[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 240553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED AUG 24 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM
THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON
SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION TWELVE IS CENTERED NEAR 23.6N 76.0W...OR
ABOUT 135 MILES...120 NM...SE OF NASSAU AT 24/0600 UTC MOVING NW
AT 6 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22
KNHC AND THE PUBLIC ADVISORY UNDER HEADERS MIATCPAT1/WTNT32 KNHC
FOR MORE DETAILS. MID LEVEL LOW IS LOCATED NE OF THE LOW LEVEL
CENTER THUS SHEARING THE SYSTEM AND WITH DRY UPPER AIR BEING
ADVECTED BY A RIDGE TO THE N...THE SYSTEM IS NOT YET TO TROPICAL
STROM STRENGTH. SCATTERED MODERATE/STRONG CONVECTION IS TO THE E
OF THE CENTERED WITHIN 60/75 NM OF LINE FROM 25.5N73W ACROSS THE
CENTRAL BAHAMAS TO 22N76.5W.

A 1010 MB LOW IS CENTERED BETWEEN THE CAPE VERDE ISLANDS AND THE
LESSER ANTILLES NEAR 17N39.5W...ALONG A TROPICAL WAVE S OF 23N
ALONG 39W/40W MOVING W 10 KT. THE LOW LEVEL CENTER IS COMPLETELY
EXPOSED DUE TO SOUTHWESTERLY SHEAR AS A RESULT OF A MID LEVEL
INVERTED TROUGH ALONG 40W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 16N-21N BETWEEN 33W-38W. ALTHOUGH IS SYSTEM
IS NOT IN A FAVORABLE ENVIRONMENT AT THE MOMENT...AS THE SYSTEM
MOVES FURTHER W THE SHEAR SHOULD RELAX AND THE POSSIBILITY OF
TROPICAL CYCLONE DEVELOPMENT SOMEWHAT IMPROVES.

...TROPICAL WAVES...
E ATLC TROPICAL WAVE IS ALONG 23W/24W S OF 17N MOVING W 10 KT.
LOW AMPLITUDE WAVE WITH WEAK SIGNATURE CURVATURE OBSERVED S OF
13N. ISOLATED SHOWERS ARE WITHIN THE ITCZ FROM 9N-12N BETWEEN
20W AND THE WAVE AXIS.

SEE SPECIAL FEATURES FOR LOW/TROPICAL WAVE ALONG 39W/40W.

E CARIBBEAN TROPICAL WAVE IS ALONG 64W/65W S OF 21N MOVING W 15
KT. WAVE IS AT THE W EDGE OF AN UPPER LEVEL INVERTED TROUGH
MASKING SIGNS OF THE SIGNATURE CURVATURE. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 12.5N-20N BETWEEN
60W AND THE WAVE AXIS.

TROPICAL WAVE IS THE YUCATAN PENINSULA ALONG 90W S OF 21N MOVING
W 10-15 KT. AS THIS WAVE IS COMPLETELY OVER LAND...THE SATELLITE
SIGNATURE IS NON-EXISTENT. WAVE IS EMBEDDED WITHIN THE
EASTERLIES THUS AND ASSOCIATED CONVECTION IS BEING SHEARED INTO
THE BAY OF CAMPECHE. DEEPEST CONVECTION IS WELL INLAND OVER
CENTRAL AMERICA AND THE YUCATAN.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 10N21W 16N37W 8N52W 10N63W.
SCATTERED MODERATE/STRONG CONVECTION IS MOVING OFF AFRICA WITHIN
75/90 NM OF THE COAST FROM 8N-13N. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 120/150 NM N OF THE AXIS FROM
50W-58W. SCATTERED MODERATE CONVECTION IS WITHIN 180 NM S OF THE
AXIS FROM 44W-50W.

...DISCUSSION...
GULF OF MEXICO...
WEAK MID/UPPER LEVEL LOW IS IN THE BAY OF CAMPECHE NEAR 20N93W
PULLING UPPER MOISTURE FROM THE CONVECTION OVER THE YUCATAN AND
THE TROPICAL WAVE INTO THE E BAY S OF 23N E OF 94W. THIS COULD
ALSO BRING SCATTERED SHOWERS/THUNDERSTORMS TO THAT AREA.
REMAINDER OF THE GULF IS DOMINATED BY A STRONG UPPER HIGH
LOCATED ALONG THE MISSISSIPPI COAST NEAR 30N89W WITH
PREDOMINANTLY EASTERLY FLOW ACROSS THE GULF. AT THE SURFACE...A
WEAK 1012 MB HIGH IS IN THE NW GULF NEAR 28N92W. AFTERNOON
THUNDERSTORMS OVER FLORIDA HAVE STARTED TO DISSIPATE AND ARE
MOVING INTO THE E GULF TO 85W. REMAINDER OF THE GULF IS UNDER
CLEAR SKIES WITH ONLY ISOLATED SHOWERS WITHIN 120 NM OF THE
UPPER HIGH. THE SW GULF WILL CONTINUE TO GET SHOWER ACTIVITY AS
THE TROPICAL WAVE MOVES ACROSS THROUGH THU FOLLOWED BY GRADUAL
CLEARING. THE E GULF HOWEVER WILL SEE AN INCREASE IN SHOWER/
THUNDERSTORM ACTIVITY AS THE T.D. TWELVE MOVES TOWARD FLORIDA.

CARIBBEAN...
SMALL UPPER LOW IS IN THE SW CARIBBEAN NEAR 12N82W WITH FLOW S
OF 14N W OF 80W INTO NICARAGUA AND COSTA RICA. THIS IS
GENERATING A SMALL AREA OF SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 60 NM 13N FROM 80W 83W. REMAINDER OF THE
CARIBBEAN HAS PREDOMINANTLY MODERATE EASTERLY FLOW WITH DEBRIS
CIRRUS CLOUDS COVERING THE N CARIBBEAN ISLANDS FROM LATE
AFTERNOON THUNDERSTORMS. THE INVERTED TROUGH OVER THE FAR E
CARIBBEAN IS ENHANCING THE CONVECTION ASSOCIATED WITH THE
TROPICAL WAVE. AN UPPER RIDGE WILL BUILD FROM OVER CUBA TO
PUERTO RICO THROUGH THU...AS MOISTURE SHIFTS W WITH THE TROPICAL
WAVE.

W ATLANTIC...
THE STRONG UPPER HIGH OVER THE GULF EXTENDS A RIDGE AXIS OFF
COAST NEAR THE GEORGIA/FLORIDA BORDER NE TO ANOTHER UPPER HIGH N
OF BERMUDA. THIS IS GIVING THE FAR W ATLC N TO NE FLOW AND DRIER
AIR...WHICH IS BEING ADVECTED INTO THE UPPER LOW OVER THE N
BAHAMA ISLANDS JUST TO THE NW OF T.D. TWELVE. A SECOND UPPER
LEVEL LOW IS TO THE ENE OF THE T.D. TWELVE...S OF THE RIDGE
EXTENDING FROM THE GULF NEAR 26N59W. THIS IS A WEAK LOW EMBEDDED
WITH VERY DRY UPPER AIR...THUS IT IS ONLY ABLE TO GENERATE SOME
ISOLATED SHOWERS WITHIN 45 NM OF LINE 23N57W-27N55W. THE
MID/UPPER RIDGE FROM THE CENTRAL ATLC IS PRODUCING SOME UPPER
DIFFLUENCE S OF THIS UPPER LOW GENERATING SCATTERED
SHOWERS/THUNDERSTORMS N OF THE CARIBBEAN ISLANDS FROM 18N-24N
BETWEEN 61W-67W. THE UPPER LOW TO THE NW OF T.D. TWELVE IS
FORECASTED TO DISSIPATE OVER THE NEXT 24 TO 48 HOURS AS THE
SECOND UPPER LOW IS FORECASTED TO BECOME THE DOMINATE FEATURE.

EAST/CENTRAL ATLANTIC...
THE REMAINDER OF THE ATLC IS DOMINATED BY THE SUBTROPICAL
SURFACE RIDGE N OF 20N E OF 65W. AT THE UPPER LEVELS...A STRONG
HIGH IS IN THE CENTRAL ATLC NEAR 21N49W COVERING THE AREA FROM
35W-60W. STRONG SUBSIDENCE AND DRY AIR ALOFT COVERS THE AREA
FROM THE ITCZ TO 30N BETWEEN 40W-60W. THIS FACT AND THE MID
LEVEL INVERTED TROUGH IS IMPEDING THE DEVELOPMENT OF THE 1010 MB
LOW IN THE SPECIAL FEATURES. OVER THE E ATLC... A MID/UPPER
LEVEL RIDGE EXTENDS OFF THE COAST MAURITANIA ALONG 18N W ACROSS
THE CAPE VERDE ISLANDS TO 32W. A NEAR STATIONARY UPPER LOW IS
CENTERED NW OF THE CANARY ISLANDS NEAR 31N21W WITH FLOW
EXTENDING S TO 25N E OF 28W. AS THERE IS DRY AIR
ALOFT...CONVECTION OR SHOWER ACTIVITY CAN NOT BE SUSTAINED.

$$
WALLACE


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