[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 300000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 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
2330 UTC.


...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 23W S OF 17N MOVING W NEAR 10 KT. A MID
LEVEL CYCLONIC ROTATION IS OBSERVED ALONG THE WAVE NEAR 15N. THE
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY. A RECENT CLUSTER OF SCATTERED
MODERATE/STRONG CONVECTION IS FROM 14N-16N BETWEEN 21W-23W.

AN ELONGATED TROPICAL WAVE EXTENDS FROM 15N38W SW TO A 1011 MB
SURFACE LOW NEAR 10N42W CONTINUING WSW TO 8N49W. THIS SYSTEM IS
MOVING W NEAR 15 KT. THIS WAVE/LOW IS WITHIN A VERY BROAD AREA
OF CYCLONIC FLOW AS INDICATED ON VISIBLE SATELLITE IMAGERY. THE
WAVE ALSO COINCIDES WITH AN ELONGATED DEEP LAYER MOISTURE
MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS
OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE 7N-8N
BETWEEN 45W-48W...9N-11N BETWEEN 41W-45W...AND 11N-16N BETWEEN
43W-46W.

A TROPICAL WAVE IS ALONG 61W S OF 16N MOVING W NEAR 15 KT. THE
WAVE FOLLOWS AN AREA OF RELATIVELY INCREASED MOISTURE OBSERVED
IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...THE WAVE IS
CURRENTLY EMBEDDED WITHIN AN AREA OF DRY STABLE AIR INHIBITING
ANY DEEP CONVECTION.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 15N16W 12N27W 15N36W 7N50W
10N60W. SCATTERED MODERATE CONVECTION IS FROM 10N-12N BETWEEN
25W-28W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS ACROSS S FLORIDA INTO THE CENTRAL GULF
ALONG 27N80W TO 26N88W. SCATTERED SHOWERS/THUNDERSTORMS ARE
WITHIN 100 NM EITHER SIDE OF THE TROUGH AXIS. THIS ACTIVITY IS
ENHANCED MAINLY BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL
RIDGE CENTERED NEAR 17N98W ASSOCIATED WITH HURRICANE JIMENA IN
THE E PACIFIC AND A BROAD UPPER LEVEL TROUGH ACROSS THE ERN
CONUS WHICH COVERS THE NRN GULF N OF 25N. THE UPPER LEVEL RIDGE
IS DRAWING MOISTURE FROM THE E PACIFIC ACROSS THE WRN GULF
GENERATING A FEW ISOLATED SHOWERS ACROSS THE SW GULF. UPPER
LEVEL DIFFLUENCE BETWEEN AN UPPER LEVEL LOW OVER THE W CARIBBEAN
NEAR 15N82W AND AN UPPER LEVEL RIDGE IN THE W ATLC IS SUPPORTING
SCATTERED SHOWERS/THUNDERSTORMS OVER CUBA AND THE STRAITS OF
FLORIDA S OF 24N. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE IN
THE FAR NW GULF N OF 29N W OF 93W AHEAD OF A COLD FRONT ACROSS
TEXAS. EXPECT THIS FRONTAL BOUNDARY TO MOVE INTO THE NW GULF
LATE SUN.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS OVER THE W CARIBBEAN CENTERED NEAR 15N82W.
UPPER LEVEL DIFFLUENCE BETWEEN THIS LOW AND THE RIDGE OVER THE
GULF OF MEXICO IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS
OVER THE YUCATAN PENINSULA S OF 22N W OF 87W. UPPER LEVEL
DIFFLUENCE BETWEEN THE UPPER LOW AND AN UPPER LEVEL RIDGE OVER
THE E CARIBBEAN E OF 77W...ALONG WITH MOIST SLY FLOW ALOFT ARE
SUPPORTING NUMEROUS SHOWERS/THUNDERSTORMS ACROSS THE FAR SW
CARIBBEAN S OF 12N BETWEEN 73W-84W...ISOLATED SHOWERS N OF 12N
BETWEEN 77W-81W...AND SCATTERED SHOWERS/THUNDERSTORMS ACROSS
CUBA N OF 21N BETWEEN 77W-85W. THE REMAINDER OF THE CARIBBEAN IS
EXPERIENCING GENERALLY FAIR WEATHER UNDER THE INFLUENCE OF DRY
AIR AND SUBSIDENCE ALOFT. A FEW ISOLATED SHOWERS ARE ACROSS
PUERTO RICO AND HISPANIOLA DUE TO EARLIER DAYTIME HEATING. FRESH
TO STRONG TRADE WINDS ARE ACROSS MUCH OF THE BASIN WITH THE
STRONGEST WINDS NEAR THE COAST OF COLOMBIA. EXPECT THE WEAK
TROPICAL WAVE CURRENTLY ALONG 61W TO PROGRESS WWD ACROSS THE E
CARIBBEAN LATER TONIGHT.

ATLANTIC OCEAN...
A LARGE SURFACE TROUGH IS ACROSS THE W ATLC EXTENDING FROM A
1004 MB LOW...THE REMNANTS OF DANNY...OFF THE COAST OF MARYLAND.
THE TROUGH ENTERS THE DISCUSSION AREA NEAR 32N73W EXTENDING TO
THE COAST OF FLORIDA NEAR 27N80W AND CONTINUING INTO THE GULF OF
MEXICO. SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING A
LARGE AREA OF SCATTERED SHOWERS/THUNDERSTORMS ALONG THE COAST OF
FLORIDA FROM 26N-29N BETWEEN 79W-81W. SCATTERED
SHOWERS/THUNDERSTORMS ARE ALSO FROM 27W-31W BETWEEN 71W-73W. THE
TROUGH IS SUPPORTED BY AN UPPER LEVEL TROUGH ACROSS THE ERN
CONUS. THE SHOWER ACTIVITY NEAR THE FRONT IS ENHANCED BY UPPER
LEVEL DIFFLUENCE BETWEEN THIS UPPER LEVEL TROUGH AND AN UPPER
LEVEL RIDGE BETWEEN 65W-75W. A SHORTWAVE UPPER LEVEL TROUGH
EXTENDS INTO THE UPPER RIDGE FROM 28N64W TO 22N56W CONTINUING TO
AN UPPER LEVEL LOW NEAR 28N47W. UPPER LEVEL DIFFLUENCE NEAR THE
SHORTWAVE UPPER TROUGH IS SUPPORTING ISOLATED SHOWERS FROM
20N-28N BETWEEN 56W-65W. ELSEWHERE ACROSS THE ATLC...A BROAD
SURFACE RIDGE DOMINATES ANCHORED BY A 1026 MB HIGH NEAR 34N45W
BRINGING GENERALLY FAIR WEATHER ACROSS THE BASIN. ACROSS THE
TROPICAL ATLC...A BROAD UPPER LEVEL RIDGE IS CENTERED NEAR
17N39W ENHANCING CONVECTION ALONG THE ITCZ AND THE TROPICAL WAVE
EXTENDING FROM 15N38W SW TO A 1011 MB SURFACE LOW NEAR 10N42W
CONTINUING WSW TO 8N49W.

$$
WALTON




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