000 AXNT20 KNHC 070001 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST THU MAR 06 2014 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC. ...SPECIAL FEATURE... A GALE IS FORECAST TO BEGIN OVERNIGHT FRI NIGHT OVER THE SW N ATLANTIC N OF 27N WITHIN 150 NM E OF A FRONT THAT WILL EXTEND FROM 31N68W TO 21N78W. PLEASE SEE THE HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT01 KNHC OR THE OFFSHORE FORECAST UNDER AWIPS/WMO HEADERS MIAOFFNT3/FZNT23 KNHC FOR MORE DETAILS. THE GALE FORECAST EARLIER FOR THE METEO FRANCE AREAS OF IRVING AND MADIERA...N OF 30N BETWEEN 22W-35W IS NO LONGER IN EFFECT. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC NEAR 7N12W AND CONTINUES ALONG 5N18W TO 3N20W TO 1N27W...WHERE THE ITCZ BEGINS AND CONTINUES TO THE EQUATOR AT 39W...THEN DIPS TO THE COAST OF SOUTH AMERICA NEAR 2S44W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM THE EQUATOR TO THE MONSOON TROUGH BETWEEN 14W-27W. ...DISCUSSION... GULF OF MEXICO... AMPLIFIED PATTERN IN PLACE OVER THE E CONUS WITH A SHARP UPPER TROUGH EXTENDING FROM A WELL DEFINED CYCLONIC CIRCULATION OVER E- CENTRAL MISSISSIPPI NEAR 32N89W THROUGH 25N91W TO A BASE OVER THE E PACIFIC NEAR 15N103W. VERY STRONG SUBSIDENCE WAS WRAPPING AROUND THE BASE AND THE EAST SIDE OF THE TROUGH. AXIS OF SUBTROPICAL JET CUT THROUGH THE BASE OF THE TROUGH THEN TURNED NNE ACROSS THE BIG BEND/NORTHERN FLORIDA WITH CORE SPEEDS OF 120- 130 KT. THE TROUGH PROVIDED SUPPORT FOR A COLD FRONT WHICH EXTENDED FROM COMPLEX LOW PRESSURE...1008 MB NEAR 28N85W TO THE YUCATAN PENINSULA NEAR 21N88W. A QUASI-STATIONARY FRONT EXTENDS FROM THE LOW NW OVER THE NORTH-CENTRAL FLORIDA TO ANOTHER LOW PRESSURE...1006 MB NEAR GAINESVILLE. A SURFACE TROUGH EXTENDS FROM THE LOW NORTHWEST TO NEAR MOBILE ALABAMA. FLOW BETWEEN UPPER LEVEL RIDGE AND TROUGH WAS DIFFLUENT AND HAD PROVIDED SUPPORT FOR A SQUALL LINE WHICH MOVED ACROSS SOUTH FLORIDA AND IS NOW OVER THE CENTRAL BAHAMAS. WSR-88D DATA ALSO INDICATED AN AREA OF SCATTERED SHOWERS OVER EXTREME SE LOUISIANA...MISSISSIPPI AND ALABAMA IN PROXIMITY TO THE UPPER LOW. ELSEWHERE...A SURFACE RIDGE IS BUILDING S FROM THE CENTRAL PLAIN STATES OVER MEXICO AND THE W GULF WITH MODERATE TO FRESH NORTHERLY WINDS IN ITS WAKE. BROKEN TO OVERCAST LOW AND MID CLOUDS WERE NOTED W OF THE FRONT AND WERE MOVING CYCLONICALLY AROUND THE S SIDE OF THE MID TO UPPER LEVEL CYCLONE. COMPLEX LOW PRESSURE WILL MOVE NE OF THE AREA AND INTENSIFY OVER THE SW N ATLANTIC ON FRI. THE COLD FRONT WILL MOVE OUT OF THE GULF EARLY FRI WITH SURFACE RIDGE WILL CONTINUING TO BUILD IN THE WAKE OF THE FRONT THROUGH SAT. A NEW COLD FRONT WILL MOVE INTO THE W GULF SUN. CARIBBEAN SEA... A BROAD UPPER RIDGE REMAINS OVER THE CARIBBEAN WITH ASSOCIATED RIDGE AXIS EXTENDING N OVER THE SW N ATLANTIC W OF 55W. WATER VAPOR IMAGERY CONTINUES TO SHOW VERY DRY AND STABLE AIR ALOFT ACROSS ALL BUT THE FAR NW CARIBBEAN WHERE A LINE OF SCATTERED THUNDERSTORMS WAS NOTED WITHIN 60 NM EITHER SIDE OF A LINE FROM EXTREME NW CUBA TO THE NE YUCATAN PENINSULA. LOCAL CONVERGENCE IN THE EASTERLY TRADE WINDS WERE GENERATING ISOLATED LOW TOP SHOWERS OVER WESTERN HISPANIOLA AND E CUBA AND OVER THE NE LEEWARD ISLANDS. A 1422 UTC ASCAT PASS INDICATED FRESH TRADES WITHIN 90-120 NM OF THE COAST OF COLOMBIA...AND MODERATE TO FRESH TRADES ELSEWHERE OVER THE CARIBBEAN E OF 70W. LIGHT TO MODERATE TRADES NOTED ELSEWHERE OF THE CARIBBEAN. A WEAK COLD FRONT WILL MOVE INTO THE NW CARIBBEAN TONIGHT AND STALL FROM CENTRAL CUBA TO THE GULF OF HONDURAS FRI NIGHT AND THEN BEGIN TO DISSIPATE FROM THE WINDWARD PASSAGE TO THE GULF OF HONDURAS SAT. HISPANIOLA... SCATTERED WARM TOP SHOWERS WERE FOCUSED OVER HAITI...THE WINDWARD PASSAGE AND EASTERN CUBA. 1200 UTC RAWINSONDE FROM SAN JUAN INDICATED LOW LEVEL MOISTURE UP TO 750 MB WITH VERY STRONG CAPPING/DRYING ABOVE THAT LEVEL. PRECIPITABLE WATER VALUES WERE WELL BELOW NORMAL AT 1.07 INCHES. THE DRY AIR WAS REFLECTED IN WATER VAPOR IMAGERY WHICH DEPICTED STRONG SUBSIDENCE AMIDST MODERATE WESTERLY FLOW ALOFT. THE PROXIMITY OF A DISSIPATING COLD FRONT IN THE WINDWARD PASSAGE MAY INCREASE SHOWER ACTIVITY IN THE AREA ON SAT. ATLANTIC OCEAN... A BROAD UPPER RIDGE OVER THE CARIBBEAN WITH ASSOCIATED RIDGE AXIS EXTENDING N OVER THE SW N ATLANTIC W OF 55W. FLOW BETWEEN UPPER LEVEL RIDGE AND TROUGH WAS DIFFLUENT AND HAD PROVIDED SUPPORT FOR A SQUALL LINE WHICH MOVED ACROSS SOUTH FLORIDA AND IS NOW OVER THE CENTRAL BAHAMAS. A COLD FRONT ENTERS THE SW N ATLC NEAR 32N62W TO 29N71W WHERE IT BECOMES QUASI STATIONARY TO A 1006 MB LOW OVER NORTH-CENTRAL FLORIDA NEAR GAINESVILLE. THE PRE-FRONTAL SQUALL LINE NOTED ABOVE EXTENDED FROM NEAR VERO BEACH FLORIDA TO WITHIN 45 NM OF THE COAST OF SE FLORIDA AND ACROSS THE MID AND UPPER FLORIDA KEYS. THE THUNDERSTORM ACTIVITY HAS RACED EASTWARD ACROSS THE NORTHERN AND CENTRAL BAHAMAS AND EXTENDS WITHIN 45-60 NM EITHER SIDE OF A LINE FROM BIMINI TO 31N77W. EXTENDS OVER THE W AND CENTRAL ATLC PROVIDING DIFFLUENCE ALOFT TO ENHANCE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS OVER THE FAR W ATLC N OF 27N W OF 75W. AN UPPER TROUGH OVER THE E ATLC EXTENDS FROM AN UPPER LOW W OF THE CANARY ISLANDS NEAR 28N21W TO THE W ATLC NEAR 15N52W. A SURFACE RIDGE DOMINATES THE REMAINDER OF THE ATLC ANCHORED BY A 1028 MB HIGH NEAR THE AZORES AND A 1024 MB HIGH NEAR 28N48W. THE SW N ATLC FRONT WILL LIFT N TONIGHT AHEAD OF AN INTENSIFYING SURFACE LOW CURRENTLY IN THE GULF OF MEXICO...EXPECTED TO TRACK NE ALONG THE GEORGIA AND CAROLINA COASTS. THE ASSOCIATED COLD FRONT WILL REACH FROM NEAR 31N72W TO CENTRAL CUBA BY FRI EVENING THEN FROM 31N66W TO 25N70W THEN WEAKENING TO FAR EASTERN CUBA BY EARLY SAT AND CONTINUING TOWARD THE CENTRAL ATLC SAT AND SUN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ COBB