[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 122344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 12 2009

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
2322 UTC.

...TROPICAL WAVES...

ATLANTIC TROPICAL WAVE EXTENDS FROM 16N44W TO 8N48W MOVING W
NEAR 12 KT. SATELLITE IMAGERY INDICATES CYCLONIC FLOW IN THE
LOW-LEVEL CLOUDS AROUND THE WAVE AXIS. THE WAVE ALSO LIES WITHIN
A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS CURRENTLY
ASSOCIATED WITH THE WAVE. HOWEVER...SCATTERED SHOWERS ARE
EMBEDDED ALONG THE ITCZ AXIS S OF 10N.

TROPICAL WAVE IS ALONG 84W S OF 14N OVER CENTRAL AMERICA MOVING
W NEAR 15 KT. THE WAVE IS EMBEDDED WITHIN A DEEP LAYER MOISTURE
MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. WHILE THE
MAJORITY OF THE WAVE AXIS IS NOW IN THE E PACIFIC
BASIN...ISOLATED MODERATE/STRONG CONVECTION IS FROM 13N-15N
BETWEEN 84W-86W...AND FROM 8N-10N BETWEEN 81W-84W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N14W 8N26W 9N44W 9N62W.
ISOLATED MODERATE CONVECTION IS FROM 4N-9N BETWEEN 17W-26W.
EMBEDDED IN THE ITCZ...A SURFACE TROUGH IS ANALYZED FROM 11N40W
TO 7N40W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
9N-12N BETWEEN 36W-41W. ANOTHER SURFACE TROUGH IS ANALYZED FROM
13N52W TO 8N54W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 11N-13N BETWEEN 50W-54W. SIMILAR ACTIVITY IS WITHIN 100
NM OF THE AXIS BETWEEN 55W-62W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A STATIONARY FRONT CONTINUES INLAND ALONG THE
GULF COAST STATES CLIPPING THE BASIN ALONG THE S TEXAS COAST
ALONG 28N97W TO 27N98W CONTINUING INTO MEXICO. MOST OF THE
SHOWER ACTIVITY ASSOCIATED WITH THE FRONT REMAINS AT THE COAST
AND INLAND N OF 30N BETWEEN 81W-95W. A SURFACE TROUGH EXTENDS
ALONG THE MEXICO COASTLINE FROM 20N96W TO THE BASE OF THE FRONT
NEAR 26N98W. SCATTERED SHOWERS/THUNDERSTORMS ARE E OF THE TROUGH
FROM 21N-27N BETWEEN 94W-96W. THE REMAINDER OF THE GULF OF
MEXICO HAS GENERALLY FAIR WEATHER DUE TO AN UPPER LEVEL HIGH
CENTERED OVER THE S CENTRAL GULF NEAR 25N88W. DIFFLUENT FLOW
ALOFT AROUND THE W SIDE OF THE UPPER RIDGE IS SUPPORTING THE
SHOWER ACTIVITY ALONG THE FRONTAL SYSTEM. EXPECT A WEAK SURFACE
RIDGE TO FORM OVER THE GULF THROUGH THU...THEN A COLD FRONT IS
EXPECTED TO MOVE OFF THE COAST OF TEXAS LATE THU.

CARIBBEAN SEA...
A SURFACE TROUGH EXTENDS ACROSS THE NRN CARIBBEAN FROM PUERTO
RICO NEAR 19N65W TO 16N74W. SURFACE CONVERGENCE NEAR THE TROUGH
IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 16N-19N
BETWEEN 67W-70W...AND FROM 17N-19N BETWEEN 73W-76W. UPPER LEVEL
NELY DIFFLUENT FLOW AROUND AN UPPER LEVEL RIDGE COVERING THE
GULF OF MEXICO...WRN ATLC...AND THE MAJORITY OF THE CARIBBEAN IS
ENHANCING THE SHOWER ACTIVITY. THIS UPPER LEVEL DIFFLUENCE IS
ALSO SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS S OF CUBA FROM
19N-21N BETWEEN 77W-79W. ISOLATED SHOWERS THUNDERSTORMS ARE S OF
12N BETWEEN 74W-84W DUE TO SURFACE CONVERGENCE NEAR THE E
PACIFIC ITCZ. ELSEWHERE ACROSS THE CARIBBEAN IS EXPERIENCING
GENERALLY FAIR WEATHER DUE TO DRY AIR AND SUBSIDENCE ALOFT
AROUND THE SRN PERIPHERY OF THE UPPER LEVEL RIDGE. MODERATE TO
FRESH TRADEWINDS ARE ACROSS MUCH OF THE BASIN.

ATLANTIC OCEAN...
A COLD FRONT N OF THE DISCUSSION AREA CONTINUING AS A
STATIONARY FRONT ACROSS THE GULF COAST STATES IS SUPPORTING
ISOLATED SHOWERS/THUNDERSTORMS IN THE WRN ATLC N OF 31N.
A BROAD SURFACE RIDGE COVERS THE SW ATLC ANCHORED BY A 1021 MB
HIGH NEAR 30N69W. TO THE N OF THE HIGH...A STATIONARY FRONT
CLIPS THE BASIN ALONG 31N BETWEEN 60W-72W. THE SURFACE RIDGE IS
SUPPORTED BY AN UPPER LEVEL RIDGE EXTENDING FROM THE GULF OF
MEXICO ACROSS THE SWRN ATLC TO NEAR 45W. A DYING COLD FRONT
ENTERS THE AREA NEAR 32N44W CONTINUING ALONG 30N50W MEETING THE
AFOREMENTIONED STATIONARY FRONT AT 31N60W. SCATTERED
SHOWERS/POSSIBLE THUNDERSTORMS ARE FROM 30N-31N BETWEEN 54W-59W.
A SURFACE TROUGH IS AHEAD OF THE FRONT EXTENDING FROM A 1009 MB
LOW NEAR 33N39W ALONG 29N40W 28N51W. NO SHOWER ACTIVITY IS
ASSOCIATED WITH THE TROUGH. ANOTHER STATIONARY FRONT ENTERS THE
ERN ATLC NEAR 31N26W ALONG 27N32W 24N40W CONTINUING AS A SURFACE
TROUGH ALONG 20N47W 17N54W TO E OF THE LEEWARD ISLANDS NEAR
17N59W. SCATTERED SHOWERS/THUNDERSTORMS ARE AHEAD OF THE FRONT
FROM 21N-26N BETWEEN 28W-32W...AND FROM 26N-30N BETWEEN 25W-28W.
IN THE UPPER LEVELS...E OF THE UPPER RIDGE AN UPPER LEVEL TROUGH
EXTENDS N OF 9N WITH AXIS ALONG 28W SUPPORTING THE SERIES OF
FRONTAL SYSTEMS IN THE ERN ATLC.

$$
WALTON




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