000 AXNT20 KNHC 191758 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED DEC 19 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 ...THE ITCZ... FROM NORTHERN COASTAL LIBERIA TO 5N20W 4N30W 2N40W...THROUGH THE EQUATOR AT 50W...TO JUST SOUTH OF THE EQUATOR ALONG 53W. SCATTERED STRONG SHOWERS/THUNDERSTORMS FROM 6N TO 7N BETWEEN 24W AND 27W...AND FROM 3N TO 4N BETWEEN 41W AND 45W. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG THUNDERSTORMS ARE ELSEWHERE WITHIN 60 NM TO 120 NM ON EITHER SIDE OF 6N16W 5N27W 3N31W 3N50W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE FROM 5N TO 6N BETWEEN 51W AND 53W...AND FROM 9N TO 10N BETWEEN 55W AND 57W. ...DISCUSSION... THE GULF OF MEXICO... A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM ARIZONA INTO THE NORTHERN HALF OF BAJA CALIFORNIA RIDGE. UPPER LEVEL ANTICYCLONIC FLOW IS RIGHT BEHIND THE TROUGH...MOVING FROM NEVADA AND CALIFORNIA TO 30N120W. UPPER LEVEL SOUTHWESTERLY WIND FLOW MOVES FROM THE EASTERN PACIFIC OCEAN ACROSS THE SOUTHERN HALF OF BAJA CALIFORNIA...ACROSS MEXICO FROM 20N TO 30N. AN UPPER LEVEL RIDGE IS ALONG 96W FROM THE CENTRAL COASTAL PLAINS OF EASTERN MEXICO NORTHWARD BEYOND EAST TEXAS. A MIDDLE TO UPPER LEVEL TROUGH PASSES THROUGH SOUTH CAROLINA TO THE SOUTHERN TIP OF FLORIDA. BROAD SURFACE LOW PRESSURE EXTENDS FROM A SHALLOW TEXAS FRONTAL BOUNDARY THAT IS UNDER THE UPPER LEVEL RIDGE...INTO THE SOUTHWESTERN CORNER OF THE AREA. A SURFACE RIDGE REMAINS FROM A 1026 MB SOUTHWESTERN GEORGIA HIGH PRESSURE CENTER TO THE SOUTH CENTRAL GULF OF MEXICO. THE CARIBBEAN SEA... A MIDDLE LEVEL TROUGH CONTINUES FROM THE NORTHEASTERN CORNER OF THE AREA TO THE SOUTH CENTRAL COASTAL WATERS OF VENEZUELA AND THE NETHERLANDS ANTILLES...TO THE SOUTHWESTERN CORNER OF THE AREA NEAR THE COLOMBIA/PANAMA BORDER. MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE COVERS THE ENTIRE AREA...EXCEPT FOR THE EXTREME SOUTHEASTERN CORNER. MOISTURE IS STREAMING NORTHWARD WITH AN UPPER LEVEL RIDGE FROM THE WESTERN END OF THE ITCZ TO ITS PEAK NEAR 19N57W. A SURFACE TROUGH CONTINUES FROM EASTERN CUBA NEAR 21N77W TO 20N80W 18N84W AND CURVING SOUTHWESTWARD TO THE HONDURAS/NICARAGUA BORDER NEAR 14N86W. SHOWERS ARE DISSIPATING WITHIN A 30 NM RADIUS OF 18N84W. THE ATLANTIC OCEAN... THE SOUTH CAROLINA-TO-FLORIDA MIDDLE TO UPPER LEVEL TROUGH MOVES EASTWARD. CYCLONIC FLOW ON THE EASTERN SIDE OF THE TROUGH AFFECTS THE ATLANTIC OCEAN NORTH OF THE BAHAMAS. A SEPARATE MIDDLE LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 24N72W JUST EAST OF THE BAHAMAS. BROAD AND NOT-WELL-DEFINED CYCLONIC FLOW IS ASSOCIATED WITH A DISORGANIZED MIDDLE TO UPPER LEVEL TROUGH THAT ROUGHLY PASSES THROUGH 32N53W TO 26N66W. A COLD FRONT PASSING THROUGH 32N50W TO 24N70W WAS BEING SUPPORTED BY THE NOT-WELL-DEFINED MIDDLE TO UPPER LEVEL TROUGH. AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTER IS NEAR 28N37W. ANTICYCLONIC FLOW IS WITHIN 450 NM OF THE CENTER IN THE NORTHERN SEMICIRCLE...AND WITHIN 600 NM OF THE CENTER IN THE SOUTHERN SEMICIRCLE. A DEEP LAYER TROUGH PASSES THROUGH 32N15W...PASSING OVER THE CANARY ISLANDS...TO 22N22W TO 21N29W. A COLD FRONT PASSES THROUGH 32N12W TO 22N20W TO 19N25W. A DISSIPATING COLD FRONT CONTINUES FROM 19N25W TO 18N34W TO 19N42W. A DISSIPATING STATIONARY FRONT CONTINUES FROM 19N42W TO 24N48W TO 27N50W. ANY SHOWERS WITH THIS FRONT ARE NORTH OF 26N BETWEEN 6W AND 15W. UPPER LEVEL SOUTHWESTERLY WIND FLOW IS SOUTH OF 12N55W 16N35W BEYOND 18N16W. $$ MT