[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081157
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 08 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
1030 UTC.

...SPECIAL FEATURES...

HURRICANE MICHAEL IS CENTERED NEAR 32.2N 41.8W AT 08/0900 UTC OR
ABOUT 925 MI...1490 KM WSW OF THE AZORES...MOVING NNW AT 4 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 974 MB. MAXIMUM SUSTAINED
WIND SPEED IS 85 KT WITH GUSTS TO 105 KT. NUMEROUS MODERATE TO
STRONG CONVECTION IS FROM 30N-34N BETWEEN 39W-44W. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23
KNHC FOR MORE DETAILS.

TROPICAL STORM LESLIE IS CENTERED NEAR 28.3N 62.5W AT 08/1200
UTC OR ABOUT 310 MI...500 KM SSE OF BERMUDA...MOVING N AT 4 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 986 MB. MAXIMUM SUSTAINED
WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 25N-32N BETWEEN 59W-66W. 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 1011 MB LOW MOVED OFF THE COAST
OF WEST AFRICA LATE LAST NIGHT AND EARLIER THIS MORNING...WITH
THE WAVE AXIS ANALYZED FROM 22N16W TO THE LOW LEVEL CENTER NEAR
14N20W...MOVING W AT 15 KT. THIS SYSTEM COINCIDES WITH A SURGE
OF DEEP LAYER MOISTURE NOTED ON TOTAL PRECIPITABLE WATER
IMAGERY. NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS
AFFECTING THE CAPE VERDE ISLANDS FROM 10N-19N BETWEEN 25W-18W.
THE WAVE HAS POTENTIAL FOR DEVELOPMENT AND CONTAINS A MEDIUM
CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

SEE SPECIAL FEATURES SECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE TROPICAL WAVE
AND ASSOCIATED LOW MENTIONED ABOVE CONTINUING GENERALLY WESTWARD
ALONG 11N24W 12N34W TO 10N49W...WHERE THE ITCZ DEVELOPS AND
CONTINUES TO THE COAST OF TRINIDAD AND TOBAGO NEAR 10N61W.
BESIDES CONVECTION NEAR THE TROPICAL WAVE AND ASSOCIATED LOW...
SCATTERED MODERATE CONVECTION IS FROM 6N-10N BETWEEN 15W-28W...
AND FROM 8N-11N BETWEEN 30W-45W. A SURFACE TROUGH IS ANALYZED
200 NM N OF THE MONSOON TROUGH AND WEST OF THE TROPICAL WAVE
FROM 19N33W TO 14N30W. SCATTERED MODERATE CONVECTION IS WITHIN
60 NM O EITHER SIDE OF THE TROUGH AXIS N OF 16N.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL ANTI-CYCLONIC CIRCULATION IS CENTERED OVER
S-ERN TEXAS ON WATER VAPOR IMAGERY. NNE UPPER LEVEL FLOW AROUND
THE ERN SIDE OF THE CIRCULATION EXTENDS ACROSS THE GULF CARRYING
A DRY AND SUBSIDENT AIRMASS ALOFT ACROSS THE AREA THIS MORNING.
THIS ENVIRONMENT ALOFT IS SUPPRESSING DEEP CONVECTION
MAINTAINING FAIR CONDITIONS ACROSS THE DISCUSSION AREA...EXCEPT
FOR A WEAK 1009 MB SURFACE LOW ANALYZED IN THE N-CENTRAL BASIN
CENTERED NEAR 28N88W...WITH A SURFACE TROUGH EXTENDING SW FROM
THE LOW CENTER TO NEAR 26N93W. NIGHT VISION SATELLITE IMAGERY
SHOWS SCATTERED WEAK SHOWERS MAINLY TO THE ESE OF THIS
SYSTEM...WITHIN 60-120 NM. THIS SYSTEM IS EXPECTED TO BEGIN TO
DRIFT NORTHEASTWARD AND GAIN SPEED LATER THIS MORNING...BECOMING
EMBEDDED IN A FRONTAL SYSTEM SWEEPING ACROSS THE SE CONUS WITHIN
THE NEXT 24 HOURS. THIS FRONT WILL BEGIN TO AFFECT THE NW GULF
BASIN LATER THIS AFTERNOON. OTHERWISE...WEAK SURFACE RIDGING
COVERS THE REMAINDER OF THE BASIN EXTENDING ACROSS THE SOUTHERN
GULF.

CARIBBEAN SEA...
WATER VAPOR IMAGERY SHOWS DRY AIR ALOFT AND STRONG SUBSIDENCE
COVERING MUCH OF THE CARIBBEAN BASIN THIS MORNING...BETWEEN AN
ELONGATED DRY UPPER TROUGH MOVING ACROSS THE NW CARIBBEAN AND AN
UPPER ANTI-CYCLONIC CIRCULATION CENTERED WELL ENE OF PUERTO
RICO. THIS SCENARIO IS SUPPORTIVE OF FAIR WEATHER CONDITIONS
ACROSS MOST OF THE DISCUSSION AREA...EXCEPT FOR SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS OVER THE SW BASIN S OF 16N W
OF 80W DUE TO CLOSE PROXIMITY TO THE ERN PACIFIC MONSOON TROUGH
EXTENDING THROUGH INLAND PORTIONS OF COSTA RICA AND PANAMA TO
NRN COLOMBIA. TRADEWIND FLOW OF 10-15 KT IS ACROSS THE MAJORITY
OF THE BASIN WITH SOME STRONGER WINDS UP TO 20 KT NEAR THE COAST
OF COLOMBIA. FAIR CONDITIONS WILL CONTINUE ACROSS THE MAJORITY
OF THE BASIN WITH SHOWERS AND THUNDERSTORMS LINGERING OVER THE
SW CORNER DURING THE NEXT 24 HOURS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH COVERS THE WRN ATLC W OF TROPICAL STORM
LESLIE. HOWEVER...WATER VAPOR IMAGERY REVEALS MOSTLY DRY AIR
EMBEDDED AROUND THE UPPER TROUGH...ALLOWING FOR ONLY A FEW
ISOLATED SHOWERS N OF THE NW BAHAMAS FROM 26N-32N BETWEEN
73W-80W. A WEAK 1015 MB HIGH IS ANALYZED RIGHT IN THIS REGION
CENTERED NEAR 29N74W. THIS FEATURE IS HELPING TO MAINTAIN FAIR
WEATHER ASIDE THE AREA OF SHOWERS ALREADY MENTIONED. TO THE
EAST...TROPICAL STORM LESLIE SPINS IN THE CENTRAL ATLC PRODUCING
A LARGE AREA OF WINDS...SEAS ...AND CONVECTION. SMALL BUT MIGHTY
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 1023
MB HIGH NEAR 33N25W KEEPING FAIR WEATHER CONDITIONS ACROSS THE
AREA. THE FAIR WEATHER ENVIRONMENT IS ENHANCED ALOFT BY SAHARAN
DUST NOTED ON METEOSAT-9 SAL PRODUCT. A VIGOROUS FRONTAL SYSTEM
CURRENTLY MOVING ACROSS THE SE CONUS WILL BEGIN TO AFFECT THE
FAR WRN ATLC OVER THE NEXT 24 HOURS.

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

$$
GARCIA




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