[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201158
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SUN JAN 20 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 7N11W TO 5N24W 3N40W...CROSSING THE EQUATOR AT 50W...
AND CONTINUING INTO NORTHEASTERN BRAZIL NEAR 1S52W. ISOLATED
MODERATE SHOWERS TO POSSIBLE THUNDERSTORMS ARE SOUTH OF 10N
EAST OF 60W. SCATTERED MODERATE TO STRONG SHOWERS/THUNDERSTORMS
FROM THE EQUATOR TO 3N BETWEEN 47W AND 51W. UPPER LEVEL
SOUTHWESTERLY WINDS ARE BLOWING ACROSS THE AREA OF THIS
PRECIPITATION.

...DISCUSSION...

THE GULF OF MEXICO AND THE ATLANTIC OCEAN WEST OF 65W...
BROAD MIDDLE TO UPPER LEVEL CYCLONIC FLOW FROM A TROUGH SWEEPS
ACROSS MEXICO INTO THE GULF OF MEXICO. THIS TROUGH SUPPORTS
THE COLD FRONT THAT PASSES THROUGH THE WESTERN ATLANTIC OCEAN
ALONG 32N75W TO 30N80W TO A 1012 MB LOW PRESSURE CENTER NEAR
29N80W ALONG THE NORTHEASTERN FLORIDA COAST. THE FRONT CUTS
ACROSS FLORIDA TO THE SOUTHWESTERN FLORIDA COAST...AND TO THE
NORTHEASTERN YUCATAN PENINSULA. THE FRONT EVENTUALLY ENDS UP
IN SOUTHERN MEXICO JUST EAST OF THE ISTHMUS OF TEHUANTEPEC.
THIS FRONT HAD CLEARED ALL OF FLORIDA BY 20/0900 UTC. ISOLATED
MODERATE RAINSHOWERS ARE WITHIN 60 NM TO 90 NM WEST OF THE LINE
THROUGH 33N70W TO THE NORTHERN BAHAMAS NEAR 27N77W TO WESTERN
CUBA TO THE NORTHEASTERN YUCATAN PENINSULA. BROAD MIDDLE TO
UPPER LEVEL ANTICYCLONIC WIND FLOW IS ON TOP OF THE AREA OF
THIS FRONT IN THE ATLANTIC OCEAN. A STORM WARNING WAS ISSUED
FOR 50 KT WINDS IN THE GULF OF TEHUANTEPEC OF MEXICO ON THE
EASTERN PACIFIC OCEAN. GALE FORCE WINDS BEHIND THE COLD FRONT
ARE IN THE EAST CENTRAL/SOUTHEASTERN GULF OF MEXICO.

THE CARIBBEAN SEA...
BROAD UPPER LEVEL ANTICYCLONIC FLOW COVERS THE ATLANTIC OCEAN
SOUTH OF 32N WEST OF 55W...AND 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 ATLANTIC OCEAN ANTICYCLONIC FLOW.
A SURFACE ANTICYCLONIC CIRCULATION CENTER IS ABOUT 700 NM EAST
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 FASTER 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 19N EAST OF 82W BETWEEN 70W AND 80W
EASTERLY WINDS FROM 20 KT TO 30 KT AND SEAS FROM 9 TO 13 FT
CURRENTLY AND IN THE MIAHSFAT2 FORECAST FOR THE NEXT 48 HOURS.
PLEASE REFER TO THE MIAHSFAT2 HIGH SEAS FORECAST FOR SPECIFIC
DETAILS. POSSIBLE SHOWERS IN CLUSTERS OF LOW CLOUDS ARE NORTH OF
11N65W 14N75W 14N80W. SHOWERS ARE POSSIBLE SOUTH OF 15N WEST OF
80W IN THE WATERS EAST OF CENTRAL AMERICA...AND NORTH OF 15N
WEST OF 80W.

THE REST OF THE ATLANTIC OCEAN...
A 1028 MB HIGH PRESSURE CENTER IS ABOUT 700 NM EAST 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. PLEASE REFER TO THE
MIAHSFAT2 HIGH SEAS FORECAST FOR SPECIFIC FORECAST INFORMATION
REGARDING WIND AND SEAS NEAR THE FRONTAL BOUNDARIES. AN ATLANTIC
OCEAN COLD FRONT EXTENDS FROM AN EAST-CENTRAL ATLANTIC OCEAN
1010 MB PRESSURE CENTER/DEVELOPING GALE LOW CENTER NEAR 32N29W
TO 27N29W AND 21N36W. A DISSIPATING STATIONARY FRONT CONTINUES
FROM 21N36W TO 20N50W. A MIDDLE TO UPPER LEVEL EAST CENTRAL
ATLANTIC OCEAN TROUGH SUPPORTS THIS COLD FRONT. SHOWERS AND
POSSIBLE THUNDERSTORMS ARE NORTH OF 28N BETWEEN 24W AND 32W.

$$
MT


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