[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 251749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 25 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
1715 UTC.

...SPECIAL FEATURES...

TROPICAL WAVE THAT EXTENDED FROM THE CARIBBEAN ACROSS THE VIRGIN
ISLANDS TO OVER THE W ATLC IS NOW 2 SEPARATE FEATURES...A
TROPICAL WAVE IN THE CARIBBEAN...SEE BELOW AND A SURFACE TROUGH
N OF THE LEEWARD/VIRGIN ISLANDS. THE SURFACE TROUGH EXTENDS FROM
27N60W 25N62W TO 20N63W WITH GALE FORE WINDS MOSTLY E OF THE
SURFACE TROUGH FROM 20N TO 27N BETWEEN 58W AND 72W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF LINE
FROM 20N58W TO 24N63W WITH SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS FROM 23N-28N BETWEEN 60W-69W. ISOLATED
SHOWERS/THUNDERSTORMS ARE WITHIN 120 NM OF LINE FROM 27N69W TO
31N73W. THIS SYSTEM CONTINUES TO SHOW SOME SIGNS OF ORGANIZATION
AND UPPER LEVEL WINDS ARE FORECAST TO BECOME MORE CONDUCIVE FOR
DEVELOPMENT DURING THE NEXT DAY OR SO AS THE SYSTEM MOVES WNW
AROUND 15-20 KT. THERE IS A HIGH CHANCE OF THIS SYSTEM BECOMING
A TROPICAL DEPRESSION OR TROPICAL STORM DURING THE NEXT 48
HOURS. A RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THE
AREA LATER THIS AFTERNOON.

...TROPICAL WAVES...

TROPICAL WAVE IS FROM 20N30W TO 10N35W WITH A 1013 MB LOW ALONG
THE WAVE NEAR 14N MOVING W NEAR 15 KT. BROAD AREA OF LOW/MID
LEVEL CYCLONIC ROTATION IS OBSERVED ON THE VISIBLE SATELLITE
IMAGERY. WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM
OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 45 NM OF LINE FROM
16N27W TO 17N30W. ISOLATED SHOWERS ARE NOTED FROM 15N-20N
BETWEEN 26W-34W.

TROPICAL WAVE IS ALONG 65W S OF 19N MOVING W 20-25 KT. WAVE
COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN THE
TOTAL PRECIPITABLE WATER IMAGERY AND A WELL DEFINED INVERTED-V
CURVATURE IS OBSERVED ON VISIBLE SATELLITE IMAGERY. SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE OVER THE LEEWARD
AND VIRGIN ISLANDS.

TROPICAL WAVE IS ALONG 83W/84W S OF 17N MOVING W 20-25 KT. WAVE
COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN THE
TOTAL PRECIPITABLE WATER IMAGERY ACROSS THE SW CARIBBEAN. A
LOW/MID LEVEL CYCLONIC ROTATION IS OBSERVED MOVING INLAND OVER
NICARAGUA WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION
FROM 12N-16N W OF 82W TO INLAND OVER NICARAGUA AND NE HONDURAS.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 13N15W 15N25W 11N39W 9N51W
10N62W THEN ACROSS N PORTION OF SOUTH AMERICA AND PANAMA INTO
THE E PACIFIC REGION. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 10N-13N E OF 20W TO INLAND OVER W
AFRICA...WITHIN 150 NM N OF THE ITCZ FROM 20W-24W...AND WITHIN
90 NM S OF THE ITCZ FROM 54W-57W.

...DISCUSSION...

GULF OF MEXICO...
A STATIONARY FRONT EXTENDS FROM THE W ATLC ACROSS NE FLORIDA
FROM ST. AUGUSTINE TO CEDAR KEY CONTINUING SW INTO THE S GULF
ALONG 23N89W WHERE IT IS BEGINNING TO PULL BACK N AS A WARM
FRONT ALONG 22N94W THEN S TO 20N95W. THIS FRONTAL BOUNDARY IS
SUPPORTED BY AN UPPER LEVEL TROUGH THAT IS ACROSS THE SE US AND
AN UPPER LOW OVER CENTRAL MISSISSIPPI. A SURFACE TROUGH IS
ACROSS THE N GULF FROM TALLAHASSEE FLORIDA INTO THE GULF OF
MEXICO NEAR 30N86W THEN W INTO THE MISSISSIPPI DELTA OF
LOUISIANA WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 27N
W OF 93W TO THE COAST OF TEXAS. CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE ACROSS THE S GULF S OF 26N FROM THE
FLORIDA PENINSULA TO THE COAST OF MEXICO. THIS AREA IS FURTHER
AIDED BY AN UPPER LEVEL RIDGE ANCHORED IN THE W CARIBBEAN
PROVIDING UPPER LEVEL DIFFLUENCE OVER THE S GULF...THE YUCATAN
PENINSULA AND BAY OF CAMPECHE.

CARIBBEAN SEA...
A BROAD UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN ANCHORED OVER
NICARAGUA AND EXTENDING N INTO THE GULF OF MEXICO. UPPER LEVEL
DIFFLUENCE ON MOIST SWLY FLOW ALOFT BETWEEN THIS RIDGE AND THE
UPPER LEVEL TROUGHING OVER THE GULF OF MEXICO CONTINUES TO
SUPPORT SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 20N ACROSS
CUBA BETWEEN 82W-85W. ON THE SRN PERIPHERY OF THE UPPER LEVEL
RIDGE...UPPER LEVEL DIFFLUENCE IS ENHANCING THE ACTIVITY
ASSOCIATED WITH THE TROPICAL WAVE ALONG 83W/84W. FRESH TO STRONG
EASTERLY TRADEWINDS CONTINUE ACROSS MUCH OF THE CARIBBEAN WITH
THE STRONGEST WINDS EXPECTED IN THE CENTRAL CARIBBEAN AND NEAR
THE COAST OF COLOMBIA.

ATLANTIC OCEAN...
A STATIONARY FRONT ENTERS THE W ATLC NEAR 32N80W EXTENDING
ACROSS FLORIDA AND INTO THE GULF OF MEXICO NEAR ST. AUGUSTINE.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 180 NM SE OF
THE FRONT N OF 28N. THIS ACTIVITY IS PRIMARILY SUPPORTED ALOFT
BY AN UPPER LEVEL TROUGH ACROSS THE SE US AND THE ASSOCIATED
UPPER LEVEL DIFFLUENCE LOCATED E OF THE TROUGH AXIS. THE AREA
NOTED IN THE SPECIAL FEATURES IS SUPPORTED BY A SERIES OF UPPER
LOWS WITH THE PRIMARY LOW CENTERED NEAR 29N67W AND 20N67W. A
SURFACE RIDGE DOMINATES THE ATLC ANCHORED BY A 1025 MB HIGH NE
OF BERMUDA NEAR 34N54W. THE SURFACE RIDGE COUPLED WITH DRY
STABLE AIR IS LIMITING ANY SHOWERS MAINLY E OF 55W ACROSS THE
REMAINDER OF ATLC.

$$
WALLACE




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