000 AXNT20 KNHC 181044 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN MAR 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...ITCZ... ITCZ AXIS IS ALONG 7N12W 4N22W 6N30W 5N38W 1N50W. CONVECTION HAS DECREASED CONSIDERABLY DURING THE PAST 24 HRS. SMALL AREA OF SCATTERED MODERATE CONVECTION NOTED WITHIN 20 NM EITHER SIDE OF A LINE FROM 3N21W TO 5N25W. OTHER MODERATE NEAR 3N14W AND 2N16W. ...DISCUSSION... GULF OF MEXICO... A WELL DEFINED UPPER LEVEL TROUGH HAS SHIFTED E OF THE AREA. UPPER WINDS OVER THE GULF AREA ARE NWLY AT 40 TO 60 KT. MID LEVEL HEIGHTS ARE RISING OVER THE NW PORTION AS RIDGING DEVELOPS ALONG 100W. A 1024 MB POLAR HIGH LOCATED JUST S OF THE COAST OF LOUISIANA IS MOVING SLOWLY NE. NLY WINDS TO 20 KT CONTINUE E OF 90W THIS MORNING WHILE N OF 25N W OF 90W WINDS HAVE SHIFTED TO SE 10 TO 15 KT. S OF 25N W OF 90W WINDS ARE MOSTLY NE 10 TO 15 KT. LATEST WATER VAPOR IMAGERY SHOWS VERY DRY AIR IN THE MID AND UPPER LEVELS OVER THE SRN HALF OF THE GULF RESULTING IN CLEAR SKIES. THE CENTER OF THE POLAR HIGH NE TO THE CAROLINA COAST IN 24 HR. INCREASING E AND SE WINDS WILL DEVELOP OVER THE GULF WITH AN INCREASE IN MOISTURE DURING THE NEXT 24 TO 36 HR. CARIBBEAN... A COLD FRONT EXTENDS FROM THE WINDWARD PASSAGE SW TO ERN NICARAGUA. THE FRONT WILL CONTINUE TO MOVE E AND BECOME DIFFUSE. WINDS OVER THE NW CARIBBEAN ARE NELY 15 TO 20 KT WITH SCATTERED TO BROKEN CLOUDS AND ISOLATED SHOWERS. CONSIDERABLE CLOUDINESS IS NOTED AHEAD OF THE FRONT WITH SCATTERED SHOWERS. EARLIER CONVECTION OVER HAITI AND DOMINICAN REPUBLIC HAS DIMINISHED AND MOVED NE OVER ATLC WATERS. ELY TRADES DOMINATE THE ERN CARIBBEAN WITH SCATTERED CLOUDS AND ISOLATED WEAK SHOWERS. IN THE UPPER ATMOSPHERE A BROAD ANTICYCLONE COVERS THE ERN HALF OF THE CARIBBEAN WHILE OVER THE WRN HALF THE FLOW ALOFT IS MOSTLY SWLY. HIGH LEVEL CLOUDINESS FROM EARLIER CONVECTION OVER COLOMBIA AND WRN VENEZUELA WAS BEING ADVECTED N AND NE OVER THE ERN PORTION. SW ATLANTIC... STRONG UPPER TROUGH WITH AXIS ALONG 75W ROTATING RAPIDLY EWD. BROAD SWATH OF VERY DRY UPPER LEVELS OVER CUBA AND THE BAHAMAS SHIFTING NE BEHIND A JETSTREAM THAT CURVES CYCLONICALLY FROM ERN CUBA TO 30N64W. QUIKSCAT SHOW JETSTREAM WINDS 70 TO 90 KT. STRONG DIFFLUENT PATTERN ALOFT E OF TROUGH AXIS AIDING ISOLATED CONVECTION E OF THE JET AXIS TO 60W N OF 22N. A COLD FRONT OVER THE EXTREME SE BAHAMAS THIS MORNING CONTINUES E 15 KT. MULTILAYERED CLOUDINESS 200 NM WIDE IS ASSOCIATED WITH THE FRONT WITH EMBEDDED SHOWERS AND TSTMS. MOST OF THE ENERGY WITH THIS FEATURE IS SHIFTING N OF 30N AHEAD OF THE FRONT AND MOST FRONTAL CONVECTION HAS BEEN ON THE DECLINE THE PAST FEW HRS. OVER THE ATLC S OF 20N W OF 40W LATEST SATELLITE PICTURES SHOW SCATTERED TO BROKEN LOW AND MID CLOUDS MOVING W 20 KT WITH ISOLATED LIGHT SHOWERS. ERN ATLANTIC... A CLOSED UPPER LOW THAT WAS JUST N OF THE CANARY ISLANDS HAS FLATTENED OUT AND BECOME STATIONARY. SCATTERED CONVECTION NEAR THE CENTER HAS DECREASED INDICATING THE SYSTEM HAS WEAKENED THE PAST 24 HR. WATER VAPOR IMAGERY SHOWS A DRY SLOT ROTATING AROUND THE SW SIDE OF THE ELONGATED LOW CENTER WITH A 40 KT JET SEGMENT. WATER VAPOR IMAGERY ALSO SHOWS A NARROW BAND OF CIRRUS ASSOCIATED WITH A JET STREAM ALONG 16N50W EWD OVER THE CAPE VERDE ISLANDS. QUIKSCAT DATA SHOWS WIND VELOCITIES 60 TO 80 KT WITH THIS JET. ON THE SURFACE STRONG HIGH PRESSURE CENTERED WELL N OF THE REGION ALONG 30W EXTENDS S TO 10N E OF 50W. THE RIDGE IS RESPONSIBLE FOR A MODERATE TO FRESH NE FLOW OF COOL AIR. THE AIR PICKS UP MOISTURE FROM THE ATLC AND PRODUCES SCATTERED TO BROKEN LOW AND MID CLOUDINESS THROUGHOUT THIS REGION. $$ RRG