[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 052343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI DEC 05 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 6N11W 7N22W 5N35W 6N50W INTO
FRENCH GUIANA AND SURINAME. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 4N-7N BETWEEN 10W-16W. SIMILAR CONVECTION IS
ALSO FOUND WITHIN 100 NM N...AND 60 NM S OF THE ITCZ AXIS
BETWEEN 36W-42W.

...DISCUSSION...

GULF OF MEXICO...
A SHORT-WAVE TROUGH IS OVER THE WESTERN GULF AND EXTENDS FROM SE
LOUISIANA TO THE BAY OF CAMPECHE. STRONG SOUTHWESTERLY FLOW IS
AHEAD OF THE TROUGH AXIS COVERING THE EASTERN GULF AND THE
FLORIDA PENINSULA. THE ATTENDANT FRONTAL SYSTEM TRAILS ACROSS
THE GULF REGION...EXTENDING FROM NORTHERN FLORIDA TO 26N90W TO A
1018 MB SURFACE LOW NEAR 21N95W THEN ENTERING MEXICO NEAR
JALAPA. A PRE-FRONTAL TROUGH LIES ALONG 94W SOUTH OF 22N TO OVER
THE BAY OF CAMPECHE. A RATHER UNIFORM STRATUS CLOUDS COVER THE
EASTERN SLOPES OF THE SIERRA MADRE MOUNTAINS. SIMILAR CLOUDINESS
ARE ALSO SEEN ALONG THE COAST OF TEXAS. THE FRONT REMAINS NEARLY
STATIONARY OVER THE GULF WATERS...BUT A REINFORCING SHOT OF COLD
AIR WILL PUSH THIS FEATURE SOUTHWARD OVER THE EASTERN GULF SAT
AFTERNOON...REACHING SOUTH FLORIDA LATE SATURDAY/EARLY SUNDAY
MORNING...AND WESTERN CUBA SUNDAY AFTERNOON.  NLY WINDS OF 15-20
KT ARE NOTED BEHIND THE FRONT...PARTICULARLY OVER THE N-CENTRAL
GULF. THESE WINDS ARE ADVECTING A RELATIVELY COOLER AND DRIER
AIRMASS ACROSS THE N AND W GULF IN THE WAKE OF THE FRONT. MAINLY
ELY WINDS OF 10-15 KT ARE AHEAD OF THE FRONTAL ZONE. IN
ADDITION...STRONG N TO NE SURFACE WINDS ARE BLOWING THROUGH THE
ISTHMUS OF TEHUANTEPEC RESULTING IN GALE FORCE WINDS IN THE EAST
PACIFIC REGION.

CARIBBEAN SEA...
A SURFACE TROUGH...REMNANTS OF AN OLD FRONTAL BOUNDARY STRETCHES
FROM THE CAYMAN ISLANDS ACROSS THE PROVINCE OF CAMAGUEY CUBA TO
THE SE BAHAMAS THEN CONTINUES MAINLY EWD ACROSS THE W ATLC TO
NEAR 27N 57W. ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS.
ANOTHER SFC TROUGH IS OVER THE SW CARIBBEAN AND GOES FROM 13N79W
TO 9N81W. ISOLATED SHOWERS ARE ALSO ASSOCIATED WITH THIS
FEATURE. ALOFT...AN UPPER RIDGE DOMINATES THE CENTRAL AND
EASTERN CARIBBEAN WHILE STRONG SWLY UPPER-LEVEL FLOW IS NOTED
ACROSS MOST OF CENTRAL AMERICA AND THE NW CARIBBEAN INTO CUBA
AND THE BAHAMAS. THESE WINDS ARE TRANSPORTING SOME MID/UPPER
LEVEL MOISTURE FROM THE EPAC REGION INTO THE CARIBBEAN SEA AND
WESTERN CUBA WHERE A  NARROW BAND OF TRANSVERSE HIGH CLOUDS IS
SEEN. PATCHES OF LOW LEVEL MOISTURE...MORE CONCENTRATED SOUTH OF
HISPANIOLA CONTINUE TO MOVE ACROSS THE EAST AND CENTRAL
CARIBBEAN PRODUCING INTERVALS OF CLOUDINESS AND A FEW SHOWERS.
THE TAIL END OF AN UPPER-LEVEL TROUGH EXTENDING OVER THE CENTRAL
ATLC IS PRODUCING SOME SHOWER ACTIVITY OVER THE SOUTHERN
WINDWARD ISLANDS.

ATLANTIC OCEAN...
SW TO W WINDS ALOFT CONTINUES TO INCREASE OVER THE W ATLC AS A
DEEP LAYERED TROUGH OVER THE E AND S CONUS PROGRESSES SE. THE
ASSOCIATED COLD FRONT ENTERS THE FORECAST REGION NEAR 32N76W
THEN CONTINUES SW TO N FLORIDA AND BECOMES STATIONARY ACROSS THE
GULF OF MEXICO. LOW LEVEL CONVERGENCE IS SUPPORTING ISOLATED
SHOWERS WITHIN 60 NM EITHER SIDE OF THE FRONTAL BOUNDARY. E OF
THE FRONTAL SYSTEM...THE FLOW ALOFT IS MORE AMPLIFIED...WITH AN
UPPER RIDGE AXIS EXTENDING FROM THE NE CARIBBEAN TO BEYOND
31N58W AND AN UPPER-LEVEL TROUGH STRETCHING FROM AN UPPER-LEVEL
LOW NEAR 32N44W TO NEAR BARBADOS IN THE SOUTHERN WINDWARD
ISLANDS. SCATTERED MODERATE CONVECTION IS NEAR THE TAIL END OF
THIS TROUGH AFFECTING THE FAR SE CARIBBEAN...THE SOUTHERN
WINDWARD ISLANDS AND NE VENEZUELA. MODERATE TO STRONG UPPER-
LEVEL SUBSIDENCE AND IMPLIED DRY AIR MASS IS NOTED OVER MUCH OF
THE W AND CENTRAL ATLC NORTH OF THE AFOREMENTIONED UPPER-LEVEL
TROUGH. THIS UPPER FEATURE IS ASSOCIATED WITH A SURFACE TROUGH
EXTENDING FROM A 1011 MB SURFACE LOW NEAR 27N48W TO 26N45W TO
23N49W. A WELL DEFINED SWIRL OF LOW CLOUDS REMAINS ASSOCIATED
WITH THE SFC LOW WHILE SCATTERED SHOWERS ARE JUST AHEAD OF THE
SFC TROUGH MAINLY FROM 26N TO 29N. FARTHER SOUTH...THERE IS
ANOTHER SFC TROUGH THAT RUNS FROM 19N43W TO 10N48W. LOW/MID
CLOUDS WITH ISOLATED SHOWERS ARE WITHIN 300 NM E OF THE TROUGH
AXIS WHILE A CLUSTER OF MODERATE CONVECTION IS WEST OF THE
TROUGH NEAR 13N49W. A BROAD UPPER-LEVEL HIGH CENTERED NEAR 8N23W
DOMINATES MOST OF THE TROPICS AND IS ENHANCING CONVECTION ALON
THE ITCZ. NUMEROUS SHOWERS AND SCATTERED TSTMS ARE AHEAD OF AN
UPPER-LEVEL LOW SPINNING OVER THE E ATLC NEAR 25N28W.

$$
GR





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