[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 142343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 14 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM RAFAEL IS CENTERED NEAR 21.4N 64.5W AT 15/0000
UTC OR ABOUT 195 NM NNE OF SAN JUAN PUERTO RICO...AND ABOUT 660
NM S OF BERMUDA. RAFAEL IS MOVING NNW AT 9 KT. MINIMUM CENTRAL
PRESSURE IS 991 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH
GUSTS TO 70 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC. NUMEROUS STRONG
CONVECTION IS EAST AND NORTH OF THE CENTER FROM 19N-22N BETWEEN
61W-63W...AND FROM 21N-23N BETWEEN 61W-65W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS ELSEWHERE FROM 13N-24N
BETWEEN 60W-65W. EVEN THOUGH RAFAEL HAS MOVED NORTH OF THE
CARIBBEAN...GUSTY WINDS AND HEAVY RAINS ARE STILL IMPACTING
PORTIONS OF THE LEEWARD ISLANDS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 18N40W TO 11N39W MOVING WEST NEAR 15 KT.
THE WAVE LIES JUST WEST OF A LOW-AMPLITUDE SURGE OF DEEP LAYER
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED
MODERATE CONVECTION IS FROM 7N-13N BETWEEN 36W-41W. ACTIVITY
CONTINUES FARTHER AWAY FROM THE AXIS IN BOTH DIRECTIONS...BUT IS
LIKELY MORE TIED TO AN UPPER LEVEL TROUGH.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
SENEGAL AT 14N17W CONTINUING ALONG 9N24W TO 9N30W. THE ITCZ
BEGINS AT 9N30W ALONG 10N36W AND PICKING UP ON THE WEST SIDE OF
THE TROPICAL WAVE ALONG 9N41W 9N50W. A WEAK SURFACE TROUGH IS
ANALYZED WITHIN THE ITCZ REGION ALONG 12N49W TO 8N53W. AN UPPER
LEVEL TROUGH OVER THE TROPICAL ATLC BETWEEN 30W-50W IS DRAWING
MOISTURE NORTHWARD FROM THE MONSOON TROUGH AND ITCZ CAUSING
ISOLATED MODERATE CONVECTION TO BE FROM 10N-17N BETWEEN
23W-36W...AND FROM 9N-12N BETWEEN 41W-45W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-9N BETWEEN
32W-35W. SIMILAR ACTIVITY IS ALSO WEST OF THE SURFACE TROUGH
FROM 9N-11N BETWEEN 52W-54W.

...DISCUSSION...

GULF OF MEXICO...
FAIR WEATHER CONTINUES ACROSS MUCH OF THE GULF OF MEXICO TONIGHT
DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE EXTENDING FROM
CENTRAL MEXICO TO WEST ATLC. A FEW ISOLATED SHOWERS ARE NOTED
OVER SOUTH FLORIDA AND THE FLORIDA STRAITS. THE UPPER RIDGE
SUPPORTS A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED
OVER SOUTH CAROLINA. THIS PATTERN IS PROVIDING ANTI-CYCLONIC
SURFACE FLOW ACROSS THE GULF WITH WIND SPEEDS AVERAGING AT 10 KT
WITH STRONGER 15 KT TO POSSIBLY 20 WINDS RESIDING IN THE SE GULF
AND CONTINUING THROUGH THE FLORIDA STRAITS. A WEAK FRONTAL
BOUNDARY IS EXPECTED TO SKIRT THE NORTHERN GULF EARLY IN THE
WEEK WITH A STRONGER FRONT PUSHING IN BEHIND IT LATER IN THE
WEEK.

CARIBBEAN SEA...
THE MAJORITY OF THE CARIBBEAN IS UNDER FAIR CONDITIONS TONIGHT.
DRY AIR ALOFT COVERS THE NW CARIBBEAN AROUND A NARROW UPPER
LEVEL TROUGH EXTENDING FROM WESTERN CUBA TO HONDURAS.
HOWEVER...SOME MODERATE MOISTURE IS WRAPPING AROUND THE EAST
SIDE OF THE UPPER TROUGH HELPING SUPPORTS A FEW
SHOWERS/THUNDERSTORMS OVER NICARAGUA AND CUBA. ONLY A FEW
ISOLATED SHOWERS/THUNDERSTORMS EXIST OVER WATER. ISOLATED
SHOWERS/THUNDERSTORMS ARE ALSO OVER THE SW CARIBBEAN DUE TO THE
MONSOON TROUGH THAT EXTENDS FROM COSTA RICA TO NORTHERN COLOMBIA
ALONG 11N. AN UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE
BASIN PROVIDING MOSTLY FAIR WEATHER. HOWEVER...TROPICAL STORM
RAFAEL IS STILL PRODUCING HEAVY SHOWERS AND GUSTY WINDS ACROSS
PORTIONS OF THE LEEWARD ISLANDS EVEN THOUGH THE STORM HAS MOVED
NORTH OF THE BASIN. SEE SPECIAL FEATURES FOR MORE DETAILS. MOIST
CONDITIONS ARE EXPECTED TO REMAIN OVER THE NE CARIBBEAN. LITTLE
CHANGE IS EXPECTED ELSEWHERE ACROSS THE CARIBBEAN FOR THE NEXT
24 HOURS.

ATLANTIC OCEAN...
A SURFACE TROUGH PREVIOUSLY ANALYZED OVER THE BAHAMAS HAS NOW
DISSIPATED...BUT BROAD CYCLONIC FLOW STILL REMAINS ACROSS MUCH
OF THE WEST ATLANTIC WITH THE FOCAL POINT BEING TROPICAL STORM
RAFAEL. DUE TO DIFFLUENT FLOW BETWEEN A WEAK UPPER TROUGH OVER
THE SW NORTH ATLC AND A NARROW UPPER LEVEL RIDGE EAST OF
RAFAEL...A LARGE AREA OF SHOWERS/THUNDERSTORMS EXTENDS NORTH AND
EASTWARD OF THE STORM. SEE SPECIAL FEATURES ABOVE FOR MORE
DETAILS. ACROSS THE EASTERN ATLC...BROAD SURFACE RIDGING
DOMINATES ANCHORED BY A 1024 MB HIGH NEAR 34N35W PROVIDING FAIR
CONDITIONS. A WEAK SURFACE TROUGH IS ALONG 28N43W TO
21N46W...BUT IS NOT CAUSING ANY SIGNIFICANT WEATHER. ALOFT...AN
UPPER LEVEL TROUGH EXTENDS FROM THE CANARY ISLANDS ALONG 28N33W
TO 13N44W. DIFFLUENCE AROUND THE EAST SIDE OF THE TROUGH AXIS IS
ENHANCING CONVECTION NEAR THE ITCZ REGION. AN UPPER LEVEL RIDGE
COVERS THE FAR EASTERN TROPICAL ATLC.

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

$$
WALTON





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