[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271732
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE OCT 27 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.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 25W S OF 15N MOVING W NEAR 10 KT. VISIBLE
SATELLITE IMAGERY INDICATES GOOD LOW-LEVEL CYCLONIC FLOW NEAR
THE WAVE AXIS CONCENTRATED NEAR 12N. THE WAVE ALSO COINCIDES
WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED STRONG CONVECTION IS FROM
14N-15N BETWEEN 18W-22W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 12N-17N BETWEEN 22W-28W.

TROPICAL WAVE IS ALONG 44W/45W S OF 16N MOVING W NEAR 15 KT.
SATELLITE IMAGERY AS WELL AS A 1304 UTC ASCAT SCATTEROMETER PASS
INDICATE BROAD LOW-LEVEL CYCLONIC FLOW AROUND THE VICINITY OF
THE WAVE AXIS. THE WAVE ALSO COINCIDES WITH A SURGE IN DEEP
LAYER MOISTURE OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. NO
DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE.

TROPICAL WAVE IS ALONG 60W S OF 16N MOVING W NEAR 15 KT. THE
WAVE LEADS A MAXIMUM IN DEEP LAYER MOISTURE OBSERVED IN TOTAL
PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION IS FROM
14N-18N BETWEEN 57W-62W. THIS ACTIVITY MAY BE MORE ASSOCIATED
WITH UPPER DIFFLUENT FLOW ALOFT.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 9N13W 9N23W 8N35W 10N47W 9N53W
11N58W. ISOLATED/MODERATE CONVECTION IS ALONG THE AXIS NEAR
12W...AND BETWEEN 15W-23W.

...DISCUSSION...

THE GULF OF MEXICO...
A COLD FRONT EXTENDS ACROSS THE WRN GULF OF MEXICO FROM WRN
LOUISIANA NEAR 29N91W ALONG 24N93W 19N96W INTO MEXICO TO 22N99W.
ISOLATED SHOWERS ARE WITHIN 250 NM NW OF THE FRONT...AND WITHIN
100 NM SE OF THE FRONT. SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO
AHEAD OF THE FRONT IN THE BAY OF CAMPECHE FROM 19N-21N BETWEEN
92W-94W. A 1008 MB LOW IS NEAR THE LOUISIANA/MISSISSIPPI BORDER
AT 30N89W. A STATIONARY FRONT EXTENDS NW FROM THE LOW CONNECTING
WITH THE AFOREMENTIONED COLD FRONT. A WARM FRONT EXTENDS E FROM
THE LOW ALONG 30N86W TO 31N81W. SCATTERED SHOWERS/THUNDERSTORMS
ARE FROM 22N-31N BETWEEN 83W-87W. THE FRONTAL SYSTEM IS
SUPPORTED BY MOIST SWLY FLOW ALOFT AROUND THE BASE OF AN
UPPER LEVEL TROUGH WITH AXIS ACROSS THE MIDWEST UNITED
STATES...TEXAS AND INTO MEXICO. THE FAR SE GULF IS COVERED BY A
NARROW UPPER LEVEL RIDGE EXTENDING FROM THE YUCATAN PENINSULA
ACROSS S FLORIDA AND INTO THE WRN ATLC. EXPECT SHOWERS/POSSIBLE
THUNDERSTORMS TO CONTINUE ACROSS MUCH OF THE GULF AS THE COLD
FRONT CONTINUES TO MOVE SE ACROSS THE BASIN.

THE CARIBBEAN SEA...
THE MAJORITY OF THE CARIBBEAN SEA IS EXPERIENCING GENERALLY FAIR
WEATHER THIS AFTERNOON. A FEW ISOLATED SHOWERS ARE IN THE NW
BASIN FROM 18N-22N BETWEEN 82W-84W. THE SHOWERS ARE SUPPORTED BY
DIFFLUENT FLOW ALOFT BETWEEN AN UPPER LEVEL RIDGE EXTENDING FROM
THE YUCATAN PENINSULA ACROSS THE SE GULF AND INTO THE WRN ATLC
AND AN UPPER LEVEL TROUGH COVERING THE REMAINDER OF THE BASIN
CENTERED S OF PUERTO RICO NEAR 17N68W. THE UPPER LEVEL LOW IS
ALSO SUPPORTING A FEW ISOLATED SHOWERS/THUNDERSTORMS FROM
16N-18N BETWEEN 65W-71W. SCATTERED SHOWERS/THUNDERSTORMS ARE IN
THE FAR SW CARIBBEAN S OF 11N BETWEEN 76W-83W DUE TO SURFACE
CONVERGENCE NEAR A 1007 MB LOW OVER COLOMBIA NEAR 8N76W...AND
THE CLOSE PROXIMITY OF THE E PACIFIC ITCZ. SHOWERS ASSOCIATED
WITH A TROPICAL WAVE E OF THE LESSER ANTILLES ALONG 60W HAVE
BEGUN TO AFFECT THE ISLANDS E OF 62W. MODERATE TO FRESH
TRADEWINDS ARE ACROSS THE MAJORITY OF THE BASIN.

THE ATLANTIC OCEAN...
A STATIONARY FRONT ENTERS THE FAR WRN PORTION OF THE DISCUSSION
AREA NEAR 32N77W TO 31N80W BECOMING WARM ACROSS NRN FLORIDA AND
THE NRN GULF COAST. ISOLATED SHOWERS ARE N OF 27N W OF 75W. THE
FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH OVER MUCH OF THE ERN
CONUS...GULF OF MEXICO...AND INTO THE FAR WRN ATLC. AN UPPER
LEVEL RIDGE IS TO THE E EXTENDING FROM THE YUCATAN PENINSULA
ACROSS S FLORIDA CONTINUING TO THE NE. THE UPPER RIDGE SUPPORTS
A BROAD SURFACE RIDGE COVERING THE MAJORITY OF THE BASIN
ANCHORED BY A 1023 MB HIGH NEAR 30N66W. A LINE OF SHOWERS EXTEND
FROM 23N57W TO 23N66W IN ASSOCIATION WITH DIFFLUENT FLOW ALOFT
BETWEEN THE AFOREMENTIONED UPPER RIDGE AND AN UPPER LEVEL LOW S
OF PUERTO RICO NEAR 17N68W. FARTHER E...A DYING COLD FRONT
EXTENDS FROM 31N20W TO 24N26W. ISOLATED SHOWERS ARE POSSIBLE
WITHIN 150 NM AHEAD OF THE FRONT. A SHORTWAVE UPPER LEVEL TROUGH
WITH AXIS ALONG 22W SUPPORTS THE FRONT.

$$
WALTON





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