[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120535
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED SEP 12 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
0515 UTC.

...SPECIAL FEATURES...
TROPICAL DEPRESSION FOURTEEN WAS UPGRADED TO TROPICAL STORM
NADINE AT 12/0300 UTC. TROPICAL STORM NADINE IS CENTERED NEAR
17.8N 45.2W 12/0300 UTC OR ABOUT 940 NM E OF THE LESSER ANTILLES
MOVING WNW AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004
MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. CLUSTERS OF SCATTERED
MODERATE TO STRONG CONVECTION IS FROM 15N-24N BETWEEN 43W-50W.

...TROPICAL WAVES...

TROPICAL WAVE IS SW OF THE CAPE VERDE ISLANDS EXTENDING FROM
14N29W TO 4N26W MOVING W NEAR 20 KT. WAVE IS ALONG THE LEADING
EDGE OF AN AREA OF DEEP MOISTURE WITH A SWATH OF DRIER AIR
UNDERCUTTING THE WAVE NEAR 8N AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE FROM 10N-13N BETWEEN 28W-32W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 15N17W TO 16N19W BEING DISRUPTED BY THE PRESENCE OF
TROPICAL STORM NADINE. THE ITCZ EXTENDS FROM 10N52W TO SOUTH
AMERICA NEAR 8N60W. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 10-16N E OF 20W TO INLAND OVER W
AFRICA.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW HAS BEEN CUTOFF FROM THE BROAD UPPER TROUGH OVER
THE FAR E U.S. THE CUTOFF UPPER LOW IS OVER THE LOWER
MISSISSIPPI VALLEY WITH THE UPPER TROUGH EXTENDING S OVER THE NW
GULF OF MEXICO. AN UPPER TROUGH COVERS THE FAR E U.S. INTO THE
NW ATLC SUPPORTING A COLD FRONT IN THE W ATLC AND ENTERING THE
GULF OF MEXICO AT 12/0300 UTC OVER THE UPPER FLORIDA KEYS AS A
STATIONARY FRONT CONTINUING ALONG 26N86W TO 28N90W WHERE IT
DISSIPATES ALONG THE COAST OF LOUISIANA AND E TEXAS. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE POSSIBLE WITHIN 45 NM OF THE
FRONT E OF 91W. AN UPPER RIDGE ANCHORED OVER SW MEXICO EXTENDS
OVER THE SW GULF IS ENHANCING CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 25N W OF 94W TO INLAND OVER MEXICO.
A WEAK DIURNAL SURFACE TROUGH THAT AT 12/0300 UTC EXTENDS OFF
THE W COAST OF THE YUCATAN PENINSULA FROM 23N91W TO 18N92W WITH
ISOLATED SHORES ARE WITHIN 120 NM E OF THE TROUGH. THE REMAINDER
OF THE GULF IS UNDER MOSTLY CLEAR SKIES TONIGHT. THE FRONT WILL
GRADUALLY DISSIPATE THROUGH THU NIGHT AS IT LIFTS NORTHWARD.
HIGH PRESSURE WILL BUILD IN FROM THE NE WED THROUGH THU NIGHT. A
WEAK COLD FRONT IS EXPECTED TO ENTER THE FAR NW GULF SAT AND SUN.

CARIBBEAN SEA...
A BROAD UPPER RIDGE OVER THE W ATLC DOMINATES THE N CARIBBEAN
WHILE A SECOND UPPER RIDGE DOMINATES THE SW WATERS. A CUTOFF
UPPER LOW IS CENTERED NE OF THE LEEWARD ISLANDS EXTENDING AN
UPPER TROUGH OVER THE E CARIBBEAN E OF 70W. CLUSTERS OF
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS DOT THE NW CARIBBEAN N
OF 16N W OF 77W. THE MONSOON TROUGH EXTENDS FROM COLOMBIA ACROSS
PANAMA AND COSTA RICA INTO THE E PACIFIC REGION GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 10N BETWEEN
75W-84W. MODERATE TO FRESH TRADE WINDS ARE ACROSS THE S CENTRAL
CARIBBEAN WATERS WITH LIGHT TO MODERATE TRADE WINDS ELSEWHERE.
THESE TRADE WINDS ARE USHERING IN SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS ACROSS THE E CARIBBEAN N OF 15N E OF 70W.
OTHERWISE THE REMAINDER OF THE CARIBBEAN IS UNDER MOSTLY CLEAR
SKIES TONIGHT. HIGH PRESSURE N OF THE AREA WILL MAINTAIN THE
TRADE WINDS ACROSS THE CARIBBEAN THROUGH THU.

ATLANTIC OCEAN...
THE PRIMARY CONCERN TONIGHT IS NEWLY FORMED TROPICAL STORM
NADINE IN THE CENTRAL TROPICAL ATLC. SEE SPECIAL FEATURES ABOVE.
AN UPPER TROUGH COVERS THE FAR E U.S. INTO THE NW ATLC
SUPPORTING A COLD FRONT THAT EXTENDS INTO THE W ATLC/CENTRAL
ATLC NEAR 32N58W EXTENDING ALONG 27N64W TO 25N70W WHERE IT
BECOMES A STATIONARY FRONT THROUGH THE N BAHAMA ISLANDS INTO THE
GULF OF MEXICO OVER THE UPPER FLORIDA KEYS. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE WITHIN 120 NM EITHER SIDE OF THE
FRONT. A SURFACE RIDGE IS BUILDING S OVER THE W ATLC W OF THE
ABOVE FRONTAL BOUNDARY ANCHORED BY A 1026 MB HIGH ALONG THE
COAST OF NEW JERSEY. A CUTOFF UPPER LOW IS CENTERED IN THE W
TROPICAL ATLC NE OF THE LEEWARD ISLANDS NEAR 20N60W EXTENDING AN
UPPER TROUGH OVER THE E CARIBBEAN AND NNE TO NEAR 27N56W
PRECEDING TROPICAL STORM NADINE. A SURFACE RIDGE COVERS THE E
ATLC ANCHORED BY A 1023 MB HIGH NEAR 34N39W. SATELLITE IMAGES
INDICATES SAHARAN DUST COVERS THE E TROPICAL ATLC FROM 16N-29N E
OF 40W AND FROM 24N-30N BETWEEN 40W-48W. COLD FRONT WILL MOVE
SLOWLY E THROUGH THU WHILE THE STATIONARY PORTION DISSIPATES.
HIGH PRESSURE WILL CONTINUE TO BUILD IN ACROSS THE AREA BEHIND
THE FRONT. NEWLY UPGRADED TROPICAL STORM NADINE IN THE CENTRAL
TROPICAL ATLC IS FORECAST TO MOVE IN A GENERAL NW DIRECTION
THROUGH THU AS IT SLOWLY INTENSIFIES INTO A HURRICANE BEFORE IT
TURNS IN A NE DIRECTION.

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

$$
PAW




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