[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 161742
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON NOV 16 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
1700 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 8N10W 6N26W 7N41W 6N46W 3N52W.
ISOLATED MODERATE/STRONG CONVECTION IS WITHIN 150 NM N OF THE
AXIS BETWEEN 14W-18W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 200 NM N OF THE AXIS BETWEEN 30W-40W. A
SURFACE TROUGH IS ANALYZED FROM 10N45W TO 5N43W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS E OF THE AXIS FROM 2N-7N
BETWEEN 40W-42W...AND SHEARED E ALONG A LINE FROM 10N44W TO
15N37W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 1500 UTC...A COLD FRONT HAS EMERGED OFF THE COAST OF TEXAS
OVER THE NW GULF OF MEXICO EXTENDING FROM A 1012 MB LOW CENTERED
OVER NRN ARKANSAS NEAR 36N91W TO THE TEXAS/LOUISIANA COAST NEAR
30N93W CONTINUING ALONG 28N95W TO THE TIP OF SRN TEXAS NEAR
26N97W AND INTO MEXICO. RADAR IMAGERY INDICATES A NARROW LINE OF
SHOWERS/THUNDERSTORMS ALONG THE FRONT AXIS. A CLUSTER OF
SHOWERS/THUNDERSTORMS ARE ALSO AHEAD OF THE FRONT NEAR
28N93W...AND A FEW CLUSTERS FROM 24N-26N BETWEEN 95W-98W. THE
FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH OVER THE CENTRAL
CONUS EXTENDING OVER NRN MEXICO AND THE FAR NW GULF OF MEXICO.
A SURFACE RIDGE DOMINATES THE ERN GULF OF MEXICO ANCHORED BY A
1019 MB HIGH NEAR 28N87W. THE RIDGE IS PROVIDING GENERALLY FAIR
WEATHER ACROSS THE REMAINDER OF THE BASIN. AN AREA OF
STRATOCUMULUS CLOUDS LIE OVER ERN PORTIONS OF THE SURFACE RIDGE
OFF THE W FLORIDA COASTLINE. LIGHT SFC WINDS FLOW
ANTI-CYCLONICALLY AROUND THE SURFACE RIDGE WITH STRONGER WINDS
ACROSS THE WRN GULF AHEAD OF THE COLD FRONT. AN UPPER LEVEL
RIDGE EXTENDS OVER THE MAJORITY OF THE BASIN WITH AXIS EXTENDING
FROM S OF MEXICO ACROSS THE CENTRAL GULF AND FLORIDA TO THE W
ATLC.  STRONG SUBSIDENCE AND DRY AIR REMAINS OVER THE ERN BASIN
NOTED IN WATER VAPOR IMAGERY. EXPECT THE SURFACE RIDGE TO WEAKEN
AS THE COLD FRONT CONTINUES PUSHING SE ACROSS THE BASIN. AS THE
FRONT REACHES THE BAY OF CAMPECHE TUE...GALE FORCE WINDS ARE
EXPECTED S OF 21N W OF 95W.

CARIBBEAN SEA...
MUCH OF THE CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER
UNDER THE INFLUENCE OF DRY AIR AND SUBSIDENCE ASSOCIATED WITH AN
UPPER LEVEL RIDGE COVERING THE WRN CARIBBEAN EXTENDING FROM THE
E PACIFIC NEAR 12N95W UP ACROSS THE GULF OF MEXICO AND NW
CARIBBEAN INTO THE WRN ATLC. SCATTERED SHOWERS/THUNDERSTORMS ARE
IN THE SW CARIBBEAN AFFECTING PORTIONS OF PANAMA S OF 10N
BETWEEN 76W-82W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC
ITCZ. AN AREA OF STRONG SHOWERS/THUNDERSTORMS ARE ACROSS PUERTO
RICO AND THE NW LEEWARD ISLANDS N OF 16N BETWEEN 61W-67W
ASSOCIATED WITH SURFACE CONVERGENCE NEAR A SURFACE TROUGH
EXTENDING FROM THE ATLC ACROSS CENTRAL PUERTO RICO TO NEAR
17N68W. AN UPPER LEVEL TROUGH EXTENDING FROM THE ATLC ACROSS
PUERTO RICO AND INTO THE ERN CARIBBEAN TO NEAR 9N70W SUPPORTS
THE SURFACE TROUGH. UPPER LEVEL DIFFLUENCE BETWEEN THIS UPPER
TROUGH AND AN UPPER LEVEL RIDGE TO ITS E IS ENHANCING THE LARGE
AREA OF STRONG SHOWER ACTIVITY. MODERATE TRADE WINDS ARE ACROSS
MUCH OF THE BASIN. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE OVER
THE NE CARIBBEAN AS THE SURFACE TROUGH REMAINS MAINLY
STATIONARY.

ATLANTIC OCEAN...
LOW PRESSURE IS ACROSS THE WRN ATLC CENTERED AT A 1008 MB LOW
NEAR 30N67W. A PAIR OF SURFACE TROUGHS EXTEND E OF THE LOW
CENTER. THE FIRST IS ALONG 28N65W 24N67W TO THE SE BAHAMAS NEAR
22N73W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE E OF THE
AXIS N OF 23N BETWEEN 61W-66W. THE SECOND SURFACE TROUGH EXTENDS
ALONG 31N61W 24N62W 20N64W ACROSS PUERTO RICO TO NEAR 17N68W. AN
AREA OF STRONG SHOWERS/THUNDERSTORMS ARE E OF THE SRN PORTION OF
THE TROUGH FROM 16N-21N BETWEEN 59W-66W AFFECTING PUERTO RICO
AND THE NW LEEWARD ISLANDS. ISOLATED SHOWERS/THUNDERSTORMS ARE N
OF 21N WITHIN 250 NM E OF THE TROUGH AXIS. THIS SYSTEM IS
SUPPORTED BY AN UPPER LEVEL TROUGH CENTERED NEAR 28N66W. UPPER
LEVEL DIFFLUENCE BETWEEN THIS UPPER TROUGH AND AN UPPER LEVEL
RIDGE TO THE E WITH AXIS ALONG 48W IS SUPPORTING THE LARGE AREA
OF SHOWER ACTIVITY. ACROSS THE ERN ATLC...A BROAD SURFACE RIDGE
EXTENDS FROM A 1031 MB HIGH NEAR 35N41W. A COLD FRONT PROTRUDES
INTO THE RIDGE ENTERING THE DISCUSSION AREA NEAR 32N16W
CONTINUING SW ALONG 25N22W 21N34W 22N41W EXTENDING NW AS A
STATIONARY FRONT ALONG 26N48W 32N53W OUT OF THE DISCUSSION AREA.
ISOLATED SHOWERS ARE WITHIN 150 NM E AND SE AHEAD OF THE COLD
FRONT BETWEEN 14W-34W. ISOLATED SHOWERS ARE WITHIN 100 NM SW
AND W OF THE STATIONARY FRONT BETWEEN 45W-54W. A LONGWAVE UPPER
LEVEL TROUGH EXTENDING FROM THE NE ATLC ALONG 20W N OF 30N
CONTINUING TO NEAR 20N32W SUPPORTS THE FRONTAL SYSTEM. A
SHORTWAVE TROUGH EXTENDS FROM THE BASE OF THE LONGWAVE TO NEAR
8N44W. UPPER LEVEL DIFFLUENCE AND STRONG SHEAR TO THE NE BETWEEN
THIS SHORTWAVE TROUGH AND AN UPPER LEVEL RIDGE TO THE E OVER THE
TROPICAL ATLC SUPPORTS SHOWER ACTIVITY NEAR THE ITCZ.

$$
WALTON






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