[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 270604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON AUG 27 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...

THE CENTER OF TROPICAL STORM ISAAC AT 27/0600 UTC IS NEAR
24.8N 83.5W. THIS POSITION IS ABOUT 96 NM/175 KM TO THE WEST
OF KEY WEST FLORIDA...AND ABOUT 395 NM/730 KM TO THE SOUTHEAST
OF THE MOUTH OF THE MISSISSIPPI RIVER. ISAAC IS MOVING
WEST-NORTHWESTWARD 12 KNOTS. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 990 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 55 KT
WITH GUSTS TO 65 KT. PLEASE READ THE FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC
ADVISORY...MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. CONVECTIVE
PRECIPITATION...NUMEROUS STRONG FROM 24N TO 27N BETWEEN 82W AND
85W...WITHIN 150 NM OF THE CENTER IN THE NORTHWESTERN QUADRANT.
THIS PRECIPITATION COVERS THE COASTAL WATERS OF SOUTHWESTERN
FLORIDA FROM THE COAST TO A DISTANCE OF 200 NM OFFSHORE...
NUMEROUS STRONG ALSO IS IN THE EASTERN SECTIONS OF FLORIDA FROM
THE WATERS THAT ARE BETWEEN ANDROS ISLAND NEAR 25N79W AND
SOUTHEASTERN FLORIDA NEAR 28N81W ROUGHLY BETWEEN MELBOURNE AND
WINTER HAVEN. A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION
CENTER IS WITHIN 60 NM OF THE NORTHERN COAST OF THE YUCATAN
PENINSULA OF MEXICO. COMPARATIVELY DRIER AIR IN SUBSIDENCE IS IN
THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA FROM 17N TO 22N IN
THE YUCATAN CHANNEL BETWEEN 82W AND 89W. ALL RESIDENTS FROM
FLORIDA TO LOUISIANA SHOULD STAY TUNED TO ALL BULLETINS THAT ARE
ISSUED BY THE NATIONAL HURRICANE CENTER AND THE LOCAL NATIONAL
WEATHER SERVICE OFFICES FOR UPDATES ABOUT T.S. ISAAC.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 27N33W 23N36W...
TO A 1011 MB LOW PRESSURE CENTER THAT IS NEAR 19N38W. THE LOW
PRESSURE CENTER HAS BEEN MOVING NORTHWESTWARD 14 KNOTS DURING
THE LAST 24 HOURS. NUMEROUS STRONG CONVECTIVE PRECIPITATION
IS FROM 21N TO 23N BETWEEN 36W AND 38W. BROKEN TO OVERCAST
MULTILAYERED CLOUDS AND OTHER POSSIBLE PRECIPITATION COVER THE
AREA FROM 16N TO 29N BETWEEN 27W AND 44W. BROAD MIDDLE LEVEL
TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN
TO THE SOUTH OF 30N BETWEEN 20W AND 55W. COMPARATIVELY DRIER
AIR IN SUBSIDENCE COVERS THE ATLANTIC OCEAN TO THE NORTH OF 20N
BETWEEN 40W AND 60W...THE AREA INTO WHICH THE TROPICAL WAVE IS
MOVING. AN ATLANTIC OCEAN SURFACE RIDGE EXTENDS FROM A 1025 MB
HIGH PRESSURE CENTER THAT IS NEAR 33N51W TO 23N53W 12N55W...
TOWARD SURINAME. UPPER LEVEL WINDS ARE FORECAST TO BECOME LESS
FAVORABLE BY LATER TODAY...AND THE POTENTIAL FOR THE DEVELOPMENT
OF THIS SYSTEM IS BECOMING LESS LIKELY. THIS LOW PRESSURE CENTER
HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES WEST-NORTHWESTWARD TO NORTHWESTWARD
9 TO 13 KNOTS.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE EMERGED OFF THE COAST OF AFRICA
ALONG 17W/19W TO THE SOUTH OF 21N. ISOLATED TO WIDELY SCATTERED
MODERATE CONVECTIVE PRECIPITATION IS FROM 9N TO 14N BETWEEN
AFRICA AND 28W. PART OF THIS PRECIPITATION ALSO IS RELATED TO
THE MONSOON TROUGH.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH IS DISRUPTED BY THE 17W/19W TROPICAL WAVE
AND THE LARGE-SCALE WIND FLOW THAT IS MOVING AROUND THE 27N33W
19N38W TROPICAL WAVE. THE MONSOON TROUGH EXTENDS FROM THE 19N38W
LOW PRESSURE CENTER...TO 15N40W 10N48W 9N50W. THE ITCZ CONTINUES
FROM 9N50W TO 8N55W AND 8N59W. CONVECTIVE PRECIPITATION...
SCATTERED MODERATE TO ISOLATED STRONG FROM 12N TO 13N BETWEEN
43W AND 51W...ISOLATED MODERATE FROM 8N TO 9N BETWEEN 50W AND
55W.

...DISCUSSION...

THE GULF OF MEXICO...

TROPICAL STORM ISAAC IS MOVING THROUGH THE SOUTHEASTERN CORNER
OF THE AREA. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR
DETAILS ABOUT THIS CYCLONE.

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
WITHIN 60 NM OF THE NORTHERN COAST OF THE YUCATAN PENINSULA
OF MEXICO. COMPARATIVELY DRIER AIR IN SUBSIDENCE IS IN THE
NORTHWESTERN CORNER OF THE CARIBBEAN SEA FROM 17N TO 22N
IN THE YUCATAN CHANNEL BETWEEN 82W AND 89W. NO SIGNIFICANT
DEEP CONVECTIVE PRECIPITATION. UPPER LEVEL NORTHERLY WIND
FLOW COVERS THE GULF OF MEXICO TO THE WEST OF THE YUCATAN
PENINSULA CYCLONIC CENTER.

A SURFACE RIDGE PASSES THROUGH SOUTHWESTERN LOUISIANA TO
24N94W IN THE WEST CENTRAL GULF OF MEXICO...TO 17N99W IN
SOUTHERN MEXICO.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT4...FOR MORE DETAILS ABOUT
TROPICAL STORM ISAAC.

FROM THE ATLANTIC OCEAN...INTO THE EASTERN HALF OF THE
CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS
NEAR 20N65W. LARGE-SCALE CYCLONIC WIND FLOW COVERS THE ATLANTIC
OCEAN AND THE CARIBBEAN SEA FROM 14N TO 30N BETWEEN 55W AND 70W.
CONVECTIVE PRECIPITATION...ISOLATED MODERATE TO LOCALLY STRONG
FROM IS IN THE CARIBBEAN SEA TO SOUTH OF 17.5N TO THE EAST OF
72W AND TO THE NORTH OF 17.5N TO THE EAST OF THE WINDWARD PASSAGE
AND FROM 15N TO EASTERN JAMAICA BETWEEN 76W AND 77W...WIDELY
SCATTERED MODERATE TO ISOLATED STRONG IN THE ATLANTIC OCEAN
FROM 26N TO 33N BETWEEN 59W AND 63W.

THE REST OF THE CARIBBEAN SEA...

THE MONSOON TROUGH IS ALONG 9N74W IN COLOMBIA...THROUGH 9N81W
IN PANAMA...BEYOND 10N86W IN COSTA RICA. ISOLATED MODERATE TO
LOCALLY STRONG CONVECTIVE PRECIPITATION IS IN COLOMBIA FROM
4N77W AT THE COAST TO 10N73W NEAR THE BORDER WITH VENEZUELA.
CONVECTIVE DEBRIS CLOUDS AND POSSIBLE LINGERING PRECIPITATION
ARE IN THE WATERS THAT ARE TO THE SOUTH OF 10N TO THE WEST OF
80W...IN PANAMA TO THE WEST OF 81W...AND IN MUCH OF COSTA RICA.

BROAD UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE AREA TO THE
WEST OF 70W...AWAY FROM THE ATLANTIC OCEAN-TO-CARIBBEAN SEA
CYCLONIC WIND FLOW.

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT TROPICAL
STORM ISAAC. A SECOND AREA OF 20 TO 25 KNOT WINDS AND 8 TO 10
FOOT SEA HEIGHTS DURING THE 48 HOUR FORECAST PERIOD IS FROM
11N TO 18N BETWEEN 66W AND 79W.

THE REST OF THE ATLANTIC OCEAN...

BROAD MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS
THE ATLANTIC OCEAN TO THE SOUTH OF 30N BETWEEN 20W AND 55W.
COMPARATIVELY DRIER AIR IN SUBSIDENCE COVERS THE ATLANTIC OCEAN
TO THE NORTH OF 20N BETWEEN 40W AND 60W...THE AREA INTO WHICH
THE 27N33W 19N38W TROPICAL WAVE IS MOVING.

AN UPPER LEVEL TROUGH EXTENDS FROM A 35N12W CYCLONIC CIRCULATION
CENTER TO 30N13W...ACROSS THE CANARY ISLANDS TO 25N19W AND
23N21W. NO SIGNIFICANT DEEP CONVECTIVE PRECIPITATION.

A SURFACE RIDGE PASSES THROUGH 37N12W TO A 1023 MB HIGH PRESSURE
CENTER THAT IS NEAR 33N25W TO A 1025 MB HIGH PRESSURE CENTER
THAT IS NEAR 33N51W...HIGH PRESSURE CENTER THAT IS NEAR
33N51W...TO 23N53W 12N55W...AND TOWARD SURINAME.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...FOR DETAILS
ABOUT 20 KNOT WINDS AND 9 FOOT SEA HEIGHTS FROM 25N TO 30N
BETWEEN 56W AND 61W. A SECOND FEATURE OF INTEREST IS A 1009 MB
LOW PRESSURE CENTER THAT STARTS NEAR 18.5N 37.5W...A POSSIBLE
TROPICAL CYCLONE IN 24 HOURS AND 48 HOURS.

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

$$
MT





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