[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151230
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU SEP 15 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 1015 UTC.

...SPECIAL FEATURE...

HURRICANE OPHELIA IS CENTERED NEAR 34.8N 75.9W AT 15/1200 UTC...
OR ABOUT 30 NM EAST-NORTHEAST OF CAPE LOOKOUT NORTH CAROLINA AND
ABOUT 40 NM SOUTHWEST OF CAPE HATTERAS NORTH CAROLINA...MOVING
NE AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB.
MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 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 CONTINUES TO
HUG THE COAST OF NORTH CAROLINA THIS MORNING AND LOOKS TO
CONTINUE THIS TREND FOR A GOOD PART OF THE DAY. A MID/UPPER
TROUGH MOVING NE OVER NEW ENGLAND CONTINUES TO DISRUPT THE
OUTFLOW FORMING W SHEAR OVER OPHELIA. HOWEVER...HEAVY
SHOWERS/ISOLATED THUNDERSTORMS REMAIN ALONG THE COASTAL PLAINS
OF NORTH CAROLINA E OF RALEIGH BETWEEN JACKSONVILLE AND
ELIZABETH CITY. OVER WATER THE ACTIVITY COVERS THE AREA FROM
33N-37N W OF 73W TO INLAND OVER NORTH CAROLINA.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 21W/22W S OF 17N MOVING W
10-15 KT. WAVE IS ON THE TRAILING EDGE OF AN UPPER TROUGH
THAT CONTAINS DRY AIR AND SAHARAN DUST. CLUSTERS OF SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION DOT THE AREA FROM
6N-15N BETWEEN 19W-25W.

CENTRAL ATLC TROPICAL WAVE IS ALONG 45W/46W S OF 15N MOVING
W 10-15 KT WITH A 1009 MB LOW ALONG THE WAVE NEAR 9N. BROAD
CURVATURE IS OBSERVED ON INFRARED SATELLITE IMAGERY. WAVE IS
ALSO EMBEDDED IN A COPIOUS AMOUNT OF TROPICAL MOISTURE PRODUCING
A LARGE AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
WITHIN 150 NM OF LINE 7.5N46.5W TO 14N41.5W.

W ATLC TROPICAL WAVE IS ALONG 55W/56W S OF 18N MOVING
W 10-15 KT. WAVE CONTINUES TO DISPLAY A WELL-DEFINED AND SHARP
CURVATURE AND IS EMBEDDED WITHIN VERY DRY AIR BENEATH AN UPPER
RIDGE WITH SW WINDS PUSHING SHOWER ACTIVITY E OF THE WAVE AXIS.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60 NM OF
LINE 15N53W-20N54W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N16W 15N20W THEN ALONG 10N24W
6N37W 9N43W THEN ALONG 12N48W 11N62W. SCATTERED MODERATE/STRONG
CONVECTION IS WITHIN 120 NM OF THE ITCZ AXIS FROM 27W-34W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 45 NM OF
17.5N E OF 18W TO INLAND OVER MAURITANIA AFRICA AND WITHIN 60 NM
OF THE ITCZ AXIS FROM 47W-50. CLUSTERS OF SIMILAR CONVECTION ARE
FROM 2N-9N BETWEEN 32W-43W.

...DISCUSSION...

GULF OF MEXICO...
STRONG MID/UPPER RIDGE EXTENDS FROM AN UPPER HIGH OVER N CENTRAL
MEXICO E ACROSS S TEXAS INTO THE GULF NEAR CORPUS CHRISTI TO
NEAR 30N86W. THIS IS BRINGING DRY CONTINENTAL AIR OVER THE N
GULF N OF AN UPPER LEVEL SHEAR AXIS THAT EXTENDS FROM TAMPA
FLORIDA TO NEAR TAMPICO MEXICO. A MID/UPPER LEVEL HIGH IS W OF
THE BAY OF CAMPECHE OVER MEXICO NEAR 18N98W. DIFFLUENCE OVER THE
BAY OF CAMPECHE IS GENERATING SHOWERS/THUNDERSTORMS INLAND OVER
S MEXICO AND ALONG THE W COAST OF THE BAY OF CAMPECHE...BUT DUE
TO THE DRY AIR OVER THE GULF ONLY ISOLATED SHOWERS ARE ABLE TO
FORM THE SW GULF. A 1017 MB HIGH IS IN THE NE GULF NEAR 28N87W.
THE GULF WILL REMAIN DRY THROUGH A MAJOR PORTION OF THE WEEKEND.

CARIBBEAN...
THE UPPER LEVEL FLOW OVER THE CARIBBEAN CONTINUES TO BE
DOMINATED BY AN UPPER LOW CENTERED SW OF JAMAICA NEAR 17N80W.
THE DEEPEST MOISTURE REMAINS LOCATED OVER THE SW CARIBBEAN WHERE
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE S
OF 11N FROM OVER COLOMBIA TO CENTRAL AMERICA. ELSEWHERE...THERE
ARE SOME PATCHES OF UPPER MOISTURE MOVING AROUND THE UPPER LOW
WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 125 NM
OF LINE FROM 17N75W-21N85W INCLUDING JAMAICA. A SURFACE TROUGH
EXTENDS ACROSS E PUERTO RICO INTO THE E CARIBBEAN ALONG 16N68W
TO 15N72W. SCATTERED SHOWERS DOT THE AREA WITHIN 120 NM OF THE
TROUGH. AN UPPER INVERTED TROUGH EXTENDS FROM CENTRAL VENEZUELA
TO THE LEEWARD/VIRGIN ISLANDS DRAWING DRY AIR OVER THE SE
CARIBBEAN...THE WINDWARD ISLANDS...AND A PORTION OF THE LEEWARD
ISLANDS.

ATLANTIC...
HURRICANE OPHELIA CONTINUES TO DRAW DRY CONTINENTAL AIR ACROSS
NE FLORIDA TO S OF THE SYSTEM. AN UPPER RIDGE EXTENDS FROM NEAR
OPHELIA S TO THE S/CENTRAL BAHAMAS. DEEP LAYERED MID-LATITUDE
TROUGH OVER THE CENTRAL ATLC IS JUST TO THE E. THE UPPER LEVEL
TROUGH NOW EXTENDS THROUGH 32N47W SW TO 23N66W AS THE UPPER
RIDGE TO THE S BUILDS NORTHWARD. THE ATTENDANT STATIONARY FRONT
EXTENDS THROUGH 32N42W TO 25N51W WHERE A SURFACE TROUGH
CONTINUES ALONG 22N61W ACROSS E PUERTO RICO NEAR 18N66W.
DIFFLUENCE CONTINUES TO GENERATE CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION 90/120 NM EITHER SIDE OF THE
FRONT/TROUGH E OF 58W AND WITHIN 120/150 NM EITHER SIDE OF THE
TROUGH FROM 58W-64W. SCATTERED SHOWERS ARE WITHIN 120 NM OF
SURFACE TROUGH W OF 64W INTO THE CARIBBEAN. DRY UPPER AIR AND
STRONG SUBSIDENCE ARE N OF THE CONVECTION TO 30N BETWEEN 47W-60W
AND N OF 25N BETWEEN 60W-67W. AN UPPER HIGH IS DEEP IN THE
TROPICS NEAR THE LOW/TROPICAL WAVE ALONG 46W WITH ANTICYCLONIC
FLOW COVERING THE AREA S OF 23N BETWEEN 28W-60W. THIS RIDGE IS
PROVIDING THE UPPER LEVEL DIFFLUENCE GENERATING THE
SHOWERS/CONVECTION ASSOCIATED WITH THE FRONT/SURFACE TROUGH. AN
UPPER TROUGH OVER THE E ATLC OFF THE AFRICAN COAST HAS BEGUN TO
RETREAT N FROM AN UPPER LOW OFF THE COAST OF PORTUGAL THROUGH
THE CANARY ISLANDS TO JUST S OF THE CAPE VERDE ISLANDS NEAR
14N27W.

$$
WALLACE



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