[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271737
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST TUE NOV 27 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
1700 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF
GUINEA AT 10N14W TO 9N18W. THE ITCZ BEGINS AT 9N18W AND
CONTINUES ALONG 8N35W 8N49W 6N58W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 4N-11N BETWEEN 17W-28W. SIMILAR
ACTIVITY IS FROM 7N-11N BETWEEN 44W-53W.

...DISCUSSION...

GULF OF MEXICO...
A SHORTWAVE UPPER TROUGH IS MOVING THROUGH THE NORTHERN GULF
SUPPORTING A COLD FRONT THAT STRETCHES FROM MOBILE ALABAMA NEAR
31N88W TO NORTHERN MEXICO ALONG 27N93W 25N98W 27N103W...AS OF
1500 UTC. A PRE-FRONTAL SURFACE TROUGH IS SE OF THE FRONTAL
BOUNDARY ALONG 28N89W TO 23N95W. STRONG SHOWERS WITH ISOLATED
THUNDERSTORMS ARE WITHIN 100 NM EAST OF THE FRONT...AND WITHIN
60 NM WEST OF THE FRONT MAINLY NORTH OF 28N. ISOLATED
SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 60 NM EITHER SIDE OF
THE AXIS ELSEWHERE. SCATTERED SHOWERS ARE ALSO WITHIN 60 NM OF
THE SURFACE TROUGH NORTH OF 25N WITH ISOLATED SHOWERS WITHIN 60
NM OF THE AXIS ELSEWHERE. NORTH TO NORTHEAST WINDS UP TO 20 KT
ARE BEHIND THE FRONT. LIGHT SOUTHEAST TO SOUTH WINDS ARE AHEAD
OF THE FRONT AND ACROSS THE EASTERN GULF WHERE CLEAR SKIES ARE
STILL PRESENT. THE FRONT IS EXPECTED TO CONTINUE MOVING SE OVER
THE NEXT 24 HOURS WITH SHOWERS EXPECTED NEAR THE AXIS. THE
PORTION OF THE FRONT OVER THE GULF WILL LIKELY WEAKEN AFTER THAT
TIME PERIOD WITH THE PORTION OF THE WEST ATLC CONTINUING TO MOVE
EAST.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE CONTINUES TO COVER THE CARIBBEAN CENTERED
NEAR 13N73W. MOSTLY DRY AIR WRAPS AROUND THE RIDGE KEEPING MUCH
OF THE CENTRAL AND EASTERN AREAS UNDER FAIR WEATHER. HOWEVER...A
SURFACE TROUGH DRAPED THROUGH THE WESTERN CARIBBEAN AND CENTRAL
AMERICA ALONG 21N84W TO 11N83W IS SUPPORTING HEAVY SHOWERS AND
SCATTERED THUNDERSTORMS ACROSS THE NW CARIBBEAN FROM 16N-22N
BETWEEN 82W-87W...AND EAST OF COSTA RICA AND NICARAGUA FROM
10N-14N BETWEEN 81W-84W. A FEW ISOLATED SHOWERS/THUNDERSTORMS
ARE ALSO NORTH OF PANAMA ASSOCIATED WITH THE MONSOON TROUGH THAT
EXTENDS ALONG 10N TO NORTHERN COLOMBIA. STRONG TRADEWIND FLOW OF
20-25 KT IS PRESENT ACROSS THE CENTRAL CARIBBEAN WITH LIGHTER
ACROSS THE EASTERN CARIBBEAN. THE SURFACE TROUGH IS EXPECTED TO
CONTINUE IMPACTING THE FAR WESTERN CARIBBEAN FOR THE NEXT 24
HOURS. STRONG SHOWERS AND THUNDERSTORMS ARE POSSIBLE NEAR THE
AXIS.

ATLANTIC OCEAN...
BROAD UPPER LEVEL RIDGING COVERS THE SW NORTH ATLC EXTENDING
FROM THE CARIBBEAN. THE UPPER RIDGE SUPPORTS A SURFACE RIDGE
AROUND A 1028 MB HIGH NEAR 33N62W. TO THE EAST...A SHORTWAVE
UPPER TROUGH ALONG 34N55W TO 22N50W SUPPORTS A STATIONARY FRONT
THAT ENTERS THE DISCUSSION AREA NEAR 32N41W AND CONTINUES ALONG
27N44W 25N52W 22N57W. IT THEN CONTINUES AS A DISSIPATING
STATIONARY FRONT TO NORTH OF PUERTO RICO ALONG 21N62W 19N66W.
SCATTERED SHOWERS AND THUNDERSTORMS ARE NEAR THE FRONT FROM
21N-26N BETWEEN 43W-53W. ISOLATED SHOWERS ARE WITHIN 90 NM
EITHER SIDE OF THE FRONT ELSEWHERE. AN UPPER LEVEL RIDGE IS EAST
OF THE SHORTWAVE UPPER TROUGH ALONG 42W...AND IT FEEDS INTO A
LARGER UPPER LEVEL RIDGE COVERING THE NE ATLC. THIS UPPER RIDGE
SUPPORTS A 1033 MB HIGH NORTH OF THE AZORES NEAR 45N23W. IT IS
PROVIDING SURFACE RIDGING ACROSS MUCH OF THE E TROPICAL ATLC.
HOWEVER...A WEAK 1012 MB SURFACE LOW IS JUST OFFSHORE OF NW
AFRICA NEAR 26N15W WITH A SURFACE TROUGH EXTENDING THROUGH IT
FROM INLAND AFRICA TO 23N19W. THIS IS THE SAME LOW THAT WAS
PRODUCING GALE FORCE WINDS NORTH OF THE AREA YESTERDAY. THE LOW
WILL CONTINUE TO WEAKEN ALLOWING THE SURFACE RIDGE TO CONTINUE
TO BUILD IN ACROSS THE EASTERN TROPICAL ATLC.

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

$$
WALTON





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