[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281031
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE OCT 28 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...TROPICAL WAVES...
TROPICAL WAVE WAS RELOCATED ALONG 47W/48W S OF 17N MOVING W
10-15 KT BASED ON LONG TERM SATELLITE IMAGERY. MID LEVEL
INVERTED-V CURVATURE IS OBSERVED WITHIN SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 11N-16N BETWEEN 44W-50W.

TROPICAL WAVE IS ALONG 58W/59W FROM 10N-18N MOVING W 10 KT. A
WELL DEFINED INVERTED-V CURVATURE IS OBSERVED ON SATELLITE
IMAGERY WITH CLUSTERS OF SCATTERED MODERATE CONVECTION FROM
14N-18N BETWEEN 57W-61W.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 11N14W 6N29W 13N43W 8N58W. A SURFACE
TROUGH IS EMBEDDED WITHIN THE ITCZ ALONG 38W/39W FROM 6N-16N.
CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 120
NM EITHER SIDE OF THE ITCZ E OF 23W TO INLAND OVER W AFRICA AND
WITHIN 225 NM EITHER SIDE OF THE ITCZ BETWEEN 23W-41W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH COVERS THE E US AND INTO THE GULF N OF 25N
WITH A JET STREAM OF 90 TO 120 KT OVER THE NE GULF. THE
ASSOCIATED FAST MOVING COLD FRONT ENTERS THE GULF ACROSS THE
FLORIDA KEYS TO THE N COAST OF THE YUCATAN PENINSULA TO MEXICO
NEAR TUXPAN. A SURFACE RIDGE CONTINUES TO BUILD BEHIND THE FRONT
ANCHORED BY A SERIES OF HIGHS OVER THE CENTRAL PLAIN STATES. THE
AIR MASS N OF THE FRONT REMAINS RATHER DRY WITH DEW POINTS ALONG
THE N GULF COAST DOWN TO THE 20 TO 30 DEGREE RANGE AND
TEMPERATURES DROPPING INTO THE 40 TO 50 DEGREE RANGE. LOW CLOUDS
WITH ISOLATED SHOWERS DELINEATE THE FRONT AS THE AIR MASS
REMAINS DRIER BY THE PREVIOUS FRONTAL PASSAGE. COLD AIR
STRATOCUMULUS CLOUDS ARE DEVELOPING BEHIND THE FRONT AS WELL AS
STRONG NORTHERLY WINDS. THE S GULF IS DOMINATED BY SW UPPER
WINDS WHICH IS ADVECTING UPPER MOSITURE FROM THE E PACIFIC
REGION ACROSS MEXICO TO OVER THE SW GULF MAINLY IN THE FORM OF
THIN HIGH CLOUDS. THE FRONT IS EXPECTED TO CLEAR THE ENTIRE GULF
LATER TODAY.

CARIBBEAN SEA...
THE REMNANTS OF A FRONTAL BOUNDARY REMAINS IN THE NW CARIBBEAN
EXTENDING ACROSS CUBA NEAR 22N80W TO THE GULF OF HONDURAS NEAR
ROATAN ISLAND. THIS FRONT CONTINUES TO PRODUCE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM SE OF THE FRONT AND
ISOLATED SHOWERS WITHIN 45 NM NW OF THE FRONT. THE UPPER LEVELS
OF THE CARIBBEAN ARE DOMINATED BY AN UPPER RIDGE ANCHORED IN THE
W ATLC N OF PUERTO RICO GIVING THE CARIBBEAN E OF THE FRONT
STRONG SUBSIDENCE AND DRY STABLE AIR. THE REMNANTS OF A SURFACE
TROUGH EXTENDS FROM 19N62W ACROSS PUERTO RICO AND ALONG THE S
COAST OF THE DOMINICAN REPUBLIC GENERATING LOW LEVEL ISOLATED
SHOWERS WITHIN 90 NM EITHER SIDE OF THE TROUGH. SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 75 NM
ALONG THE COAST OF COLOMBIA TO COSTA RICA. OTHERWISE THE
REMAINDER OF THE CARIBBEAN IS TRANQUIL THIS MORNING.

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH THAT COVERS THE E US EXTENDS OVER THE W
ATLC W OF 70W WITH A WEAK COLD FRONT ENTERING THE REGION NEAR
32N66W ALONG 26N71W ACROSS THE BAHAMAS AND INTO THE NW CARIBBEAN
NEAR 22N80W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN
90 NM E OF THE FRONT. A SECOND STRONGER AND FASTER MOVING
COLD FRONT ENTERS THE W ATLC NEAR 32N74W AND INTO THE GULF OF
MEXICO ACROSS THE FLORIDA KEYS. DENSE LOW LEVEL CLOUDS WITH
POSSIBLE ISOLATED SHOWERS ARE WITHIN 150 NM N OF THE STRONG
FRONT TO 80W. THESE FRONTS ARE EXPECTED TO MERGE LATE TODAY INTO
TONIGHT. BROAD UPPER RIDGE COVERS THE REMAINDER OF THE W ATLC
AND INTO THE CENTRAL ATLC ANCHORED N OF PUERTO RICO NEAR 22N65W
WITH ENOUGH UPPER DIFFLUENCE OVER THE CENTRAL ATLC TO GENERATE
SCATTERED SHOWERS E OF 55W TO A SURFACE TROUGH IN THE CENTRAL
ATLC EXTENDING FROM 31N47W TO 18N53W. A NARROW UPPER LEVEL SHEAR
AXIS EXTENDS INTO THE CENTRAL ATLC NEAR 32N41W S TO 22N43W THEN
SW TO THE COAST OF SOUTH AMERICA NEAR 9N60W. THIS SHEAR AXIS IS
ENHANCING THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG
58W/59W. A STRONG UPPER RIDGE COVERS THE REMAINDER OF THE
TROPICAL ATLC ANCHORED NEAR 10N27W AND COVERS THE AREA S OF 26N
E OF THE CENTRAL ATLC SHEAR AXIS. THE UPPER DIFFLUENCE
ASSOCIATED WITH THIS UPPER RIDGE IS GENERATING THE CONVECTION
SURROUNDING THE SURFACE TROUGH EMBEDDED WITHIN THE ITCZ. A WEAK
RIDGE COVERS THE E/CENTRAL ATLC N OF 20N E OF 60W WITH A
WEAKNESS IN THE IMMEDIATE VICINITY OF THE SURFACE TROUGH.

$$
WALLACE





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