[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171129
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...ITCZ...

ITCZ IS CENTERED ALONG 10N3W 3N35W 9N50W 10N70W 5N80W.
SCATTERED MODERATE CONVECTION FROM 3N-12N BETWEEN 18-30W.
SCATTERED MODERATE CONVECTION FROM 10N-13N BETWEEN 35W-42W.

...DISCUSSION...

GULF OF MEXICO...
A RATHER COMPLEX PATTERN IS TAKING SHAPE OVER THE GLFMEX WHICH
WILL RESULT IN UNSETTLED/WET CONDITIONS THROUGH THE WEEKEND. AT
THE UPPER LEVELS...A PERSISTENT LONGWAVE TROUGH REMAINS
ENTRENCHED OVER THE E UNITED STATES EXTENDING SWD THROUGH THE
SOUTH-CENTRAL STATES INTO N PORTIONS OF MEXICO WITH ASSOCIATED
110 KT SOUTHERN STREAM JET EXTENDING ACROSS CENTRAL MEXICO.
WATER VAPOR IMAGERY INDICATES A SERIES OF WEAK SHORTWAVE
DISTURBANCES MOVING QUICKLY EWD OVER THE GULF WITHIN THE STRONG
S STREAM FLOW.  THESE DISTURBANCES ARE PRODUCING WIDESPREAD
CLOUDINESS AND SCATTERED SHOWERS/THUNDERSTORMS OVER THE GLFMEX.
THE STRONGEST/MOST NUMEROUS OF THIS ACTIVITY IS CURRENTLY
FOCUSED ALONG A FORMING FRONTAL BOUNDARY FROM THE FLORIDA
STRAITS WESTWARD TO A 1019 MB LOW OVER THE CENTRAL GULF NEAR
25N89W THEN SW TO A SECOND 1019 MB LOW NE OF VERACRUZ MEXICO
NEAR 21N95W.  THE AFOREMENTIONED SHORTWAVES WILL MOVE ACROSS THE
GLFMEX TODAY ALLOWING THE OVERALL CLOUD AND PRECIP SHIELD TO
MIGRATE EWD OVER THE E GLFMEX WITH THICKENING HIGH CLOUDINESS
OVER FLORIDA.  THEREAFTER...THE FRONTAL BOUNDARY BECOMES BETTER
DEFINED ACROSS E GLFMEX AND S FLORIDA RESULTING IN INCREASING
SHOWERS/THUNDERSTORMS FRI NIGHT AND SAT. THE BOUNDARY THEN GETS
SWEPT E OF THE AREA AS A STRONG COLD FRONT SUN AS THE UPPER
LEVEL PATTERN BECOMES HIGHLY AMPLIFIED AND CYCLOGENESIS OCCURS
OVER THE W ATLC.

CARIBBEAN...
A BROAD/FLAT MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN
WITH THE RESULTING FLOW BEING PREDOMINANTLY WLY.  UPSTREAM
PACIFIC MOISTURE IS RIDING UP AND OVER THE RIDGE PRODUCING
GENERALLY DRY CONDITIONS ABOVE 600 MB. AT THE LOWER LEVELS...A
DIFFUSE STATIONARY FRONT BISECTS THE CARIBBEAN EXTENDING FROM
THE E COAST OF THE DOMINICAN REPUBLIC TO COSTA RICA. ISOLATED
THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG THE BOUNDARY
ESPECIALLY JUST E OF COSTA RICA.  ELSEWHERE...PATCHY LOW TO
MID-LEVEL CLOUDS AND ISOLATED SHOWERS REMAIN BEHIND THE FRONT
BUT THE COVERAGE HAS STEADILY DECREASED OVER THE LAST 24 HOURS
AS THE AIR MASS BECOMES INCREASINGLY MODIFIED OVER THE WARM
CARIBBEAN WATERS.  E OF THE STATIONARY FRONT...A WEAK ELY
DISTURBANCE MOVING ACROSS E CARIBBEAN IS PRODUCING SCATTERED
SHOWERS WITHIN 45 NM EITHER SIDE OF A LINE EXTENDING FROM THE
MONA PASSAGE TO THE ISLAND OF MARGARITA.  NEAR ZONAL FLOW WILL
CONTINUE OVER THE CARIBBEAN THROUGH THE WEEKEND WITH THE PATTERN
BECOMING MORE AMPLIFIED BEGINNING LATE SUNDAY INTO MONDAY AS A
TROUGH DIGS OVER THE E UNITED STATES AND GLFMEX.

ATLANTIC...
THE FLOW OVER THE W ATLC IS BECOMING INCREASINGLY ZONAL AS A
MIDDLE TO UPPER LEVEL TROUGH JUST E OF BERMUDA LIFTS NE.  THE
ATTENDANT COLD FRONT LIES OVER THE CENTRAL ATLC FROM 32N52W TO
24N62W WHERE IT BECOMES STATIONARY TO E HISPANIOLA.  MUCH OF THE
UPPER LEVEL SUPPORT IS WELL N OF THE AREA AND ONLY WIDELY
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS LIE WITHIN 150 NM E
OF THE FRONT. BEHIND THE FRONT...HIGH PRESSURE IS MOVING RAPIDLY
OFF THE E COAST OF THE UNITED STATES PRODUCING STRONG NE FLOW
AND A LARGE FIELD OF COLD-AIR STRATOCUMULUS CLOUDS.  OVER THE E
ATLC...A STAGNANT HIGH OVER LOW TYPE PATTERN IS IN PLACE E OF
50W WITH A WELL-DEFINED RIDGE JUST N OF THE AREA ALONG 38N AND A
TROUGH TRAPPED TO THE SOUTH FROM MOROCCO SWD TO 10N50W. THIS
PATTERN IS PRODUCING VERY STABLE CONDITIONS N OF 15N.
HOWEVER...MIDDLE TO UPPER LEVEL DIFFLUENT FLOW SOUTH OF THE
UPPER TROUGH AXIS IS PRODUCING ENHANCED ITCZ ACTIVITY E OF 45W.
AT THE SURFACE...A 1035 MB STATIONARY HIGH IS LOCATED OVER THE
AZORES WITH ASSOCIATED RIDGE EXTENDING SW TO 25N55W.

$$
RHOME






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