[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 160559
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI SEP 16 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 34.7N 74.8W...OR 48 NM
SE OF CAPE HATTERAS NORTH CAROLINA...AT 16/0600 UTC DRIFTING
NORTHWARD. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM
SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 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. AFTER BATTERING THE NORTH CAROLINA COAST FOR
WELL OVER 24 HOURS...OPHELIA HAS GRADUALLY MOVED OFF THE COAST.
OUTER RAINBANDS CONTINUE MOVING ACROSS THE OUTER BANKS ACROSS
PAMLICO SOUND WITH FEWER THUNDERSTORMS. SMALL AREA OF SCATTERED
MODERATE/STRONG CONVECTION IS NE OF THE CENTER WITHIN A 30/45 NM
RADIUS OF 35N74W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER
THE AREA FROM 33N-37N BETWEEN 72W-75W.

W/CENTRAL ATLC TROPICAL WAVE IS TILTED SW/NE ALONG 6N50W 14N48W
21N46W MOVING W 10 KT WITH A 1012 MB LOW ALONG THE NEAR 10N.
ALTHOUGH THE WAVE IS WELL DEFINED THE LOW LEVEL CENTER IS
ELONGATED ALONG THE WAVE AXIS AND RATHER ILL-DEFINED. WAVE IS
ROUNDING THE BASE OF AN UPPER LEVEL RIDGE WHICH WILL INCREASE
THE SHEAR SLIGHTLY AND IS MOVING INTO AN AREA OF MORE CONDUCIVE
TO TROPICAL DEVELOPMENT. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS W OF THE LOW FROM 9N-12.5N BETWEEN 49.5W-53.5W AND
E OF THE WAVE FROM 15N-18.5N BETWEEN 41W-46W.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALSO TILED SLIGHTLY SW/NE FROM THE CAPE
VERDE ISLANDS NEAR 18N24W TO 5N26W WITH A WEAK 1013 MB LOW ALONG
THE WAVE NEAR 13N. WAVE IS BENEATH A NARROW UPPER TROUGH WHICH
CONTAINS DRY AIR AND SAHARAN DUST N OF 10N. THUS...SCATTERED
STRONG CONVECTION IS S OF THE LOW FROM 7N-9.5N BETWEEN
23W-26.5W.

W ATLC TROPICAL WAVE IS ALONG 58W/59W S OF 20N MOVING W 10 KT. N
PORTION OF THE WAVE IS BEING DRAWN NW INTO THE AREA OF WEATHER N
OF PUERTO RICO AND THE VIRGIN ISLANDS. WAVE REMAINS IN A
RELATIVELY DRY ATMOSPHERE AND IS UNABLE TO SUSTAIN ANYTHING MORE
THAN ISOLATED SHOWERS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N16W 13N23W THEN ALONG 11N28W
8N36W TO 12N46W BECOMING ILL DEFINED ACROSS THE REMAINDER OF THE
ATLC. SCATTERED MODERATE WITH EMBEDDED CLUSTERS OF
SCATTERED/NUMEROUS STRONG CONVECTION COVER THE AREA WITHIN 100
NM OF THE ITCZ AXIS BETWEEN 31W-42W. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 120 NM ALONG THE
COAST OF AFRICA FROM 7N-15N AND FROM 3N-13N BETWEEN 20W-50W.

...DISCUSSION...

GULF OF MEXICO...
STRONG BROAD MID/UPPER RIDGE EXTENDS FROM AN UPPER HIGH OVER N
CENTRAL MEXICO ACROSS S TEXAS INTO THE GULF BETWEEN CORPUS
CHRISTI AND BROWNSVILLE TO THE SE LOUISIANA COAST NEAR 29N90W.
THIS CONTINUES TO BRING DRY CONTINENTAL AIR OVER THE W GULF W OF
94W. AN UPPER LEVEL SHEAR AXIS IS BEING CREATED BY A SECOND
UPPER RIDGE WITH THE HIGH ANCHORED OFF THE E COAST OF FLORIDA.
THE SHEAR AXIS IS FROM THE FLORIDA PANHANDLE NEAR PANAMA CITY
SSW INTO THE BAY OF CAMPECHE NEAR 18N93W. A 1019 MB HIGH IS IN
THE N/CENTRAL GULF NEAR 27N47W. THE GULF WILL REMAIN DRY THROUGH
THE WEEKEND.

CARIBBEAN...
WEAKENING UPPER LOW IS CENTERED WSW OF JAMAICA NEAR 17N81W WITH
AN ELONGATED TROUGH EXTENDING FROM JAMAICA TO THE YUCATAN
PENINSULA. THE DEEPEST MOISTURE REMAINS LOCATED S OF THE TROUGH
WITH SCATTERED MODERATE/STRONG CONVECTION LOCATED JUST S OF THE
UPPER LOW WITHIN 75/90 NM OF 15N FROM 80W TO THE TIP OF
NICARAGUA/HONDURAS. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE
S OF 17N W OF 79W WITH THE STRONGEST THUNDERSTORMS IN THE GULF
OF HONDURAS INTO GUATEMALA. CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE N OF THE TROUGH AXIS FROM
17N-21N W OF 74W.  AN UPPER HIGH IN THE SW CARIBBEAN NEAR 12N76W
EXTENDS A RIDGE NE TO HISPANIOLA. DIFFLUENCE AT THE RIDGE APEX
IS GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION
INLAND OVER HISPANIOLA THEN MOVING S INTO THE CARIBBEAN N OF
17N. THE REMAINDER OF THE E CARIBBEAN IS DOMINATED BY AN UPPER
LOW N OF PUERTO RICO AND AN UPPER HIGH IN THE TROPICAL ATLC. DRY
AIR COVERS THE CARIBBEAN FROM 11N-16N E OF 75W ACROSS THE LESSER
ANTILLES.

WEST ATLANTIC...
TROPICAL STORM OPHELIA IS BEGINNING TO WEAKEN AND SHOWERS/
THUNDERSTORMS ARE BECOMING MORE DIFFUSED. THE UPPER RIDGE THAT
EXTENDS FROM NEAR OPHELIA S TO E CUBA IS HAVING A DRYING EFFECT
ON THE W ATLC AND ESPECIALLY THE BAHAMAS. A CUT-OFF UPPER LOW
HAS DEVELOPED FROM THE DEEP LAYERED TROUGH IN THE CENTRAL ATLC.
THE LOW IS CENTERED N OF PUERTO RICO NEAR 23N66W BRINGING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS TO PUERTO RICO AND THE
VIRGIN ISLANDS. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 19N-25N
BETWEEN 63W-69W ALIGNED WITH A SURFACE TROUGH ALONG 68W FROM
19N-24N. UPPER LEVEL TROUGH OVER THE CENTRAL ATLC IS NOW
DRIFTING EASTWARD N OF 25N FROM 40W-66W WITH A SHORTWAVE TROUGH
DIGGING S INTO THE REGION ALONG THE W SIDE. ATTENDANT SURFACE
TROUGH EXTENDS THROUGH 32N44W TO 23N59W AND A SECOND SURFACE
TROUGH...TIED TO THE SHORTWAVE EXTENDS FROM 31N51W 29N58W TO
30N64W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 20N-26N BETWEEN 57W-64W WITH SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM W OF THE SURFACE
TROUGH E OF 57W. A STRONG UPPER HIGH IS DEEP IN THE TROPICS NEAR
13N45W WITH A RIDGE WITH BROAD FLOW COVERING THE AREA S OF 22N
FROM 28W-65W PROVIDING A FAIRLY DECENT AMOUNT OF MOISTURE AND
DIFFLUENCE ASSOCIATED WITH THE TROPICAL WAVE ALONG 48W/50W. AN
UPPER TROUGH IN THE E ATLC IS DIGGING S ALONG 32N25W S PAST THE
CAPE VERDE ISLANDS TO NEAR 15N26W. A RIDGE IS BUILDING OVER
AFRICA AND WILL BE IN THE E ATLC WITHIN 24 HOURS.

$$
WALLACE






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