[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 121114
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 12 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...SPECIAL FEATURES...

TROPICAL STORM FRED IS CENTERED NEAR 17.8N 33.6W AT 12/0900 UTC
OR ABOUT 560 NM WNW OF THE CAPE VERDE ISLANDS. FRED IS NOW
STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB.
MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. T.S. FRED HAS BEEN
SHEARED TONIGHT WITH A SMALL AREA OF SCATTERED MODERATE
CONVECTION WELL REMOVED FROM THE EXPOSED LOW LEVEL CENTER.
CONVECTION IS FROM 19N-21N BETWEEN 32W-35W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 22W S OF 1920N WITH A 1010 MB LOW ALONG
THE WAVE NEAR 12N MOVING W NEAR 10-15 KT. WAVE IS EMBEDDED
WITHIN A DEEP LAYERED MOISTURE MAXIMUM AS INDICATED BY THE TOTAL
PRECIPITABLE WATER IMAGERY AND CONVECTION IS NOW MORE
CONCENTRATED ALONG THE WAVE AXIS. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM OF LINE
FROM 10N20W TO OVER THE CAPE VERDE ISLANDS NEAR 15N23W.

TROPICAL WAVE IS ALONG 84W/85W S OF 20N MOVING W NEAR 15 KT.
WAVE REMAINS TO THE E OF THE DEEP LAYERED MOISTURE MAXIMUM AS
INDICATED BY THE TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED
SHOWERS/THUNDERSTORMS ARE WITHIN 45 NM OF LINE FROM 11N81W TO
17N84W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 14N15W 11N27W 11N35W 9N53W
9N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS INLAND
AND WITHIN 150 NM ALONG THE COAST OF W AFRICA FROM 9N-13N.
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF LINE FROM
9N17W TO 6N21W. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION
DOT THE AREA FROM 8N-12N BETWEEN 31W-46W AND FROM 9N-13N BETWEEN
55W-61W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS FROM THE W ATLC TO A WEAK 1013 MB LOW
OVER THE FLORIDA PENINSULA JUST N OF LAKE OKEECHOBEE INTO THE
GULF ALONG 27N85W ALONG 29N94W TO A 1008 MB LOW ALONG THE COAST
OF TEXAS BETWEEN CORPUS CHRISTI AND BROWNSVILLE. AN UPPER TROUGH
EXTENDS FROM THE DESERT SW OVER TEXAS/MEXICO ALONG THE RIO
GRANDE TO NEAR THE 1008 SURFACE LOW WHILE AN UPPER RIDGE EXTENDS
FROM VERACRUZ MEXICO TO NE FLORIDA. THIS SCENARIO COUPLED WITH
THE ABUNDANCE OF DEEP LAYER MOISTURE IS GENERATING
SCATTERED/HEAVY SHOWERS WITH SCATTERED/NUMEROUS THUNDERSTORMS
ACROSS THE W GULF S OF THE SURFACE TROUGH W OF 94W INTO THE BAY
OF CAMPECHE. SCATTERED/HEAVY SHOWERS WITH ISOLATED THUNDERSTORMS
OVER THE E GULF E OF A LINE FROM CUBA NEAR 23N84W TO LOUISIANA
NEAR 29N90W LEAVING ISOLATED SHOWERS ACROSS THE CENTRAL GULF.

CARIBBEAN SEA...
AN UPPER RIDGE COVERS THE W CARIBBEAN EXTENDING FROM COSTA RICA
TO W OF THE CAYMAN ISLANDS WHILE AN UPPER TROUGH COVERS THE E
CARIBBEAN EXTENDING FROM AN UPPER LOW N OF PUERTO RICO. EVEN
THOUGH THERE IS DIFFLUENCE ALOFT...THE SURFACE HAS BEGUN TO DRY
OUT OVER THE W CARIBBEAN LEAVING ISOLATED SHOWERS N OF 20N N OF
20N TO ACROSS CUBA BETWEEN 77W-83W. SCATTERED STRONG CONVECTION
ASSOCIATED THE ITCZ CROSSING THE SW CARIBBEAN FROM COLOMBIA AND
PANAMA IS S OF S OF 11N E OF 78W TO INLAND OVER COLOMBIA.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 10N TO INLAND
OVER PANAMA FROM 78W-82W. ISOLATED SHOWERS/THUNDERSTORMS
CONTINUE INLAND AND WITHIN 60 NM ALONG THE S COAST OF
HISPANIOLA. OTHERWISE THE E CARIBBEAN E OF 80W IS REMARKABLY
CLEAR THIS MORNING.

ATLANTIC OCEAN...
A SURFACE TROUGH ENTERS THE REGION THROUGH 32N74W EXTENDING SW
TO A 1013 MB LOW OVER THE FLORIDA PENINSULA JUST N OF LAKE
OKEECHOBEE AND INTO THE GULF OF MEXICO. DIFFLUENCE ALOFT FROM
THE UPPER RIDGE IN THE GULF OF MEXICO IS ENHANING SCATTERED
SHOWERS/THUNDERSTORMS FROM 26N-30N W OF 76W TO INLAND OVER THE
FLORIDA PENINSULA AND BETWEEN THE BAHAMAS AND CUBA FROM 76W-78W.
AN UPPER TROUGH DIPS S OVER THE W ATLC TO 23N BETWEEN 70W-77W
WITH WEAK COLD FRONT ENTERING THE REGION NEAR 32N69W TO 25N74W.
A NARROW UPPER RIDGE IS JUST TO THE E EXTENDING FROM HAITI TO
32N66W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED
SHOWERS/THUNDERSTORMS WITHIN 200 NM E OF THE FRONT AND WITHIN 75
NM W OF THE FRONT S OF 28N. AN UPPER LOW IS N OF PUERTO RICO
NEAR 23N65W WITH THE UPPER TROUGH DIPPING S OVER THE E CARIBBEAN
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 21N TO
INLAND OVER HISPANIOLA BETWEEN 69W-70W. A BROAD UPPER TROUGH
COVERS THE N/CENTRAL ATLC N OF 28N BETWEEN 35W-56W WITH THE
ASSOCIATED COLD FRONT ENTERING THE REGION NEAR 32N37W EXTENDING
SW ALONG 28N45W THEN W 28N52W THEN NW TO BEYOND 32N60W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90/120 NM
EITHER SIDE OF THE FRONTAL BOUNDARY. A WEAKENING UPPER LOW IS S
OF THE UPPER TROUGH/FRONT CENTERED NEAR 21N41W SUPPORTING A
SURFACE TROUGH THAT EXTENDS FROM 22N49W TO 15N51W WITH NO
SIGNIFICANT WEATHER. A BROAD UPPER RIDGE COVERS THE E ATLC FROM
THE TROPICS TO 30N ANCHORED NEAR 19N21W AND PROVIDING THE SLY
SHEAR OVER TROPICAL STORM FRED.

$$
WALLACE






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