[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111158
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE SEP 11 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...

TROPICAL STORM LESLIE IS CENTERED NEAR 47.2N 55.7N AT 11/1200
UTC OR ABOUT 30 NM S OF STONES COVE NEWFOUNDLAND...OR ABOUT 122
NM W OF ST. JOHNS NEWFOUNDLAND MOVING NNE AT 35 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 968 MB. MAXIMUM SUSTAINED WIND SPEED
IS 60 KT WITH GUSTS TO 75 KT. SEE LATEST NHC INTERMEDIATE PUBLIC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32 AND
THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/
WTNT22 KNHC FOR MORE DETAILS. SWELLS GENERATED BY LESLIE WILL
CONTINUE TO AFFECT ATLANTIC CANADA TODAY. SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS ARE N OF 47W W OF 51W TO INLAND
OVER CANADA.

HURRICANE MICHAEL WAS DOWNGRADED TO TROPICAL STORM AT 11/0900
UTC. TROPICAL STORM MICHAEL IS CENTERED NEAR 37.1N 47.7W AT
11/0900 UTC OR ABOUT 985 NM W OF THE AZORES MOVING N AT 16 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. MAXIMUM SUSTAINED
WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM
OF THE CENTER OVER THE SW QUADRANT.

A TROPICAL WAVE IS ANALYZED MIDWAY BETWEEN THE CAPE VERDE
ISLANDS AND THE LESSER ANTILLES EXTENDING FROM 22N41W TO A 1007
MB LOW EMBEDDED WITHIN THE MONSOON TROUGH NEAR 16N42W MOVING W
NEAR 15 KT. WAVE/LOW ARE EMBEDDED WITHIN AN AREA OF DEEP
MOISTURE AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY.
CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION ARE FROM
18N-22N BETWEEN 40W-47W AND FROM 14N-18N BETWEEN 43W-47W. THIS
SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD AT ABOUT 13 KT.

...TROPICAL WAVES...

A TROPICAL WAVE WAS INTRODUCED ON THE 11/0600 UTC ANALYSIS
EXTENDING FROM 15N20W TO 6N18W MOVING W 10-15 KT. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 60/75 NM OF LINE FROM
12N22W TO 10N25W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 19N16W CONTINUING ALONG 14N26W 17N37W THROUGH THE 1007
MB NEAR 16N42W TO 15N51W. THE ITCZ CONTINUES FROM 10N52W TO
SOUTH AMERICA NEAR 8N60W. A WEAKENING SURFACE TROUGH IS W OF THE
TROPICAL WAVE EXTENDING ALONG 50W BETWEEN 17N-21N. CLUSTERS OF
ISOLATED MODERATE CONVECTION IS FROM 4N-8N BETWEEN 20W-33W.

...DISCUSSION...

GULF OF MEXICO...
A NARROWING UPPER TROUGH COVERS THE NE U.S. TO OVER THE GULF OF
MEXICO TO 26N AND SUPPORTING A COLD FRONT THAT AT 11/0900 UTC
EXTENDS FROM THE W ATLC TO S FLORIDA ENTERING THE GULF AS
STATIONARY FRONT NEAR NAPLES CONTINUING W TO 26N88W WHERE IS
BEGINNING TO DRIFT N AS A WARM FRONT ALONG 27N94W TO 25N97W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 75 NM N OF
THE FRONT W OF 87W. AN UPPER RIDGE ANCHORED OVER SW MEXICO
EXTENDS OVER THE SW GULF AND COUPLED WITH A WEAK DIURNAL SURFACE
TROUGH THAT EXTENDS OFF THE W COAST OF THE YUCATAN PENINSULA
FROM 23N91W TO 17N93W AND ARE GENERATING CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S OF 22N TO INLAND OVER MEXICO
ACROSS THE BAY OF CAMPECHE. THE REMAINDER OF THE GULF IS UNDER
MOSTLY CLEAR SKIES THIS MORNING. W PORTION OF THE FRONT WILL
DRIFT NW TO INLAND ACROSS TEXAS LATE TONIGHT WHILE HIGH PRESSURE
ACROSS THE E U.S. PUSHES E PORTION OF FRONT SLOWLY S AND INTO S
FLORIDA THROUGH WED DISSIPATING WED NIGHT. HIGH PRESSURE WILL
BUILD IN FROM THE NE WED THROUGH THU.

CARIBBEAN SEA...
A BROAD UPPER RIDGE OVER THE W ATLC DOMINATES MOST OF THE
CARIBBEAN THIS MORNING. THE MONSOON TROUGH EXTENDS FROM COLOMBIA
ACROSS THE SW CARIBBEAN ALONG 10N ACROSS COSTA RICA INTO THE E
PACIFIC REGION GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS IN THE SW CARIBBEAN S OF 12N W OF 75W. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE IN THE GULF OF HONDURAS S OF
16N W OF 88W TO INLAND OVER GUATEMALA AND BELIZE...AND FROM
18N-20N BETWEEN 79W-81W. 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 ACROSS THE E CARIBBEAN E OF 70W. OTHERWISE THE
REMAINDER OF THE CARIBBEAN IS UNDER CLEAR SKIES THIS MORNING.
HIGH PRESSURE N OF THE AREA WILL MAINTAIN THE TRADE WINDS ACROSS
THE CARIBBEAN THROUGH THU.

ATLANTIC OCEAN...
TROPICAL STORMS LESLIE AND MICHAEL ARE N OF 32N. SEE SPECIAL
FEATURES ABOVE. BROAD UPPER TROUGH COVERS THE NE U.S. SUPPORTING
A COLD FRONT THAT AT 11/0900 UTC EXTENDS INTO THE W ATLC NEAR
32N62W EXTENDING ALONG 27N70W TO ACROSS S FLORIDA NEAR MIAMI
WHERE IT BECOMES STATIONARY INTO THE GULF OF MEXICO. SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90 NM EITHER SIDE OF
THE FRONT. A SURFACE RIDGE EXTENDS FROM THE E ATLC AND A 1023 MB
HIGH NEAR 32N36W ALONG 27N49W TO A 1017 MB HIGH E OF THE TURKS
AND CAICOS NEAR 23N67W. SATELLITE IMAGES INDICATES SAHARAN DUST
COVERS THE E TROPICAL ATLC FROM 15N-29N E OF 40W. THE TROPICAL
WAVE/LOW IN THE SPECIAL FEATURES WILL MOVE W-NW THROUGH THE WEEK
TAKING A DECIDEDLY NW MOTION WED THROUGH THU. THE COLD FRONT
WILL SHIFT SLOWLY S TO SE THROUGH LATE TONIGHT WITH THE FRONT
BECOMING NEARLY STATIONARY THROUGH 32N59W TO NW BAHAMAS AND S
FLORIDA. HIGH PRESSURE WILL BUILD IN ACROSS THE AREA BEHIND THE
FRONT. NE PORTION OF FRONT TO DRIFT NW LATE THU THROUGH SAT AS
TROPICAL LOW IN CENTRAL ATLC MOVES NW.

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

$$
PAW






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