[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 171735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI 17 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
1715 UTC.

...ITCZ...

ITCZ IS CENTERED ALONG 8N10W 6N20W 7N30W 5N47W. WIDELY SCATTERED
MODERATE CONVECTION WITHIN 175 NM OF THE AXIS BETWEEN 15W-25W.
SCATTERED MODERATE WITHIN 300 NM N AND 200 NM S OF THE AXIS
BETWEEN 25W-31W.

...DISCUSSION...

GULF OF MEXICO...
THE SFC ANALYSIS OVER THE GULF OF MEXICO WAS ENOUGH TO GIVE
SOMEONE FITS THIS MORNING AND THE THICK DECK OF MID/UPPER LEVEL
CLOUDS CENTERED SMACK DAB OVER THE AREA OF INTEREST DIDN'T HELP
MATTERS. SFC FEATURES WERE QUITE OBSCURE AND NONE OF THE
NUMERICAL MODELS REALLY AGREED ON POSITIONING...BUT I THINK I
WAS ABLE TO COME UP WITH A FAIRLY GOOD SOLUTION AT 15Z. VISIBLE
IMAGERY PUTS A WEAK 1020 MB LOW IN THE BAY OF CAMPECHE NEAR
20N94W MOVING S...AND THIS IS THE FEATURE THAT HAS PULLED A COLD
FRONT DOWN THE MEXICAN COAST PAST VERACRUZ. AN OVERCAST LAYER OF
LOW CLOUDS EXTENDS UP TO 150/200 NM INLAND OF THE MEXICAN COAST
AND S OF THE RIO GRANDE AS MOIST AND CHILLY FLOW BANKS UP
AGAINST THE MOUNTAINS. ELSEWHERE...A SECOND WEAK 1021 MB LOW IS
CENTERED BENEATH THE THICK CLOUD SHIELD NEAR 25N89W WITH A COLD
FRONT TRAILING SW TO THE CAMPECHE LOW...AND THEN A STATIONARY
FRONT STRETCHES E TO THE FLORIDA STRAITS. DIFFLUENT WESTERLY
FLOW IN THE UPPER LEVELS OVER THE SYSTEM IS PRODUCING SCATTERED
SHOWERS AND A FEW EMBEDDED TSTMS FROM 22N-27N BETWEEN 87W-94W
AND THIS WHOLE AREA IS EXPECTED TO MOVE E OVER THE NEXT 2 DAYS
POSSIBLY SPREADING OVER S FLORIDA DURING THE WEEKEND. A STRONGER
COLD FRONT WILL MOVE OFF THE TEXAS COAST SAT NIGHT AND WILL
BRING STRONG NLY WINDS OVER THE ENTIRE AREA BY SUN NIGHT.

CARIBBEAN...
UPPER LEVEL RIDGE AXIS IS CENTERED OVER NRN VENEZUELA AND
COLOMBIA REACHING OUT IN THE PACIFIC OCEAN AND IS BRINGING
UNIFORM WESTERLY UPPER LEVEL FLOW AND MOSTLY DRY AIR ACROSS THE
AREA. THE PRES GRADIENT REMAINS TIGHT WITH STRONG HIGH PRES OVER
THE W ATLC SO SFC WINDS ARE STILL A LITTLE BLUSTERY ESPECIALLY
WHERE THE NE FLOW MOVES THROUGH THE PASSAGES. THE NE FLOW IS
PRODUCING SOME CLOUDINESS OVER E CNTRL AMERICA FROM HONDURAS TO
W PANAMA WITH EVEN ISOLATED MODERATE CONVECTION UP TO 90 NM OFF
THE COAST OF COSTA RICA. A DISSIPATING STATIONARY FRONT EXTENDS
ACROSS THE DOMINICAN REPUBLIC TO 14N75W BUT VISIBLE IMAGERY
SUGGESTS THAT THE BOUNDARY HAS JUST ABOUT FIZZLED.

WEST ATLANTIC...
A SFC TROF WITH A SHARP WIND SHIFT IS LOCATED JUST OFFSHORE THE
FLORIDA EAST COAST EXTENDING FROM ABOUT KEY LARGO NWD ALONG 80W
TO OFF THE SOUTH CAROLINA COAST. DOPPLER RADAR INDICATES A
BROKEN BAND OF SHOWERS SITTING STATIONARY ABOUT 50 NM OFFSHORE
ALTHOUGH A FEW SHOWERS HAVE BEEN MOVING INLAND OVER PARTS OF S
FLORIDA MUCH OF THE MORNING. THE TROF IS EXPECTED TO COMBINE
WITH THE FRONTAL SYSTEM OVER THE GULF OF MEXICO BY SAT AND THEN
MOVE OUT TO SEA. BROAD UPPER LEVEL RIDGING EXTENDS E OF THE
FLORIDA COAST ALONG 70W AND TRANSITIONS TO A TROF ALONG 58W. THE
TROF IS SUPPORTING A COLD FRONT FROM 32N51W TO 25N60W AND THEN
AS A STATIONARY FRONT TO THE DOMINICAN REPUBLIC. WIDELY
SCATTERED SHOWERS EXTEND UP TO 75 NM AHEAD OF THE FRONT
PRIMARILY N OF 25N ALONG THE ADVANCING PART OF THE FRONT.

CENTRAL/EAST ATLANTIC...
A NARROW UPPER TROF EXTENDS DOWN THE CENTER OF THE ATLC BASIN
ALONG 30N38W 20N42W 10N42W WITH A LARGE AREA OF DIFFLUENT FLOW
PRODUCING A CONVECTIVELY-ACTIVE PATTERN OVER THE TROPICS. ASIDE
FROM ITCZ CONVECTION...ANOTHER PATCH OF SCATTERED MODERATE
CONVECTION IS LOCATED FROM 9N-14N BETWEEN 32W-37W WITH THE
CIRRUS OUTFLOW EXPANDING TOWARDS W AFRICA IN BROAD ANTICYCLONIC
FLOW. A SHEARED UPPER TROF EXTENDS FROM N MOROCCO SW ACROSS THE
CANARY ISLANDS TO 27N30W WITH MODERATE/STRONG SUBSIDENCE
PRODUCING A STABLE LAYER OVER THE NE ATLC.

$$
BERG


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