[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 241158
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1045 UTC.

...SPECIAL FEATURES...
THE CENTER OF TROPICAL DEPRESSION TWELVE WAS NEAR 24.4N 76.6W
OR ABOUT 70 MILES/115 KM SE OF NASSAU...AND ABOUT 250 MILES/
400 KM ESE OF THE SE COAST OF FLORIDA AT 24/1200 UTC MOVING
NW AT 6 KT. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO
40 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 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. THE MID AND LOW LEVEL LOWS ARE STARTING TO
BECOME MORE INLINE THUS ONLY THE W SIDE REMAINS UNDER SHEARING
CONDITIONS. DRY UPPER AIR IS BEING ENTRAINED INTO THE LOW FORCED
S BY A RIDGE TO THE N. THE SYSTEM IS NOT YET TO TROPICAL STROM
STRENGTH BUT GOOD BE UPGRADED TODAY. SCATTERED MODERATE/STRONG
CONVECTION IS WITHIN A 75/80 NM RADIUS OF 24N75.5W WITH
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 45 NM OF
LINE 23.5N72W-27N76W.

A 1010 MB LOW IS CENTERED BETWEEN THE CAPE VERDE ISLANDS AND THE
LESSER ANTILLES NEAR 16.5N40.5W...ALONG A TROPICAL WAVE S OF 24N
ALONG 40W/41W MOVING W NEAR 10 KT. THE LOW LEVEL CENTER REMAINS
EXPOSED DUE TO SOUTHWESTERLY SHEAR AS A RESULT OF A MID LEVEL
INVERTED TROUGH ALONG 40W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 16N-20N BETWEEN 34W-39W. 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 25W S OF 15N MOVING W 10-15 KT.
THIS IS A LOW AMPLITUDE WAVE WITH WEAK SIGNATURE CURVATURE
OBSERVED S OF 13N. SCATTERED MODERATE CONVECTION IS WITHIN 45 NM
OF THE ITCZ AXIS FROM 23W-25W.

SEE SPECIAL FEATURES FOR LOW/TROPICAL WAVE ALONG 40W/41W.

E CARIBBEAN TROPICAL WAVE IS ALONG 66W/67W S OF 21N MOVING W
15-20 KT. WAVE IS MOVING W OF THE UPPER LEVEL INVERTED TROUGH
THAT HAD BEEN MASKING THE SIGNATURE CURVATURE. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 120 NM
OF LINE FROM 16N65W ACROSS THE LEEWARD AND VIRGIN ISLANDS TO
20N61W. SCATTERED SHOWERS/THUNDERSTORMS ARE SPREADING W FROM THE
WAVE AXIS TO 74W.

TROPICAL WAVE OVER THE YUCATAN PENINSULA IS MOVING INTO THE SW
GULF ALONG 91W S OF 21N MOVING W 10 KT. SATELLITE SIGNATURE IS
REAPPEARING IN THE SW GULF. WAVE REMAINS EMBEDDED WITHIN THE
EASTERLIES THUS THE ASSOCIATED CONVECTION IS BEING SHEARED
ACROSS THE BAY OF CAMPECHE. SCATTERED MODERATE CONVECTION IS S
OF 20N E OF 93.5W TO INLAND OVER THE YUCATAN AND S MEXICO.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N16W 9N19W 10N31W 17N37W 10N40W
11N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
8N-12N BETWEEN 51W-59W AND MOVING OFF AFRICA WITHIN 150 NM OF
THE COAST 13N-18N. SCATTERED MODERATE CONVECTION IS WITHIN 45 NM
OF LINE 5N22W-6N29W.

...DISCUSSION...
GULF OF MEXICO...
WEAK MID/UPPER LEVEL LOW IN THE BAY OF CAMPECHE IS APPROACHING
THE COAST OF MEXICO NEAR 20N95W PULLING UPPER MOISTURE FROM THE
CONVECTION OVER THE YUCATAN AND THE TROPICAL WAVE INTO THE E BAY
AND SCATTERED MODERATE CONVECTION WITHIN 90 NM OF THE COAST OF
MEXICO S OF 23N W OF 96W. REMAINDER OF THE GULF CONTINUES TO BE
DOMINATED BY A STRONG UPPER HIGH THAT HAS SHIFTED W TO OVER SE
LOUISIANA NEAR 30N91W WITH PREDOMINANTLY EASTERLY FLOW ACROSS
THE GULF. AT THE SURFACE...A WEAK RIDGE AXIS EXTENDS FROM THE W
ATLC ALONG 30N TO E TEXAS. ISOLATED THUNDERSTORMS ARE ALONG THE
N GULF COAST DUE TO A WEAK SURFACE TROUGHING THAT EXTENDS INLAND
OVER THE SE UNTIED STATES. THE REMAINDER OF THE GULF IS UNDER
NEARLY CLEAR SKIES DOTTED BY LOW LEVEL ISOLATED SHOWERS. THE SW
GULF WILL CONTINUE TO GET SHOWER ACTIVITY AS THE TROPICAL WAVE
MOVES ACROSS THE AREA TODAY FOLLOWED BY GRADUAL CLEARING. THE E
GULF HOWEVER WILL SEE AN INCREASE IN SHOWER/THUNDERSTORM
ACTIVITY AS T.D. TWELVE MOVES TOWARD FLORIDA.

CARIBBEAN...
SMALL UPPER LOW IS IN THE SW CARIBBEAN ALONG THE COAST OF
NICARAGUA NEAR 12N84W WITH FLOW S OF 15N W OF 80W TO INLAND OVER
NICARAGUA AND COSTA RICA. THIS IS GENERATING ISOLATED SHOWERS
ALONG THE COAST OF W PANAMA. REMAINDER OF THE CARIBBEAN HAS
PREDOMINANTLY MODERATE EASTERLY FLOW EXCEPT IN THE E WHERE THE
TROPICAL WAVE IS LOCATED. AN INVERTED TROUGH OVER THE FAR E
CARIBBEAN IS ENHANCING THE CONVECTION ASSOCIATED WITH THE
TROPICAL WAVE. THE UPPER RIDGE IS STARTING TO BUILD FROM A
DEVELOPING UPPER HIGH NEAR T.D. TWELVE EXTENDING SE TO N OF
PUERTO RICO. THIS WILL REMAIN OVER THE N CARIBBEAN ISLANDS FOR
THE NEXT DAY OR TWO. HOWEVER...MOISTURE WILL INCREASE ACROSS THE
AREA AS THE TROPICAL WAVE MOVES WESTWARD.

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
NE OF BERMUDA. THIS IS GIVING THE FAR W ATLC NE FLOW AND DRIER
AIR...WHICH IS BEING ADVECTED INTO THE UPPER LOW NEAR T.D.
TWELVE. A SECOND ELONGATED UPPER LEVEL LOW IS TO THE ENE OF THE
T.D. TWELVE...S OF THE RIDGE THAT EXTENDS FROM THE GULF...
CENTERED NEAR 27N60W WITH THE TROUGH AXIS ALONG 27N BETWEEN
50W-67W. THIS IS A WEAK LOW EMBEDDED WITH VERY DRY UPPER
AIR...THUS IT IS ONLY ABLE TO GENERATE SOME ISOLATED SHOWERS.
THE UPPER LOW NEAR 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 70W. AT THE UPPER LEVELS...A STRONG
HIGH IS IN THE CENTRAL ATLC NEAR 21N49W COVERING THE AREA FROM
40W-60W. STRONG SUBSIDENCE AND DRY AIR ALOFT COVERS THE SAME
AREA FROM THE ITCZ TO 30N. 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. AN UPPER LOW IS CENTERED NW OF THE CANARY
ISLANDS NEAR 32N21W WITH FLOW EXTENDING S TO 28N E OF 28W. AS
THERE IS DRY AIR ALOFT OVER MOST OF THE AREA...CONVECTION OR
SHOWER ACTIVITY CAN NOT BE MAINTAINED.

$$
WALLACE



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