[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120511
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON NOV 12 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 64W/65W S OF 15N MOVING W NEAR 20 KT.
WAVE REMAINS EMBEDDED WITHIN A SURGE OF AFRICAN DUST THAT IS NOW
OVER THE E CARIBBEAN. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
ARE S OF 12N BETWEEN 63W-68W.

TROPICAL WAVE PREVIOUSLY ALONG 72W WAS DROPPED FROM THE 0000
UTC MAP.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N15W 7N23W 8N30W 6N40W 4N54W.
SCATTERED MODERATE/STRONG CONVECTION IS MOVING RAPIDLY OFF THE
COAST OF GUINEA WITHIN 60/75 NM ALONG THE COAST FROM 9N-10N.
CLUSTERS OF SIMILAR CONVECTION COVERS THE AREA FROM 2N-10N
BETWEEN 16W-26W. SCATTERED CLUSTERS OF SCATTERED MODERATE
CONVECTION DOT THE REMAINDER OF THE AREA FROM 1N-11N E OF 45W TO
ACROSS THE PRIME MERIDIAN.

DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE EXTENDS FROM THE W CARIBBEAN ACROSS THE
YUCATAN NEAR 21N89W TO OVER THE MISSISSIPPI VALLEY. UPPER LEVEL
TROUGH IN THE W ATLC COVERS THE FLORIDA PENINSULA WITH DRY
STABLE AIR COVERING THE ENTIRE GULF. A SURFACE RIDGE EXTENDS
OVER THE GULF INTO THE W ATLC ANCHORED OVER NORTH CAROLINA
KEEPING THE W GULF IN RETURN FLOW AND PRODUCING SOME WIDELY
ISOLATED LOW LEVEL SHOWERS MAINLY N OF 24N W OF 90W. OTHERWISE
MOSTLY FAIR SKIES DOMINATE THE GULF AGAIN TONIGHT.

CARIBBEAN SEA...
THE MAIN FOCUS TONIGHT REMAINS THE 1006 MB LOW IN THE SW
CARIBBEAN NEAR 11N82W WITH A SURFACE TROUGH EXTENDING N ALONG
16N81W TO E OF THE CAYMAN ISLANDS NEAR 20N79W. THE LOW LEVEL
CENTER IS MOSTLY EXPOSED AS THE SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE N AND W OF THE LOW WITHIN 120 NM OF LINE FROM
NEAR THE COAST OF COSTA RICA/NICARAGUA BORDER ALONG 15N82W TO
THE COAST OF CUBA NEAR 20N75W. THIS SYSTEM IS EXPECTED TO
CONTINUE TO DRIFT WESTWARD AS IT MOVES INLAND OVER CENTRAL
AMERICA MONDAY AND NO SIGNIFICANT DEVELOPMENT IS ANTICIPATED.
HOWEVER...IT COULD PRODUCE LOCALLY HEAVY RAINFALL OVER PORTIONS
OF COSTA RICA...NICARAGUA...AND HONDURAS OVER THE NEXT COUPLE OF
DAYS. UPPER RIDGE EXTENDS ACROSS THE CARIBBEAN FROM AN UPPER
HIGH OVER THE LESSER ANTILLES NEAR 15N61W. THIS IS PROVIDING
ENOUGH UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED SHOWERS/
THUNDERSTORMS WITHIN 60 NM OF LINE FROM 14N78W TO INLAND OVER
COLOMBIA NEAR 11N74W. AFRICAN DUST IS FILTERED OVER THE E
CARIBBEAN E OF 67W WITH SCATTERED SHOWERS/THUNDERSTORMS
PRECEDING IT FROM 13N-16N BETWEEN 67W-72W.

ATLANTIC OCEAN...
BROAD UPPER TROUGH COVERS THE W ATLC WITH THE UPPER LOW OVER THE
N CANADIAN MARITIMES AND EXTENDING W FROM 50W TO OVER FLORIDA.
THE ASSOCIATED COLD FRONT EXTENDS TO 32N60W WITH A SURFACE
TROUGH EXTENDING ALONG 27N69W TO OVER THE BAHAMA ISLANDS NEAR
25N79W WITH BROKEN TO OVERCAST LOW/MID CLOUDS WITH ISOLATED
SHOWERS N OF THE FRONT AND TROUGH. A REMNANT STATIONARY FRONT
FROM AN UPPER SYSTEM THAT IS WELL N OF THE REGION EXTENDS INTO
THE CENTRAL ATLC NEAR 32N47W SW TO 23N59W CONTINUING AS A
SURFACE TROUGH TO OVER HISPANIOLA NEAR 19N72W. SCATTERED SHOWERS
AND WIDELY ISOLATED THUNDERSTORMS ARE WITHIN 120/150 NM E OF THE
FRONT WITH SIMILAR ACTIVITY WITHIN 150/200 NM W OF SURFACE
TROUGH TO THE COAST OF HISPANIOLA. AN UPPER HIGH IS OVER THE
LESSER ANTILLES NEAR 15N61W EXTENDING AN UPPER RIDGE NE ALONG
24N44W THEN N TO BEYOND 32N40W. A WEAK UPPER TROUGH IS
UNDERCUTTING THE UPPER RIDGE ABOVE EXTENDING FROM 15N43W TO
8N51W. A NARROW UPPER TROUGH IS OVER THE FAR E ATLC N OF 20N E
OF 25W TO INLAND OVER W AFRICA WITH NO ASSOCIATED SURFACE
FEATURES. THE TYPICAL E/W UPPER RIDGE CROSS THE TROPICAL ATLC E
OF 40W WITH THE AXIS ALONG 5N/6N. BROAD AREA OF AFRICAN DUST
COVERS MUCH OF THE TROPICS S OF 22N FROM 30W INTO THE E
CARIBBEAN.

$$
WALLACE




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