[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 290006
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE AUG 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

HURRICANE ISAAC IS CENTERED NEAR 29.0N 89.4W AT 29/0000 UTC
ABOUT 10 MILES SW OF THE MOUTH OF THE MISSISSIPPI RIVER... OR
ABOUT 90 MILES SE OF NEW ORLEANS LOUISIANA MOVING NW AT 7 KT.
MINIMUM CENTRAL PRESSURE IS 970 MB. MAXIMUM SUSTAINED WIND SPEED
IS 70 KT WITH GUSTS TO 85 KT. SEE THE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE
DETAILS. NUMEROUS STRONG CONVECTION IS WITHIN 150 NM OF THE
CENTER OF ISAAC. ISAAC HAS MADE LANDFALL IN EXTREME SOUTHEASTERN
LOUISIANA. ISAAC IS FORECAST TO GRADUALLY WEAKEN AS IT MOVES
INLAND. THE MAIN THREATS ASSOCIATED WITH ISAAC WILL BE VERY
HEAVY RAINFALL OVER THE N GULF COAST STATES...DANGEROUS STORM
SURGE AND SURF CONDITIONS... AND STRONG WINDS WELL AWAY FROM THE
CENTER AS THE OVERALL CIRCULATION OF ISAAC IS QUITE LARGE. FOR
MORE DETAILED INFORMATION REFER TO HURRICANE LOCAL STATEMENTS
ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE.

TROPICAL DEPRESSION ELEVEN IS CENTERED NEAR 23.8N 43.9W AT
15/2100 UTC ABOUT 1270 MI...2045 KM ENE OF THE LESSER ANTILLES
...OR ABOUT 1400 MI...2250 KM SW OF THE AZORES MOVING WNW AT 9
KT. MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND
SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS. SCATTERED MODERATE TO STRONG CONVECTION IS N
OF THE CENTER FROM 23N-26N BETWEEN 41W-46W.

A TROPICAL WAVE EXTENDS FROM 17N26W TO LOW PRES NEAR 12N29W 1010
MB. THE SYSTEM IS WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS
MOVING W AT 15-20 KT. SCATTERED MODERATE CONVECTION IS NW OF THE
LOW CENTER FROM 13N-16N BETWEEN 28W-34W. THIS SYSTEM HAS BECOME
BETTER ORGANIZED TODAY...AND ENVIRONMENTAL CONDITIONS ARE
EXPECTED TO BE CONDUCIVE FOR SLOW DEVELOPMENT DURING THE NEXT
COUPLE OF DAYS. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

A TROPICAL WAVE IS WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS. SEE
ABOVE.

...ITCZ/MONSOON TROUGH...

A MONSOON TROUGH IS SW OF THE LOW CENTERED NEAR 12N29W. IT
EXTENDS FROM 10N30W TO 9N42W. AN ITCZ IS FURTHER W FROM 15N50W
TO TRINIDAD AT 10N61W. SCATTERED MODERATE CONVECTION IS FROM
7N-12N BETWEEN 33W-37W...AND FROM 13N-15N BETWEEN 55W-58W.

...DISCUSSION...

GULF OF MEXICO...
THE DOMINATE FEATURE IN THE GULF OF MEXICO IS HURRICANE ISAAC
NEAR THE MOUTH OF THE MISSISSIPPI RIVER WITH THE LARGE
CIRCULATION COVERING MOST OF THE NORTHERN GULF OF MEXICO.
SCATTERED MODERATE CONVECTION IS OVER INLAND CENTRAL AND
NORTHERN FLORIDA N OF 26N BETWEEN 80W-82W. THE BAY OF CAMPECHE
IS THE ONLY AREA WITH FAIR WEATHER. PLEASE REFER TO THE SPECIAL
FEATURES SECTION ABOVE FOR MORE DETAILS ABOUT ISAAC. AT THE
UPPER LEVELS...A MID TO UPPER LOW IS NEAR THE NE MEXICAN COAST
AT 24N101W AND IT IS MOVING WESTWARD TOWARD CENTRAL MEXICO. DRY
AND STABLE AIR EXTENDS FROM THIS LOW TO THE SW GULF. A NEARLY
STATIONARY UPPER LEVEL RIDGE IS N OF ISSAC ALONG THE N GULF
COAST STATES FROM TEXAS NEAR 31N99W TO SOUTHERN ALABAMA NEAR
32N87W TO CENTRAL FLORIDA NEAR 27N81W. DRY AIR ALONG THE
SOUTHERN PERIPHERY OF THE RIDGE IS ADVECTING INTO THE
CIRCULATION OF ISAAC HELPING TO LIMIT ADDITIONAL DEVELOPMENT AND
INTENSIFICATION. EXPECT... ATLANTIC HIGH PRESSURE TO BUILD INTO
THE AREA FROM THE W IN THE WAKE OF ISAAC LATE WED THROUGH THE
END OF THE WEEK WITH MODERATE TO FRESH SE-S RETURN FLOW BECOMING
ESTABLISHED ACROSS THE GULF BY FRI.

CARIBBEAN SEA...
15-25 KT TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH STRONGEST
WINDS ALONG THE COAST OF N COLOMBIA. SCATTERED MODERATE TO
STRONG CONVECTION IS INLAND OVER N NICARAGUA...HONDURAS...EL
SALVADOR...AND GUATEMALA. WIDELY SCATTERED MODERATE CONVECTION
IS OVER THE REMAINDER OF CENTRAL AMERICA TO INCLUDE
PANAMA...COSTA RICA...AND THE YUCATAN PENINSULA. OVER THE
CARIBBEAN WIDELY SCATTERED MODERATE CONVECTION IS S OF CUBA FROM
17N-21N BETWEEN 78W-83W. ISOLATED MODERATE CONVECTION IS ALONG
THE COAST OF HAITI FROM 17N-19N BETWEEN 70W-73W. SIMILAR
CONVECTION IS OVER THE WINDWARD ISLANDS FROM 12N-15N BETWEEN
60W-65W. IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS CENTERED
NEAR JAMAICA AT 18N75W INFLUENCING THE DIRECTION OF THUNDERSTORM
FLOW OVER HAITI AND CUBA. EXPECT CONTINUED CONVECTION OVER THE W
CARIBBEAN AND CENTRAL AMERICA OVER THE NEXT 24 HOURS. ALSO
EXPECT CONTINUED CONVECTION OVER THE WINDWARD ISLANDS.

ATLANTIC OCEAN...
1021 MB SURFACE HIGH PRES IS S OF BERMUDA NEAR 29N56W WITH A
RIDGE AXIS REACHING TO THE W-NW TO SE GEORGIA. LIGHT TO MODERATE
WINDS DOMINATE THE WATERS W OF 50W WITH A CLUSTER OF SCATTERED
SHOWERS AND TSTMS N OF HISPANIOLA TO ACROSS THE TURKS AND
CAICOS...WITH ADDITIONAL CONVECTION E OF FLORIDA TO 77W. THE
OTHER MAIN FEATURES IN THE ATLC ARE T.D. ELEVEN...AND THE
TROPICAL WAVE AND ASSOCIATED LOW...DISCUSSED IN
THE SPECIAL FEATURES SECTION.

AN UPPER LEVEL ANTICYCLONE IS NEAR 22N31W WITH AN UPPER RIDGE
REACHING FROM 23N25W THROUGH THE ANTICYCLONE TO 21N67W. UPPER
LEVEL EASTERLIES DOMINATE THE REGION S OF 20N ON THE SOUTHERN
PERIPHERY OF THE ANTICYCLONE/RIDGE. OTHERWISE...AN UPPER LEVEL
LOW IS E OF THE RIDGE NEAR 24N20W. DRY AIR COVERS THE WATERS N
OF 24N E OF 25W. AN UPPER LEVEL TROUGH EXTENDS FROM 32N42W TO
27N50W AND THIS FEATURE IS SUPPORTING A SURFACE COLD FRONT N OF
32N...AS WELL AS A SURFACE TROUGH THAT REACHES NE FROM THE LOW
IN THE SPECIAL FEATURES SECTION.

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

$$
FORMOSA





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