[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 160538
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...SPECIAL FEATURES...

HURRICANE NADINE IS CENTERED NEAR 30.6N 46.6W 16/0300 UTC OR
ABOUT 940 NM E OF BERMUDA...AND ABOUT 1065 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. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 30N-34N BETWEEN
39W-48W.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM THE CAPE VERDE ISLANDS NEAR 17N25W TO
8N27W 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. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 8N-10N BETWEEN 26W-30W.

TROPICAL WAVE APPROACHES THE LESSER ANTILLES ALONG 19N54W TO
8N54W MOVING W NEAR 12 KT. A 1010 MB SURFACE LOW IS ANALYZED
ALONG THE WAVE AT 13N54W. THE WAVE LIES WITHIN AN AREA OF
MAXIMUM MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY.
SCATTERED MODERATE CONVECTION IS FROM 11N-13N BETWEEN 50W-55W. A
CLUSTER OF MODERATE/STRONG CONVECTION HAS ALSO POPPED UP NEAR
14N52W...AND FROM 14N-16N BETWEEN 56W-57W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
MAURITANIA AT 18N16W CONTINUING OVER ATLC WATERS ALONG12N21W
7N27W 8N36W. THE ITCZ EXTENDS FROM 8N36W TO 12N52W AND CONTINUES
ON THE WEST SIDE OF A TROPICAL WAVE ALONG 10N56W 10N62W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-9N
BETWEEN 34W-44W.

...DISCUSSION...

GULF OF MEXICO...
THE LAST TRACES OF CONVECTION THAT BUILT DURING THE AFTERNOON
HAVE MOSTLY DIED DOWN. 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 87W. A SURFACE TROUGH IN THE WESTERN CARIBBEAN ALONG
26N94W TO 22N93W IS ALSO SUPPORTING A FEW SHOWERS/THUNDERSTORMS
FROM 24N-27N BETWEEN 90W-94W. A FEW PATCHES ARE ALSO ALONG THE
MEXICAN COAST IN THE BAY OF CAMPECHE. THE REMAINDER OF THE BASIN
HAS MOSTLY CLEAR SKIES. WEAK UPPER RIDGING COVERS THE AREA TO
EITHER SIDE OF THE UPPER TROUGH INCLUDING THE FAR WESTERN GULF
AND FLORIDA. 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...
THE CARIBBEAN IS MOSTLY QUIET TONIGHT WITH CLEAR SKIES COVERING
THE MAJORITY OF THE AREA. THIS FAIR WEATHER IS 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 SHOWERS/THUNDERSTORMS CONTINUE ACROSS WESTERN
CUBA AND OFFSHORE OF HONDURAS AND NICARAGUA...BUT ALL OTHER
ACTIVITY HAS NOW DIED DOWN. 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. AN UPPER LEVEL TROUGH IS ALONG 64W
SUPPORTING A SURFACE TROUGH ALONG 32N60W 25N70W.  DRY AIR IS
MOVING AROUND THE UPPER TROUGH WHICH IS PREVENTING ANY DEEP
CONVECTION. HOWEVER...POSSIBLE ISOLATED SHOWERS ARE ALONG THE
SURFACE TROUGH AXIS. TO THE E...HURRICANE NADINE MOVES THROUGH
THE CENTRAL ATLC. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. A
WEAK 1018 MB SURFACE HIGH IS SE OF NADINE CENTERED NEAR 24N39W.
THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED SOUTH OF
NADINE NEAR 21N50W. 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. VISIBLE
SATELLITE IMAGERY FROM EARLIER IN THE DAY ALONG WITH GOES-R
ENHANCED IMAGERY INDICATE THAT AN AREA OF SAHARAN DUST EXTENDS S
OF 20N 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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