[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 181142
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SAT 18 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
1115 UTC.

...ITCZ...

ITCZ IS CENTERED ALONG 10N10W 5N20W 8N35W 6N45W 10N70W 7N80W.
NUMEROUS MODERATE TO STRONG CONVECTION FROM 6N-10N BETWEEN
18W-25W.

...DISCUSSION...

GULF OF MEXICO...
THE PATTERN OVER THE GLFMEX REMAINS FAIRLY COMPLEX WITH MULTIPLE
WEAK FEATURES AFFECTING THE AREA.  IN THE UPPER LEVELS...A BROAD
LONGWAVE TROUGH REMAINS OVER THE E TWO-THIRDS OF THE UNITED
STATES WITH ASSOCIATED 120 KT S STREAM JET EXTENDING ACROSS THE
N GLFMEX ALONG 27N. WATER VAPOR IMAGERY SHOWS MULTIPLE SHORTWAVE
IMPULSES EMBEDDED WITHIN THE STRONG WLY FLOW WITH THE MOST
NOTABLE CURRENTLY MOVING ACROSS THE E GLFMEX AND FLORIDA.  THIS
SYSTEM IS PRODUCING CLOUDINESS AND SCATTERED
SHOWERS/THUNDERSTORMS OVER THE E GLFMEX PRIMARILY FOCUSED ALONG
A STATIONARY FRONT EXTENDING FROM THE FLORIDA STRAITS WESTWARD
TO A 1015 MB LOW APPROXIMATELY 150 NM N OF THE YUCATAN
PENINSULA.  A COLD FRONT TRAILS SWD FROM THE LOW INTO S MEXICO
EAST OF THE ISTHMUS OF TEHUANTEPEC THEN BECOMING STATIONARY OVER
INTERIOR MEXICO.  A RIDGE OF HIGH PRESSURE HAS BUILT SWD FROM
THE CENTRAL UNITED STATES TO THE BAY OF CAMPECHE PRODUCING
STRONG NLY FLOW AND MODERATE COLD AIR CONVECTION N OF THE
FRONTAL BOUNDARY.  HOWEVER...A MUCH STRONGER SURGE OF
CONTINENTAL AIR WILL AFFECT THE AREA SUN AND MON AS A
CYCLOGENESIS TAKES PLACE OFF THE MID-ATLANTIC COAST TODAY AND
TONIGHT.

CARIBBEAN...
BROAD UPPER LEVEL RIDGE REMAINS OVER THE CARIBBEAN EXTENDING
FROM PANAMA NEWD OVER HISPANIOLA INTO THE CENTRAL ATLC.
RESULTING FLOW IS PRIMARILY WLY WITH UPSTREAM PACIFIC MOISTURE
PASSING JUST N OF THE AREA.  MODERATE SUBSIDENCE AND DRY/STABLE
CONDITIONS CONTINUE ABOVE 600 MB WITH LIMITED DEEP CONVECTION
OVER THE AREA.  AT THE LOWER LEVELS...A SMALL AREA OF SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 90 NM EITHER SIDE OF A
REMNANT FRONTAL BOUNDARY FROM THE WINDWARD PASSAGE TO THE BORDER
OF COSTA RICA/PANAMA.  MOISTURE IS INCREASING OVER THE NW
CARIBBEAN AHEAD OF THE COLD FRONT ADVANCING OVER THE GLFMEX AND
YUCATAN PENINSULA PRODUCING PATCHES OF CLOUDINESS AND ISOLATED
SHOWERS ESPECIALLY OVER THE GULF OF HONDURAS. A FEW SHOWERS ARE
ALSO NOTED OVER THE CENTRAL CARIBBEAN ALONG A WEAK ELY
DISTURBANCE EXTENDING FROM THE ABC ISLANDS TO THE DOMINICAN
REPUBLIC.

ATLANTIC...
A MIDDLE TO UPPER LEVEL RIDGE IS BUILDING NWD OVER THE W ATLC
AHEAD OF A STRONG SHORTWAVE TROUGH DROPPING SWD OVER THE SE
UNITED STATES. THE RESULTING PATTERN IS HIGHLY DIFFLUENT
PRODUCING INCREASING CLOUDINESS AND NUMEROUS SHOWERS/
THUNDERSTORMS JUST E OF FLORIDA FROM THE BAHAMAS NWD BEYOND 32N
W OF 70W. THE BULK OF THIS ACTIVITY IS FOCUSED E OF A COLD FRONT
TRAILING SWD ALONG THE E COAST OF FLORIDA FROM A DEVELOPING LOW
PRESSURE OFF THE CAROLINAS.  SHIFTING EWD...A WEAK SHORTWAVE
TROUGH OVER THE CENTRAL ATLC ALONG 53W N OF 20N IS PRODUCING A
SMALL AREA OF CLOUDINESS AND WIDELY SCATTERED SHOWERS/
THUNDERSTORMS N OF 26N BETWEEN 45W-52W.  SCATTERED SHALLOW
TOPPED SHOWERS ARE ALSO NOTED WITHIN 150 NM EITHER SIDE OF THE
ATTENDANT STATIONARY FRONT FROM 31N52W TO 25N60W TO HISPANIOLA.
OVER THE E ATLC...A BLOCKED HIGH OVER LOW TYPE REGIME PREVAILS
WITH A WELL-DEFINED ANTICYCLONE JUST N OF THE AREA NEAR THE
AZORES AND A FORMING UPPER LOW NEAR 27N30W. A TROUGH TRAILS SW
FROM THE UPPER LOW TO 10N45W WITH ASSOCIATED DIFFLUENT FLOW TO
THE EAST SUPPORTING CLOUDINESS AND SCATTERED SHOWERS/
THUNDERSTORMS FROM THE ITCZ NWD TO CAPE VERDE ISLANDS BETWEEN
20W-33W.

$$
RHOME





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