[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031041
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 03 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 28W S OF 13N MOVING W NEAR 15 KT. THE
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. REMAINING MOSTLY EMBEDDED
WITHIN THE ITCZ...LOW TO MID-LEVEL CYCLONIC FLOW IS INDICATED IN
SATELLITE IMAGERY...SATELLITE DERIVED WINDS...AND CIMSS WAVETRAK
MODEL GUIDANCE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 5N-12N BETWEEN 25W-30W.

TROPICAL WAVE IS ALONG 47W S OF 15N MOVING W NEAR 18 KT. THE
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY AS WELL AS A LOW-LEVEL RELATIVE
VORTICITY MAXIMUM AS DEPICTED IN CIMSS WAVETRAK MODEL GUIDANCE.
THIS MID-LEVEL LIFTING MECHANISM IS GENERATING SCATTERED
MODERATE CONVECTION FROM 9N-13N BETWEEN 44W-48W.

TROPICAL WAVE IS ALONG 68W S OF 19N MOVING W NEAR 15 KT. WEAK
CYCLONIC CURVATURE IS NOTED IN THE LOW-LEVEL CLOUD FIELD ACROSS
THE ERN CARIBBEAN AND AN 850 MB RELATIVE VORTICITY MAXIMUM IS
ALSO NOTED IN THE CIMSS WAVETRAK MODEL GUIDANCE IN THE AREA
SURROUNDING THE MONA PASSAGE FROM 15N-20N BETWEEN 67W-70W...VERY
NEAR THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS N OF THE
MONA PASSAGE FROM 18N-22N BETWEEN 66W-71W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 13N16W 11N27W 9N30W 7N45W 7N49W
7N59W. WIDELY SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 5N-12N BETWEEN 30W-38W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0900 UTC...A COLD FRONT EXTENDS ACROSS THE FLORIDA
PANHANDLE INTO THE NE GULF NEAR 29N90W AND CONTINUES WSW ALONG
28N95W TO THE TEXAS COAST NEAR CORPUS CHRISTI. THE BOUNDARY IS
SUPPORTED BY AN UPPER LEVEL TROUGH OVER THE SE CONUS AND NE GULF
REMAINING N OF 29N. A FEW POSSIBLE ISOLATED SHOWERS ARE WITHIN
60 NM OF THE FRONT AS MOSTLY STABLE NWLY UPPER LEVEL FLOW
DOMINATES ACROSS THE GULF ON ANTICYCLONIC FLOW ANCHORED BY AN
UPPER LEVEL HIGH CENTERED OVER CENTRAL MEXICO NEAR 20N101W. S OF
THE FRONTAL BOUNDARY...LIGHT SELY SURFACE WINDS ARE FORECAST TO
INCREASE GRADUALLY THROUGH THE WEEKEND AS THE NEXT LOW PRESSURE
SYSTEM DEVELOPS OVER THE SRN U.S. PLAINS BY EARLY SUNDAY.

CARIBBEAN SEA...
THE NW CARIBBEAN IS RATHER TRANQUIL AND CALM THIS MORNING UNDER
THE INFLUENCE OF DRY AIR AND SUBSIDENCE ALOFT DUE TO NLY WINDS
ON THE ERN PERIPHERY OF AN UPPER LEVEL HIGH ANCHORED OVER
CENTRAL MEXICO. AN UPPER LEVEL TROUGH EXTENDS ACROSS ERN CUBA
AND JAMAICA WITH AXIS ALONG 75W. UPPER LEVEL DIFFLUENCE E OF 75W
IS GENERATING ISOLATED SHOWERS AND TSTMS BETWEEN 70W-80W. ACROSS
THE ERN CARIBBEAN...FRESH SE TRADES ON THE ERN SIDE OF THE
TROPICAL WAVE ALONG 68W AS WELL AS AN UPPER LEVEL DIFFLUENT
PATTERN ALOFT ARE GENERATING SCATTERED SHOWERS AND ISOLATED
TSTMS NE OF A LINE FROM TRINIDAD THROUGH 15N68W TO S/CENTRAL
HISPANIOLA NEAR 19N71W. AN UPPER LEVEL DIFFLUENT ENVIRONMENT IS
ALSO ACROSS PORTIONS OF THE SW CARIBBEAN...NRN COLOMBIA AND NW
VENEZUELA. SCATTERED SHOWERS AND TSTMS ARE OVER THE SW CARIBBEAN
WATERS S OF 12N BETWEEN 69W-79W. MODERATE TO FRESH TRADE WINDS
ARE ACROSS MUCH OF THE BASIN E OF 80W...WITH STRONGER WINDS
LOCATED IN THE S/CENTRAL PORTION OF THE BASIN.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS ACROSS THE SE CONUS AND IS GENERATING A
LARGE AREA OF UPPER LEVEL DIFFLUENCE OVER THE W ATLC WATERS N OF
22N W OF 72W. THIS UPPER LEVEL DIFFLUENCE ALONG WITH A SURFACE
TROUGH THAT EXTENDS FROM 30N79W TO BISCAYNE BAY IS PRODUCING
ISOLATED SHOWERS N OF 23N W OF 78W. FARTHER TO THE E...ANOTHER
AREA OF UPPER LEVEL DIFFLUENCE IS LOCATED BETWEEN AN UPPER LEVEL
TROUGH ACROSS ERN CUBA AND AN UPPER LEVEL RIDGE EXTENDING FROM
PUERTO RICO N TO 30N65W. SCATTERED SHOWERS AND ISOLATED TSTMS
COVER THE AREA FROM 22N-31N BETWEEN 67W-76W. A LARGE UPPER LEVEL
LOW IS LOCATED N OF THE DISCUSSION AREA NEAR 40N30W AND EXTENDS
AN UPPER LEVEL TROUGH AXIS ALONG 32N30W TO 19N48W. THIS UPPER
LEVEL TROUGHING SUPPORTS A SURFACE TROUGH LOCATED ALONG 28N
BETWEEN 27W-52W. SCATTERED SHOWERS AND TSTMS ARE WITHIN 150 NM
EITHER SIDE OF THE SURFACE TROUGH. FARTHER SW...A SURFACE TROUGH
EXTENDS FROM 21N52W THROUGH A 1013 MB LOW CENTERED NEAR 17N54W
TO 14N55W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE FROM 14N-18N
BETWEEN 52W-58W. THE REMAINDER OF THE ERN ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A PAIR OF SURFACE
HIGHS...ONE A 1018 MB HIGH CENTERED NEAR 22N37W AND THE OTHER A
1020 MB HIGH CENTERED NEAR 26N21W. IN THE UPPER LEVELS ACROSS
THE ERN ATLC...AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS
CENTERED SW OF THE CAPE VERDE ISLANDS NEAR 13N28W AND IS
PROVIDING AN UPPER LEVEL DIFFLUENT ENVIRONMENT FOR THE
CONVECTION ASSOCIATED WITH THE TROPICAL WAVES AND ITCZ E OF 50W.

$$
HUFFMAN





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