[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 292333
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED JUL 29 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2300 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 29W/30W S OF 23N MOVING W  10-15 KT.
SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE
LOW/MID-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS.
THIS WAVE ALSO LEADS A HIGH AMPLITUDE DEEP LAYER MOISTURE
MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE CONVECTION IS FROM 9N-11N BETWEEN 30W-32W.

A TROPICAL WAVE IS ALONG 59W S OF 18N MOVING W NEAR 20 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS
CURRENTLY ASSOCIATED WITH THIS WAVE. HOWEVER...SCATTERED SHOWERS
ARE FROM 12N-16N BETWEEN 57W-63W...AFFECTING THE LESSER ANTILLES.

A TROPICAL WAVE IS ALONG 87W S OF 20N MOVING W NEAR 25 KT. THIS
WAVE LIES IN A BROAD AREA OF DEEP LAYER MOISTURE OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 10N-23N BETWEEN 83W-90W. THIS
CONVECTION IS ENHANCED BY ATMOSPHERIC INSTABILITY AND UPPER
LEVEL DIFFLUENCE.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 11N27W 9N40W 11N57W
10N64W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
10N-13N BETWEEN 14W-18W. SCATTERED MODERATE CONVECTION IS FROM
9N-11N BETWEEN 22W-26W.

...DISCUSSION...

GULF OF MEXICO...
ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE NRN GULF OF MEXICO
N 29N DUE TO UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL
TROUGH OVER THE ERN CONUS AND AN UPPER LEVEL HIGH OVER THE
CENTRAL GULF NEAR 26N87W. SCATTERED SHOWERS/THUNDERSTORMS ARE
ALSO ACROSS THE ERN GULF OF MEXICO E OF 27W INCLUDING THE
FLORIDA PENINSULA DUE TO UPPER LEVEL DIFFLUENCE BETWEEN THE
UPPER LEVEL HIGH OVER THE CENTRAL GULF AND A SHORTWAVE UPPER
LEVEL TROUGH JUST E OF THE FLORIDA PENINSULA WITH AXIS ALONG
78W. A TROPICAL WAVE ALONG 87W IS ENHANCING SCATTERED
SHOWERS/THUNDERSTORMS ACROSS THE YUCATAN PENINSULA...WRN
CUBA...AND THE ADJACENT WATERS S OF 23N E OF 91W. ELSEWHERE
ACROSS THE GULF...A BROAD SURFACE RIDGE DOMINATES BRINGING
GENERALLY FAIR WEATHER. DRY AIR AND SUBSIDENCE ALOFT SUPPORT THE
SURFACE RIDGE. ANTI-CYCLONIC SURFACE FLOW IS AROUND THE RIDGE
WITH WINDS REACHING 15-20 KT IN THE WRN GULF. EXPECT THE SURFACE
RIDGE TO LIFT N OF 30N BY MONDAY.

CARIBBEAN SEA...
A TROPICAL WAVE ALONG 87W IS GENERATING SCATTERED
SHOWERS/THUNDERSTORMS ACROSS THE WRN CARIBBEAN FROM 10N-23N
BETWEEN 83W-90W INCLUDING MUCH OF CENTRAL AMERICA...THE YUCATAN
PENINSULA AND WRN CUBA. ATMOSPHERIC INSTABILITY FROM DAYTIME
HEATING AND DIFFLUENT FLOW ALOFT ARE ENHANCING THIS ACTIVITY.
SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO ACROSS CENTRAL AND WRN
CUBA N OF 21N BETWEEN 76W-83W DUE TO DIFFLUENT FLOW NEAR THE
SHORTWAVE UPPER LEVEL TROUGH IN THE WRN ATLC ALONG 78W THAT
EXTENDS ACROSS CUBA TO 20N79W. SCATTERED SHOWERS/THUNDERSTORMS
ARE ALSO IN THE S CENTRAL CARIBBEAN S OF 10N BETWEEN 76W-83W
INCLUDING MOST OF PANAMA. THIS ACTIVITY IS ENHANCED BY SURFACE
CONVERGENCE IN THE PROXIMITY OF THE E PACIFIC ITCZ. ELSEWHERE
ACROSS THE CARIBBEAN...DRY AIR AND SUBSIDENCE ALOFT ARE
PRODUCING GENERALLY FAIR WEATHER...EXCEPT FOR SCATTERED SHOWERS
S OF 16N E OF 63W INFLUENCED BY THE APPROACHING TROPICAL WAVE
CURRENTLY ALONG 59W. FRESH TO STRONG TRADE WINDS ARE ACROSS MUCH
OF THE CARIBBEAN WITH THE STRONGEST NEAR THE COAST OF COLUMBIA
WHERE A GALE WARNING IS CURRENTLY IN EFFECT. THE GALE FORCE
WINDS ARE EXPECTED TO CONTINUE THROUGH EARLY TOMORROW MORNING.

ATLANTIC OCEAN...
A SHORTWAVE UPPER LEVEL TROUGH ALONG 78W IS ENHANCING SCATTERED
SHOWERS/THUNDERSTORMS NW OF A LINE FROM 23N80W TO 30N73W. THE
REMAINDER OF THE ATLC IS DOMINATED BY DRY STABLE AIR AND A
BROAD SURFACE RIDGE ANCHORED BY A 1026 MB SURFACE HIGH NEAR
33N57W BRINGING GENERALLY FAIR WEATHER ACROSS THE BASIN...EXCEPT
FOR AN AREA OF CLOUDINESS N OF THE TROPICAL WAVE ALONG 29W/30W
FROM 23N-29N BETWEEN 22W-32W.

$$
WALTON



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