[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151734
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN NOV 15 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
1645 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 11N15W 7N25W 7N36W 6N42W 8N61W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-11N
BETWEEN 24W-40W MAINLY E OF A SURFACE TROUGH ANALYZED FROM
10N37W TO 6N38W. ISOLATED MODERATE CONVECTION IS FROM 12N-18N
BETWEEN 36W-42W SHEARED NE OF A SECOND SURFACE TROUGH ANALYZED
FROM 14N44W TO 7N49W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE RIDGE DOMINATES THE GULF OF MEXICO ANCHORED BY A 1018
MB HIGH IN THE N GULF NEAR 28N86W. THE RIDGE IS PROVIDING
GENERALLY FAIR WEATHER ACROSS THE BASIN. A LARGE AREA OF
STRATOCUMULUS CLOUDS LIE OVER THE N AND ERN PORTIONS OF THE
SURFACE RIDGE. HOWEVER...CLEAR SKIES ARE OVER FLORIDA AND THE NE
GULF STATES. LIGHT SFC WINDS FLOW ANTI-CYCLONICALLY AROUND THE
SURFACE RIDGE WITH STRONGER SLY RETURN FLOW  UP TO 20 KT ACROSS
THE WRN GULF. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE EXTENDS
OVER THE MAJORITY OF THE BASIN WITH AXIS EXTENDING FROM
NICARAGUA NEAR 12N85W UP THE THE YUCATAN PENINSULA AND ACROSS
THE ERN CONUS. STRONG SUBSIDENCE AND DRY AIR REMAINS ACROSS THE
BASIN NOTED IN WATER VAPOR IMAGERY. EXPECT THE SURFACE RIDGE TO
GRADUALLY DRIFT AND WEAKEN ALLOWING SLY RETURN FLOW TO INCREASE
ACROSS THE WRN GULF AHEAD OF THE NEXT COLD FRONT FORECAST TO
MOVE OFF THE TEXAS COAST MON AFTERNOON.

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
NICARAGUA NEAR 12N85W UP ACROSS THE GULF OF MEXICO AND ERN
CONUS. SCATTERED SHOWERS/THUNDERSTORMS ARE IN THE SW CARIBBEAN
AFFECTING PORTIONS OF COSTA RICA AND PANAMA S OF 11N BETWEEN
77W-85W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC ITCZ. AN
UPPER LEVEL TROUGH EXTENDS FROM THE ATLC ACROSS PUERTO RICO AND
INTO THE ERN CARIBBEAN TO NEAR 11N66W. UPPER LEVEL DIFFLUENCE
BETWEEN THIS UPPER TROUGH AND AN UPPER LEVEL RIDGE TO ITS E IS
SUPPORTING A FEW ISOLATED SHOWERS/THUNDERSTORMS ACROSS PUERTO
RICO AND THE LEEWARD ISLANDS N OF 16N BETWEEN 62W-68W. MODERATE
TRADE WINDS ARE ACROSS MUCH OF THE BASIN. EXPECT LITTLE CHANGE
DURING THE NEXT 24 HRS.

ATLANTIC OCEAN...
LOW PRESSURE IS ACROSS THE WRN ATLC CENTERED AT A 1005 MB LOW
NEAR 31N68W. A SURFACE TROUGH EXTENDS E OF THE LOW CENTER ALONG
34N67W 30N64W 25N64W 21N69W. SCATTERED SHOWERS/THUNDERSTORMS ARE
WITHIN 200 NM E OF THE TROUGH AXIS...WITH ISOLATED SHOWERS
WITHIN 400 NM E OF THE AXIS. THE SYSTEM IS SUPPORTED BY AN UPPER
LEVEL TROUGH CENTERED NEAR 32N67W WITH AXIS EXTENDING S ACROSS
THE LEEWARD ISLANDS INTO THE ERN CARIBBEAN. UPPER LEVEL
DIFFLUENCE AROUND THE E SIDE OF UPPER TROUGH IS ENHANCING THE
LARGE AREA OF SHOWER ACTIVITY E OF THE SURFACE TROUGH. THE UPPER
DIFFLUENT ZONE IS ALSO SUPPORTING AN AREA OF SCATTERED
SHOWERS/THUNDERSTORMS E OF THE LESSER ANTILLES FROM 12N-15N
BETWEEN 53W-59W. A WEAK 1013 MB LOW IS OVER THE ERN ATLC NEAR
29N28W. A COLD FRONT EXTENDS FROM THE LOW CENTER TO THE SW ALONG
25N35W 26N46W BECOMING STATIONARY TO THE NW ALONG 29N51W 32N54W.
A SECOND STATIONARY FRONT EXTENDS TO THE NE FROM THE LOW CENTER
TO 32N21W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 120 NM SE
OF THE LOW AND ADJACENT FRONTAL SYSTEMS BETWEEN 22W-33W.
ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO N OF 23N BETWEEN 53W-60W
NEAR THE STATIONARY FRONT THAT EXTENDS TO THE NW FROM THE COLD
FRONT. THIS FRONTAL SYSTEM IS SUPPORTED BY A LONGWAVE UPPER
LEVEL TROUGH EXTENDING FROM THE NE ATLC ACROSS THE AZORES TO
NEAR 22N34W. IN THE TROPICS...A SHORTWAVE UPPER TROUGH IS
SHEARING MOISTURE FROM THE ITCZ TO THE ENE SUPPORTING CLOUDS AND
POSSIBLE ISOLATED SHOWERS FROM 13N-21N BETWEEN 34W-42W.

$$
WALTON



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