[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171821
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN DEC 17 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...THE ITCZ...
8N11W 7N20W 7N30W 5N40W 3N50W INTO NORTHEASTERN BRAZIL NEAR
2N52W. WIDELY SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS ARE FROM THE EQUATOR TO 10N BETWEEN 30W AND
10N32W 4N35W AND THE EQUATOR AT 40W. ISOLATED MODERATE
SHOWERS TO LOCALLY STRONG THUNDERSTORMS FROM 2N TO 10N
BETWEEN 20W AND 30W...AND FROM 4N TO 8N BETWEEN 35W AND 43W.

...DISCUSSION...
THE GULF OF MEXICO...
THE UPPER LEVEL SHORTWAVE TROUGH FROM YESTERDAY HAS MOVED INTO
THE WESTERN ATLANTIC OCEAN...FROM A CYCLONIC CIRCULATION CENTER
NEAR 30N72W TO 26N74W TO THE STRAITS OF FLORIDA. BROKEN TO
OVERCAST MULTILAYERED CLOUDS WITH POSSIBLE PRECIPITATION ARE
SOUTH OF 25N EAST OF 87W. MIDDLE TO UPPER LEVEL WESTERLY FLOW
NOW COVERS THE ENTIRE AREA. DRY AIR ALSO IS IN THE GULF OF
MEXICO...COMPARATIVELY DRIER AIR IS NORTH OF 25N FROM MEXICO AND
TEXAS TO FLORIDA...AND ON THE WESTERN SIDE OF THE SHORTWAVE
TROUGH. A SURFACE TROUGH RUNS FROM THE NORTHWESTERN CARIBBEAN
SEA NEAR 19N86W INTO THE SOUTHEASTERN GULF OF MEXICO NEAR
26N87W. BROKEN TO OVERCAST MULTILAYERED CLOUDS FROM 16N TO THE
YUCATAN PENINSULA BETWEEN 83W AND 87W. ISOLATED MODERATE SHOWERS
FROM 20N TO 22N BETWEEN 82W AND 86W.

THE CARIBBEAN SEA...
WATER VAPOR SATELLITE IMAGERY AND 17/1500 UTC CIMSS SATELLITE
DERIVED WIND DATA SHOW THE FLOW FROM 500 MB TO 350 MB TO BE
ANTICYCLONIC...AND FROM 600 MB AND LOWER TO BE CYCLONIC.
THE COMPARATIVELY DRIEST PART OF ALL THE MIDDLE TO UPPER LEVEL
DRY AIR OVER THE ENTIRE AREA IS SOUTH OF 18N EAST OF 83W.
A SURFACE TROUGH RUNS FROM THE NORTHWESTERN CARIBBEAN SEA
NEAR 19N86W INTO THE SOUTHEASTERN GULF OF MEXICO NEAR 26N87W.
BROKEN TO OVERCAST MULTILAYERED CLOUDS FROM 16N TO THE YUCATAN
PENINSULA BETWEEN 83W AND 87W. ISOLATED MODERATE SHOWERS FROM
20N TO 22N BETWEEN 82W AND 86W.

THE ATLANTIC OCEAN...
THE GULF OF MEXICO UPPER LEVEL SHORTWAVE TROUGH FROM YESTERDAY
HAS MOVED INTO THE WESTERN ATLANTIC OCEAN TODAY. IT STRETCHES
FROM A CYCLONIC CIRCULATION CENTER NEAR 30N72W TO 26N74W TO THE
STRAITS OF FLORIDA. AN UPPER LEVEL WIND MAXIMA/JET STREAM IN
A BAND OF BROKEN TO OVERCAST MULTILAYERED CLOUDS ROUGHLY COVERS
THE ATLANTIC WATERS FROM 20N TO 30N WEST OF 50W. THE FASTEST
WIND SPEEDS FROM 90 KT TO 100 KT ABOUT 250 MB ARE NORTH OF
22N50W 20N73W TO 32N. AN UPPER LEVEL RIDGE IS IMMEDIATELY EAST
OF THE 34N53W 28N59W MIDDLE TO UPPER LEVEL TROUGH. THIS 34N53W
28N59W TROUGH SUPPORTS THE COLD FRONT THAT PASSES THROUGH 32N53W
TO 25N67W...WITH A SURFACE TROUGH CONTINUING FROM 25N67W TO
23N78W SOUTH OF ANDROS ISLAND IN THE BAHAMAS. WIDELY SCATTERED
MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE FROM 25N
TO 28N BETWEEN 50W AND 59W. OTHER SHOWERS AND POSSIBLE
THUNDERSTORMS ARE ELSEWHERE NORTH OF 22N BETWEEN 40W AND 80W.
A DEEP LAYER TROUGH STRETCHES FROM AN EASTERN ATLANTIC OCEAN
CYCLONIC CIRCULATION CENTER NEAR 34N32W TO 22N32W TO 16N36W TO
13N44W TO 8N51W. MIDDLE TO UPPER LEVEL DRY AIR IS WITHIN 240 TO
360 NM ON EITHER SIDE OF THE TROUGH SOUTH OF 26N WEST OF 32W.
A COLD FRONT PASSES THROUGH 32N23W TO 27N24W. A DISSIPATING COLD
FRONT CONTINUES ALONG 27N24W 22N26W 16N32W. THE 1000 MB LOW
PRESSURE GALE CENTER RELATED TO THIS FEATURE IS NEAR 33N32W.
AN OCCLUDED FRONT IS WRAPPED AROUND THE GALE CENTER. SHOWERS AND
THUNDERSTORMS ARE FROM 29N TO 32N BETWEEN 30W AND 36W...ISOLATED
MODERATE WITHIN A 30 TO 60 NM RADIUS OF 27N25W. AN UPPER LEVEL
RIDGE IS ALONG 6N20W 16N20W 27N19W BEYOND 31N19W. UPPER LEVEL
SOUTHWESTERLY FLOW MOVES FROM NORTHEASTERN SOUTH AMERICA
NORTHEASTWARD...TO THE SOUTHEAST OF THE DEEP LAYER EASTERN
ATLANTIC OCEAN TROUGH...ACROSS THE CAPE VERDE ISLANDS...TO
MOROCCO AFRICA.

$$
MT




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