[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091158
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON NOV 09 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
1045 UTC.

...SPECIAL FEATURES...

HURRICANE IDA IS CENTERED NEAR 25.8N 88.2W AT 09/1200 UTC OR
ABOUT 205 NM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER AND ABOUT
285 NM SSW OF PENSACOLA FLORIDA MOVING NNW AT 14 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE BASED ON DATA FROM THE HURRICANE HUNTER
AIRCRAFT IS 993 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH
GUSTS TO 85 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION COVERS THE AREA FROM 26N-29N
BETWEEN 84W-87W AND FROM 24N-28N BETWEEN 87W-89W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 55W S OF 16N MOVING W NEAR 20 KT. WAVE
POSITION IS BASED ON CONTINUITY AND IS MOVING BENEATH A NARROW
UPPER RIDGE. NO SIGNIFICANT DEEP CONVECTION ACCOMPANIES THE WAVE.

TROPICAL WAVE IS ALONG 70W S OF 17N MOVING W NEAR 15 KT. WAVE
WAVE POSITION IS BASED ON CONTINUITY AND CONTINUES TO BE
ILL-DEFINED AND DIFFICULT TO TRACK AS IT MOVES WESTWARD BENEATH
DRY AND STABLE AIR. NO SIGNIFICANT DEEP CONVECTION ACCOMPANIES
THE WAVE.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 7N27W 7N42W 9N52W 10N62W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM
ALONG THE COAST OF W AFRICA FROM 7N-10N AND WITHIN 75/90 NM OF
LINE FROM 6N40W TO12N38W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE WITHIN 120 NM OF LINE FROM 5N15W TO 3N30W AND
WITHIN 60 NM OF 8N FROM 27W-33W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE IDA REMAINS THE PRIMARY CONCERN THIS MORNING FOR THE
GULF OF MEXICO BUT IS BEGINNING TO LOSE ITS DEEP CONVECTION...
SEE SPECIAL FEATURES ABOVE. CONVECTION ASSOCIATED WITH IDA
REMAINS ENHANCED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER
LEVEL RIDGE EXTENDING FROM THE WESTERN CARIBBEAN NORTHWARD
ACROSS CUBA JUST W OF THE FLORIDA PENINSULA GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S OF 26N E OF 86W TO OVER FLORIDA
AND INTO THE STRAITS OF FLORIDA. AN UPPER LEVEL TROUGH IN THE W
GULF EXTENDS FROM TEXAS NEAR 29N96W TO THE E BAY OF CAMPECHE
NEAR 19N91W AND SUPPORTS A SURFACE TROUGH THAT EXTENDS FROM
26N95W ALONG 21N93W TO THE E BAY OF CAMPECHE NEAR 19N91W. WIND
SHIFT REMAINS MAINLY ASSOCIATED WITH THE SURFACE TROUGH AXIS.
HOWEVER...UPPER LEVEL DIFFLUENCE N OF 24N W OF 90W IS GENERATING
CLUSTERS OF SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS OVER THAT
AREA TO INLAND OVER LOUISIANA. THE TIGHT PRESSURE GRADIENT
REMAINS BETWEEN HURRICANE IDA AND THE SURFACE RIDGE OVER THE W
ATLC/SE U.S. CONTINUES TO PRODUCE GALE FORCE WINDS IN THE
STRAITS OF FLORIDA.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE ANCHORED IN THE NW CARIBBEAN NEAR 19N82W
EXTENDS AND AXIS N ACROSS CUBA INTO THE E GULF OF MEXICO. THE
SOUTHERN RIDGE AXIS EXTENDS S TO OVER PANAMA/COLOMBIA NEAR 9N76W
PROVIDING DIFFLUENCE ALOFT TO PRODUCE SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS S OF A LINE FROM COLOMBIA NEAR 11N75W TO NICARAGUA
NEAR 13N84W. AN UPPER TROUGH FROM THE W/CENTRAL ATLC DIPS S OVER
THE E CARIBBEAN E OF 85W GIVING THE AREA NW UPPER LEVEL FLOW AND
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 17N TO
OVER CUBA BETWEEN 75W-86W AND FROM 17N-20N E OF 75W TO ACROSS
THE LEEWARD ISLANDS INCLUDING THE VIRGIN ISLANDS TO HISPANIOLA.
PRIMARILY MODERATE SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY
FROM 12N-16N WITH SOME ISOLATED SHOWERS LOW LEVEL FAST MOVING
SHOWERS ARE BEING USHERED IN ON MODERATE EASTERLY TRADEWINDS.

ATLANTIC OCEAN...
A SURFACE RIDGE REMAINS IN CONTROL OF THE W ATLC N OF 23N W OF
60W ANCHORED BY SEVERAL SURFACE HIGHS N OF THE REGION. A
STATIONARY FRONT ENTERS THE CENTRAL ATLC NEAR 32N44W EXTENDING
SW ALONG 27N52W TO 23N58W WHERE IT CONTINUES AS SURFACE TROUGH
TO 19N66W. THE FEATURE IS SUPPORTED ALOFT BY A UPPER LEVEL
TROUGH THAT EXTENDS S INTO THE E CARIBBEAN COVERING THE AREA
BETWEEN 55W-78W. JUST TO THE E IS A NARROW HIGHLY AMPLIFIED
UPPER RIDGE THAT EXTENDS FROM 16N55W TO BEYOND 32N40W PROVIDING
DIFFLUENCE ALOFT TO GENERATE A BROAD AREA OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 15N-22N BETWEEN 54W-62W AND WITHIN
75 NM OF 53W FROM 23N-27N. A NARROW UPPER LEVEL TROUGH IS OVER
THE E/CENTRAL ATLC EXTENDING FROM 32N35W DIPPING INTO THE
TROPICS TO NEAR 13N51W AND CONTINUES TO ENHANCE CONVECTION N OF
THE ITCZ. THE E ATLC IS REMAINS UNDER THE INFLUENCE OF A SURFACE
RIDGE ANCHORED ON A 1031 MB HIGH ANCHORED E OF THE AZORES.

$$
WALLACE





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