[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU NOV 08 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 58W S OF 13N MOVING W 10-15 KT. PRESSURE
DROP OF 3 MB AND AN INCREASE IN SHOWER ACTIVITY INDICATED THE
PASSAGE OF THE WAVE THROUGH FRENCH GUIANA AND SURINAME YESTERDAY
EVENING. A SMALL...LOW AMPLITUDE MOISTURE SURGE WITH THIS WAVE
IS STILL NOTED IN THE UW-CIMSS TPW PRODUCT. THE AXIS OF THE WAVE
IS NOW OVER GUYANA...BUT AT THE MOMENT THIS FEATURE IS NOT
GENERATING MUCH SHOWER ACTIVITY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N13W 8N33W 7N50W 7N63W. THE AXIS IS
A LITTLE MORE ACTIVE TODAY WITH SCATTERED MODERATE CONVECTION
NOTED WITHIN 180-200 NM S OF THE AXIS E OF 45W THROUGH THE
AFRICAN COAST. A CLUSTER OF MODERATE TO ISOLATED STRONG
CONVECTION IS WITHIN 120 NM N OF AXIS BETWEEN 40W-45W. THIS
ACTIVITY APPEARS TO BE ASSOCIATED WITH A LOW AMPLITUDE TROPICAL
WAVE IN THE VICINITY AND WILL BE ADDED TO THE 0000 UTC SFC MAP.
THE WAVE SHOWS UP IN THE LOW LEVEL DERIVED WINDS FROM CIMSS AND
THE HOVMOLLER DIAGRAM. IN ADDITION...THE WAVE IS AT THE LEADING
EDGE OF A FAIRLY DENSE AREA OF AFRICAN DUST AS IS TYPICAL FOR
THE SUMMER TIME TROPICAL WAVE. ALSO...THE GFS MODEL HAS MOISTURE
FROM THIS WAVE AFFECTING THE LESSER ANTILLES DURING THE UPCOMING
WEEKEND.

DISCUSSION...

GULF OF MEXICO...
THE UW-CIMSS TPW PRODUCT SHOWED VERY WELL THE MOVEMENT OF THE
COLD FRONT ACROSS THE GULF AND THE FLORIDA PENINSULA YESTERDAY
AND TODAY. THE FRONT APPEARS TO HAVE SPLIT. THE WESTERN PART IS
DISSIPATING OVER THE WESTERN GULF AND THE YUCATAN PENINSULA
GENERATING PATCHES OF LOW/MID CLOUDS WITH EMBEDDED LIGHT
SHOWERS. THE SECOND PART EXTENDS FROM SE FLORIDA ACROSS THE
CENTRAL BAHAMAS AND THE W ATLC. THE MIAMI DOPPLER RADAR SHOWS
SCATTERED SHOWERS AND ISOLATED TSTMS OVER SOUTH FLORIDA AND
ADJACENT WATERS RELATED TO THE FRONT. WINDS AND SEAS ARE MOSTLY
RELAXING ACROSS THE GULF...EXCEPT FOR A BIT STRONGER NNE FLOW
NEAR THE YUCATAN CHANNEL S OF 25N. LIGHT ONSHORE SE WINDS HAVE
DEVELOPED NEAR THE TEXAS AND WRN LOUISIANA COAST AS HIGH PRES N
OF THE AREA HAS MOVED E. COLD AIR STRATOCUMULUS CLOUDS ARE SEEN
OVER THE EASTERN GULF SOUTH OF 26N MOVING SOUTH THROUGH THE
YUCATAN CHANNEL INTO THE NW CARIBBEAN UNDER A NLY WIND FLOW.
FAIR WEATHER PREVAILS OVER THE REMAINDER OF THE GULF.
ALOFT...FAIRLY UNIFORM NW FLOW BETWEEN RIDGE OVER MEXICO AND
LONG WAVE UPPER TROUGH OVER THE EASTERN SEABOARD IS OVER THE
GULF. DRY MID/UPPER AIR DOMINATES THE REGION AIDING IN THE
PLEASANT CONDITIONS.

CARIBBEAN SEA...
A DISSIPATING COLD FRONT IS OVER THE NW CARIBBEAN GENERATING
SOME CLOUDINESS AND ISOLATED SHOWERS OVER THE GULF OF HONDURAS
AND BELIZE. A SFC TROUGH REMAINS BETWEEN SE JAMAICA TO JUST
OFFSHORE THE COSTA RICA/PANAMA BORDER. THIS FEATURE IS PRODUCING
A LARGE AREA OF SHOWERS WITH ISOLATED TSTMS OVER THE SW
CARIBBEAN JUST OFFSHORE NICARAGUA AND COSTA RICA W OF 78W.
ADDITIONAL CLUSTERS OF MODERATE CONVECTION HAVE DEVELOPED OVER
WESTERN PANAMA. A TYPICAL 1008 MB LOW IS OVER THE COLOMBIAN
COAST NEAR 10N76W...WHICH IS ALSO GENERATING CLUSTERS OF
MODERATE TO ISOLATED STRONG CONVECTION OVER NORTHERN COLOMBIAN
AND COASTAL WATERS. ANOTHER SFC TROUGH IS ENHANCING SOME
SHOWER/TSTM ACTIVITY OVER HISPANIOLA AND PUERTO RICO. SWLY WINDS
AHEAD OF THE ABOVE MENTIONED LONG WAVE UPPER TROUGH ARE HELPING
TO DEVELOP THIS ACTIVITY. A FLATTENING UPPER-LEVEL RIDGE
DOMINATES THE BASIN.

ATLANTIC OCEAN...
A COLD FRONT ENTERS THE WRN ATLC AREA NEAR 31N65W THEN CONTINUES
SW THROUGH THE CENTRAL BAHAMAS TO SE FLORIDA. THE FRONT IS
GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE NW
BAHAMAS AND SE FLORIDA. MODERATE NLY WINDS ARE BEHIND THE FRONT.
THESE WINDS EXPECTED TO RELAX FURTHER THROUGH FRI AS HIGH PRES
BUILDS OVER THE NE GULF. A LITTLE FURTHER E...A 1008 MB LOW IS
NEAR 27N62W THAT HAS A TROUGH EXTENDING S TO HISPANIOLA...AND A
SEPARATE TROUGH EXTENDING ENE TO ANOTHER 1006 MB SFC LOW LOCATED
NEAR 34N56W. THE TROUGHING IS GENERATING SCATTERED SHOWERS AND
ISOLATED TSTMS PARTICULARLY BETWEEN 21N-25N...AND NEAR 29N54W
WHERE TSTMS ARE MORE CONCENTRATED. A 1008 MB SFC LOW IS NOW N OF
THE AREA NEAR 35N27W...BUT AN ELONGATED TRAILING TROUGH EXTENDS
THROUGH THE FORECAST AREA ALONG 31N25W 26N28W. THERE IS ONLY
ISOLATED SHOWERS NEAR THE TROUGH. THE REMAINDER OF THE E ATLC IS
DOMINATED BY FAIR WEATHER AND MODEST SFC RIDGING. ALOFT...A LONG
WAVE UPPER TROUGH DIGS INTO THE BAHAMAS AND CUBA. AN UPPER RIDGE
EXTENDS FROM THE CARIBBEAN INTO THE CENTRAL ATLC BEYOND 32N50W.
AN UPPER LOW IS NEAR 37N34W WHILE AN UPPER RIDGE COVERS THE
REMAINDER OF THE ATLC FORECAST AREA AND THE WEST COAST OF
AFRICA.

$$
GR






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