[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 090600
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

HURRICANE IDA IS CENTERED NEAR 24.4N 87.5W AT 09/0600 UTC OR
ABOUT 295 NM SSE OF THE MOUTH OF THE MISSISSIPPI RIVER MOVING
NNW AT 12 KT. ESTIMATED MINIMUM PRESSURE BASED ON DATA FROM THE
HURRICANE HUNTER AIRCRAFT IS 987 MB. MAXIMUM SUSTAINED WIND
SPEED IS 90 KT WITH GUSTS TO 110 KT. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE
DETAILS. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN A 60 NM
RADIUS OF 24.5N87W. SCATTERED MODERATE CONVECTION COVERS THE
REMAINDER OF THE AREA FROM 23N-27N BETWEEN 82W-89W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 52W S OF 18N MOVING W NEAR 15 KT. WAVE
RESIDES BENEATH A DRY UPPER LEVEL TROUGH AXIS JUST TO THE E. NO
SIGNIFICANT DEEP CONVECTION ACCOMPANIES THE WAVE.

TROPICAL WAVE IS ALONG 70W S OF 17N MOVING W NEAR 15 KT. WAVE
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 5N31W 8N49W 8N61W.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 6N-11N BETWEEN
38W-42W AND FROM 11N-13N BETWEEN 36W-40W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 150 NM OF LINE
FROM THE COAST OF W AFRICA NEAR 7N12W ALONG 5N24W TO 7N34W AND
FROM 13N18N BETWEEN 36W-41W.

...DISCUSSION...

GULF OF MEXICO...
HURRICANE IDA IS THE PRIMARY CONCERN TONIGHT FOR THE GULF OF
MEXICO...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 AND AN UPPER LEVEL
TROUGH THAT EXTENDS FROM TEXAS NEAR 29N97W TO THE E BAY OF
CAMPECHE NEAR 19N91W. THE UPPER LEVEL TROUGH ALSO SUPPORTS A
SURFACE TROUGH THAT EXTENDS FROM 28N95W THROUGH A ELONGATING
1008 MB LOW NEAR 23N95W THEN TO THE E BAY OF CAMPECHE NEAR
19N91W. WIND SHIFT IS MAINLY ASSOCIATED WITH THE SURFACE TROUGH
AXIS. HOWEVER...UPPER LEVEL DIFFLUENCE N OF 25N W OF 90W IS
GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE
AREA TO INLAND OVER LOUISIANA AND TEXAS. THE INCREASED PRESSURE
GRADIENT CREATED BETWEEN HURRICANE IDA AND THE SURFACE RIDGE
OVER THE W ATLC INTO THE SE U.S. IS PRODUCING GALE FORCE WINDS
IN THE STRAITS OF FLORIDA.

CARIBBEAN SEA...
HURRICANE IDA HAS MOVED INTO THE SE GULF OF MEXICO THROUGH THE
YUCATAN CHANNEL BUT CONTINUES TO GENERATE CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 18N ACROSS CUBA BETWEEN
77W-85W. THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL
DIFFLUENCE ASSOCIATED WITH AN UPPER LEVEL RIDGE ANCHORED IN THE
NEAR 16N82W EXTENDING N ACROSS CUBA INTO THE E GULF OF MEXICO.
THE SOUTHERN RIDGE AXIS EXTENDS S TO OVER E PANAMA PROVIDING
DIFFLUENCE ALOFT TO PRODUCE ISOLATED SHOWERS/THUNDERSTORMS
MAINLY S OF 12N W OF 73W AND IN THE GULF OF HONDURAS S OF 18N
BETWEEN 84W-87W. AN UPPER TROUGH FROM THE W/CENTRAL ATLC DIPS S
OVER THE E CARIBBEAN E OF 80W GIVING THE AREA NW UPPER LEVEL
FLOW AND GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS FROM 17N-20N E OF 77W TO ACROSS THE LEEWARD
ISLANDS INCLUDING THE VIRGIN ISLANDS TO HISPANIOLA. PRIMARILY
MODERATE SUBSIDENCE IS NOTED ON WATER VAPOR IMAGERY FROM 11N-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 22N W OF
60W ANCHORED BY SEVERAL SURFACE HIGHS N OF THE REGION. A COLD
FRONT ENTERS THE CENTRAL ATLC NEAR 32N45W EXTENDING SW TO 28N51W
WHERE IT BECOMES STATIONARY TO 24N60W THEN CONTINUES AS SURFACE
TROUGH TO 21N68W. THE FRONT IS SUPPORTED ALOFT BY A UPPER LEVEL
TROUGH THAT EXTENDS S INTO THE E CARIBBEAN COVERING THE AREA
BETWEEN 50W-80W. JUST TO THE E IS A NARROW HIGHLY AMPLIFIED
UPPER RIDGE THAT EXTENDS FROM 16N56W TO BEYOND 32N40W PROVIDING
DIFFLUENCE ALOFT TO GENERATE A BROAD AREA OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 15N-22N BETWEEN 55W-62W AND FROM
23N-27N BETWEEN 49W-55W. A NARROW UPPER LEVEL TROUGH IS OVER THE
E/CENTRAL ATLC EXTENDING FROM 32N33W DIPPING INTO THE TROPICS
NEAR 12N52W AND CONTINUES TO ENHANCE CONVECTION N OF THE ITCZ.
THE E ATLC IS REMAINS UNDER THE INFLUENCE OF A SURFACE RIDGE
ANCHORED ON A 1032 MB HIGH ANCHORED E OF THE AZORES.

$$
WALLACE




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