[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081151
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU OCT 08 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
0945 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION HENRI IS CENTERED NEAR 19.9N 61.3W AT
08/0900 UTC...OR ABOUT 145 NM NE OF THE NRN LEEWARD ISLANDS
MOVING WNW AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009
MB. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT.
FURTHER WEAKENING IS EXPECTED AND HENRI IS LIKELY TO BECOME A
REMNANT LOW WITHIN THE NEXT 24 HRS. SCATTERED STRONG CONVECTION
IS FROM 17N-23N BETWEEN 56W-61W. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC
FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 54W S OF 14N MOVING W NEAR 20 KT.
SATELLITE IMAGERY INDICATES LOW-LEVEL CYCLONIC FLOW AROUND THE
WAVE AXIS. THE WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE
MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 9N-15N BETWEEN
52W-57W.

TROPICAL WAVE IS ALONG 74W S OF 17N MOVING W NEAR 20 KT. THE
WAVE LIES IN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. DRY AIR AND SUBSIDENCE ALOFT
ARE CONFINING DEEP CONVECTION TO INLAND OVER COLOMBIA.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 8N-10N
BETWEEN 73W-76W. A CLUSTER OF SHOWERS/THUNDERSTORMS ARE ALSO S
OF HAITI NEAR 18N74W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 14N17W 10N24W 6N33W 9N52W 7N61W.
ISOLATED MODERATE CONVECTION IS WITHIN 150 NM S OF THE AXIS
BETWEEN 22W-30W. SCATTERED STRONG CONVECTION IS FROM 5N-8N
BETWEEN 31W-36W. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM N
OF THE AXIS BETWEEN 36W-51W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF OF MEXICO REMAINS CALM AND CLEAR UNDER THE INFLUENCE OF
A 1019 MB SURFACE HIGH CENTERED NEAR 28N85W. AN UPPER LEVEL
RIDGE COVERS THE BASIN CENTERED S OF LOUISIANA NEAR 28N90W
PROVIDING DRY AIR AND SUBSIDENCE ALOFT SUPPORTING THE FAIR
WEATHER. ANTI-CYCLONIC SURFACE WINDS ARE AROUND THE SURFACE
RIDGE REACHING 15 KT IN THE ERN AND MIDDLE GULF...20 KT IN THE
SW GULF...AND UP TO 25 KT IN THE NW GULF. THE RIDGE SUPPORTED
RECORD HIGHS OVER PORTIONS OF SOUTH FLORIDA YESTERDAY AND RECORD
HIGHS ARE EXPECTED TODAY AS WELL. THE RIDGE IS FORECAST TO
PERSIST OVER THE NEXT 24 HRS...THEN MOVE EAST AS A COLD FRONT
MOVES OFF THE TEXAS COAST FRI.

CARIBBEAN SEA...
MOST OF THE CARIBBEAN IS UNDER DRY SUBSIDENT AIR SUPPORTING
GENERALLY FAIR WEATHER THROUGHOUT EXCEPT FOR A CLUSTER OF
SHOWERS/THUNDERSTORMS OFF THE COAST OF CUBA FROM 19N-22N BETWEEN
81W-83W. AN UPPER RIDGE CENTERED OVER THE GULF OF MEXICO EXTENDS
OVER MUCH OF THE NW CARIBBEAN. AN UPPER LEVEL LOW S OF CENTRAL
AMERICA NEAR 12N87W IS SUPPORTING A FEW ISOLATED SHOWERS/
THUNDERSTORMS OVER THE SW CARIBBEAN S OF 10N W OF 77W. A
TROPICAL WAVE IS ALONG 74W SUPPORTING A CLUSTER OF SHOWERS/
THUNDERSTORMS S OF HAITI NEAR 18N74W. HOWEVER...DUE TO THE DRY
AIR AND SUBSIDENCE ALOFT NO OTHER SHOWERS/THUNDERSTORMS ARE
ASSOCIATED WITH THE WAVE EXCEPT INLAND OVER COLOMBIA. SEE ABOVE.
AN UPPER LEVEL TROUGH IS OVER THE ERN CARIBBEAN EXTENDING FROM
NEAR 13N70W ACROSS THE MONA PASSAGE INTO THE ATLC. MOIST SWLY
FLOW AROUND THE BASE OF THE UPPER TROUGH IS SUPPORTING A CLUSTER
OF SHOWERS/THUNDERSTORMS FROM 12N-13N BETWEEN 68W-70W. FRESH TO
STRONG TRADE WINDS ARE ACROSS MUCH OF THE BASIN. EXPECT THE WAVE
ALONG 74W TO CONTINUE WWD.

ATLANTIC OCEAN...
TROPICAL DEPRESSION HENRI REMAINS THE BIGGEST WEATHER MAKER OVER
THE ATLANTIC. SEE SPECIAL FEATURES ABOVE. ELSEWHERE ACROSS THE
ATLC...A BROAD SURFACE RIDGE DOMINATES ANCHORED BY A PAIR OF
1022 MB HIGHS CENTERED NEAR 25N43W AND 30N31W. IN THE UPPER
LEVELS...AN UPPER LEVEL RIDGE ALONG WITH DRY AIR AND SUBSIDENCE
ALOFT COVER THE SWRN ATLC W OF 60W. A NARROW UPPER LEVEL TROUGH
EXTENDS FROM THE ERN CARIBBEAN ACROSS THE MONA PASSAGE TO NEAR
30N41W. STRONG SWLY WINDS ALOFT BETWEEN THIS UPPER TROUGH AND AN
UPPER LEVEL RIDGE OVER THE TROPICAL ATLC CENTERED NEAR 15N49W
ARE SHEARING HENRI AND SUPPORTING A SWATH OF HIGH CLOUDS AND
POSSIBLE ISOLATED SHOWERS FROM 20N-25N BETWEEN 44W-55W...AND N
OF 26N BETWEEN 35W-41W. AN UPPER LEVEL TROUGH DIGS INTO THE ERN
ATLC WITH AXIS ALONG 30W.

$$
WALTON



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