[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 062358
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 06 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...ITCZ...

FROM NORTHERN LIBERIA AND SIERRA LEONE NEAR 8N12W...TO 8N20W
5N30W 2N40W...INTO EXTREME NORTHEASTERN BRAZIL NEAR THE EQUATOR
AT 50W. WIDELY SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS FROM 3N TO 7N BETWEEN 12W AND 35W.

...DISCUSSION...

THE GULF OF MEXICO...
THE UPPER LEVEL WIND FLOW THAT IS ACROSS THE AREA IS FROM THE
SOUTHWEST. HIGH LEVEL MOISTURE IS MOVING NORTHEASTWARD FROM 90W
ACROSS FLORIDA. DRY AIR IN SUBSIDENCE IS MOVING FROM MEXICO
TOWARD 90W. A SURFACE RIDGE GOES FROM THE FLORIDA BIG BEND TO
THE EAST CENTRAL GULF WATERS TO THE NORTHERN YUCATAN PENINSULA.
THE NEXT COLD FRONT FOR THE AREA IS FORECAST TO REACH THE TEXAS
GULF COAST/THE NORTHWESTERN GULF OF MEXICO DURING THE NEXT
12 HOURS TO 24 HOURS. IT IS FORECAST TO BE COMPARATIVELY
SLOW-MOVING BECAUSE IT STAYS IN THE SAME AREA OF THE
NORTHWESTERN GULF OF MEXICO THROUGH 72 HOURS.

THE CARIBBEAN SEA...
A WEAKENING STATIONARY FRONT CUTS ACROSS WESTERN CUBA NEAR
23N81W TOWARD THE SOUTHEASTERN PART OF THE YUCATAN PENINSULA.
LITTLE TO NO PRECIPITATION ACCOMPANIES THIS WEAKENING FRONT.
THE SURFACE PRESSURE GRADIENT IS WEAK. UPPER LEVEL DRY AIR IN
SUBSIDENCE IS EVERYWHERE. BROAD EASTERLY SURFACE FLOW COVERS
THE AREA FROM THE EASTERN CARIBBEAN SEA ISLANDS TO 70W. THE FLOW
BECOMES CYCLONIC TO THE SOUTH OF HISPANIOLA AND JAMAICA BETWEEN
70W AND CENTRAL AMERICA. THE AREAS WITH THE COMPARATIVELY
GREATEST POSSIBILITIES FOR SHOWERS ARE FROM NORTHERN HAITI TO
A SPOT THAT IS ABOUT 45 NM TO THE SOUTH OF COAST OF HAITI...
FROM 15N TO TO 18N BETWEEN 75W AND 81W...AND MAYBE IN THE
MONA PASSAGE.

THE ATLANTIC OCEAN...
BROAD UPPER LEVEL ANTICYCLONIC FLOW AND DRY AIR IN SUBSIDENCE
COVER THE ATLANTIC OCEAN TO THE NORTH OF 20N TO THE WEST OF 40W.
AN UPPER LEVEL TROUGH PASSES THROUGH 31N23W TO 26N27W TO 21N30W
AND 18N36W. IT IS NOT EASY TO DISCERN THE EXISTENCE OF THE
TROUGH AFTER 18N36W. THIS TROUGH BLENDS WITH THE AREA OF
A SECOND UPPER LEVEL TROUGH THAT IS A LITTLE BIT MORE TO THE EAST
OF THE FIRST TROUGH. A COLD FRONT PASSES THROUGH 32N25W TO 30N30W
29N36W 31N42W. LITTLE TO NO PRECIPITATION ACCOMPANIES THIS FRONT.
AN UPPER LEVEL TROUGH PASSES THROUGH 31N12W...OVER THE CANARY
ISLANDS...TO 26N21W...20N25W 16N37W 14N46W TO 13N57W.

$$
MT





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