[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU 09 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...

AXIS OF ITCZ IS CENTERED ALONG 10N7W 4N25W 10N46W 7N70W 7N80W
7N80W. SCATTERED MODERATE CONVECTION FROM 3N-6N BETWEEN 20W-38W.
WIDELY SCATTERED MODERATE CONVECTION FROM 8N-13N BETWEEN 36W-41W
AND FROM 10N-14N BETWEEN 50W-55W.

...DISCUSSION...

GULF OF MEXICO...
A POTENT SHORTWAVE TROUGH MOVING THROUGH THE CENTRAL UNITED
STATES IS THE BIGGEST WEATHER MAKER TODAY.  GOOD UPPER LEVEL
DYNAMICS/LIFT AND AMPLE LOW LEVEL MOISTURE INFLOW ASSOCIATED
WITH THIS SYSTEM IS PRODUCING AN IMPRESSIVE LINE OF
SHOWERS/THUNDERSTORMS OVER THE E UNITED STATES EXTENDING SWD
INTO THE N GLFMEX OVER SE LOUISIANA TO 27N93W.  THE STRONGEST
DYNAMICS ARE CONFINED N OF THE 30N SO COVERAGE AND INTENSITY OF
THUNDERSTORM ACTIVITY TAILS OFF AS THE LINE EMERGES INTO THE N
GULF.  ATTENDANT COLD FRONT STRETCHES FROM THE TENNESSEE VALLEY
SWD OVER SE LOUISIANA TO THE COAST OF MEXICO NEAR TAMPICO THEN
AS A STATIONARY FRONT OVER INTERIOR MEXICO ALONG THE E SLOPES OF
THE SIERRA MADRE ORIENTAL MOUNTAINS.  A SECOND SHORTWAVE TROUGH
CURRENTLY DROPPING SWD FROM THE ROCKIES WILL FURTHER AMPLIFY THE
PATTERN SETTING UP A LARGE-SCALE TROUGH REGIME OVER THE E UNITED
STATES DURING THE NEXT 24-36 HOURS.  THIS WILL ALLOW THE COLD
FRONT TO MAKE SIGNIFICANT SWD PROGRESS EXTENDING FROM CENTRAL
FLORIDA TO THE YUCATAN PENINSULA BY FRI NIGHT AND CLEARING THE
GLFMEX COMPLETELY ON SAT.  ALSO...THE AMPLIFYING MIDDLE TO UPPER
LEVEL PATTERN WILL PROVIDE MORE DYNAMICS/LIFT ALONG THE GULF
PORTION OF THE COLD FRONT SUPPORTING INCREASING SHOWERS/
THUNDERSTORMS AS THE FRONT SWEEPS THROUGH FLORIDA ON FRI.
STRONG HIGH PRESSURE IS EXPECTED TO BUILD IN BEHIND THE FRONT
SUPPORTING BRISK NLY FLOW AND MODERATE COLD AIR ADVECTION.  IN
FACT...THIS AIRMASS LOOKS TO BE ONE OF THE COOLEST THUS FAR.

CARIBBEAN...
THE CARIBBEAN REMAINS HIGH AND DRY UNDER THE INFLUENCE OF STRONG
MIDDLE TO UPPER LEVEL RIDGING AND SUBSIDENCE.  A MIDDLE TO UPPER
LEVEL TROUGH OVER THE E PACIFIC JUST S OF CENTRAL AMERICA IS
HELPING TO PRODUCE SCATTERED ITCZ CONVECTION OVER PANAMA AND
COSTA RICA.  OTHERWISE...DRY/STABLE CONDITIONS PREVAIL IN THE
MIDDLE TO UPPER LEVELS...ESPECIALLY E OF 70W.  POCKETS OF LOW
LEVEL MOISTURE EXTEND FROM THE CENTRAL CARIBBEAN WESTWARD OVER
CENTRAL AMERICA SUPPORTING PATCHY AREAS OF LOW CLOUDINESS AND
SHOWERS.  MIDDLE TO UPPER LEVEL RIDGING WILL GRADUALLY WEAKEN
OVER THE NEXT FEWS DAYS IN ADVANCE OF THE AMPLIFYING TROUGH OVER
THE E UNITED STATES AND GULF OF MEXICO.  THIS SHOULD SUPPORT
SOME INCREASE IN CLOUDINESS AND SHOWER ACTIVITY ESPECIALLY OVER
THE W CARIBBEAN AS AN UPPER JET FORMS JUST N OF THE AREA.

ATLANTIC OCEAN...
LARGE SCALE ANTICYCLONE CENTERED OVER THE BAHAMAS DOMINATES THE
W ATLC WITH ASSOCIATED RIDGE EXTENDING NEWD INTO THE CENTRAL
ATLC ALONG 27N50W 28N40W.  THE RIDGE IS BEING PARTIALLY ERODED
BY A WEAK SHORTWAVE TROUGH DROPPING SWD ALONG 32N50W 25N65W BUT
IS OTHERWISE WELL-DEFINED.  AS SUCH...UPSTREAM DISTURBANCES ARE
CONFINED N OF 30N KEEPING THE W ATLC UNDER DRY/TRANQUIL
CONDITIONS.  OVER THE CENTRAL ATLC...A PERSISTENT MIDDLE TO
UPPER LEVEL TROUGH EXTENDS FROM JUST E OF THE AZORES SWD ALONG
27N40W 20N50W TO THE WINDWARD ISLANDS.  WATER VAPOR IMAGERY
INDICATES THE TROUGH IS BECOMING CUTOFF FROM THE WLY FLOW AND A
UPPER LOW IS FORMING NEAR 20N50W.  THIS PATTERN IS PRODUCING
DIFFLUENT MIDDLE TO UPPER LEVEL FLOW TO THE EAST AND SUPPORTING
WIDESPREAD CLOUDINESS AND SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM THE ITCZ NWD TO 25N BETWEEN THE CAPE VERDE
ISLANDS AND 53W.  THE STRONGEST AND MOST NUMEROUS
SHOWER/THUNDERSTORM ACTIVITY IS LOCATED FROM 10N-20N BETWEEN
35W-50W.  THIS AREA SHOULD REMAIN UNSETTLED OVER THE NEXT FEW
DAYS AS THE UPPER LOW BECOMES CUTOFF AND NEARLY STATIONARY.

$$
RHOME






This weather bulletin was brought to you by:
www.nashvilleweather.net