[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 092342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 09 2011

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

A 1007 MB SURFACE LOW IS CENTERED OFF THE EASTERN FLORIDA
PENINSULA NEAR 27N79W WITH A SURFACE TROUGH AXIS EXTENDING S-SW
ALONG 25N80W TO WESTERN CUBA NEAR 23N83W AND INTO THE NW
CARIBBEAN SEA NEAR 20N85W. THIS DEVELOPING AREA OF LOW PRESSURE
IS SUPPORTED ALOFT BY AN UPPER LEVEL LOW CENTERED IN THE EASTERN
GULF OF MEXICO NEAR 26N83W WHICH HAS BEEN SLOW TO PROGRESS
NORTHWARD OVER THE PAST 24-36 HOURS. LOW-LEVEL MOISTURE
CONVERGENCE EXTENDS FROM THE CENTRAL CARIBBEAN SEA NORTHWARD
ACROSS A LARGE PORTION OF THE SW NORTH ATLC AND IS GENERATING A
BROAD AREA OF SCATTERED TO NUMEROUS MODERATE AND WIDELY
SCATTERED STRONG CONVECTION OVER THE CENTRAL CARIBBEAN SEA FROM
12N-21N BETWEEN 69W-78W...AND AREAS OF SCATTERED MODERATE
CONVECTION ACROSS THE SW NORTH ATLC FROM 21N-33N BETWEEN
69W-82W. MOST OF THIS CONVECTION IS LIKELY CONTINUING TO BE
ENHANCED BY STRONG MIDDLE TO UPPER LEVEL DIFFLUENCE TO THE EAST
OF THE UPPER LEVEL TROUGH AXIS E OF A LINE FROM 26N83W TO
15N79W. ENERGY WITH THIS SYSTEM IS EXPECTED TO SLOWLY LIFT
NORTHWARD WITH THE LOW LIFTING NORTH-NORTHWESTWARD ACROSS THE NE
GULF OF MEXICO NEAR 28N84W BY LATE MONDAY. REGARDLESS OF
DEVELOPMENT...STRONG WINDS...PRIMARILY NORTH OF THE LOW
CENTER...AND HEAVY RAINFALL IS EXPECTED TO CONTINUE ACROSS MUCH
OF THE BAHAMAS...SOUTHEASTERN U.S...AND ADJACENT COASTAL WATERS
THROUGH MONDAY.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 10N59W TO 18N54W MOVING W AT
15-20 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOWS A POLEWARD
EXTENSION OF LOW-LEVEL MOISTURE IN THE VICINITY OF THE WAVE AXIS
BETWEEN 50W-59W. NO SIGNIFICANT DEEP CONVECTION IS NOTED WITH
THE WAVE AT THIS TIME.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO
07N20W TO 07N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 07N26W TO 07N30W TO 06N38W TO 06N47W. ISOLATED
MODERATE CONVECTION IS FROM 04N-07N BETWEEN 22W-29W. SCATTERED
MODERATE CONVECTION IS FROM 07N-12N BETWEEN 41W-54W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS CENTERED OVER THE EASTERN GULF NEAR 26N83W
WHICH EXTENDS A TROUGH AXIS SOUTHWARD OVER WESTERN CUBA AND INTO
THE SOUTH-CENTRAL CARIBBEAN SEA. WHILE MOST OF THE ACTIVE
WEATHER AND CONVECTION IS EAST OF THE UPPER LEVEL TROUGH
AXIS...THE MIDDLE TO UPPER LEVEL LOW IS GENERATING A FEW
ISOLATED SHOWERS AND TSTMS ACROSS THE EASTERN GULF WATERS N OF
25N E OF 87W. FARTHER WEST...A WEAK SURFACE RIDGE AXIS EXTENDS
FROM THE SE CONUS NEAR 29N91W TO EAST-CENTRAL MEXICO NEAR
21N98W. MOIST AND UNSTABLE SOUTHEASTERLY RETURN FLOW IS NOTED
ACROSS PORTIONS OF THE NW GULF THIS EVENING WITH SCATTERED
SHOWERS AND TSTMS ASSOCIATED WITH AN OUTFLOW BOUNDARY EXTENDING
FROM GALVESTON BAY NEAR 30N95W TO NEAR BROWNSVILLE
TEXAS...REMAINING N OF 25N W OF 93W. OVER THE NEXT FEW DAYS AS
THE SPECIAL FEATURES LOW CONTINUES TO DEVELOP AND DRIFT
NORTHWARD...GLOBAL MODEL GUIDANCE IS INDICATING A SECONDARY
SURFACE LOW DEVELOPING ACROSS THE NE GULF WATERS BY LATE MONDAY.
BETWEEN NOW AND LATE MONDAY...NE WINDS ACROSS THE NE GULF ARE
EXPECTED TO REMAIN STRONG TO NEAR GALE FORCE N OF 27N E OF 90W.

CARIBBEAN SEA...
THE UPPER LEVEL LOW AND ASSOCIATED TROUGH AXIS OVER THE EASTERN
GULF OF MEXICO EXTENDS TO A BASE OVER THE SOUTH-CENTRAL
CARIBBEAN. THIS UPPER LEVEL TROUGH IS SUPPORTING A WEAK SURFACE
TROUGH EXTENDING FROM WESTERN CUBA NEAR 23N83W TO 20N85W.
FURTHER LOW-LEVEL STREAMLINE ANALYSIS SHOWS SURFACE TROUGHING
EXTENDS OVER MUCH OF THE WESTERN CARIBBEAN WITH A POSSIBLE
SURFACE TROUGH AXIS EXTENDING FROM NORTHERN COLOMBIA NEAR 11N74W
TO 16N78W. WITH UPPER LEVEL DIFFLUENCE MAXIMIZED EAST OF THE
UPPER LEVEL TROUGH AXIS...NUMEROUS SHOWERS AND TSTMS ARE
OCCURRING OVER THE CARIBBEAN WATERS BETWEEN 69W-78W. ACROSS THE
FAR EASTERN CARIBBEAN...AN UPPER LEVEL RIDGE AXIS EXTENDS ALONG
70W...WITH WATER VAPOR IMAGERY INDICATING DRY AIR E OF 65W WHICH
IS MAINTAINING MOSTLY CLEAR SKIES AND FAIR WEATHER CONDITIONS
THIS EVENING.

ATLANTIC OCEAN...
AN UPPER LEVEL LOW AND ASSOCIATED TROUGH OVER THE EASTERN GULF
OF MEXICO IS PROVIDING FOR A LARGE AREA OF DIFFLUENT FLOW ALOFT
ACROSS THE SW NORTH ATLC THIS EVENING. THIS IS HELPING SUPPORT A
1007 MB LOW CENTERED NEAR 27N79W WHICH IS QUITE EVIDENT ON
MELBOURNE FLORIDA DOPPLER RADAR IMAGERY AT THIS TIME. SCATTERED
SHOWERS AND TSTMS ARE OCCURRING FROM THE CENTRAL CARIBBEAN SEA
WATERS ACROSS THE WINDWARD PASSAGE REGION STRETCHING TO BEYOND
32N AND REMAINING W OF 69W. FARTHER EAST...AN UPPER LEVEL TROUGH
CONTINUES TO SWING SOUTHEASTWARD ACROSS THE NORTHERN CENTRAL
ATLC IN SUPPORT OF A COLD FRONT ANALYZED INTO THE DISCUSSION
AREA NEAR 32N38W. THE COLD FRONT CONTINUES SW ALONG 26N45W TO
24N53W WHERE IT BECOMES STATIONARY TO 23N62W. SCATTERED SHOWERS
AND ISOLATED TSTMS ARE WITHIN 180 NM EITHER SIDE OF THE FRONT.
THE REMAINDER OF THE EASTERN ATLC IS DOMINATED BY A SURFACE
RIDGE ANCHORED BY A 1032 MB HIGH CENTERED NW OF THE IBERIAN
PENINSULA NEAR 45N15W. THE SURFACE RIDGE AXIS EXTENDS FROM THE
HIGH ACROSS THE AZORES TO 27N34W. ALSO OF NOTE...A 1008 MB LOW
IS CENTERED OFF THE AFRICAN COAST NEAR 19N21W. AN EARLIER
MORNING ASCAT PASS AROUND 09/1046 UTC INDICATED STRONG N-NE
WINDS TO 25 KT FROM 20N-24N E OF 25W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN




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