[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 042344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU AUG 04 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM HARVEY CENTERED NEAR 32.4N 61.8W...OR ABOUT 150
NM E OF BERMUDA...AT 04/2100 UTC MOVING ENE 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. HARVEY CONTINUES TO MOVE AWAY FROM BERMUDA AS IT IS
ADVECTED ALONG BY STRONGER MID-LATITUDE WESTERLY FLOW...BUT IT
HAS BEEN ABLE TO MAINTAIN DEEP CONVECTION DESPITE BEING ON THE
CUSP OF STRONGER SHEAR. NUMEROUS MODERATE/STRONG CONVECTION
WRAPS AROUND THE NRN AND WRN SEMICIRCLES FROM 31.5N-35N BETWEEN
58W-62W.

NEWLY-FORMED TROPICAL DEPRESSION NINE CENTERED NEAR 12.7N
34.5W...OR ABOUT 605 NM W OF THE SOUTHERNMOST CAPE VERDE
ISLANDS...AT 04/2100 UTC MOVING W 10 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 CYCLONIC ENVELOPE
OF CLOUDINESS WHICH IS BEGINNING TO SPLIT OFF FROM THE ITCZ. THE
CENTER OF CIRCULATION DOES APPEAR TO BE BECOMING MORE
ESTABLISHED NEAR THE MAIN CLUSTER OF DEEP CONVECTION...WHICH IS
SEPARATING FROM THE MORE SCATTERED ACTIVITY ALONG THE ITCZ.
NUMEROUS MODERATE CONVECTION IS FROM 12N-15N BETWEEN 34W-37W.
SCATTERED MODERATE IS ELSEWHERE FROM 7N-13N BETWEEN 30W-43W. LOW
SHEAR VALUES AND SUFFICIENTLY WARM OCEAN TEMPS WILL FOSTER
STEADY DEVELOPMENT OF THIS SYSTEM AS IT TREKS ACROSS THE
ATLC...BUT IT WILL BE ANOTHER 5 DAYS OR SO BEFORE IT BECOMES A
THREAT FOR THE ERN CARIBBEAN ISLANDS IF AT ALL.

...TROPICAL WAVES...

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 77W S OF 20N MOVING W 10
KT. THE WAVE'S LOCATION IS HIGHLY UNCERTAIN DUE TO NO SIGNATURE
IN SATELLITE IMAGERY. DEEP CONVECTION IS ALL OVER LAND...AS IT
USUALLY IS THIS TIME OF DAY.

TROPICAL WAVE MOVING INLAND ALONG THE YUCATAN AND BELIZE COAST
ALONG 88W S OF 21N MOVING W 10-15 KT. THERE IS SLIGHT INDICATION
OF THE WAVE IN VISIBLE IMAGERY WITH "PINCHING" IN THE CLOUD
FIELD NEAR COZUMEL...AND A MID-LEVEL CIRCULATION NOTED S OF EL
SALVADOR. SCATTERED MODERATE/STRONG CONVECTION IS OVER THE
YUCATAN SWD TO WRN HONDURAS FROM 13N-21N BETWEEN 87W-93W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 21N10W 13N20W 16N32W...THEN ALONG
10N32W 8N40W 10N50W 8N62W. SCATTERED MODERATE CONVECTION MOVING
OFF THE COAST OF AFRICA FROM 7N-16N BETWEEN 11W-20W. SCATTERED
MODERATE S OF 11.5N BETWEEN 58W-67W...PARTIALLY NEAR TRINIDAD
AND TOBAGO AND OVER ERN VENEZUELA.

...DISCUSSION...

GULF OF MEXICO...
WIDESPREAD SHOWERS/TSTMS HAVE DEVELOPED OVER THE NRN GULF WATERS
DURING THE DAY RESULTING FROM A NUMBER OF FACTORS. A WEAK 1016
MB SFC LOW IS LOCATED NEAR THE MISSISSIPPI DELTA WITH A TROF
EXTENDING EWD TO APALACHEE BAY...AND SWD TO THE CNTRL GULF. IN
ADDITION...A MID/UPPER TROF THAT IS NEARLY STATIONARY S OF
MOBILE ALABAMA IS MAKING THE ATMOSPHERE MORE UNSTABLE A
TRIGGERING SCATTERED MODERATE CONVECTION N OF 24N BETWEEN
87W-96W. THE UPPER FLOW IS PRIMARILY W/SWLY UNDERNEATH THE TROF
AND INTO FLORIDA...WHICH IS ADVECTING ADDITIONAL UPPER LEVEL
MOISTURE OVER THE AREA FROM TSTMS OVER MEXICO. THE ATMOSPHERE IS
EXPECTED TO REMAIN QUITE SOUPY OVER THE GULF AT LEAST THROUGH
EARLY NEXT WEEK...AND WILL SUPPORT CONTINUED SHOWERS/TSTMS
ESPECIALLY OVER THE NRN GULF AND THE BAY OF CAMPECHE NEAR TRPCL
WAVE.

CARIBBEAN...
EXCEPT FOR AREAS STRETCHING FROM CANCUN MEXICO SWD TO WRN
PANAMA...THE BULK OF THE CARIBBEAN IS ENJOYING MAINLY FAIR SKIES
AND TYPICAL SUMMERTIME TEMPERATURES. A SWATH OF DRY AIR HAS
OVERSPREAD MUCH OF THE AREA FROM THE LESSER ANTILLES WWD TO
ABOUT 80W AND IS SERIOUSLY LIMITING DEEP CONVECTION...OR ANY
TSTM ACTIVITY FOR THAT MATTER. IN ADDITION...A BROAD MID/UPPER
LEVEL LOW IS SPIRALING WWD ACROSS THE LESSER ANTILLES NEAR
15N62W AND IS PROVIDING A SUBSIDENT REGIME FOR VERY LITTLE
CLOUDINESS. FARTHER W...A SHARP UPPER TROF EXTENDS FROM THE
YUCATAN CHANNEL TO JUST W OF JAMAICA AND IS ALSO PROVIDING
ENOUGH SUBSIDENCE FOR VERY FEW TSTMS OVER THE AREA. HOWEVER...A
DIFFLUENT UPPER HIGH CENTERED JUST E OF COSTA RICA IS ENHANCING
TSTMS PRIMARILY OVER LAND AREAS OF CNTRL AMERICA...BUT A FEW
CLUSTERS HAVE BEEN LINGERING OFF THE NICARAGUAN COAST. DIURNAL
TSTM ACTIVITY HAS ALSO BEEN PROLIFIC OVER HISPANIOLA AND CUBA.
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...
AN UPPER LEVEL HIGH IS LOCATED NEAR THE TURKS AND CAICOS ISLANDS
NEAR 22N70W AND LIES ON THE S SIDE OF STRONG 40-50 KT WESTERLIES
WHICH RUN E OF THE GEORGIA/CAROLINA COAST. THIS FLOW IS KICKING
T.S. HARVEY OUT OF THE AREA JUST AHEAD OF A SHORTWAVE TROF WHICH
IS ALONG 32N67W 27N65W. A SFC TROF WHICH EXTENDS SW OF HARVEY IS
PRODUCING WIDELY SCATTERED MODERATE CONVECTION PRIMARILY FROM
26N-29N BETWEEN 69W-74W. A SECOND AREA OF WIDELY SCATTERED
MODERATE HAS FORMED S OF HARVEY FROM 23N-30N BETWEEN 59W-66W
NEAR THE NOSE OF THE SUBTROPICAL RIDGE. A SMALL MID/UPPER LOW IS
LOCATED NEAR 29N42W AND IS CONNECTED TO THE MUCH LARGER UPPER
LOW MOVING INTO THE E CARIBBEAN...AND BOTH ARE PRODUCING A DRY
AND SUBSIDENT ENVIRONMENT ALOFT OVER THE CNTRL 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
18N31W AND IS PLACING EASTERLY FLOW OVER THE DEPRESSION...BUT
THE TRADES ARE ACTUALLY DEEP ENOUGH FOR SHEAR VALUES TO BE QUITE
LOW (LESS THAN 20 KT) AND CONDUCIVE FOR DEVELOPMENT. VISIBLE
IMAGERY INDICATES THAT THE SAHARAN AIR LAYER AND ASSOCIATED DUST
IS LOCATED S OF 26N AND IS ENSHROUDING T.D. NINE...BUT THE
SYSTEM APPEARS ABLE TO SUSTAIN ITSELF BY ENTRAINING MOIST AIR
FROM THE S.

$$
BERG






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