[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 042359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE OCT 04 2011

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 2345 UTC.

...SPECIAL FEATURES...
THE CENTER OF TROPICAL STORM PHILIPPE AT 04/2100 UTC IS NEAR
24.1N 60.0W OR ABOUT 550 NM SSE OF BERMUDA. PHILIPPE IS MOVING
WESTWARD AT 9 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 997
MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 55 KT WITH GUSTS TO 65
KT. SOME ADDITIONAL STRENGTHENING IS POSSIBLE OVER THE NEXT
COUPLE OF DAYS. PLEASE READ THE LATEST NHC FORECAST/ ADVISORY
UNDER THE AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE
DETAILS. A CLUSTER OF NUMEROUS STRONG CONVECTION IS NEAR THE
STORM CENTER FROM 23N-24N BETWEEN 59W-60W. NUMEROUS MODERATE
CONVECTION IS ELSEWHERE FROM 22N-25N BETWEEN 57W-61W.

...TROPICAL WAVES...
TROPICAL WAVE IS MOVING ACROSS THE CENTRAL TROPICAL ATLC ALONG
16N36W TO 5N44W MOVING W AT 15-20 KT. THE WAVE LIES ON THE WRN
EDGE OF A SURGE OF DEEP LAYER MOISTURE EVIDENT IN TOTAL
PRECIPITABLE WATER IMAGERY. THE WAVE IS ALSO ON THE ERN SIDE OF
AN UPPER LEVEL TROUGH THAT EXTENDS FROM THE AZORES ISLANDS TO
NEAR 17N45W. THIS IS PROVIDING SWLY SHEAR ACROSS THE WAVE WHICH
IS DRAWING MOISTURE TO THE NE OF THE WAVE. CURRENTLY SCATTERED
MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE WAVE
AXIS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NE OF THE
WAVE FROM 14N-19N BETWEEN 27W-33W.

...THE ITCZ/THE MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
7N23W. THE ITCZ AXIS CONTINUES W OF THE CENTRAL ATLC TROPICAL
WAVE ALONG 9N45W 8N61W. A CLUSTER OF STRONG CONVECTION IS MOVING
OFF THE AFRICAN COAST OVER GUINEA-BISSAU FROM 10N-13N BETWEEN
14W-17W. SIMILAR ACTIVITY IS ALSO MOVING ACROSS SIERRA LEONE.
SCATTERED MODERATE/STRONG CONVECTION IS N OF THE MONSOON AXIS
FROM 9N-13N BETWEEN 22W-26W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS N OF THE ITCZ AXIS FROM 7N-9N BETWEEN 45W-52W.
SIMILAR ACTIVITY IS FROM 8N-10N BETWEEN 54W-58W. CLUSTERS OF
STRONG CONVECTION ARE ALSO ALONG THE SOUTH AMERICAN COASTLINE
BETWEEN 54W-62W. ISOLATED MODERATE CONVECTION IS E OF THE
WINDWARD ISLANDS FROM 10N-13N BETWEEN 55W-62W.

...DISCUSSION...

THE GULF OF MEXICO...
MAIN FEATURE IN THE GULF IS A STATIONARY FRONT THAT EXTENDS FROM
24N81W TO THE YUCATAN PENINSULA AT 22N87W. SCATTERED SHOWERS
WITH ISOLATED THUNDERSTORMS ARE SOUTH OF THE FRONT WITHIN 70 NM
BETWEEN 80W-85W. THE REMAINDER OF THE GULF IS UNDER SURFACE
RIDGING FROM A HIGH PRESSURE CENTER LOCATED NEAR 36N90W.  IN
THE UPPER LEVELS A WEAK TROUGH IS CURRENTLY CENTERED OVER THE
BASIN AND DRY AIR SUBSIDENCE IS OCCURRING WHICH IS FAVORING FAIR
WEATHER CONDITIONS TO THE ENTIRE GULF EXCEPT E OF THE FRONTAL
BOUNDARY. MOSTLY LIGHT NELY-ELY WINDS OF 10-15 KT ARE OVER THE
ENTIRE BASIN EXCEPT N OF THE STATIONARY FRONT WHERE WINDS OF
20-25 KT ARE OBSERVED FROM 24N-26N BETWEEN 81W-84W. SIMILAR WIND
MAGNITUDE IS FROM 23N-24N BETWEEN 85W-87W. EXPECT LITTLE CHANGE
OVER THE NEXT 24 HOURS.

THE CARIBBEAN SEA...
A STATIONARY FRONT IS JUST NW THE WESTERN CARIBBEAN EXTENDING
FROM 24N81W TO THE YUCATAN PENINSULA AT 22N87W. COMBINATION OF
THE MOISTURE ASSOCIATED TO THE FRONT ALONG WITH DAYTIME HEATING
IS PRODUCING SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS OVER
WESTERN CUBA. OTHER REGIONS BEING AFFECTED BY THESE FACTORS ARE
EASTERN CUBA...THE CAYMAN ISLANDS AND JAMAICA. MODERATE
CONVECTION AND THUNDERSTORMS ARE OBSERVED FROM 19N-20N BETWEEN
81W-82W. SCATTERED SHOWERS WITH ISOLATED MODERATE CONVECTION IS
SEEN FROM 16N-21N BETWEEN 82W-85W. A SURFACE TROUGH IS
APPROACHING THE YUCATAN PENINSULA FROM 15N88W TO 20N87W. THIS
INSTABILITY IN THE ATMOSPHERE MIGHT BE ASSOCIATED TO BOTH THE
HIGH MOISTURE OVER THE REGION ASSOCIATED TO THE FRONT AS WELL AS
UPPER LEVEL DIFFLUENCE FROM THE GULF UPPER TROUGH AND AN UPPER
RIDGE CENTERED NEAR 17N86W. OVER HONDURAS...NICARAGUA AND 150 NM
E OF NICARAGUA COAST SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS OCCURRING MOSTLY ASSOCIATED TO THE MONSOON TROUGH
PROXIMITY AS WELL AS DAYTIME HEATING. SIMILAR CONVECTION IS
OBSERVED OVER NORTHERN PANAMA. OVER NORTHERN COLOMBIA AND
NORTHERN VENEZUELA CLOSE TO THEIR COASTLINES NUMEROUS MODERATE
TO STRONG CONVECTION WITH THUNDERSTORMS ARE OCCURRING DUE TO
PROXIMITY TO THE EASTERN REAR OF THE MONSOON TROUGH...DAYTIME
HEATING...AND AN UPPER LEVEL LOW CENTERED NEAR 10N73W. SCATTERED
SHOWERS ASSOCIATED TO A REGION OF DEEP LAYER MOISTURE ARE
OBSERVED W OF THE WINDWARD ISLAND FROM 13N-15N BETWEEN 61W-65W.
ELSEWHERE IN THE CARIBBEAN DRY AIR SUBSIDENCE FROM THE UPPER
LEVELS IS AFFECTING THE REGION WHICH IS FAVORING FAIR WEATHER.
EXPECT SIMILAR WEATHER CONDITIONS IN THE NEXT 24 HOURS.

THE ATLANTIC OCEAN...
A COLD FRONT ENTERS THE WESTERN ATLC AND EXTENDS FROM 30N66W SW
TO 27N71W. FROM THERE A QUASI-STATIONARY FRONT EXTENDS SW
CROSSING THE BAHAMAS AND THEN ENTERS THE GULF OF MEXICO NEAR
24N81W. SCATTERED MODERATE TO ISOLATED STRONG SHOWERS ARE
OBSERVED WITHIN 135 NM EITHER SIDE OF THE FRONT N OF 25N.
PRECIPITATION IN THIS REGION IS DUE TO THE PLUM OF MOISTURE
ASSOCIATED TO THE FRONTAL BOUNDARY AND UPPER LEVEL DIFFLUENCE
FROM AN UPPER LEVEL TROUGH WITH AXIS NEAR 73W AND AN UPPER LEVEL
RIDGE THAT CROSSES CUBA AND EXTENDS TO THE NE UP TO 60W.
TROPICAL STORM PHILIPPE IS IN THE CENTRAL ATLANTIC LYING BETWEEN
AN UPPER LEVEL RIDGE TO THE W AND A BROAD UPPER LEVEL HIGH
CENTERED NEAR 35N46W. SEE THE SPECIAL FEATURES SECTION ABOVE FOR
MORE DETAILS ON PHILIPPE. OVER THE EASTERN ATLANTIC A SURFACE
TROUGH EXTENDS FROM 23N33W TO 30N29W. SHOWERS AND THUNDERSTORMS
ARE OBSERVED WITHIN 75 NM E OF THE TROUGH. A TROPICAL WAVE IS
ALSO ANALYZED...SEE THE TROPICAL WAVES SECTION ABOVE. IN THE
UPPER LEVELS AN ELONGATED TROUGH THAT EXTENDS S TO 15 N IS
SHEARING THE TROPICAL WAVE CONVECTION NE OF ITS AXIS. THIS UPPER
LEVEL TROUGH IS ALSO SUPPORTING THE SURFACE TROUGH SHOWERS AND
THUNDERSTORMS.

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

$$
RAMOS/WALTON





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