[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 170531
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT OCT 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0415 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 75W S OF 16N MOVING W NEAR 15 KT. WAVE
COINCIDES WITH A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS
CURRENTLY ASSOCIATED WITH THE WAVE.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N13W 7N28W 8N43W 9N63W. THE
ITCZ IS ACTIVE EARLY THIS MORNING WITH SCATTERED MODERATE/STRONG
CONVECTION WITHIN 150 NM S OF THE AXIS BETWEEN 13W-20W...WITHIN
200 NM BOTH SIDES OF THE AXIS BETWEEN 20W-40W. A SURFACE TROUGH
IS EMBEDDED WITHIN THE ITCZ ALONG 46W FROM 7N-11N. SCATTERED
MODERATE/STRONG CONVECTION IS ALONG A LINE FROM 10N46W TO
12N37W. SIMILAR ACTIVITY IS WITHIN 150 NM BOTH SIDES OF THE AXIS
BETWEEN 47W-51W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 0300 UTC...A COLD EXTENDS FROM THE WRN ATLC ACROSS FLORIDA
ENTERING THE GULF OF MEXICO NEAR SARASOTA FLORIDA AT 27N83W
CONTINUING ALONG 25N89W TO N OF TAMPICO MEXICO NEAR 24N98W.
SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 100 NM OF THE FRONT.
AN UPPER LEVEL TROUGH OVER THE ERN CONUS EXTENDS OVER THE NRN
GULF N OF 25N SUPPORTING THE FRONT. AN UPPER LEVEL RIDGE
EXTENDING FROM MEXICO COVERS THE SW GULF. SURFACE WINDS OF 20 TO
25 KT ARE BEHIND THE FRONT. EXPECT THE FRONT TO CONTINUE MOVING
SE ACROSS THE GULF REACHING THE STRAITS OF FLORIDA BY LATE
TONIGHT AND INTO SUN. HIGH PRESSURE WILL BUILD IN THE WAKE OF
THE FRONT.

THE CARIBBEAN SEA...
MOST OF THE SHOWER ACTIVITY OVER THE CARIBBEAN HAS NOW
DISSIPATED LEAVING THE BASIN FAIRLY CALM. A FEW ISOLATED
SHOWERS/POSSIBLE THUNDERSTORMS REMAIN IN THE CENTRAL CARIBBEAN
FROM 14N-16N BETWEEN 70W-73W. RADAR IMAGERY FROM PUERTO RICO
INDICATES ISOLATED SHOWERS S OF THE ISLAND FROM 17N-18N BETWEEN
64W-66W. THIS ACTIVITY MAY BE ENHANCED BY A SURFACE TROUGH
ANALYZED IN THE ERN CARIBBEAN ALONG 63W/64W FROM 10N-16N. IN THE
UPPER LEVELS...AN UPPER LEVEL INVERTED TROUGH EXTENDS FROM
NICARAGUA NEAR 14N86W TO THE WINDWARD PASSAGE NEAR 20N74W
CONTINUING E TO NEAR 18N64W. AN UPPER LEVEL RIDGE COVERS THE
CENTRAL AND ERN CARIBBEAN CENTERED NEAR 12N67W. MODERATE TRADE
WINDS ARE ACROSS MUCH OF THE BASIN. EXPECT THE TROPICAL WAVE
ALONG 75W TO CONTINUE WWD ACROSS THE WRN CARIBBEAN.

THE ATLANTIC OCEAN...
AS OF 0300 UTC...A COLD FRONT ENTERS THE DISCUSSION AREA NEAR
32N77W EXTENDING SW TO NEAR DAYTONA FLORIDA CONTINUING INTO THE
GULF OF MEXICO. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 200
NM AHEAD OF THE FRONT. AN UPPER LEVEL TROUGH OVER THE ERN CONUS
EXTENDING OVER THE WRN ATLC SUPPORTS THE FRONTAL SYSTEM. THE
REMAINDER OF THE WRN ATLC IS DOMINATED BY A BROAD SURFACE RIDGE
SUPPORTED BY AN UPPER LEVEL HIGH CENTERED NEAR 25N60W. FARTHER
E...ANOTHER COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N36W
ALONG 27N40W 26N45W. ISOLATED SHOWERS ARE OUT AHEAD OF THE FRONT
N OF 25N BETWEEN 31W-36W. THE FRONT IS SUPPORTED BY AN UPPER
LEVEL TROUGH ALONG 35W. A WEAK 1014 MB SURFACE LOW IS NEAR
26N30W. A SURFACE TROUGH EXTENDS AROUND THE LOW ALONG 28N32W
29N27W 26N25W 22N28W 18N40W. ISOLATED SHOWERS ARE FROM 22N-30N
BETWEEN 23W-27W. THIS SYSTEM IS SUPPORTED BY ANOTHER UPPER LEVEL
TROUGH EXTENDING FROM AN UPPER LOW NEAR 35N21W TO 14N34W.
DIFFLUENCE ALOFT OVER THE TROPICAL ATLC IS SUPPORTING THE
SHOWERS/THUNDERSTORMS ALONG THE ITCZ AXIS.

$$
WALTON





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