[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271149
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1115 UTC.

...SPECIAL FEATURES...

THE CENTER OF TROPICAL STORM ISAAC AT 27/1200 UTC IS NEAR 25.7N
84.7W. THIS POSITION IS ABOUT 185 MI...295 KM WSW OF FT. MYERS
FLORIDA...OR ABOUT 360 MI...575 KM SE OF THE MOUTH OF THE
MISSISSIPPI RIVER. ISAAC IS MOVING WEST-NORTHWESTWARD 12 KNOTS.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 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 WITHIN 125
NM OF THE CENTER IN THE WESTERN SEMICIRCLE AND FROM 27N TO 29N
BETWEEN 78W IN THE ATLANTIC OCEAN TO 82W IN FLORIDA AND JUST TO
THE WEST OF ANDROS ISLAND IN THE BAHAMAS. A MIDDLE LEVEL TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER IS ON TOP OF THE
NORTHERN SECTION OF THE YUCATAN PENINSULA OF MEXICO.
COMPARATIVELY DRIER AIR IN SUBSIDENCE IS IN THE NORTHWESTERN
CORNER OF THE CARIBBEAN SEA FROM 18N 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 28N37W 24N39W...
TO A 1011 MB LOW PRESSURE CENTER THAT IS NEAR 18N40W. THE LOW
PRESSURE CENTER HAS BEEN MOVING NORTHWESTWARD 14 KNOTS DURING
THE LAST 24 HOURS. SCATTERED MODERATE TO STRONG CONVECTIVE
PRECIPITATION IS FROM 21N TO 23N BETWEEN 37W AND 39W. SOME CLOUD
TOP TEMPERATURES IN THIS AREA HAVE BEEN WARMING DURING THE LAST
SIX HOURS OR SO. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND
OTHER POSSIBLE PRECIPITATION COVER THE AREA FROM 17N TO 29N
BETWEEN 26W AND 42W. 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 1023 MB HIGH
PRESSURE CENTER THAT IS NEAR 33N53W TO 24N56W...INTO THE EASTERN
CARIBBEAN SEA NEAR 16N62W...TOWARD NORTHEASTERN VENEZUELA.
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 23N16W 17N17W 10N17W. THE POSITION OF THE WAVE FOR
27/0600 UTC WAS RELOCATED A BIT TO THE EAST BASED ON THE
27/0000 UTC POSITION...BASED ON 27/0600 UTC SURFACE
OBSERVATIONS. CONVECTIVE PRECIPITATION...SCATTERED MODERATE
TO ISOLATED STRONG FROM 12N TO 14N BETWEEN 19W AND 24W...
ISOLATED MODERATE ELSEWHERE FROM 6N TO 9N BETWEEN AFRICA
AND 17W AND FROM 7N TO 16N BETWEEN AFRICA AND 30W. PART
OF THIS PRECIPITATION MAY BE RELATED TO THE MONSOON TROUGH.

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

THE MONSOON TROUGH IS DISRUPTED BY THE 16W/17W TROPICAL WAVE
AND THE LARGE-SCALE WIND FLOW THAT IS MOVING AROUND THE 28N37W
18N40W TROPICAL WAVE. THE MONSOON TROUGH EXTENDS FROM THE 18N40W
LOW PRESSURE CENTER...TO 14N41W 11N43W. THE ITCZ CONTINUES FROM
11N43W TO 7N50W 7N54W. CONVECTIVE PRECIPITATION...SCATTERED
MODERATE TO ISOLATED STRONG FROM 12N TO 13N BETWEEN 43W AND
56W...ISOLATED MODERATE FROM 9N TO 11N BETWEEN 50W AND 60W.

...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 ON
TOP OF THE NORTHERN SECTION OF THE YUCATAN PENINSULA OF MEXICO.
COMPARATIVELY DRIER AIR IN SUBSIDENCE IS IN THE NORTHWESTERN
CORNER OF THE CARIBBEAN SEA FROM 18N 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 COASTAL
MEXICO NEAR 19N96W IN THE SOUTHWESTERN CORNER OF THE GULF OF
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 20N66W. LARGE-SCALE CYCLONIC WIND FLOW COVERS THE ATLANTIC
OCEAN AND THE CARIBBEAN SEA FROM 14N TO 30N BETWEEN 55W AND 70W.
CONVECTIVE PRECIPITATION...SCATTERED MODERATE TO STRONG IN
INDIVIDUAL CELLS IN THE CARIBBEAN SEA FROM 12N TO 17N BETWEEN
62W AND 69W...ISOLATED MODERATE FROM 17N IN THE CARIBBEAN SEA
TO 23N BETWEEN 60W AND 70W...SCATTERED MODERATE TO ISOLATED
STRONG IN THE ATLANTIC OCEAN FROM 28N TO 32N BETWEEN 59W AND
63W...SCATTERED MODERATE TO STRONG WITHIN 30 TO 60 NM TO THE
NORTH AND SOUTH OF JAMAICA...ISOLATED MODERATE IN CUBA ALONG
80W.

THE REST OF THE CARIBBEAN SEA...

THE MONSOON TROUGH IS ALONG 8N74W IN COLOMBIA...THROUGH 8N81W
IN PANAMA...BEYOND NORTHWESTERN COSTA RICA. NUMEROUS STRONG
CONVECTIVE PRECIPITATION IS IN THE COLOMBIA COASTAL WATERS OF
THE EASTERN PACIFIC OCEAN FROM 3.5N TO 7N. RAINSHOWERS ARE
POSSIBLE FROM SOUTHERN NICARAGUA TO THE PANAMA COASTAL WATERS
NEAR 10N78W.

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

PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2...AND THE
OFFSHORE FORECAST...MIAOFFNT3...FOR MORE DETAILS ABOUT THE
20 TO 25 KNOT WINDS AND 8 TO 10 FOOT SEA HEIGHTS DURING THE
48 HOUR FORECAST PERIOD FROM 11N TO 18N BETWEEN 66W AND 83W.

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 28N37W 18N40W TROPICAL WAVE IS MOVING.

AN UPPER LEVEL TROUGH EXTENDS FROM A 38N9W CYCLONIC CIRCULATION
CENTER THAT IS NEAR SOUTHERN PORTUGAL...TO 33N12W...ACROSS THE
CANARY ISLANDS TO 24N20W. NO SIGNIFICANT DEEP CONVECTIVE
PRECIPITATION.

A SURFACE RIDGE PASSES THROUGH 35N13W TO A 1023 MB HIGH PRESSURE
CENTER THAT IS NEAR 33N24W TO A SECOND 1023 MB HIGH PRESSURE
CENTER THAT IS NEAR 33N53W...TO 24N56W...INTO THE EASTERN
CARIBBEAN SEA NEAR 16N62W...TOWARD NORTHEASTERN VENEZUELA.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...FOR DETAILS
ABOUT 20 KNOT WINDS AND 9 FOOT SEA HEIGHTS FROM 25N TO 29N
BETWEEN 56W AND 60W. A SECOND FEATURE OF INTEREST IS A 1009 MB
LOW PRESSURE CENTER THAT STARTS NEAR 19N40W...BECOMES A POSSIBLE
TROPICAL CYCLONE IN 24 HOURS NEAR 21N43W...AND A POSSIBLE
TROPICAL CYCLONE IN 48 HOURS NEAR 22N45W.

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

$$
MT





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