[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032352
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 03 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
VALID THROUGH 2315 UTC.

...SPECIAL FEATURE...

THE CENTER OF TROPICAL STORM NADINE AT 04/0000 UTC IS NEAR 36.5N
31.0W. NADINE IS ABOUT 210 NM WSW OF THE AZORES. NADINE IS
MOVING NE AT 16 KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS
1002 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO
40 KT. PLEASE READ THE FORECAST/ ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT4/WTNT24 KNHC...AND THE PUBLIC
ADVISORY...MIATCPAT4/WTNT34 KNHC...FOR MORE DETAILS. MOST OF THE
CONVECTION HAS BEEN SHEARED OFF TO THE EAST WITH ONLY WEAK
CONVECTION RANGING FROM 33N-36N BETWEEN 26W-29W.

THE CENTER OF TROPICAL DEPRESSION FIFTEEN AT 03/2100 UTC IS NEAR
18.6N 42.0W OR ABOUT 1040 NM W OF THE CAPE VERDE ISLANDS MOVING
NNW AT 12 KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008
MB. THE MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40
KT. PLEASE READ THE FORECAST/ ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT5/WTNT25 KNHC...AND THE PUBLIC
ADVISORY...MIATCPAT5/WTNT35 KNHC...FOR MORE DETAILS. NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION IS EAST OF THE CENTER FORM
17N-21N BETWEEN 37W-41W...WITH SCATTERED MODERATE/ISOLATED
STRONG CONVECTION FROM 21N-24N BETWEEN 32W-41W.

...TROPICAL WAVES...

TROPICAL WAVE IS JUST EAST OF THE LESSER ANTILLES ALONG 19N58W
TO 8N61W MOVING W NEAR 15 KT. THE WAVE LIES WITHIN A SURGE OF
DEEP LAYER MOISTURE INDICATED IN TOTAL PRECIPITABLE WATER
IMAGERY. ANALYSIS OF LOW LEVEL CLOUDS IN VISIBLE SATELLITE
IMAGERY ALSO INDICATES THAT LOW LEVEL CYCLONIC FLOW IS PRESENT
AROUND THE WAVE AXIS. CURRENTLY SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 12N-16N BETWEEN 57W-61W.

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

THE MONSOON TROUGH EXTENDS FROM THE COAST OF MAURITANIA AT
17N16W TO 11N23W 6N31W. THE ITCZ BEGINS AT 6N31W TO 11N37W WHERE
IT SPLITS DUE TO T.D. FIFTEEN AND PICKS UP ON THE WEST SIDE OF
THE SYSTEM ALONG 12N46W 14N51W 11N56W 12N59W. A CLUSTER OD
NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS MOVING OFF THE
COAST OF AFRICA FROM 10N-14N BETWEEN 14W-18W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-8N BETWEEN
30W-38W...AND FROM 10N-12N BETWEEN 51W-54W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL TROUGH EXTENDING THROUGH THE EASTERN CONUS AND
INTO THE WESTERN GULF OF MEXICO IS PROVIDING A LARGE AREA OF
DIFFLUENT FLOW ACROSS THE EASTERN HALF OF THE GULF. THIS
DIFFLUENCE ALOFT ALONG WITH THE INFLUENCE OF A DISSIPATING
STATIONARY FRONT AT THE SURFACE EXTENDING FROM THE FLORIDA
PANHANDLE NEAR 31N85W THROUGH THE YUCATAN PENINSULA TO 17N89W IS
SUPPORTING WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS EAST OF
THE FRONTAL BOUNDARY CONTINUING INTO CENTRAL FLORIDA. THE FRONT
IS BEGINNING TO LOSE ITS FRONTAL CHARACTERISTICS...BUT A CLEAR
BOUNDARY STILL REMAINS AT THE SURFACE. SOUTH FLORIDA IS THE ONLY
AREA OF THE EASTERN GULF STILL WITH CLEAR SKIES. THE FAR WESTERN
GULF...ESPECIALLY THE NW CORNER...ALSO HAS EXCEPTIONALLY CLEAR
SKIES TONIGHT AS DRY AIR AND SUBSIDENCE SINK DOWN AROUND THE
WEST SIDE OF THE UPPER TROUGH. WINDS ARE LIGHT IN THE NW CORNER
WITH STRONG WINDS NEAR THE FRONT REACHING UP TO 15 KT. THE FRONT
WILL LIKELY BECOME A TROUGH WITHIN THE NEXT 12-24 HOURS. THE
TROUGH...ALONG WITH MOIST CONDITIONS...WILL BEGIN TO DRIFT
WESTWARD SPREADING MOISTURE IN THE CENTRAL AND WESTERN GULF
THROUGH THE END OF THE WEEK AND WEEKEND. UPPER LEVEL TROUGHING
WILL ALSO REMAIN OVER THE BASIN PROVIDING DIFFLUENT FLOW ALOFT
FURTHER SUPPORTING MOIST CONDITIONS.

THE CARIBBEAN SEA...
AN UPPER LEVEL TROUGH OVER THE WESTERN GULF OF MEXICO IS
PROVIDING DIFFLUENCE ALOFT ACROSS THE EASTERN GULF AS WELL AS
THE NW CARIBBEAN AND CENTRAL AMERICA WEST OF 83W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE ACROSS MUCH OF HONDURAS AND
NICARAGUA. ACTIVITY CONTINUES FARTHER SOUTH ACROSS COSTA RICA
AND PANAMA...BUT IS MORE ASSOCIATED WITH THE MONSOON TROUGH THAT
EXTENDS THROUGH BOTH COUNTRIES TO NORTHERN COLOMBIA. AN AREA OF
ENHANCED MOISTURE IS ALSO ACROSS THE NORTH CENTRAL CARIBBEAN
AROUND THE NORTHERN EXTENT OF AN UPPER LEVEL LOW CENTERED IN THE
SW CARIBBEAN NEAR 13N77W. ISOLATED SHOWERS/THUNDERSTORMS ARE
FROM 15N-19N BETWEEN 73W-83W AND ACROSS SOUTHERN CUBA. MOST OF
THE EASTERN CARIBBEAN IS EXPERIENCING FAIR WEATHER. HOWEVER...A
TROPICAL WAVE APPROACHES FROM THE EAST AND IS ALREADY SUPPORTING
SHOWERS/THUNDERSTORMS ACROSS THE FAR EASTERN CARIBBEAN INCLUDING
PORTIONS OF THE LESSER ANTILLES. TRADEWIND FLOW OF 15-20 KT IS
ACROSS THE MAJORITY OF THE AREA. EXPECT MOIST CONDITIONS TO
REMAIN OVER THE WESTERN CARIBBEAN AND INCREASE OVER THE EASTERN
CARIBBEAN AS THE TROPICAL WAVE MOVES INTO THE BASIN WITHIN THE
NEXT 6-12 HOURS.

THE ATLANTIC OCEAN...
A LARGE UPPER LEVEL RIDGE COVERS THE WEST ATLC SUPPORTING A
SURFACE RIDGE ANCHORED BY A 1024 MB HIGH NEAR 32N66W...WHICH IS
PROVIDING MOSTLY FAIR CONDITIONS ACROSS THE WEST ATLC. A FEW
SHOWERS/THUNDERSTORMS HAVE EMERGED OFF THE NE COAST OF FLORIDA
ASSOCIATED WITH AN UPPER LEVEL TROUGH IN THE GULF OF MEXICO. A
SMALL UPPER LEVEL LOW IS IN THE CENTRAL ATLC NEAR 23N56W
SANDWICHED BETWEEN THE LARGE UPPER RIDGE OVER THE WESTERN ATLC
AND AN UPPER LEVEL RIDGE COVERING THE TROPICAL ATLC. THE UPPER
LOW SUPPORTS A FEW ISOLATED SHOWERS FROM 18N-24N BETWEEN
51W-57W. TO THE E...TROPICAL DEPRESSION FIFTEEN SPINS IN THE
TROPICAL REGION...WHILE TROPICAL STORM NADINE CONTINUES TO MORE
TOWARDS THE AZORES ISLANDS NORTH OF THE DISCUSSION AREA. SEE
SPECIAL FEATURES ABOVE FOR MORE DETAILS ON BOTH SYSTEMS. ANOTHER
UPPER LEVEL RIDGE COVERS THE EASTERN ATLC SUPPORTING ANOTHER
SURFACE RIDGE THAT IS PROVIDING FAIR CONDITIONS ACROSS THE FAR
EASTERN ATLC.

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

$$
WALTON




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