[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 231741
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN SEP 23 2012

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

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

POST-TROPICAL CYCLONE NADINE WAS AGAIN UPGRADED TO TROPICAL
STORM NADINE AT 23/1500 UTC. TROPICAL STORM NADINE IS CENTERED
NEAR 30.6N 25.6W AT 23/1500 UTC OR ABOUT 450 NM S OF THE AZORES
MOVING W AT 2 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 986 MN.
MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUST TO 60 KT. PLEASE
SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 28N-34W BETWEEN 22W-28W.

...TROPICAL WAVES...

TROPICAL WAVE IS E OF THE LESSER ANTILLES EXTENDING FROM 15N51W
TO 10N55W MOVING W 15-20 KT. WAVE IS BETWEEN AN UPPER TROUGH THE
W AND AN UPPER RIDGE TO THE E. CONVECTION IS MORE ASSOCIATED
WITH THE ITCZ THAN THE WAVE ITSELF.

TROPICAL WAVE EXTENDS FROM THE SW GULF OF MEXICO NEAR 21N94W
ACROSS S MEXICO INTO THE E PACIFIC NEAR 18N95W MOVING W 10-15
KT. WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP MOISTURE THAT
COVERS THE S GULF OF MEXICO AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE S OF 20N E OF THE WAVE TO 91W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM A 1012 MB LOW OFF THE COAST OF
MAURITANIA NEAR 18N17W ALONG 10N24W TO 7N32W WHERE THE ITCZ
CONTINUES ALONG 6N38W TO E OF THE TROPICAL WAVE NEAR 11N53W THEN
RESUMES W OF THE WAVE NEAR 11N56W INTO THE SE CARIBBEAN TO
11N67W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 10N-13N BETWEEN 50W-56W...FROM 10N-15N
BETWEEN 56W-62W...AND FROM 11N-14N BETWEEN 62W-67W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE ASSOCIATED WITH THE 1012 MB
FROM 15N-19N E OF 20W TO INLAND OVER MAURITANIA...WITHIN 200 NM
S OF THE MONSOON TROUGH/ITCZ BETWEEN 19W-36W...WITHIN 90 NM N OF
THE ITCZ BETWEEN 36W-41W...AND WITHIN 60 NM EITHER SIDE OF THE
ITCZ BETWEEN 45W-50W.

...DISCUSSION...

GULF OF MEXICO...
BROAD DEEP LAYERED TROUGH REMAINS OVER THE E CONUS INTO THE NW
ATLC AND N GULF SUPPORTING A COLD FRONT THAT AT 23/1500 UTC
EXTENDS ACROSS JACKSONVILLE FLORIDA AND OVER THE FLORIDA
PANHANDLE ACROSS MOBILE ALABAMA TO N LOUISIANA. THIS FRONT IS
NOT CAUSING ANY SIGNIFICANT WEATHER. HOWEVER...A COUPLE OF
SURFACE TROUGHS ARE IMPACTING THE S GULF OF MEXICO. A SURFACE
TROUGH EXTENDS FROM GRAND BAHAMA ISLAND ACROSS EXTREME S FLORIDA
JUST N OF KEY WEST ALONG 25N82W TO N OF THE YUCATAN PENINSULA
NEAR 22N88W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS. A
SECOND SURFACE TROUGH EXTENDS ALONG THE COAST OF MEXICO FROM
LAGUNA MADRE TO 21N96W GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 21N-27N W OF 91W TO INLAND OVER MEXICO
ENHANCED BY AN UPPER RIDGE THAT EXTENDS ACROSS S MEXICO INTO THE
NW CARIBBEAN. THIS IS LEAVING THE REMAINDER OF THE GULF UNDER
MOSTLY CLEAR SKIES THIS AFTERNOON. TROPICAL WAVE WILL MOVE
ACROSS THE REMAINDER OF THE BAY OF CAMPECHE THROUGH TONIGHT AND
INLAND OVER MEXICO MON. WEAK COLD FRONT WILL MOVE ACROSS THE N
GULF THIS AFTERNOON THEN BECOME STATIONARY ACROSS THE CENTRAL
GULF BY TONIGHT. THE FRONT WILL GRADUALLY WASH OUT THROUGH WED
AS HIGH PRESSURE NE OF THE AREA GRADUALLY WEAKENS.

CARIBBEAN SEA...
AN UPPER RIDGE EXTENDS ACROSS S MEXICO AND THE YUCATAN PENINSULA
TO 19N80W ENHANCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N
OF 16N W OF 84W TO OVER THE YUCATAN AND THROUGH THE YUCATAN
CHANNEL. AN UPPER LOW IS OVER THE E CARIBBEAN NEAR 16N64W
EXTENDING AN UPPER TROUGH W TO 17N78W ENHANCING THE ACTIVITY
ASSOCIATED WITH THE ITCZ AXIS ACROSS THE SE CARIBBEAN. THE
MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N75W ACROSS S
NICARAGUA INTO THE E PACIFIC REGION NEAR 12N84W GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 75 NM EITHER
SIDE OF THE MONSOON TROUGH BETWEEN 75W-80W AND FROM THE MONSOON
TROUGH TO 14N W OF 80W TO INLAND OVER CENTRAL AMERICA. THIS IS
LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES
THIS AFTERNOON. FRESH TO STRONG TRADE WINDS WILL CONTINUE IN THE
SW CARIBBEAN THROUGH AT MON NIGHT BEFORE DIMINISHING. TROPICAL
WAVE E OF THE LESSER ANTILLES WILL ENTER THE E CARIBBEAN MON
NIGHT CONTINUING INTO THE CENTRAL CARIBBEAN WED AND THU.

ATLANTIC OCEAN...
BROAD DEEP LAYERED TROUGH REMAINS OVER THE E CONUS INTO THE NW
ATLC AND N GULF SUPPORTING A COLD FRONT THAT AT 23/1500 UTC
EXTENDS INTO THE DISCUSSION AREA NEAR 32N79W ACROSS JACKSONVILLE
FLORIDA AND OVER THE FLORIDA PANHANDLE. A PRE-FRONTAL SURFACE
TROUGH EXTENDS FROM 32N75W TO 28N79W GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM SE OF THE TROUGH
AXIS. A SURFACE TROUGH OVER THE SE GULF OF MEXICO EXTENDS FROM
GRAND BAHAMA ISLAND INTO THE GULF OF MEXICO JUST S OF MIAMI
FLORIDA GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS WITHIN 120 NM EITHER SIDE OF THE TROUGH AXIS. A
NARROW UPPER LOW/TROUGH IS WEDGE BETWEEN A PAIR OF UPPER RIDGES
ROUGHLY CENTERED NEAR 31N58W WITH A SURFACE TROUGH EXTENDING
THROUGH 32N59W ALONG 30N59W TO 27N60W. THE UPPER TROUGH IS
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 23N-27N
BETWEEN 56W-62W. THE E ATLC IS DOMINATED BY NEWLY REFORMED
TROPICAL STORM NADINE...SEE SPECIAL FEATURES ABOVE. A SURFACE
TROUGH EXTENDS FROM SW OF NADINE NEAR 25N31W TO 20N45W WITH
ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE TROUGH AXIS.
THIS IS THE LEAVING THE REMAINDER OF THE ATLC WITH FAIR WEATHER
THIS AFTERNOON. THE PRE-FRONTAL SURFACE TROUGH WILL LIFT N AND
MERGE WITH THE WEAK COLD FRONT TODAY. THE COLD FRONT WILL REACH
FROM NEAR 32N76W TO CAPE CANAVERAL TONIGHT AND FROM 32N69W TO
MIAMI FLORIDA MON NIGHT WHERE IT WILL BECOME STATIONARY AND
GRADUALLY DISSIPATE THROUGH WED AS HIGH PRESSURE BUILDS S IN ITS
WAKE.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW




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