[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 270616
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST THU DEC 27 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0545 UTC

...THE ITCZ...

FROM NORTHERN COASTAL SIERRA LEONE TO 6N20W 4N30W...CROSSING
THE EQUATOR ALONG 40W TO NORTHEASTERN COASTAL BRAZIL NEAR
2S44W. ISOLATED MODERATE SHOWERS AND POSSIBLE LOCAL
THUNDERSTORMS ARE SOUTH OF 7N EAST OF 50W. OVERCAST HIGH CLOUDS
ARE WITHIN 180 NM TO 240 NM ON EITHER SIDE OF 23N24W 15N32W
9N39W...AND FROM 15N TO 20N BETWEEN AFRICA AND 26W.

...DISCUSSION...

THE GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH IS DIGGING SOUTHWARD THROUGH
CALIFORNIA INTO THE NORTHERN HALF OF THE BAJA PENINSULA AND
NORTHERN MEXICO. DRY MIDDLE TO UPPER LEVEL WESTERLY-TO-
SOUTHWESTERLY WIND FLOW CROSSES MEXICO NORTH OF 22N. A BAND
OF MOISTURE FROM THE EASTERN PACIFIC OCEAN IS WITHIN 120 NM
TO 180 NM ON EITHER SIDE OF THE LINE THROUGH 17N109W TO 20N100W
IN MEXICO TO THE CENTRAL GULF OF MEXICO NEAR 26N90W BEYOND
30N/83W ALONG THE FLORIDA/GEORGIA BORDER. MORE DRY AIR IS
SOUTHEAST OF THE MOISTURE BAND. A MIDDLE TO UPPER LEVEL TROUGH
PASSES THROUGH LOUISIANA TO DEEP SOUTH TEXAS. THIS TROUGH
SUPPORTS THE COLD FRONT THAT PASSES THROUGH THE NORTH CENTRAL
U.S.A. GULF COAST STATES INTO THE SOUTHWESTERN CORNER OF THE
GULF OF MEXICO. A SURFACE RIDGE COVERS SOUTH CAROLINA/GEORGIA/
FLORIDA. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE
SHOWERS ARE WITHIN 60 NM ON EITHER SIDE OF THE FRONT. THE
FORECAST IS FOR THIS FRONT TO DISSIPATE DURING THE NEXT
24 HOURS. A SECOND FRONT WILL FOLLOW THE FIRST ONE...BUT NOT
FOR ANOTHER FEW DAYS...TO BE IN THE WESTERN GULF OF MEXICO
BY 29/0000 UTC.

THE CARIBBEAN SEA...
ONE AREA OF UPPER LEVEL ANTICYCLONIC FLOW/RIDGE IS IN THE
WESTERN CARIBBEAN SEA. THIS RIDGE HAS AMPLIFIED FROM ITS STATE
OF 24 HOURS AGO. THE RIDGE NOW POKES AS FAR NORTH AS CUBA AND
THE BAHAMAS SOUTH OF 24N. MIDDLE TO UPPER LEVEL DRY AIR/
SUBSIDENCE EVERYWHERE. HIGH LEVEL CLOUDS FROM EASTERN PACIFIC
OCEAN ITCZ PRECIPITATION HAS CROSSED THE AREA OF NORTHWESTERN
COLOMBIA/PANAMA/COSTA RICA INTO THE SOUTHWESTERN CORNER OF THE
AREA. THE MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW FROM THE
WESTERN CARIBBEAN SEA RIDGE COVERS THE AREA AS FAR TO THE EAST
AS 66W. THE ATLANTIC OCEAN-TO-CARIBBEAN SEA MIDDLE TO UPPER
LEVEL TROUGH REACHES 15N62W IN THE EASTERN CARIBBEAN SEA. THE
TROUGH IS SURROUNDED BY ALL THE DRY AIR/SUBSIDENCE. A LITTLE BIT
OF BROAD SURFACE LOW PRESSURE MOVES FROM NORTHERN COLOMBIA INTO
THE SOUTHWESTERN CORNER OF THE AREA. THE 1008 MB ISOBAR MOVES
FROM COLOMBIA INTO THE SOUTHWESTERN CORNER OF THE AREA IN ORDER
TO COVER THE FEW COMPARATIVELY LOWER 1005 MB OBSERVATIONS IN
THAT AREA. POSSIBLE SHOWERS IN BROKEN LOW TO MIDDLE LEVEL CLOUDS
NORTH OF 18N70W 16N63W 14N60W...FROM 15N TO 20N BETWEEN 72W AND
82W...AND FROM 16N TO 20N BETWEEN 83W AND 85W.

THE ATLANTIC OCEAN...
A DEEP LAYER TROUGH IS IN THE WESTERN ATLANTIC OCEAN STRETCHING
FROM THE WATERS EAST OF VIRGINIA THROUGH 33N73W TO 30N75W.
THIS TROUGH SUPPORTS THE COLD FRONT THAT PASSES THROUGH 32N71W
TO 30N73W TO THE NORTHERN BAHAMAS NEAR 25N78W. THIS FRONT IS
SURROUNDED BY MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE. ISOLATED
MODERATE SHOWERS ARE EAST OF THE FRONT IN AN AREA OF UPPER LEVEL
DIFFLUENT WIND FLOW NORTH OF 28N BETWEEN 60W AND 70W. MIDDLE TO
UPPER LEVEL ANTICYCLONIC WIND FLOW...FROM THE CARIBBEAN SEA
RIDGE...COVERS THE ATLANTIC OCEAN WEST OF 54W. A DEEP LAYER
CYCLONIC CIRCULATION CENTER REMAINS IN THE CENTRAL ATLANTIC
OCEAN NEAR 21N54W ON WATER VAPOR IMAGERY...AND A 1012 MB LOW
PRESSURE CENTER IS NEAR 26N41W ON THE 27/0000 UTC SURFACE MAP
ANALYSIS. THE DEEP LAYER TROUGH RUNS FROM THE 21N54W CYCLONIC
CENTER TO 19N41W 16N49W TO 15N62W IN THE EASTERN CARIBBEAN SEA.
AN OCCLUDED FRONT EXTENDS FROM THE 26N41W SURFACE LOW PRESSURE
CENTER NORTHEASTWARD TO 31N41W. A STATIONARY FRONT CONTINUES
FROM THE 26N41W LOW PRESSURE CENTER TO 25N38W AND 20N41W.
WIDELY SCATTERED TO SCATTERED MODERATE SHOWERS AND ISOLATED
STRONG THUNDERSTORMS ARE FROM 22N BEYOND 32N BETWEEN 33W
AND 40W.

$$
MT




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