[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271724
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON 27 DEC 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...ITCZ...

ITCZ IS CENTERED ALONG 11N10W 4N20W 3N29W 5N40W 2N50W. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 75 NM OF LINE 4N35W-7N40W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 60/75 NM OF LINE 2N6W-3N15W...WITHIN 45/60 NM OF LINE
3N27W-4N32W...AND FROM 3N-12N BETWEEN 40W-47W. SCATTERED SHOWERS
ARE WITHIN 120 NM OF LINE 3N26W-5N17W TO THE COAST OF AFRICA
NEAR 7N11W.

...DISCUSSION...

THE GULF OF MEXICO INTO THE W ATLANTIC AND NW CARIBBEAN...
MID/UPPER RIDGE IS BUILDING N OVER MEXICO INTO THE CENTRAL
UNITED STATES WITH ANTICYCLONIC FLOW W OF 95W. BROAD DEEP
LAYERED TROUGH COVERS THE EAST HALF OF THE UNTIED STATES INTO
THE NW ATLANTIC WITH AN UPPER TROUGH AXIS EXTENDING ALONG THE
CAROLINA COAST ACROSS FLORIDA INTO THE E GULF OF MEXICO ALONG
27N84W TO THE BAY OF CAMPECHE NEAR 18N94W. AN ASSOCIATED COLD
FRONT ENTERS THE W ATLC OVER BERMUDA ALONG 27N68W TO THE S
BAHAMAS NEAR 21N73W WHERE IT CONTINUES SSW AS A STATIONARY FRONT
THROUGH THE WINDWARD PASSAGE...BETWEEN S HAITI AND JAMAICA...TO
THE COAST OF NICARAGUA NEAR 12N84W. THE DOWN-SLOPE FLOW OF THE
RIDGE OVER MEXICO COUPLE WITH THE CYCLONIC FLOW OVER THE E GULF
IS PRODUCING STRONG SUBSIDENCE AND DRY UPPER AIR OVER THE ALL OF
THE GULF AND THE W ATLC AND NW CARIBBEAN W OF THE COLD FRONT.
BROKEN/OVERCAST COLD AIR STRATOCUMULUS CLOUDS COVER THE W ATLC
AND NW CARIBBEAN W OF THE FRONT AND THE GULF OF MEXICO S OF 28N
W OF 85W AND S OF 25N BETWEEN 80W AND 85W. BROKEN/OVERCAST
LOW/MID CLOUDS WITH ISOLATED SHOWERS ARE WITHIN 45 NM OF THE
FRONT N OF WINDWARD PASSAGE.

REMAINDER OF THE CARIBBEAN SEA...
BROAD MID/UPPER RIDGE AXIS EXTENDS FROM OVER E BRAZIL OFF THE
COAST OF SOUTH AMERICA NEAR 6N57W INTO THE E CARIBBEAN ALONG
14N68W THEN SPLITS...WITH ONE AXIS CONTINUING W TO 12N80W AND A
SECOND VEERING N ACROSS THE VIRGIN ISLANDS NEAR 18N64W
CONTINUING ACROSS THE CENTRAL ATLC. THIS IS PRODUCING GENERAL SE
TO E FLOW OVER THE CARIBBEAN E OF THE FRONT THAT EXTENDS FROM
THE W ATLC. STRONG SUBSIDENCE AND DRY AIR AT ALL LEVELS COVERS
THE REMAINDER OF THE CARIBBEAN.

REMAINDER OF THE ATLANTIC...
MID/UPPER LEVEL RIDGE AXIS EXTENDS FROM THE CARIBBEAN OVER THE
VIRGIN ISLANDS NEAR 18N64W NE TO BEYOND 32N58W. ANTICYCLONIC
FLOW COVERS THE AREA WITHIN 200 TO 300 NM OF THE AXIS. THIS FLOW
IS NARROWING OVER TIME DUE TO A STRONG DEEP LAYERED LOW JUST TO
THE E WITH THE UPPER LOW AND SURFACE 1009 MB LOW CENTERED NEAR
23N47W. MID/UPPER LEVEL CYCLONIC FLOW IS FROM 15N-28N BETWEEN
42W-52W. A SURFACE TROUGH EXTENDS FROM 30N47W TO 19N48W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 75 NM OF
LINE 23N46W-20N48W. STRONG SUBSIDENCE AND DRY AIR AT ALL LEVELS
COVERS THE AREA N OF 6N W OF 50W AND FROM 11N-18N BETWEEN
45W-50W...THUS LIMITING CONVECTION IN THE W ITCZ. A MID/UPPER
LEVEL HIGH IS IN THE E TROPICAL ATLC NEAR 7N28W WITH A RIDGE
AXIS EXTENDING N ALONG 21N30W THEN NARROWING TO 32N34W. THIS
NARROWING IS DUE TO A MID/UPPER LEVEL TROUGH OVER THE NE ATLC.
DIFFLUENCE TO THE W OF THE RIDGE IS PRODUCING BROKEN/OVERCAST
MULTILAYERED CLOUDS WITH SCATTERED SHOWERS/THUNDERSTORMS FROM
12N-28N BETWEEN 34W-45W. THE MID/UPPER LEVEL TROUGH OVER THE NE
ATLC IS N OF 20N E OF 25W. STRONG SUBSIDENCE AND DRY UPPER AIR
IS N OF 20N E OF 24W TO INLAND OVER NW AFRICA.

$$
WALLACE


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