[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 130556
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE SEP 13 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 FEATURE...

TROPICAL STORM OPHELIA IS CENTERED NEAR 31.9N 77.9W...OR 122 NM
ESE OF CHARLESTON SOUTH CAROLINA AND 178 NM SSW OF CAPE HATTERAS
NORTH CAROLINA...AT 13/0600 UTC MOVING DRIFTING NW. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 990 MB. MAXIMUM SUSTAINED WIND SPEED
IS 60 KT WITH GUSTS TO 75 KT. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC AND THE PUBLIC
ADVISORY UNDER HEADERS MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS.
OPHELIA REMAINS OVER COOLER WATERS AND THE ENTRAINMENT OF DRY
AIR FROM OFF THE CONTINENT NOW HAS THE DEEP CONVECTION OFFSHORE
TO THE E OF THE CENTER. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 30/45 NM OF LINE 30N77.5W 32N76.5W
33.5N78W. OUTER RAINBANDS WITH SHOWERS/THUNDERSTORMS ARE FROM
29N-35N BETWEEN 75W-80W AND ARE MOVING ACROSS THE OUTER BANKS OF
NORTH CAROLINA ON THE SOUTH END OF PAMLICO SOUND AND JUST OFF
THE COAST OF SOUTH CAROLINA S TO CHARLESTON.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE ALONG 33W S OF 15N MOVING W 5-10 KT.
LOW-LATITUDE WAVE EMBEDDED WITHIN A COPIOUS AMOUNT OF TROPICAL
MOISTURE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 75 NM OF THE AXIS FROM 12N-15N AND WITHIN 90 NM OF THE
AXIS FROM 4N-7N.

CENTRAL ATLC TROPICAL WAVE TILTED ALONG 8N48W 15N47W 21N44W
MOVING W 10-15 KT. WAVE CONTINUES TO BE SURROUNDED BY DRY
SAHARAN AIR/DUST WITH SIGNATURE CURVATURE OBSERVED IN THE LOW
CLOUD FIELD.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 77W S OF 20N MOVING W
15-20 KT. WAVE IS COLLOCATED WITH AN INVERTED UPPER LEVEL TROUGH
WHICH IS MOVING W FROM THE WINDWARD PASSAGE TO OVER JAMAICA AND
E CUBA...BUT THE LOW-LEVEL CIRCULATION IS WEAK AND HARD TO
DISTINGUISH. SLIGHT CURVATURE IS NOTED OVER THE S BAHAMAS N OF E
CUBA. ASSOCIATED SHOWERS/CONVECTION HAS DISSIPATED OVER THE PAST
6 HOURS.

TROPICAL WAVE OVER THE S MEXICO ALONG 92W/93W S OF 25N MOVING NW
10 KT. SIGNATURE CURVATURE WAS OBSERVED IN THE LOW CLOUD FIELD
PRIOR TO BEING OVERRUN BY HIGH CIRRUS IN THE LAST COUPLE OF
HOURS. WAVE IS ALSO LOCATED FAIRLY CLOSE TO AN UPPER LEVEL
TROUGH THOUGH OVER THE W BAY OF CAMPECHE TO THE E. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION OVER THE CENTRAL BAY OF
CAMPECHE S OF 20N FROM 92W-95W ARE LIKELY AIDED BY THIS WAVE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N13W 8N21W 9N31W...THEN ALONG
10N35W 12N45W...THEN ALONG 10N50W 10N59W. SCATTERED MODERATE/
STRONG CONVECTION IS MOVING OFF SW AFRICA FROM 5N-12N E OF 17W
TO JUST INLAND OVER SIERRA LEONE TO GUINEA BISSAU. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION DOT THE AREA
AROUND THE ITCZ FROM 1N TO THE ITCZ AXIS BETWEEN 17W-39W AND
FROM 8N-15N BETWEEN 34W-45W.

...DISCUSSION...

GULF OF MEXICO...
TROPICAL STORM OPHELIA CONTINUES TO MEANDER JUST OFF THE
SOUTHEAST COAST OF THE UNITED STATES AND HAS BEEN BRINGING DRIER
CONTINENTAL AIR OVER FLORIDA N OF LAKE OKEECHOBEE AND THE FAR NE
GULF WATERS. MOISTURE IS MORE CONCENTRATED OVER THE S GULF BUT
STILL THE SHOWER/THUNDERSTORM ACTIVITY IS LIMITED TO THE BAY OF
CAMPECHE. AN UPPER LOW WITH A STRONG SUBSIDENCE ENVIRONMENT IS
CENTERED NEAR 27N92W DRIFTING TOWARDS THE TEXAS COAST. AN UPPER
LEVEL HIGH IS CENTERED NEAR THE YUCATAN CHANNEL WITH A SHARP
RIDGE AXIS N OVER THE E GULF TO THE FLORIDA PANHANDLE SUPPLYING
TROPICAL MOISTURE OVER THE AREA. AT THE SURFACE...A 1017 MB HIGH
IS OFF THE W FLORIDA PANHANDLE NEAR 30N87W. MOISTURE AND SHOWERS
WILL REMAIN FOCUSED OVER THE S AND W GULF OVER THE NEXT FEW
DAYS...AND THE NE GULF WILL REMAIN POSITIONED IN THE DRY REGIME
SW OF OPHELIA.

CARIBBEAN...
AN UPPER LEVEL HIGH IS CENTERED NEAR THE YUCATAN CHANNEL WITH A
SHARP RIDGE AXIS EXTENDING S TO JUST N OF E PANAMA. UPPER
DIFFLUENCE IS LOCATED ON THE W SIDE OF THE HIGH AND IS PRODUCING
SCATTERED CLUSTERS OF SHOWERS/ISOLATED THUNDERSTORMS FROM CANCUN
SE OVER HONDURAS AND NICARAGUA. THE NE FLOW ON THE E SIDE OF THE
HIGH IS DRIVING DRIER AIR S TO CUBA AND HAS PUSHED THE STRONGEST
CONVECTION S OF 13N BETWEEN COLOMBIA AND NICARAGUA. AN UPPER
TROUGH EXTENDS FROM THIS AREA OF CONVECTION NE TO THE HAITI WITH
E FLOW FEEDING INTO THE TROUGH BRINGING MORE DRY AIR IN FROM THE
CENTRAL ATLC WATERS ACROSS THE E CARIBBEAN. A SMALL PATCH OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE LESSER
ANTILLES SAINT LUCIA TO ANGUILLA. CARIBBEAN WILL REMAIN
RELATIVELY DRY FOR THE REMAINDER OF THE WEEK EXCEPT IN THE SW
FROM COLOMBIA TO CENTRAL AMERICA.

ATLANTIC...
TROPICAL STORM OPHELIA IS CENTERED JUST N OF THE AREA OFF THE
SOUTH CAROLINA COAST AND IS DRAGGING DRY AIR ACROSS FLORIDA AND
THE N BAHAMA ISLANDS. A STRONG UPPER LEVEL TROUGH THAT DUG S
JUST TO THE E OF OPHELIA REMAINS N OF 25N AND HAS BEGUN TO PUSH
EASTWARD BETWEEN 38W-60W. THIS HAS PUSHED A COLD FRONT THROUGH
THE AREA ALONG 32N41W TO 25N49W THEN DISSIPATES ALONG 23N56W TO
27N62W. A SURFACE TROUGH PRECEDES THIS FRONT FROM 31N36W TO
24N47W WITH SCATTERED MODERATE CONVECTION WITHIN 60 NM OF THE
TROUGH BETWEEN 22N-29N. A MID/UPPER LEVEL LOW IS LOCATED OVER
THE CENTRAL TROPICAL ATLC NEAR 20N47W AND IS PUTTING MODERATE SW
SHEAR OVER THE TROPICAL WAVE NEAR 46W...PUSHING ALL THE SHOWER
ACTIVITY FARTHER E. FARTHER E...A STATIONARY UPPER TROUGH IS
DIGGING SW PAST SPAIN/PORTUGAL DOWN ACROSS THE CANARY ISLANDS
WITH A WEAK JET RACING NE ACROSS WESTERN SAHARA AND MOROCCO
BECOMING STRONGER INTO THE MEDITERRANEAN SEA. AN UPPER LEVEL
RIDGE HAS BUILT IN FROM N TO S ALONG 35W AND IS PUSHING DRIER
AIR S ACROSS THE CAPE VERDE ISLANDS...VIRTUALLY LIMITING DEEP
CONVECTION TO S OF THE ITCZ E OF 30W.

$$
WALLACE


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