[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 161200
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 16 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

HURRICANE NADINE IS CENTERED NEAR 30.5N 44.7W 16/0900 UTC OR
ABOUT 1035 NM E OF BERMUDA...AND ABOUT 985 NM WSW OF THE AZORES.
NADINE IS MOVING E AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
IS 983 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO
85 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. A CLUSTER OF STRONG
CONVECTION HAS FORMED FROM 30N-31N BETWEEN 43W-45W. SCATTERED
MODERATE CONVECTION IS ELSEWHERE FROM 28N-34N BETWEEN 38W-47W.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS JUST WEST OF THE CAPE VERDE ISLANDS FROM
18N27W TO 11N26W MOVING W AT 10-15 KT. THIS WAVE IS NOT AS
ROBUST AS SOME OF THE STRONGER WAVES THAT HAVE EMERGED OFF
AFRICA...BUT IT STILL ALIGNS WITH A SMALL SURGE OF DEEP LAYER
MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. NO DEEP
CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE.

TROPICAL WAVE APPROACHES THE LESSER ANTILLES ALONG 18N56W TO
11N54W MOVING W AT 10-15 KT. A 1010 MB SURFACE LOW IS ANALYZED
ALONG THE WAVE AT 13N55W. THE WAVE LIES WITHIN AN AREA OF
MAXIMUM MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 13N-18N
BETWEEN 56W-60W. THIS ACTIVITY MAY BEGIN TO IMPACT THE LESSER
ANTILLES SHORTLY. LOCALLY HEAVY RAINS AND SQUALLS COULD AFFECT
PORTIONS OF THE LESSER ANTILLES TODAY THROUGH AND MONDAY.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
MAURITANIA AT 18N16W CONTINUING OVER ATLC WATERS ALONG 10N26W
9N41W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-10N
BETWEEN 30W-46W.

...DISCUSSION...

GULF OF MEXICO...
PATCHES OF SHOWERS/THUNDERSTORMS CONTINUE OVER SEVERAL AREAS OF
THE GULF OF MEXICO. ISOLATED SHOWERS/THUNDERSTORMS REMAIN OVER
THE SE GULF NEAR THE WEST COAST OF FLORIDA AND ACROSS SOUTH
FLORIDA AND THE FLORIDA STRAITS. THIS ACTIVITY IS LINKED TO
DIFFLUENCE ALOFT AROUND THE E SIDE OF AN UPPER LEVEL TROUGH
ALONG 85W. A SURFACE TROUGH IN THE WESTERN CARIBBEAN ALONG
27N96W TO 23N93W IS ALSO SUPPORTING A FEW SHOWERS/THUNDERSTORMS
NEAR THE AXIS. A FEW PATCHES ARE ALSO ALONG THE MEXICAN AND SE
TEXAS COAST. THE REMAINDER OF THE BASIN HAS MOSTLY CLEAR SKIES.
WEAK UPPER RIDGING COVERS THE AREA TO THE WEST OF THE UPPER
TROUGH ACROSS THE WESTERN GULF. THE SURFACE TROUGH IS EXPECTED
TO DRIFT WEST AND WILL EVENTUALLY BE ABSORBED BY A FRONTAL
BOUNDARY THAT WILL REACH THE BASIN ON MONDAY. MOIST CONDITIONS
AND BROAD SURFACE TROUGHING WILL REMAIN ACROSS THE BASIN UNTIL
THEN.

CARIBBEAN SEA...
LITTLE HAS CHANGED ACROSS THE CARIBBEAN OVER THE PAST 6 HOURS.
FAIR WEATHER PREVAILS ACROSS THE BASIN RELATED TO DRY AIR ALOFT
AROUND AN UPPER LEVEL RIDGE COVERING THE WESTERN CARIBBEAN...AND
AN INVERTED UPPER TROUGH COVERING THE EASTERN CARIBBEAN. A FEW
WIDELY ISOLATED SHOWERS/THUNDERSTORMS ARE NEAR CENTRAL CUBA AND
NEAR THE HISPANIOLA COAST. A FEW CLUSTERS OF
SHOWERS/THUNDERSTORMS ALSO CONTINUE OFFSHORE OF HONDURAS AND
NICARAGUA...AS WELL AS OVER NORTHERN COSTA RICA. TRADEWIND FLOW
OF 15-20 KT IS PRESENT ACROSS THE CENTRAL CARIBBEAN WITH LIGHTER
WINDS TO EITHER SIDE. EXPECT SHOWERS/THUNDERSTORMS ACROSS THE SW
CARIBBEAN AND CENTRAL AMERICA DURING THE DAYTIME HOURS WITH
ACTIVITY INCREASING OVER THE EXTREME EASTERN CARIBBEAN AS A
TROPICAL WAVE APPROACHES FROM THE EAST.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE COVERS THE FAR WESTERN ATLC PROVIDING
MOSTLY FAIR CONDITIONS AROUND SURFACE RIDGING EXTENDING FROM THE
NE CONUS. AN UPPER LEVEL TROUGH IS ALONG 63W SUPPORTING A
SURFACE TROUGH ALONG 31N63W 27N71W. THE UPPER TROUGH IS MOSTLY
EMBEDDED WITH DRY AIR KEEPING SHOWER ACTIVITY AT A MINIMUM
EXCEPT FOR A FEW SHOWERS/THUNDERSTORMS ABOUT 200 NM EAST OF THE
SURFACE TROUGH AXIS NORTH OF 28N. TO THE E...HURRICANE NADINE
MOVES THROUGH THE CENTRAL ATLC. SEE SPECIAL FEATURES ABOVE FOR
MORE DETAILS. A WEAK 1016 MB SURFACE HIGH IS SE OF NADINE
CENTERED NEAR 24N35W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL
RIDGE CENTERED SOUTH OF NADINE NEAR 21N51W. THE UPPER RIDGE
ALONG WITH THE SURFACE RIDGE ARE PROVIDING FAIR CONDITIONS
ACROSS THE REMAINDER OF THE CENTRAL AND EASTERN ATLC. A BROAD
UPPER LEVEL TROUGH COVERS THE EASTERN ATLC CENTERED NEAR THE
AZORES ISLANDS...BUT IS NOT CAUSING ANY ACTIVE WEATHER IN THE
DISCUSSION AREA. THE FIRST VISIBLE SATELLITE IMAGERY OF THE DAY
ALONG WITH GOES-R ENHANCED IMAGERY INDICATE THAT A THIN AREA OF
SAHARAN DUST EXTENDS S OF 30N FROM THE COAST OF AFRICA AROUND
THE TROPICAL WAVE TO NEAR 50W.

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

$$
WALTON




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