[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181159
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST FRI JAN 18 2008

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1115 UTC

...THE ITCZ...
FROM 5N3W 4N10W 3N20W...CROSSING THE EQUATOR AT 33W...STAYING
JUST SOUTH OF THE EQUATOR TO 44W...AND CONTINUING INTO
NORTHEASTERN BRAZIL NEAR 1S50W. ISOLATED MODERATE SHOWERS TO
LOCALLY STRONG THUNDERSTORMS ARE SOUTH OF 7N EAST OF 40W...
AND SOUTH OF 10N ELSEWHERE WEST OF 40W.

...DISCUSSION...

THE GULF OF MEXICO...
BROAD MIDDLE TO UPPER LEVEL SOUTHWESTERLY WIND FLOW COVERS
THE AREA. THE FRONTAL BOUNDARY IN THE GULF OF MEXICO LACKS
STRONG SUPPORT IN THE MIDDLE TO UPPER LEVELS OF THE ATMOSPHERE.
A COLD FRONT RUNS FROM A 1015 MB LOW PRESSURE CENTER NEAR
30N80W IN THE ATLANTIC OCEAN TO CENTRAL FLORIDA...TO THE
COASTAL WATERS OF THE NORTHERN YUCATAN PENINSULA. THE FRONT
BECOMES WARM AND CONTINUES TO A 1012 MB LOW PRESSURE CENTER IN
THE SOUTHWESTERN CORNER OF THE AREA. A STATIONARY FRONT
CONTINUES INTO MEXICO TO 22N100W AND FINALLY TO 26N106W.
SHOWERS/THUNDERSTORMS ARE FROM 21N TO 22N BETWEEN 94W AND
95W...AND WITHIN A 15 NM TO 30 NM RADIUS OF 22N91W.

THE CARIBBEAN SEA...
BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE ATLANTIC OCEAN
SOUTH OF 32N WEST OF 55W...INCLUDING IN THE CARIBBEAN SEA.
A MIDDLE LEVEL ANTICYCLONIC CIRCULATION CENTER IS SUPPOSED
TO BE ABOUT 90 NM NORTH OF EASTERN HISPANIOLA ACCORDING TO THE
GFS MODEL. SUCH A CENTER IS NOT EASY TO SEE WITH THE NAKED EYE
ON SATELLITE IMAGERY. MIDDLE TO UPPER LEVEL DRY AIR/SUBSIDENCE
COVERS THE ENTIRE AREA. SURFACE EASTERLY WIND FLOW IS LOOSELY
RELATED TO LARGE SCALE ANTICYCLONIC FLOW. NO ANTICYCLONIC
CIRCULATION CENTER IS ANYWHERE NEAR THE CARIBBEAN SEA. ONE
CENTER IS ABOUT 150 NM EAST-NORTHEAST OF BERMUDA IN THE ATLANTIC
OCEAN. LARGE-SCALE ANTICYCLONIC FLOW FROM THIS ATLANTIC OCEAN
HIGH PRESSURE CENTER REACHES THE CARIBBEAN SEA. THE ISOBARS ON
THE SURFACE MAP DO NOT APPEAR TO SHOW A STRONG PRESSURE
GRADIENT. THAT DOES NOT MEAN THAT A SLIGHT CHANGE IN THE
PRESSURE FIELD IS NOT ABLE TO GENERATE COMPARATIVELY STRONGER
WIND SPEEDS ACROSS THE OPEN WATERS OF THE CARIBBEAN SEA. AN
EXAMPLE OF FAST WINDS FROM WHAT DOES NOT APPEAR TO BE SUCH
A STRONG GRADIENT ACCORDING TO THE ISOBARIC ANALYSIS IS FROM
10N TO 18N BETWEEN 70W AND 80W NORTHEAST-TO-EAST WINDS FROM
20 KT TO 30 KT AND SEAS FROM 8 TO 13 FT. THE 24 HOUR AND
48 HOUR FORECASTS DO NOT CHANGE MUCH FOR THIS AREA.

THE ATLANTIC OCEAN...
A WESTERN ATLANTIC COLD FRONT RUNS FROM A 1015 MB LOW PRESSURE
CENTER NEAR 30N80W IN THE ATLANTIC OCEAN TO CENTRAL FLORIDA...
TO THE COASTAL WATERS OF THE NORTHERN YUCATAN PENINSULA.
ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE ALONG
THIS FRONT FROM 29N TO 33N BETWEEN 70W AND 77W. AN ATLANTIC
OCEAN COLD FRONT PASSES THROUGH THE EAST CENTRAL SECTIONS NEAR
32N38W TO 24N50W TO 22N66W. A MIDDLE TO UPPER LEVEL TROUGH
PASSING THROUGH 33N47W 27N50W 24N51W SUPPORTS THIS COLD FRONT.
ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE WITHIN
90 NM ON EITHER SIDE OF 22N57W 26N44W BEYOND 32N35W. A 1027 MB
HIGH PRESSURE CENTER IS ABOUT 150 NM EAST-NORTHEAST OF BERMUDA.
THIS HIGH PRESSURE CENTER AND ITS ASSOCIATED FLUCTUATIONS IN THE
PRESSURE GRADIENT ARE PRODUCING 20 KT TO 30 KT WIND SPEEDS IN
THE SOUTH CENTRAL CARIBBEAN SEA...AND IN PARTS OF THE ATLANTIC
OCEAN. PLEASE REFER TO THE MIAHSFAT2 HIGH SEAS FORECAST FOR
SPECIFIC FORECAST INFORMATION. AN ATLANTIC OCEAN MIDDLE TO UPPER
LEVEL TROUGH PASSES THROUGH 32N25W TO 21N31W TO 15N37W TO
NORTHERN GUYANA. A SURFACE RIDGE IS EAST OF THE 32N39W 23N66W
COLD FRONT ALONG 20N50W 26N31W BEYOND 32N20W.

$$
MT




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