[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081707
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE HAS BEEN ADDED TO THE SURFACE ANALYSIS AT
08/1200 UTC OVER THE FAR E ATLC. THIS TROPICAL WAVE IS ALONG
15W/16W S OF 16N MOVING W 10-15 KT. RECENT VISIBLE SATELLITE
IMAGERY INDICATES A WELL-DEFINED LOW/MID-LEVEL CYCLONIC
CIRCULATION CENTER ASSOCIATED WITH THIS WAVE NEAR 11N16W.
TIME-HEIGHT ANALYSES FROM BAMAKO IN MALI INDICATE THAT THE
DIRECTION OF THE FLOW BELOW 550 MB SHIFTED FROM NORTHEASTERLY TO
SOUTHEASTERLY BETWEEN 07/1200 UTC AND 07/1800 UTC...SUGGESTING
WAVE PASSAGE AT BAMAKO DURING THIS TIME. SUNY ALBANY GFS
ANALYSES DEPICT THE LOW-LEVEL VORTICITY MAXIMUM ASSOCIATED WITH
THIS WAVE TRACKING WESTWARD ACROSS WEST CENTRAL AFRICA DURING
THE LAST FEW DAYS. THE 5-DAY HOVMOLLER DIAGRAM FOR SATELLITE
IMAGERY ALSO INDICATES AN AREA OF ENHANCED CLOUDINESS ASSOCIATED
WITH THE WAVE TRACKING WESTWARD ACROSS WEST CENTRAL AFRICA
DURING THE LAST FEW DAYS. A BAND OF NUMEROUS MODERATE/ISOLATED
STRONG CONVECTION ASSOCIATED WITH THIS WAVE IS WITHIN 90 NM
EITHER SIDE OF A LINE FROM 11N15W TO 10N17W TO 10N21W.

A TROPICAL WAVE EXTENDS FROM 18N33W TO 15N27W TO 8N22W MOVING W
NEAR 15 KT. THIS WAVE IS EMBEDDED WITHIN A WELL-DEFINED MAXIMUM
IN DEEP LAYER MOISTURE THAT IS TILTED FROM NW TO SE BASED ON THE
TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. RECENT VISIBLE
SATELLITE IMAGERY DEPICTS CYCLONIC MOTION OF LOW LEVEL CLOUDS IN
THE VICINITY OF THIS WAVE...PARTICULARLY FROM 10N-14N. SCATTERED
MODERATE CONVECTION IS FROM 8N-10N BETWEEN 22W-24W. SCATTERED
MODERATE CONVECTION IS ALSO FROM 13N-16N BETWEEN 23W-27W.

A TROPICAL WAVE IS ALONG 42W/43W S OF 16N MOVING W 15-20 KT.
THIS WAVE COINCIDES WITH AN INVERTED-V PATTERN IN THE COVERAGE
OF LOW-LEVEL CLOUDS...ALONG WITH AN AREA OF ENHANCED
LOW/MID-LEVEL CYCLONIC CIRCULATION NEAR 14N43W...BASED ON RECENT
VISIBLE SATELLITE IMAGERY. DEEP LAYER DRY AIR AND ATMOSPHERIC
STABILITY IN THE VICINITY OF AN UPPER LEVEL RIDGE ARE LIMITING
DEEP CONVECTION NEAR THIS WAVE. HOWEVER...SCATTERED SHOWERS ARE
OCCURRING FROM 11N-14N BETWEEN 38W-41W.

A TROPICAL WAVE IS ALONG 58W S OF 15N MOVING W NEAR 15 KT.
SATELLITE-DERIVED WINDS INDICATE CYCLONIC CURVATURE IN THE FLOW
WITHIN THE 950-800 MB LAYER NEAR THIS WAVE. THE CIMSS WAVETRAK
PRODUCT ALSO CONFIRMS THAT THIS WAVE COINCIDES WITH A MAXIMUM IN
LOW-LEVEL CYCLONIC CIRCULATION. SCATTERED MODERATE CONVECTION IS
FROM 10N-13N BETWEEN 55W-58W.

A TROPICAL WAVE IS ALONG 75W S OF 20N MOVING W NEAR 20 KT. THIS
WAVE COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED ON
THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. RECENT VISIBLE
SATELLITE IMAGERY INDICATES CURVATURE IN LOW-LEVEL CLOUD BANDS
ALONG THE WAVE AXIS FROM 13N-18N. MID/UPPER-LEVEL DRY AIR IS
INHIBITING THE AREAL COVERAGE DEEP CONVECTION NEAR THIS WAVE.
HOWEVER...SCATTERED MODERATE CONVECTION IS FROM 14N-16N BETWEEN
77W-80W AND FROM 9N-11N BETWEEN 79W-82W.

A TROPICAL WAVE IS ALONG 94W/95W S OF 21N MOVING W NEAR 15 KT.
THIS WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE
BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. THE
CIMSS WAVETRAK PRODUCT INDICATES THAT THIS WAVE COINCIDES WITH A
MAXIMUM IN LOW-LEVEL CYCLONIC CIRCULATION. STABLE ATMOSPHERIC
CONDITIONS ASSOCIATED WITH AN UPPER LEVEL ANTICYCLONE CENTERED
OVER THE YUCATAN PENINSULA NEAR 20N88W ARE INHIBITING DEEP
CONVECTION OVER N PORTIONS OF THIS WAVE. HOWEVER...SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING OVER SE MEXICO
AND THE SW GULF OF MEXICO FROM 17N-20N BETWEEN 92W-95W. DEEP
CONVECTION ASSOCIATED WITH THIS WAVE IS OCCURRING IN THE E
PACIFIC REGION...WHICH IS DISCUSSED IN THE TROPICAL WEATHER
DISCUSSION FOR THE E PACIFIC OCEAN UNDER AWIPS/WMO HEADERS
MIATWDEP/AXPZ20.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 13N17W 11N23W 9N37W 13N52W
10N63W. A SURFACE TROUGH MOVING WESTWARD AT 5-10 KT IS EMBEDDED
WITHIN THE ITCZ AND EXTENDS FROM 17N47W TO 10N52W WITH SCATTERED
MODERATE CONVECTION FROM 10N-15N BETWEEN 48W-55W.
ADDITIONALLY...SCATTERED MODERATE CONVECTION IS FROM 8N-10N
BETWEEN 28W-30W. SCATTERED MODERATE CONVECTION IS ALSO FROM
9N-11N BETWEEN 61W-64W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH AXIS EXTENDS NORTHEASTWARD FROM CENTRAL
MEXICO TO THE E COAST OF MEXICO NEAR 23N98W ACROSS THE NW GULF
TO 28N93W TO AN UPPER LEVEL VORTICITY MAXIMUM OVER SE LOUISIANA
NEAR 30N90W. ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS UPPER
LEVEL TROUGH IS COMBINING WITH DEEP LAYER MOISTURE TO SUPPORT
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS S OF 27N W OF 90W.
THE SOUTHERN PORTIONS OF THIS ACTIVITY ARE BEING ENHANCED BY LOW
LEVEL CONVERGENCE OVER THE N PORTIONS OF THE TROPICAL WAVE ALONG
94W/95W S OF 21N. ADDITIONALLY...A SURFACE TROUGH OVER THE N
GULF EXTENDS FROM THE FLORIDA PANHANDLE NEAR 27N85W TO 27N89W.
LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS AND
THUNDERSTORMS WITHIN 120 NM EITHER SIDE OF THIS SURFACE
TROUGH...WHICH ARE BEING ENHANCED BY ATMOSPHERIC INSTABILITY
NEAR THE AFOREMENTIONED UPPER LEVEL TROUGH. THE QUIKSCAT PASS
AROUND 08/1145 UTC DEPICTS CYCLONIC CURVATURE IN THE LOW LEVEL
FLOW NEAR THE SURFACE TROUGH. ACROSS THE SE GULF...STABLE
ATMOSPHERIC CONDITIONS ASSOCIATED WITH AN UPPER LEVEL
ANTICYCLONE CENTERED OVER THE YUCATAN PENINSULA NEAR 20N88W ARE
RESULTING IN GENERALLY FAIR WEATHER.

CARIBBEAN SEA...
UPPER LEVEL DIFFLUENCE IN NORTHEASTERLY FLOW ALOFT OVER THE NW
CARIBBEAN IS SUPPORTING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS FROM 18N-20N BETWEEN 80W-83W. OVER THE CENTRAL
CARIBBEAN...AN UPPER LEVEL TROUGH AXIS EXTENDS FROM 18N73W TO N
COLOMBIA NEAR 10N75W. HOWEVER...DEEP LAYER DRY AIR EMBEDDED
WITHIN THIS UPPER LEVEL TROUGH IS INHIBITING DEEP CONVECTION
NEAR THE TROUGH. ACROSS THE E CARIBBEAN...DEEP LAYER DRY AIR IS
RESULTING IN GENERALLY FAIR WEATHER. HOWEVER...SCATTERED SHOWERS
AND THUNDERSTORMS ARE OCCURRING S OF 12N E OF 65W...INCLUDING NE
PORTIONS OF VENEZUELA. THIS ACTIVITY IS BEING SUPPORTED BY LOW
LEVEL CONVERGENCE NEAR THE ITCZ AXIS. THE SURFACE PRESSURE
GRADIENT S OF A SURFACE RIDGE OVER THE CENTRAL AND E ATLC IS
SUPPORTING FRESH TO STRONG TRADE WINDS ACROSS MUCH OF THE
CENTRAL AND E CARIBBEAN. THE STRONGEST WINDS ARE NEAR THE COAST
OF COLOMBIA...WHERE NE WINDS OF 25 TO 30 KT ARE OCCURRING.

ATLANTIC OCEAN...
AN UPPER LEVEL SHORTWAVE TROUGH AXIS IS OVER THE SW NORTH ATLC
AND EXTENDS FROM 29N78W TO 30N71W TO 32N65W TO NE OF THE
DISCUSSION AREA. ATMOSPHERIC LIFT S OF THIS UPPER LEVEL
SHORTWAVE TROUGH AXIS IS SUPPORTING A SURFACE TROUGH EXTENDING
FROM 30N72W TO THE NW BAHAMAS NEAR 26N77W TO 25N78W. LOW LEVEL
CONVERGENCE NEAR THE SURFACE TROUGH AND ATMOSPHERIC INSTABILITY
ASSOCIATED WITH THE UPPER LEVEL SHORTWAVE TROUGH ARE SUPPORTING
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 23N BETWEEN
71W-76W AND N OF 30N BETWEEN 65W-71W. TO THE E...AN UPPER LEVEL
LOW IS CENTERED NEAR 24N68W...WITH UPPER LEVEL DIFFLUENCE IN
SOUTHWESTERLY FLOW ALOFT TO THE E OF THE UPPER LEVEL LOW
SUPPORTING SCATTERED SHOWERS FROM 21N-26N BETWEEN 62W-67W.
ALSO...AN UPPER LEVEL LOW IS CENTERED NEAR 31N46W WITH AN
ASSOCIATED SURFACE TROUGH EXTENDING FROM 31N49W TO 27N48W TO
24N46W. LOW LEVEL CONVERGENCE NEAR THIS SURFACE TROUGH AND
ATMOSPHERIC INSTABILITY NEAR THIS UPPER LEVEL LOW ARE SUPPORTING
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS N OF 27N BETWEEN
43W-52W. FARTHER TO THE E...A DEEP LAYER RIDGE IS PRESENT ACROSS
THE CENTRAL AND E ATLC WITH AN ASSOCIATED 1028 MB SURFACE HIGH
NEAR 36N37W. STABLE ATMOSPHERIC CONDITIONS IN THE VICINITY OF
THIS DEEP LAYER RIDGE ARE RESULTING IN GENERALLY FAIR WEATHER
ACROSS MUCH OF THE CENTRAL AND E ATLC.

$$
COHEN




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