[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091110
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 09 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
1045 UTC.

...SPECIAL FEATURES...

HURRICANE MICHAEL IS CENTERED NEAR 33.8N  42.7W AT 09/0900 UTC
OR ABOUT 925 MI...1485 KM WSW OF THE AZORES MOVING NW AT 4 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 975 MB. MAXIMUM SUSTAINED
WIND SPEED IS 85 KT WITH GUSTS TO 105 KT. SCATTERED MODERATE
CONVECTION IS FROM 32N-35N BETWEEN 41W-44W. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS.

TROPICAL STORM LESLIE IS CENTERED NEAR 30.8N 62.5W AT 09/0900
UTC OR ABOUT 170 MI...275 KM SE OF BERMUDA MOVING N AT 7 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB. MAXIMUM SUSTAINED
WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. A TROPICAL STORM
WARNING IS IN EFFECT FOR BERMUDA. SWELLS GENERATED BY LESLIE
WILL ALSO CONTINUE TO AFFECT BERMUDA. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 29N-34N BETWEEN 61W-65W. 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.

A TROPICAL WAVE AND ASSOCIATED 1008 MB LOW IS ANALYZED A COUPLE
OF HUNDRED MILES WEST OF THE CAPE VERDE ISLANDS FROM 20N25W TO
THE LOW LEVEL CENTER NEAR 15N27W...MOVING W AT 10-15 KT. THIS
SYSTEM COINCIDES WITH A SURGE OF DEEP LAYER MOISTURE NOTED ON
TOTAL PRECIPITABLE WATER IMAGERY...AROUND THE OCEANIC MONSOONAL
GYRE DESCRIBED BELOW. SCATTERED MODERATE CONVECTION IS FROM
13N-17N BETWEEN 26W-31W. ENVIRONMENTAL CONDITIONS APPEAR
FAVORABLE FOR GRADUAL DEVELOPMENT OF THE WAVE. THIS SYSTEM HAS A
MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA INTO MAURITANIA
WHERE IT HAS BROKEN DUE TO THE CIRCULATION AROUND THE TROPICAL
WAVE/LOW DISCUSSED IN THE SPECIAL FEATURES SECTION. THE MONSOON
TROUGH CONTINUES FROM THE LOW CENTER AT 15N27W ALONG 11N40W TO
10N50W...WHERE IT TRANSITIONS INTO THE ITCZ CONTINUING W TO THE
COAST OF TRINIDAD AND TOBAGO NEAR 11N61W. A SURFACE TROUGH IS
WEST OF THE TROPICAL WAVE AND N OF THE MONSOON TROUGH ANALYZED
FROM 19N38W TO 13N35W. CLUSTERS OF STRONG CONVECTION ARE FROM
5N-11N BETWEEN 20W-40W. SIMILAR CONVECTION IS MOVING OFF THE
COAST OF LIBERIA...SIERRA LEONE AND GUINEA E OF 16W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 50 NM ON EITHER
SIDE OF THE SURFACE TROUGH N OF 16N.

...DISCUSSION...

GULF OF MEXICO...
A VIGOROUS UPPER LEVEL LONGWAVE TROUGH MOVES ACROSS THE FAR E
AND SE CONUS NOTED ON WATER VAPOR IMAGERY. THIS UPPER FEATURE IS
SUPPORTING A COLD FRONT EXTENDING INTO THE GULF OF MEXICO FROM
THE FLORIDA PANHANDLE NEAR 30N84W ALONG 27N90W TO THE SRN TEXAS
COAST NEAR 26N97W. MARINE OBSERVATIONS N OF THE FRONT SHOW NNE
SURFACE WINDS OF UP TO 20 KT W OF 88W. A PRE-FRONTAL TROUGH IS
ALSO ANALYZED FROM NRN FLORIDA NEAR 30N82W TO 27N85W. MOSAIC
DOPPLER RADAR IMAGERY AND LIGHTNING DATA SHOW THE EXTENSION OF
THE SHOWERS AND THUNDERSTORMS ALONG THE FRONTAL BOUNDARY WITHIN
70 NM ON EITHER SIDE OF IT. LOW LEVEL CONVERGENCE IN THE
VICINITY OF THE PRE-FRONTAL TROUGH IS GENERATING STRONG
CONVECTION MOVING INLAND OVER NRN FLORIDA...LEAVING ONLY
SCATTERED MODERATE SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 30
NM ON EITHER SIDE OF ITS AXIS OVER THE TAMPA BAY AREA AND FAR
ERN GULF WATERS. THIS TROUGH WILL EVENTUALLY MERGE WITH THE
FRONT AS IT PUSHES SSE ACROSS THE NRN GULF DURING THE NEXT 24
HOURS. MODERATE TO HEAVY RAINFALL AND DANGEROUS LIGHTNING WILL
CONTINUE ALONG THE FRONT DURING THE FORECAST PERIOD. THE
REMAINDER OF THE BASIN IS UNDER MOSTLY FAIR WEATHER THIS
MORNING.

CARIBBEAN SEA...
MUCH OF THE CARIBBEAN IS UNDER FAIR CONDITIONS THIS MORNING DUE
TO DRY AIR ALOFT COVERING A GREAT PORTION OF THE BASIN. HOWEVER
...TOTAL PRECIPITABLE WATER IMAGERY SHOWS MODERATE TO HIGH
AMOUNTS OF LOW LEVEL MOISTURE OVER THE FAR SW BASIN ADVECTING
WESTWARD AGAINST THE COAST OF HONDURAS...NRN NICARAGUA AND COSTA
RICA S OF 16N W OF 73W. WHILE MOST OF THE SHOWER AND
THUNDERSTORM ACTIVITY IS OCCURRING INLAND OVER THE MAJORITY OF
CENTRAL AMERICA...WEAK SHOWERS ARE WIDELY SCATTERED ACROSS THE
SW BASIN DUE TO CLOSE PROXIMITY TO THE ERN PACIFIC MONSOON
TROUGH EXTENDING THROUGH INLAND PORTIONS OF COSTA RICA TO NRN
COLOMBIA. TRADEWIND FLOW OF 10-15 KT IS ACROSS THE MAJORITY OF
THE BASIN WITH SOME STRONGER WINDS GUSTING TO 25 KT NEAR THE
COAST OF COLOMBIA. THE DRY SPELL ALOFT WILL CONTINUE ACROSS THE
BASIN WITH FAIR CONDITIONS OVER THE MAJORITY OF THE BASIN DURING
THE NEXT 24 HOURS. SHOWERS AND THUNDERSTORMS WILL LINGER OVER
THE SW CORNER DURING THE FORECAST PERIOD.

ATLANTIC OCEAN...
WEATHER CONDITIONS ACROSS THE FAR WRN ATLC ARE ALREADY
DETERIORATING THIS MORNING AS A COLD FRONT EMERGES OFF THE ERN
CONUS SEABOARD WITH SCATTERED SHOWERS AND THUNDERSTORMS MOSTLY N
OF THE AREA...AND WILL BEGIN TO IMPACT OUR DISCUSSION AREA OFF
THE COAST OF FLORIDA AND GEORGIA LATER THIS AFTERNOON. THIS
FRONTAL BOUNDARY IS SUPPORTED ALOFT BY AN UPPER LEVEL LONGWAVE
TROUGH MOVING ACROSS THE FAR E AND SE CONUS NOTED ON WATER VAPOR
IMAGERY. TROPICAL STORM LESLIE SPINS IN THE CENTRAL ATLC
PRODUCING A LARGE AREA OF WINDS...SEAS...AND CONVECTION.
HURRICANE MICHAEL IS WELL TO THE ENE OF LESLIE. SEE SPECIAL
FEATURES SECTION FOR MORE DETAILS ON BOTH SYSTEMS. THE REMAINDER
OF THE CENTRAL AND EASTERN ATLC IS DOMINATED BY A BROAD UPPER
LEVEL RIDGE COVERING THE ERN ATLC E OF 40W...AND A SURFACE 1024
MB HIGH NEAR 31N32W AND A 1022 MB HIGH NEAR 34N20W KEEPING FAIR
WEATHER CONDITIONS ACROSS THE AREA. THE FAIR WEATHER ENVIRONMENT
IS ENHANCED ALOFT BY SAHARAN DUST NOTED ON METEOSAT-9 SAL
PRODUCT.

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

$$

GARCIA



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