[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161713
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU 16 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 ALONG 7N10W 8N18W 4N30W 6N42W 5N50W. NUMEROUS
MODERATE/STRONG CONVECTION 220 NM S OF THE AXIS BETWEEN 10W-18W
HUGGING THE AFRICAN COAST. SCATTERED MODERATE WITHIN 250 NM OF
THE AXIS BETWEEN 17W-27W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD POSITIVELY TILTED UPPER LEVEL TROF EXTENDING FROM THE
WESTERN GREAT LAKES TO THE DESERT SOUTHWEST IS INCREASING MOIST
SWLY FLOW OVER THE GULF OF MEXICO AS IT SAGS STEADILY TO THE S.
WIDESPREAD MID/UPPER LEVEL CLOUDINESS IS MOVING FROM SW TO NE
FROM THE ACAPULCO/MEXICO CITY AREA INTO THE W GULF. A COASTAL
TROF HAS FORMED BENEATH THIS FLOW FROM ABOUT 100 NM SE OF
BROWNSVILLE TEXAS TO A 1021 MB LOW NEAR 28N96W TO NEAR HOUSTON
WITH BROAD ISENTROPIC LIFT FROM THE SE PRODUCING LOW-LEVEL
CLOUDINESS AND LIGHT SHOWERS OVER SE TEXAS. DOPPLER RADAR AND
LIGHTNING DETECTION ALSO INDICATE A FEW SHOWERS AND TSTMS OVER
THE COASTAL WATERS N OF 24N BETWEEN 93W-97W. THERE IS AN
APPRECIABLE AIR-SEA TEMPERATURE DIFFERENCE ACROSS THE TROF...
FROM ABOUT LOWER 70S F OVER THE GULF WATERS TO THE 40S AND 50S F
OVER SE TEXAS...AND WITH A SHORTWAVE POISED TO MOVE OUT OF THE
SOUTHERN PLAINS LATER TODAY FRONTOGENESIS IS EXPECTED TO OCCUR
ALONG THIS BOUNDARY. THIS FEATURE IS THEN EXPECTED TO SAG SWD
OVER THE GULF WATERS FRI AND SAT BEFORE A STRONGER SURGE OF COLD
AIR MOVES IN ON SUN. ELSEWHERE...STRONG HIGH PRES OVER THE SE
U.S. IS FUNNELING AN ALMOST SOLID LAYER OF STRATOCUMULUS FROM
THE W ATLC WATERS TO THE FLORIDA EAST COAST...PRODUCING A FEW
ISOLATED SHOWERS AND DRIZZLE ESPECIALLY FROM WEST PALM BEACH TO
JACKSONVILLE.

CARIBBEAN...
A DIFFUSE COLD FRONT CONTINUES TO PUSH SWD OVER THE W CARIBBEAN
AND NOW EXTENDS FROM THE N COAST OF DOMINICAN REPUBLIC THROUGH
HAITI THEN SW TO THE COAST OF NICARAGUA WHERE IT HANGS UP ALONG
THE CNTRL AMERICAN MOUNTAINS. PATCHY LOW/MID LEVEL CLOUDS ARE
LOCATED BEHIND THE FRONT BUT THE COVERAGE AND THICKNESS IS NOT
AS GREAT AS YESTERDAY AS THE AIR MASS MODIFIES OVER THE TROPICAL
WATERS. A SFC TROF AHEAD OF THE FRONT EXTENDS FROM THE MONA
PASSAGE SW TO NEAR THE PANAMA CANAL AND IS INCREASING LOW-LEVEL
CONVERGENCE ALONG THE N COAST OF DOMINICAN REPUBLIC AS THE FRONT
APPROACHES. THIS IS TRIGGERING WIDELY SCATTERED SHOWERS/TSTMS
FROM 18N-20N BETWEEN 65W-69W JUST N OF PUERTO RICO. THE UPPER
LEVEL FLOW IS PREDOMINANTLY WESTERLY WITH LITTLE MOISTURE
STREAMING IN FROM THE PACIFIC.

WEST ATLANTIC...
A FLATTENING UPPER LEVEL TROF IS LIFTING TO THE NE NEAR 60W WITH
BROAD WESTERLY FLOW REPLACING IT FROM THE U.S. EAST COAST. A
COLD FRONT IS AHEAD OF THIS TROF FROM 32N58W TO 23N65W TO THE N
COAST OF DOMINICAN REPUBLIC WITH A LARGE AREA OF STRATOCU BEHIND
THE FRONT ORIGINATING FROM OFF THE U.S. COAST. A 250 NM THICK
BAND OF LOW/MID CLOUDS IS LOCATED ALONG THE FRONT WITH ISOLATED
SHOWERS/TSTMS FORMING NEAR THE ACTUAL BOUNDARY.

REMAINDER OF ATLANTIC...
THE UPPER LEVEL FLOW EAST OF 60W TRANSITIONS FROM A BROAD RIDGE
EXTENDING NE OF THE NORTHERN LEEWARD ISLANDS INTO A VERY LARGE
TROF WHICH DIPS DOWN PAST THE EQUATOR BETWEEN 25W-50W. A
SHORTWAVE TROF IS EMBEDDED WITHIN THIS LARGER TROF ALONG 30N20W
15N50W AND DIFFLUENT FLOW TO ITS SE IS PRODUCING AN AREA OF
SCATTERED MODERATE CONVECTION FROM 7N-13N BETWEEN 43W-50W. AN
E/W ORIENTED UPPER TROF STRETCHES FROM NRN MOROCCO TO 27N30W AND
IS PRODUCING BROAD W/SW FLOW OVER MOST OF THE E ATLC. A SECOND
DIFFLUENT REGION IS LOCATED OFF THE COAST OF AFRICA AND IS
ENHANCING A LARGE AREA OF SCATTERED CONVECTION ALONG THE ITCZ
BETWEEN 10W-28W. ELSEWHERE...A DISSIPATING 1010 MB LOW IS STILL
LOCATED JUST OFFSHORE THE WESTERN SAHARA/MAURITANIA COAST NEAR
21.5N19W AND NOW MOVING QUICKLY SW WITHIN STRONG NELY SFC LOW.
CONVECTION ASSOCIATED WITH THE LOW HAS ALL DISSIPATED AND THE
FEATURE ITSELF SHOULD DEGENERATE INTO A REMNANT TROF WITHIN THE
NEXT 6-12 HRS.

$$
BERG



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