[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191140
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SUN 19 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1100 UTC.

...ITCZ...

ITCZ IS CENTERED ALONG 10N10W 5N30W 5N40W 5N62W 6N80W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 3N-6N BETWEEN
10W-20W.  SCATTERED MODERATE FROM 2N-6N BETWEEN 25W-40W.

...DISCUSSION...

GULF OF MEXICO...
THE MAIN WEATHER MAKER OVER THE AREA TODAY WILL BE AN AMPLIFYING
LONGWAVE TROUGH OVER THE E TWO THIRDS OF THE UNITED STATES.
THIS TROUGH WILL USHER IN SOME OF THE COLDEST AIR SEEN THUS FAR
THIS WINTER WITH ASSOCIATED COLD FRONT EMERGING INTO THE N GULF
LATER TODAY. STRONG NLY FLOW TO NEAR GALE FORCE WILL DEVELOP
BEHIND THE FRONT AS IT SWEEPS RAPIDLY ACROSS THE GLFMEX CLEARING
THE ENTIRE AREA BY EARLY MONDAY.  OUT AHEAD OF THIS SYSTEM...A
BAND OF CLOUDINESS AND SCATTERED SHOWERS/THUNDERSTORMS LIES OVER
THE S GLFMEX AND S FLORIDA FROM 21N-24N.   THIS ACTIVITY WILL BE
SLIDING SWD THROUGHOUT THE DAY WITH DRY CONDITIONS AND CLEAR
SKIES IN ITS WAKE.

CARIBBEAN...
STRONG MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE ENTIRE
CARIBBEAN WITH AXIS EXTENDING E/W FROM NICARAGUA TO THE LEEWARD
ISLANDS.  RESULTING FLOW IS PRIMARILY WESTERLY ACROSS THE
CARIBBEAN BASIN WITH MODERATE SUBSIDENCE PRODUCING DRY/STABLE
CONDITIONS ABOVE 700 MB.  AT THE LOWER LEVELS...MOISTURE IS
LIMITED OVER THE E HALF OF THE CARIBBEAN RESULTING IN MOSTLY
CLEAR SKIES. IN FACT...THE ONLY SIGNIFICANT WEATHER OF NOTE IS A
NARROW BAND OF SCATTERED SHOWERS ALONG A REMNANT FRONTAL TROUGH
EXTENDING FROM E CUBA TO THE BORDER OF PANAMA/COSTA RICA.
ELSEWHERE...A WEAK AND PRIMARILY DRY COLD FRONT HAS PUSHED INTO
THE NW CARIBBEAN EXTENDING FROM E CUBA NEAR 21N77W TO E
HONDURAS.  NLY FLOW BEHIND THE FRONT IS PRODUCING OVERCAST LOW
CLOUDINESS AND SHOWERS ALONG WINDWARD FACING SLOPES OF HONDURAS
AND GUATEMALA. WHILE CURRENTLY DRY/TRANQUIL...THE PATTERN WILL
BECOME INCREASING UNSTABLE/WET OVER THE NEXT 24-36 HOURS AS AN
AMPLIFYING TROUGH OVER THE E UNITED STATES AND GLFMEX WILL PUSH
A MUCH STRONGER COLD FRONT INTO THE AREA ON MON.  THE BULK OF
THE UPPER LEVEL DYNAMICS/LIFT WILL PASS JUST N OF THE AREA.
HOWEVER...SUFFICIENT MOISTURE POOLING ALONG THE BOUNDARY WILL
SUPPORT SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS.
MEANWHILE OVER THE E CARIBBEAN...A WEAK LOW LEVEL ELY
DISTURBANCE CURRENTLY ENTERING THE EXTREME SE CARIBBEAN WILL
PRODUCE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
WINDWARD ISLANDS MAINLY S OF 13N TODAY.

ATLANTIC...
HIGHLY AMPLIFIED PATTERN IS UNFOLDING OVER THE W ATLC AS A
MIDDLE TO UPPER LEVEL TROUGH DIGS SWD OVER THE E UNITED STATES.
THE AMPLIFYING TROUGH WILL IGNITE CYCLOGENESIS OFF THE
MID-ATLANTIC COAST TODAY AND MONDAY RESULTING IN A STRONG COLD
FRONT SWEEPING ACROSS THE AREA MONDAY AND TUE. THE FRONT WILL
PRODUCE STRONG WINDS TO GALE FORCE AND ROUGH SEAS OVER A LARGE
PORTION OF THE W ATLC.  CURRENTLY...A WEAK COLD FRONT TRAILS SWD
OVER THE W ATLC ROUGHLY HALFWAY IN BETWEEN BERMUDA AND THE
MID-ATLANTIC COAST ENTERING THE AREA ALONG 31N70W TO A 1013
FRONTAL LOW NEAR 27N73W.  THE COLD FRONT CONTINUES SWD OVER THE
S BAHAMAS TO E CUBA.  SCATTERED SHOWERS/THUNDERSTORMS LIE AHEAD
OF THE FRONT PRIMARILY FROM 23N TO BERMUDA.  FURTHER E...A
NEARLY STATIONARY MID/UPPER LEVEL TROUGH OVER THE CNTRL ATLC
WATERS ALONG 50W IS PRODUCING AN AREA OF CLOUDINESS AND
SCATTERED SHOWERS/ THUNDERSTORMS N OF 10N BETWEEN 45W-51W.  THE
UPPER TROUGH SHOULD BECOME SHEARED OUT TODAY AHEAD OF THE
AMPLIFYING UPSTREAM PATTERN RESULTING IN DECREASING SHOWER
ACTIVITY.   OVER THE E ATLC... A CUTOFF LOW HAS FORMED NEAR
26N35W WITH INDUCED RIDGING AND DIFFLUENT FLOW TO THE EAST.
THIS PERSISTENT PATTERN CONTINUES TO SUPPORT ENHANCED ITCZ
CONVECTION E OF 40W WITH ASSOCIATED HIGH CLOUDINESS AND WIDELY
SCATTERED SHOWERS EXTENDING NWD TO 15N AND EWD TO THE CAPE VERDE
ISLANDS.  THIS OVERALL PATTERN IS EXPECTED TO REMAIN IN PLACE
FOR THE NEXT FEW DAYS KEEPING THE E TROPICAL ATLC UNSETTLED.

$$
RHOME


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