[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 050537
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI AUG 05 2005

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

TROPICAL STORM HARVEY IS CENTERED NEAR 32.5N 60.1W...OR ABOUT
240 NM E OF BERMUDA...AT 05/0300 UTC MOVING ENE AT 10 KT.
MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. THE STROM APPEARS TO BE UNDERGOING INCREASE SW
SHEAR AND WITH A DEEP LAYERED TROUGH TO THE NNE OF HARVEY...A
DECREASE IN FORWARD SPEED IS EXPECTED OVER THE NEXT 24 HOURS.
CONVECTION IS NE OF THE CENTER WITHIN 75 NM OF LINE
33N59W-36N58W.

TROPICAL DEPRESSION NINE IS CENTERED NEAR 13.0N 35.2W...OR ABOUT
640 NM W OF THE SOUTHERNMOST CAPE VERDE ISLANDS...AT 05/0300 UTC
MOVING W AT 11 KT. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH
GUSTS TO 35 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. THE CENTER OF T.D. NINE
IS EMBEDDED WITHIN A BROAD ENVELOPE OF CLOUDINESS WHICH IS
SPLITTING OFF FROM THE ITCZ AND REMAINS FAIRLY UNORGANIZED. T.D.
NINE IS ON THE S SIDE OF AN UPPER RIDGE AND SHOULD REMAIN FOR
THE DAY COUPLE OF DAYS. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS 11.5N-15N BETWEEN 34.5W-37W.

...TROPICAL WAVES...

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 77W/78W S OF 15N MOVING W
10 KT. WAVE POSITION IS BASED ON CONTINUITY DUE TO NO SIGNATURE
IN THE SATELLITE IMAGERY. NO ASSOCIATED DEEP CONVECTION.

TROPICAL WAVE INLAND OVER THE YUCATAN PENINSULA ALONG 89W/90W S
OF 21N MOVING W 10-15 KT. SIGNATURE CURVATURE IS NOT WELL
DEFINED IN THE ATLC BASIN BEING OVER LAND BUT IS CLEARLY DEFINED
IN THE E PACIFIC REGION. CONVECTION ASSOCIATED WITH THIS WAVE IS
MOVING INTO THE BAY OF CAMPECHE WITH SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS S OF 21NE OF 93W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N14W 11N20W 16N32W...THEN ALONG
10N37W 9N41W 10N49W 7N60W. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 6N-14N E OF 22W TO INLAND
OVER AFRICA. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM
5N-11N BETWEEN 31W-50W.

...DISCUSSION...

GULF OF MEXICO...
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS CONTINUE ACROSS THE N
GULF. A WEAK 1015 MB SURFACE LOW IS CENTERED JUST OFF THE
MISSISSIPPI DELTA WITH A TROUGH EXTENDING E TO 29N85W AND SW IN
THE CENTRAL GULF NEAR 25N91W. IN THE UPPER LEVELS...NEAR
STATIONARY MID/UPPER TROUGH COVERS THE N GULF N OF 24N W OF 84W.
THIS IS MAKING THE ATMOSPHERE MORE UNSTABLE A TRIGGERING THE
SHOWER/THUNDERSTORM ACTIVITY. THE UPPER FLOW IS PRIMARILY W/SW S
OF THE TROUGH...WHICH IS ADVECTING ADDITIONAL UPPER LEVEL
MOISTURE OVER THE AREA FROM THUNDERSTORMS OVER MEXICO. THE
ATMOSPHERE IS EXPECTED TO REMAIN QUITE WET OVER THE GULF AT
LEAST THROUGH EARLY NEXT WEEK...AND WILL SUPPORT CONTINUED
SHOWERS/THUNDERSTORMS ESPECIALLY OVER THE N GULF AND THE BAY
OF CAMPECHE NEAR TROPICAL WAVE.

CARIBBEAN...
BROAD MID/UPPER HIGH IN THE E PACIFIC EXTENDS A RIDGE INTO THE
SW CARIBBEAN ALONG 12N W OF 75W. BROAD MID/UPPER LEVEL CUT-OFF
LOW IS IN THE E CARIBBEAN NEAR 15N64W WITH CYCLONIC FLOW
COVERING THE AREA E OF 70W ACROSS THE LESSER ANTILLES AND IS
PROVIDING DRY AIR THAT COVERS MOST OF THE CARIBBEAN FROM THE
LESSER ANTILLES TO 80W AND IS SERIOUSLY LIMITING CONVECTION OR
SHOWER ACTIVITY. IN THE CENTRAL CARIBBEAN...A SHARP UPPER TROUGH
EXTENDS FROM CENTRAL CUBA TO SE OF JAMAICA WITH DIFFLUENCE TO
THE W OF THE TROUGH AXIS GENERATING SCATTERED THUNDERSTORMS N OF
19N TO OVER W CUBA BETWEEN THE CAYMAN ISLANDS AND THE YUCATAN
CHANNEL. DIFFLUENCE FROM THE UPPER RIDGE IN THE E PACIFIC TO THE
SW CARIBBEAN IS ENHANCING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS PRIMARILY OVER LAND AREAS OF CENTRAL AMERICA AND
IN THE SW S OF 14N W OF 80W. MOISTURE VALUES MAY INCREASE
SLIGHTLY OVER THE NEXT SEVERAL DAYS OVER THE ENTIRE AREA...BUT
THE CONVECTIVELY ACTIVE AREA WILL REMAIN OVER THE SW CARIBBEAN
REGION.

ATLANTIC...
SMALL...WEAK UPPER LEVEL HIGH IS LOCATED BETWEEN THE TURKS/
CAICOS ISLANDS  AND HISPANIOLA NEAR 20N71W AND LIES ON THE S
SIDE OF THE WESTERLIES WHICH RUN E OF THE GEORGIA/CAROLINA
COAST. THIS FLOW IS PUSHING T.S. HARVEY OUT OF THE AREA JUST
AHEAD OF A SHORTWAVE TROUGH WHICH IS ALONG 32N66W-27N65W. A
SURFACE TROUGH SW OF HARVEY WHICH EXTENDS FROM 27N68W TO A WEAK
1015 MB LOW NEAR 28N76W TO THE COAST OF FLORIDA NEAR 28N80W IS
PRODUCING SCATTERED SHOWERS/THUNDERSTORMS WITHIN 90 NM OF THE
TROUGH AXIS W OF 70W. A SECOND AREA OF SCATTERED THUNDERSTORMS
ARE ALONG A SECOND SURFACE TROUGH EXTENDING FROM 30N59W 25N66W
TO THE BAHAMAS NEAR 23N73W NEAR THE NOSE OF THE SUBTROPICAL
RIDGE. A SMALL MID/UPPER LOW IS LOCATED NEAR 29N42W AND IS NO
LONGER CONNECTED TO THE MUCH LARGER UPPER IN THE E CARIBBEAN IS
PRODUCING A DRY AND MODERATE/STRONG SUBSIDENCE ENVIRONMENT ALOFT
OVER THE CENTRAL ATLC. UPPER LEVEL RIDGING DOMINATES THE E ATLC
FROM ABOUT THE CAPE VERDE ISLANDS NW TO 32N32W. A FLAT UPPER
HIGH LIES JUST N OF T.D. NINE NEAR 19N32W AND IS PLACING
EASTERLY FLOW OVER THE DEPRESSION...BUT THE TRADES ARE ACTUALLY
DEEP ENOUGH FOR SHEAR VALUES TO BE QUITE LOW AND CONDUCIVE FOR
DEVELOPMENT. THE LAST VISIBLE SATELLITE IMAGERY INDICATES THAT
THE SAHARAN DUST IS LOCATED S OF 25N AND IS COVERING T.D.
NINE...BUT THE SYSTEM APPEARS ABLE TO SUSTAIN ITSELF BY
ENTRAINING MOIST AIR FROM THE S.

$$
WALLACE


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