[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131157
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURE...

TROPICAL STORM OPHELIA IS CENTERED NEAR 32.2N 77.8W...OR 125 NM
S OF WILMINGTON NORTH CAROLINA...AT 13/1200 UTC MOVING NNW 3 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 989 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. ALTHOUGH OPHELIA REMAINS OVER COOLER WATER THE
ASSOCIATED DEEP CONVECTION OFFSHORE E OF THE CENTER HAS
INCREASED SLIGHTLY OVER THE LAST 6 HOURS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF LINE
30N77W 32N76W 33.5N78W. THE OUTER RAINBANDS HAVE TIGHTENED OVER
THE PAST 6 HOURS AS WELL. SHOWERS/THUNDERSTORMS ARE FROM
28.5N-34N BETWEEN 74.7W-80W AND ARE CONFINED TO SOUTH CAROLINA
COAST.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE ALONG 34W 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 LINE FROM 10N36.5N TO 14N33W AND ALONG THE ITCZ
AXIS.

CENTRAL ATLC TROPICAL WAVE IS TILTED ALONG 8N50W 16N47W 22N45W
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 78W/79W S OF 20N MOVING W
15 KT. WAVE IS COLLOCATED WITH A DEVELOPING UPPER LOW FROM THE
INVERTED UPPER LEVEL TROUGH WHICH IS MOVING W FROM THE WINDWARD
PASSAGE SW TO THE SW CARIBBEAN NEAR 13N80W...BUT THE LOW-LEVEL
CIRCULATION IS WEAK AND HARD TO DISTINGUISH. SLIGHT CURVATURE IS
NOTED OVER THE S BAHAMAS. SCATTERED SHOWERS/THUNDERSTORMS ARE
FROM 17N-20N BETWEEN 74W-82W INCLUDING JAMAICA.

TROPICAL WAVE OVER THE GULF OF MEXICO AND S MEXICO ALONG 93W/94W
S OF 25N MOVING NW 10 KT. SIGNATURE CURVATURE WAS OBSERVED IN
THE LOW CLOUD FIELD. WAVE IS ALSO LOCATED FAIRLY CLOSE TO AN
UPPER LEVEL TROUGH THOUGH OVER THE W BAY OF CAMPECHE. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE BAY OF CAMPECHE S OF
21N W OF 93W ARE LIKELY AIDED BY THIS WAVE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N15W 6N31W 10N46W 11N62W.
SCATTERED MODERATE/STRONG CONVECTION HAS MOVED OFF SW AFRICA S
OF THE ITCZ AXIS WITHIN THE POINTS 6N12W-6N22W-10N17W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF THE AXIS
FROM 33W-37W AND WITHIN A 60/75 NM RADIUS OF 4N31W. CLUSTERS OF
SCATTERED MODERATE CONVECTION DOT THE AREA WITHIN 200/250 NM S
OF THE ITCZ AXIS FROM 22W-39W AND N OF THE ITCZ AXIS TO 16N
BETWEEN 37W-45W.

...DISCUSSION...

GULF OF MEXICO...
TROPICAL STORM OPHELIA CONTINUES TO MEANDER JUST OFF THE
SOUTHEAST COAST OF THE UNITED STATES AND CONTINUES TO BRING
DRIER CONTINENTAL AIR ACROSS FLORIDA N OF LAKE OKEECHOBEE.
MOISTURE IS MORE CONCENTRATED OVER THE S GULF BUT STILL THE
SHOWER/THUNDERSTORM ACTIVITY IS LIMITED TO THE BAY OF CAMPECHE.
A WEAKENING UPPER LOW WITH A STRONG SUBSIDENCE ENVIRONMENT IS
CENTERED NEAR 26N92W. AN UPPER LEVEL HIGH IS CENTERED JUST N OF
THE YUCATAN CHANNEL WITH A RIDGE AXIS N TO OVER THE NE GULF AND
THE E FLORIDA PANHANDLE SUPPLYING TROPICAL MOISTURE OVER THE
AREA. AT THE SURFACE...A 1018 MB HIGH IS ALONG THE LOUISIANA
COAST NEAR 29N90W. MOISTURE AND SHOWERS WILL REMAIN FOCUSED MORE
OVER THE W GULF OVER THE NEXT COUPLE OF DAYS...AND THE NE GULF
WILL REMAIN POSITIONED IN A FAIRLY DRY REGIME SW OF OPHELIA.

CARIBBEAN...
AN UPPER LEVEL HIGH IS CENTERED JUST N OF THE YUCATAN CHANNEL
WITH A SHARP RIDGE AXIS EXTENDING S ACROSS CENTRAL AMERICA.
UPPER DIFFLUENCE IS LOCATED ON THE SW SIDE OF THE HIGH AND IS
PRODUCING SCATTERED CLUSTERS OF SHOWERS/ISOLATED THUNDERSTORMS
FROM CANCUN SE OVER HONDURAS. THE N TO NE FLOW ON THE E SIDE OF
THE HIGH IS KEEPING THE STRONGEST CONVECTION OVER THE BASE OF
THE DEVELOPING UPPER LOW. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE S OF 13N FROM COLOMBIA TO
NICARAGUA INCLUDING COSTA RICA. A DEVELOPING UPPER LOW EXTENDS
FROM THIS AREA OF CONVECTION NE TO THE WINDWARD PASSAGE WITH E
FLOW FEEDING INTO THE TROUGH BRINGING SOME DRY AIR IN FROM THE
CENTRAL ATLC WATERS ACROSS THE E CARIBBEAN. A SMALL AREA OF
SCATTERED SHOWERS/THUNDERSTORMS MOVED ACROSS THE LESSER ANTILLES
DURING THE NIGHT AND IS NOW WITHIN 90 NM OF LINE FROM THE
WINDWARD ISLANDS NEAR 13N62W TO S OF THE MONA PASSAGE NEAR
17N68W. 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 CONTINUES TO DRAW DRY AIR ACROSS
FLORIDA AND THE NORTHERN MOST BAHAMA ISLANDS. A STRONG UPPER
LEVEL TROUGH TO THE E OF OPHELIA REMAINS N OF 24N PUSHING E
BETWEEN 36W-62W. THIS HAS PUSHED THE COLD FRONT THROUGH THE AREA
TO ALONG 32N40W TO 24N52W THEN DISSIPATES ALONG 23N56W TO
25N62W. THIS FRONT IS OVERTAKING THE SURFACE TROUGH THAT
PRECEDES IT FROM 31N37W TO 23N49W WITH SCATTERED
SHOWERS/THUNDERSTORMS WITHIN 90 NM OF LINE FROM 22N57W 26N45W TO
32N35W. WEAKENING MID/UPPER LEVEL LOW IS LOCATED OVER THE
CENTRAL TROPICAL ATLC NEAR 20N46W AND IS PUTTING WEAK/MODERATE
SW SHEAR OVER THE TROPICAL WAVE NEAR 48W...PUSHING ALL THE
SHOWER ACTIVITY FARTHER E. OVER THE NE ATLC...A STATIONARY UPPER
TROUGH REMAINS...EXTENDING 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/BERG



This weather bulletin was brought to you by:
www.nashvilleweather.net