND COSTA RICA. EASTERLY TRADE WINDS 15 TO 20 KTS WILL CONTINUE OVER THE NEXT 24 HOURS. NO SIGNIFICANT CHANGE IS EXPECTED IN THIS PATTERN UNTIL WED WHEN THE NORTHERN STREAM BECOMES MORE AMPLIFIED AND THE CENTRAL ATLANTIC RIDGE REORGANIZES FARTHER NORTH...ALLOWING THE TRADE WINDS TO DROP A NOTCH OVER THE CENTRAL CARIBBEAN. ATLANTIC OCEAN... A LONG STATIONARY FRONT LIES NEAR THE 30 N LATITUDE ACROSS THE CENTRAL AND WESTERN ATLANTIC FROM 30N44W TO JUST OFF THE EAST COAST OF NORTHERN FLORIDA NEAR 30N80W. THIS FRONTAL BOUNDARY BISECTS THE HIGH PRES RIDGE OVER THE CENTRAL ATLC BETWEEN 1022 MB HIGH PRES NEAR 33N52W AND 1025 MB HIGH PRES NEAR 36N8W. TOTAL PRECIPITABLE WATER IMAGERY SHOWS MOISTURE CONTINUING TO CONVERGE ON THIS BOUNDARY...WITH A FEW ISOLATED SHOWERS ALONG THE 30 N LINE BETWEEN 48W AND 70W. WHAT REMAINS OF THIS WEAK LOW LEVEL BOUNDARY WILL LIFT NORTHWARD OVERNIGHT TONIGHT IN ADVANCE OF THE DEEP LAYERED TROUGH CURRENTLY OVER THE ROCKIES AS IT PULLS EASTWARD INTO THE PLAINS AND MISSISSIPPI VALLEY. FARTHER E...THE SOUTHERLY POSITION OF THE RIDGE AXIS ACROSS THE CENTRAL ATLANTIC HAS ENHANCED THE PRES GRADIENT BETWEEN THE RIDGE AND THE ITCZ. THEREFORE...20 TO 25 KT NORTHEASTERLY TRADE WINDS ARE OBSERVED BETWEEN 40W AND 50W S OF 15N. MODERATE TRADES WILL CONTINUE TODAY BUT SHOULD DIMINISH AS THE HIGH PRES RIDGE REORGANIZES FARTHER N ON WED. FINALLY...THE 100 KT WESTERLY UPPER JET OVER THE TROPICAL ATLC ALONG 13N WILL WEAKEN AND TURN NORTHWESTERLY AS THE PATTERN DOWNSTREAM BEGINS TO AMPLIFY WED. $$ FG/CW