[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212247
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU AUG 21 2008

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
2115 UTC.

...SPECIAL FEATURES...
TROPICAL STORM FAY IS CENTERED NEAR 29.4N 81.4W JUST W OF
FLAGLER BEACH FLORIDA AT 21/2100 UTC. FAY IS MOVING WEST AT 4 KT
AND THIS SLOW MOTION IS EXPECTED TO CONTINUE FOR THE NEXT COUPLE
OF DAYS. MINIMUM CENTRAL PRESSURE IS 993 MB. MAXIMUM SUSTAINED
WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. PLEASE SEE THE LATEST
NHC THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/
WTNT21 KNHC AND PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. THE UPPER OUTFLOW
PATTERN ASSOCIATED WITH FAY IS MOST PRONOUNCED N OF THE CENTER.
OVERALL CONVECTION IS HEAVIEST E OF THE CENTER OVER THE
ATLANTIC...WITH RAIN BANDS EXTENDING S TO BISCAYNE BAY MIAMI.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 26N-32N
BETWEEN 76W-82W. WIDELY SCATTERED MODERATE CONVECTION IS FROM
28N-33N BETWEEN 82W-85W. FAY IS EXPECTED TO PRODUCE RAINFALL
ACCUMULATIONS OF 5 TO 10 INCHES ACROSS THE CENTRAL TO NORTHERN
PORTION OF THE FLORIDA PENINSULA...INCLUDING THE FLORIDA
PANHANDLE...SOUTHERN GEORGIA...AND SOUTHEASTERN ALABAMA...WITH
ISOLATED MAXIMUM AMOUNTS OF 15 INCHES POSSIBLE. ISOLATED STORM
TOTAL ACCUMULATIONS OF 20 TO 30 INCHES HAVE ALREADY BEEN
OBSERVED WITH THIS SYSTEM OVER THE EAST CENTRAL COASTAL AREAS OF
FLORIDA.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 33W/34W S OF 19N WITH A 1010 MB LOW ALONG
THE WAVE NEAR 12N MOVING W NEAR 15 KT. WAVE REMAINS EMBEDDED
WITHIN THE ITCZ AND ISOLATED SHOWERS ARE FROM 14N-17N BETWEEN
30W-33W.

A SMALL 1008 MB LOW IS ANALYZED IN THE CENTRAL ATLC NEAR 12N47W
MOVING W NEAR 10-15 KT. SCATTERED MODERATE TO STRONG CONVECTION
IS OBSERVED W OF THE LOW FROM 11N-14N BETWEEN 47W-53W.

TROPICAL WAVE IN THE W TROPICAL ATLC IS ALONG 55W S OF 18N
MOVING W NEAR 10-15 KT. NO ASSOCIATED SHOWER ACTIVITY OR
CONVECTION.

TROPICAL WAVE IN THE CENTRAL CARIBBEAN IS ALONG 76W S OF 20N
MOVING W NEAR 10-15 KT. NO ASSOCIATED SHOWER ACTIVITY OR DEEP
CONVECTION.

...THE ITCZ...
THE ITCZ IS CENTERED ALONG 13N16W 13N24W 12N32W 12N36W 12N46W
12N53W 9N61W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM
11N-18N BETWEEN 15W-21W. SCATTERED MODERATE CONVECTION IS FROM
6N-11N BETWEEN 33W-38W. SIMILAR CONVECTION IS WITHIN 120 NM ON
EITHER SIDE OF A LINE FROM 8N42W TO 10N62W...INCLUDING FAR NE
VENEZUELA AND TRINIDAD AND TOBAGO.

...DISCUSSION...

GULF OF MEXICO...





SHOWER ACTIVITY ACROSS THE NE GULF WATERS AND CONVECTIVE BANDS
OF SCATTERED SHOWERS/TSTMS ALONG 26N E OF 85W ASSOCIATED WITH
T.S. FAY ARE IN THE ERN GULF...SEE SPECIAL FEATURES ABOVE. AN
UPPER LOW IS OVER OKLAHOMA EXTENDING UPPER TROUGHING SW OVER WEST
TEXAS GENERATING AN AREA OF UPPER DIFFLUENCE ACROSS E TEXAS...
LOUISIANA AND THE NW GULF. SCATTERED SHOWERS/ISOLATED TSTMS ARE
INLAND ACROSS ERN TEXAS AND WRN LOUISIANA AND OVER THE WRN GULF
WATERS FROM 22N-28N BETWEEN 96W-98W ALONG THE IMMEDIATE TEXAS
AND MEXICO COASTLINES. AN UPPER LEVEL RIDGE IS ANCHORED OFF THE
W COAST OF MEXICO AND EXTENDS INTO THE SW GULF ALONG 22N TO 92W
WITH A SECOND UPPER RIDGE ANCHORED OVER WRN CUBA COVERING THE
SRN GULF. THE REMAINDER OF THE GULF REMAINS RATHER CLEAR WITH A
WEAK RIDGE AXIS EXTENDING FROM THE MISSISSIPPI RIVER DELTA TO
THE YUCATAN CHANNEL WITH HIGHER PRESSURE VALUES AND LIGHT WINDS
OBSERVED.

CARIBBEAN SEA...





AN INDUCED INVERTED UPPER TROUGH EXTENDS FROM CENTRAL NICARAGUA
TO THE MONA PASSAGE SEPARATING AN UPPER RIDGE ANCHORED OVER WRN
CUBA AND A SECOND UPPER RIDGE ANCHORED OVER THE ERN CARIBBEAN.
THE ITCZ AXIS EXTENDS ACROSS SRN PORTIONS OF PANAMA IS
GENERATING SCATTERED SHOWERS AND THUNDERSTORMS S OF 11N BETWEEN
75W-83W. MODERATE EASTERLY TRADE WINDS CONTINUE OVER THE AREA
AND COUPLED WITH ADVECTED TROPICAL MOISTURE FROM THE UPPER RIDGE
OVER THE ERN CARIBBEAN ARE USHERING IN SCATTERED SHOWERS AND
THUNDERSTORMS S OF 16N BETWEEN 68W-75W. A SIMILAR AREA OF
SHOWERS IS OVER THE ABC ISLANDS FROM 11N-13N BETWEEN 66W-68W.
THE REMAINDER OF THE CARIBBEAN IS DOMINATED BY MODERATE
SUBSIDENCE AND DRY STABLE AIR...THUS CLEAR SKIES ARE OBSERVED
ELSEWHERE THIS AFTERNOON.

ATLANTIC OCEAN...





THE MAIN CONCERN FOR THE FAR W ATLC IS T.S. FAY WITH THE
CONVECTIVE ACTIVITY AND HEAVY RAINFALL LOCATED OFF THE NERN
FLORIDA PENINSULA AND SE U.S. COAST...SEE SPECIAL FEATURES
ABOVE. AN UPPER LOW IS IN THE W ATLC CENTERED OVER ERN HISPANIOLA
NEAR 19N69W COVERING THE AREA FROM 25N TO THE GREATER ANTILLES
BETWEEN 63W-75W. A DEEP LAYERED TROUGH IS OVER THE NW ATLC TO
30N NE OF T.S. FAY WITH THE ASSOCIATED FRONTAL BOUNDARY N OF THE
REGION. HOWEVER...IT IS INDUCING AN UPPER RIDGE TO THE E OF
BERMUDA AND GENERATING SCATTERED SHOWERS/THUNDERSTORMS N OF 29N
FROM 58W-68W. A SECOND LARGER BENIGN UPPER LOW COVERS MOST OF
THE CENTRAL ATLC CENTERED NEAR 23N51W WITH AN UPPER HIGH
ANCHORED OVER THE SE CARIBBEAN NEAR 11N64W. AN E/W UPPER RIDGE
COVERS THE E ATLC CENTERED NEAR 20N28W WITH A WEAK UPPER TROUGH
BEGINNING TO PUSH S OVER THE NE ATLC W OF THE CANARY ISLANDS
ALONG 28N. MODERATE SUBSIDENCE AND SOMEWHAT DRY STABLE AIR
COVERS THE ATLC E OF 45W GIVING THE REMAINDER OF THE AREA FAIR
WEATHER CONDITIONS. A SURFACE RIDGE REMAINS OVER MOST OF THE
ATLC N OF 23N E OF 55W ANCHORED BY A SERIES OF HIGHS N OF THE
REGION.

$$
FORMOSA





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