[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271134
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST FRI NOV 27 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N13W 5N25W 5N43W 4N56W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-6N BETWEEN 18W-22W.
ISOLATED MODERATE/STRONG CONVECTION IS FROM 1N-6N BETWEEN 23W-31W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE HIGH PRESSURE CONTINUES ACROSS THE GULF OF MEXICO IN THE
WAKE OF A COLD FRONT NOW IN THE WRN ATLC AND CARIBBEAN. THIS AREA OF
HIGH PRESSURE ACCOMPANIED BY A COOL AIR MASS IS ANCHORED BY A 1027
MB HIGH OVER SRN TEXAS. MAINLY NLY SURFACE WINDS OF 15-20 KT ARE
ACROSS THE BASIN. IN THE UPPER LEVELS...WSW FLOW COVERS THE AREA
AROUND THE NW PERIPHERY OF AN UPPER LEVEL RIDGE OVER THE CARIBBEAN.
MODERATE UPPER LEVEL MOISTURE IS BEING DRAWN ACROSS THE NW GULF WITH
ASSOCIATED UPPER LEVEL CLOUDS N OF 23N W OF 90W. THE REMAINDER OF
THE BASIN IS UNDER MAINLY CLEAR SKIES WITH PATCHES OF STRATOCUMULUS
CLOUDS DUE TO MODERATE DRY AIR AND SUBSIDENCE ALOFT. EXPECT THE HIGH
PRESSURE TO SHIFT EWD ACROSS THE NRN GULF...ALONG WITH SLY RETURN
FLOW INCREASING SUN OVER THE WRN GULF AHEAD OF THE NEXT COLD FRONT
FORECAST TO MOVE OFF THE TEXAS COAST AROUND SUNRISE MON.

CARIBBEAN SEA...
AS OF 0900 UTC...A COLD FRONT EXTENDS ACROSS W CUBA FROM 22N79W
BECOMING STATIONARY AT 21N80W TO HONDURAS NEAR 16N85W. ISOLATED
SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 90 NM OF THE FRONT.
SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE ALSO AFFECTING ERN
NICARAGUA AND COSTA RICA FROM 9N-13N BETWEEN 81W-85W ASSOCIATED WITH
AN AREA OF WEAK DIFFLUENT FLOW ALOFT. BESIDES THE MOISTURE
ASSOCIATED WITH THE FRONT...DRY AIR AND SUBSIDENCE COVERS THE
REMAINDER OF THE CARIBBEAN AROUND AN UPPER LEVEL RIDGE WITH AXIS
NEAR 75W. THIS PATTERN IS PRODUCING GENERALLY FAIR WEATHER ACROSS
THE MAJORITY OF THE BASIN. NLY SURFACE WINDS OF 20-25 KT ARE W OF
THE FRONT IN THE NW CARIBBEAN. ELSEWHERE...FRESH TO STRONG
TRADEWINDS DOMINATE. EXPECT THE FRONT TO REMAIN STATIONARY ACROSS
CENTRAL CUBA AND BECOME DIFFUSE BY LATER TONIGHT...WHILE THE NRN
PORTION CONTINUES TO MOVE E TOWARDS THE WINDWARD PASSAGE. EXPECT
SHOWER ACTIVITY TO REMAIN ALONG THE FRONT AXIS...AND IN THE SW
CARIBBEAN.

ATLANTIC OCEAN...
AS OF 0900 UTC...A COLD FRONT DRAPES ACROSS THE WRN ATLC ENTERING
THE DISCUSSION AREA NEAR 32N70W CONTINUING TO THE NW BAHAMAS NEAR
25N76W TO W CUBA NEAR 22N79W...AND BECOMING STATIONARY INTO THE
CARIBBEAN. SCATTERED SHOWERS/THUNDERSTORMS ARE AHEAD OF THE FRONT
FROM 25N-31N BETWEEN 65W-73W. ISOLATED SHOWERS ARE POSSIBLE ALONG
THE FRONT AXIS. THE FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH OVER
THE ERN CONUS WITH AXIS ALONG 80W. AN UPPER LEVEL SHORTWAVE RIDGE IS
TO THE E FROM N OF PUERTO RICO ALONG 19N66W TO 40N51W EXTENDING FROM
A LONGWAVE RIDGE OVER THE CARIBBEAN. DIFFLUENT FLOW ALOFT BETWEEN
THESE TWO UPPER LEVEL FEATURES IS ENHANCING THE SHOWER ACTIVITY
AHEAD OF THE COLD FRONT. A 1013 MB LOW IS CENTERED NEAR 30N58W. A
SURFACE TROUGH EXTENDS FROM THE LOW TO NEAR 27N58W. POSSIBLE
ISOLATED SHOWERS ARE TO THE W OF THE LOW N OF 28N BETWEEN 58W-60W.
THE LOW IS SUPPORTED BY A SHORTWAVE UPPER LEVEL TROUGH WITH AXIS
ALONG 52W. DIFFLUENT FLOW ALOFT BETWEEN THIS UPPER TROUGH AND AN
UPPER LEVEL RIDGE WITH AXIS ALONG 40W IS ENHANCING A LARGE AREA OF
SHOWERS/THUNDERSTORMS FROM 12N-29N BETWEEN 41W-48W. A SURFACE TROUGH
N OF THE ITCZ EXTENDS FROM 8N54W TO 18N52W ENHANCING SCATTERED
SHOWERS/THUNDERSTORMS FROM 15N-20N BETWEEN 48W-51W. THE REMAINDER OF
THE ERN ATLC IS DOMINATED BY A BROAD SURFACE RIDGE ANCHORED BY A
1023 MB HIGH NEAR 29N30W. IN THE UPPER LEVELS...AN UPPER LEVEL
TROUGH COVERS THE ERN ATLC WITH AXIS ALONG 30W. AN UPPER LEVEL JET
ALONG THE ERN SIDE OF THE UPPER TROUGH IS SUPPORTING AN AREA OF
ISOLATED FROM 16N-26N BETWEEN 13W-24W.

$$
WALTON








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