[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 102353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 10 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 FEATURE...

TROPICAL WAVE IS EAST OF THE LESSER ANTILLES ALONG 17N53W TO A
1008 MB SURFACE LOW AT 9N54W. THE SYSTEM IS EXPECTED TO MOVE
W-NW AT ABOUT 10 KT. THE WAVE LIES WITHIN A LARGE AREA OF
ENHANCED DEEP LAYER MOISTURE RANGING FROM 8N16N BETWEEN 47W-60W.
BROAD LOW-LEVEL CIRCULATION IS ALSO AROUND THE WAVE IN THIS
AREA. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
7N-17N BETWEEN 44W-60W. GUSTY WINDS AND HEAVY RAINFALL ARE
POSSIBLE OVER THE LESSER ANTILLES AS THE SYSTEM MOVES CLOSER TO
THE ISLANDS. SOME GRADUAL DEVELOPMENT OF THIS SYSTEM IS POSSIBLE
OVER THE NEXT COUPLE OF DAYS.

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

THE MONSOON TROUGH EXTENDS THROUGH WEST AFRICA TO THE COAST OF
GUINEA NEAR 11N15W CONTINUING OVER ATLC WATERS ALONG 5N19W
5N32W. THE ITCZ BEGINS AT 5N32W AND CONTINUES TO 6N44W. NO DEEP
CONVECTION IS ASSOCIATED WITH THE ITCZ/MONSOON TROUGH AT THIS
TIME.

...DISCUSSION...

THE GULF OF MEXICO...
WEAK SURFACE RIDGING WITH LIGHT ANTI-CYCLONIC SURFACE FLOW IS
ACROSS THE GULF OF MEXICO EXTENDING FROM A HIGH CENTER OVER
MISSOURI. MOSTLY FAIR WEATHER IS IMPACTING THE BASIN DUE TO DRY
AIR ALOFT AROUND A BROAD UPPER LEVEL TROUGH COVERING THE EASTERN
CONUS. HOWEVER...BOTH THE NW AND SE GULF ARE EXPERIENCING SOME
SHOWERS/THUNDERSTORMS AT THIS TIME. IN THE NW GULF...SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 26N-29N BETWEEN 92W-97W.
THIS ACTIVITY IS LIKELY TIED TO A SMALL MID-LEVEL TROUGH OVER
SOUTHERN TEXAS. ISOLATED SHOWERS/THUNDERSTORMS ARE IN THE SE
GULF S OF 26N E OF 88W. THIS IS LINKED TO WEAK DIFFLUENCE AROUND
THE EAST SIDE OF THE UPPER TROUGH AXIS WHICH EXTENDS INTO THE
GULF ALONG 88W. SURFACE RIDGING IS EXPECTED TO REMAIN OVER THE
BASIN FOR THE NEXT COUPLE OF DAYS.

THE CARIBBEAN SEA...
AN UPPER LEVEL RIDGE COVERS THE NW CARIBBEAN TONIGHT WITH AXIS
EXTENDING FROM CENTRAL CUBA TO GUATEMALA AND CONTINUING INTO
MEXICO. AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO IS HELPING
PROVIDE DIFFLUENT FLOW OVER PORTIONS OF THE NW CARIBBEAN
PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER WESTERN
CUBA WITH ISOLATED SHOWERS FROM 17N-20N BETWEEN 82W-88W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO ACROSS A GOOD
PORTIONS OF HONDURAS AND NICARAGUA AND CONTINUING OFFSHORE TO
82W. SIMILAR ACTIVITY IS ACROSS COSTA RICA AND PANAMA AND THE
AREA S OF 12N W OF 79W ASSOCIATED WITH THE E PACIFIC MONSOON
TROUGH EXTENDING THROUGH BOTH COSTA RICA AND PANAMA TO NORTHERN
COLOMBIA. THE REMAINDER OF THE BASIN IS EXPERIENCING MOSTLY FAIR
WEATHER DUE TO DRY AIR ALOFT AROUND A NARROW UPPER TROUGH
EXTENDING FROM THE CENTRAL ATLC INTO THE EASTERN CARIBBEAN TO
NORTHERN VENEZUELA. TRADEWIND FLOW OF 10-15 KT IS ACROSS MUCH OF
THE AREA WITH A FEW STRONGER WINDS NORTH OF COLOMBIA. ISOLATED
LOW-LEVEL SHOWERS ARE EMBEDDED WITH IN THE EASTERLY FLOW. A
TROPICAL WAVE EAST OF THE LESSER ANTILLES IS EXPECTED TO BRING
GUSTY WINDS AND HEAVY RAINFALL TO PORTIONS OF THE ISLANDS OVER
THE NEXT COUPLE OF DAYS. SEE SPECIAL FEATURES ABOVE FOR MORE
DETAILS ON THE WAVE.

THE ATLANTIC OCEAN...
A BROAD UPPER TROUGH COVERING THE EASTERN CONUS CONTINUES OVER
THE FAR WESTERN ATLC ALONG WITH DRY AIR PROVIDING FAIR
CONDITIONS ACROSS THE W ATLC W OF 76W. TO THE EAST...A 1013 MB
SURFACE LOW IS NORTH OF THE SE BAHAMAS CENTERED NEAR 26N72W WITH
A SURFACE TROUGH EXTENDING TO THE NORTH TO 31N72W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE MAINLY EAST OF THE LOW CENTER
FROM 22N-28N BETWEEN 70W-72W. SIMILAR ACTIVITY IS WITHIN 120 NM
EAST OF THE TROUGH AXIS. FAIR CONDITIONS COVER THE REMAINDER OF
THE WEST ATLC DUE TO DRY AIR ALOFT AROUND THE EAST SIDE OF AN
UPPER LEVEL RIDGE EXTENDING FROM THE NW CARIBBEAN ACROSS CENTRAL
CUBA TO NEAR 38N46W. A NARROW UPPER LEVEL TROUGH IS TO THE EAST
OF THE RIDGE EXTENDING FROM EAST OF THE AZORES ISLANDS NEAR
36N20W CONTINUING ALONG 27N34W 25N54W TO THE EASTERN CARIBBEAN
AT 18N63W. DIFFLUENCE ALOFT AROUND THE EAST SIDE OF THE UPPER
TROUGH IS HELPING SUPPORT SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 21N-24N BETWEEN 44W-56W. A BROAD SURFACE
RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR 36N41W IS
PROVIDING MOSTLY FAIR CONDITIONS ACROSS THE REMAINDER OF THE
CENTRAL AND EASTERN ATLC SUPPORTED BY AN UPPER LEVEL RIDGE NORTH
OF THE DISCUSSION AREA. UPPER LEVEL RIDGING ALSO COVERS THE
TROPICAL ATLC.

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

$$
WALTON





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