[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 251715
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN OCT 25 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1615 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 21N43W TO 7N49W MOVING W NEAR 20 KT.
VISIBLE SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE
BROAD LOW-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS.
THE WAVE ALSO LIES WITHIN A BROAD AREA OF AMPLIFIED MOISTURE
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE
CONVECTION IS FROM 13N-18N BETWEEN 45W-48W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N12W 7N17W 8N24W 6N37W 9N53W
7N59W. SCATTERED STRONG CONVECTION IS ALONG THE AFRICA COAST
FROM 6N-9N BETWEEN 9W-13W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 150 NM OF THE AXIS BETWEEN 20W-35W. SIMILAR
ACTIVITY IS ALSO WITHIN 400 NM N OF THE AXIS BETWEEN 38W-45W.

...DISCUSSION...

GULF OF MEXICO...
A STATIONARY FRONT REMAINS IN THE FAR SE GULF OF MEXICO ENTERING
THE STRAITS OF FLORIDA NEAR 25N80W CONTINUING TO 22N87W. MOST OF
THE ASSOCIATED SHOWER ACTIVITY HAS NOW DISSIPATED.
HOWEVER...ISOLATED SHOWERS REMAIN POSSIBLE ALONG THE FRONT.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ACROSS THE WRN GULF
FROM 20N-27N BETWEEN 92W-95W. THIS ACTIVITY IS ENHANCED BY
DIFFLUENT FLOW AROUND THE BASE OF AN UPPER LEVEL TROUGH OVER
MUCH OF THE CENTRAL CONUS AND THE GULF OF MEXICO WITH AXIS OVER
CENTRAL MEXICO. A WEAK SURFACE RIDGE IS OVER THE NRN GULF
EXTENDING UP THE ERN CONUS ANCHORED BY A 1020 MB HIGH OVER NRN
ALABAMA. SURFACE WINDS OF 10 TO 15 KT ARE ACROSS THE BASIN
MOVING ANTI-CYCLONICALLY AROUND THE WEAK SURFACE RIDGE. EXPECT
THE STATIONARY FRONT TO DISSIPATE LATER TONIGHT. ANOTHER COLD
FRONT IS EXPECTED TO MOVE OFF THE TEXAS COAST MON NIGHT.

CARIBBEAN SEA...
A WEAK SURFACE TROUGH IN THE FAR NW CARIBBEAN EXTENDS FROM
21N85W TO 16N97W. ISOLATED SHOWERS ARE POSSIBLE ALONG THE TROUGH
AXIS. THE TROUGH LIES UNDER AN UPPER LEVEL RIDGE PROVIDING A DRY
ATMOSPHERE ALOFT...INHIBITING THE SHOWER ACTIVITY NEAR THE
TROUGH. A 1009 MB SURFACE LOW JUST OFF THE COAST OF COSTA RICA
NEAR 11N82W SUPPORTS SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS
FROM 10N-14N BETWEEN 80W-84W. ANOTHER SURFACE TROUGH EXTENDS S
OF JAMAICA FROM 17N78W TO 12N78W. ISOLATED SHOWERS/THUNDERSTORMS
ARE WITHIN 75 NM OF THE TROUGH AXIS. THIS TROUGH IS SUPPORTED BY
AN UPPER LEVEL LOW OVER CUBA NEAR 22N79W. ANOTHER UPPER LEVEL
TROUGH COVERS THE ERN CARIBBEAN. DIFFLUENT FLOW ALOFT BETWEEN
THE UPPER LOW AND THIS UPPER RIDGE OVER THE ERN PORTION OF THE
BASIN SUPPORTS SCATTERED SHOWERS/THUNDERSTORMS N OF COLOMBIA AND
VENEZUELA FROM 11N-15N BETWEEN 71W-75W...AND ISOLATED SHOWERS N
OF 16N BETWEEN 72W-77W INCLUDING PORTIONS OF HISPANIOLA AND WRN
CUBA. MODERATE TRADEWINDS ARE OVER MUCH OF THE BASIN WITH
STRONGER WINDS IN THE NW CARIBBEAN AHEAD OF THE FRONT IN THE
STRAITS OF FLORIDA AS WELL AS IN THE ERN CARIBBEAN.

ATLANTIC OCEAN...
A STATIONARY FRONT ENTERS THE DISCUSSION AREA NEAR 32N78W
CONTINUING OFF THE E FLORIDA COAST ALONG 29N80W 25N80W AND INTO
THE STRAITS OF FLORIDA. SCATTERED SHOWERS/THUNDERSTORMS ARE
ALONG THE FRONT AXIS. THE FRONT IS SUPPORTED BY AN UPPER LEVEL
TROUGH COVERING MUCH OF THE CENTRAL/ERN CONUS AND GULF OF
MEXICO. THE REMAINDER OF THE WRN ATLC IS DOMINATED BY A BROAD
SURFACE RIDGE ANCHORED BY A 1028 MB HIGH NEAR 38N55W. THE
SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR
30N65W. A SURFACE TROUGH EXTENDS E OF THE LESSER ANTILLES ALONG
14N54W TO 10N54W. ISOLATED SHOWERS ARE WITHIN 100 NM OF THE
TROUGH AXIS. ACROSS THE ERN ATLC...A COLD FRONT ENTERS THE
DISCUSSION AREA NEAR 32N32W TO 29N41W. ISOLATED SHOWERS ARE N OF
29N BETWEEN 30W-36W. A DYING STATIONARY FRONT IS AHEAD OF THE
COLD FRONT EXTENDING FROM 32N27W TO 27N33W. ISOLATED SHOWERS ARE
WITHIN 175 NM AHEAD OF THE FRONT. BOTH FRONTAL SYSTEMS ARE
SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING FROM THE LESSER
ANTILLES NEAR 16N62W NE TO NEAR 32N38W. A BROAD UPPER LEVEL
RIDGE COVERS THE REMAINDER OF THE ERN AND TROPICAL ATLC
ENHANCING CONVECTION ALONG THE ITCZ.

$$
WALTON





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