[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 301154
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU AUG 30 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 30/1200 UTC IS NEAR 31.1N
91.8W. ISAAC HAS BEEN INLAND FOR AT LEAST THE LAST 24 HOURS OR
SO. ISAAC MADE LANDFALL AROUND 28/2345 UTC IN SOUTHEASTERN
LOUISIANA. THE CURRENT POSITION IS ABOUT 35 MI SE OF ALEXANDRIA
AND ABOUT 125 MI NW OF NEW ORLEANS LOUISIANA. ISAAC IS MOVING
NORTHWESTWARD 7 KNOTS. THE MINIMUM CENTRAL PRESSURE IS 985 MB.
THE MAXIMUM SUSTAINED WIND SPEEDS ARE 40 KNOTS WITH GUSTS TO 50
KNOTS. PLEASE READ THE NHC FORECAST/ ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT4/ WTNT24 KNHC AND THE PUBLIC
ADVISORY...MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. CONVECTIVE
PRECIPITATION...SCATTERED MODERATE TO ISOLATED STRONG FROM 25N
IN THE GULF OF MEXICO ACROSS LOUISIANA...
MISSISSIPPI...ALABAMA...AND POSSIBLY PARTS OF THE FLORIDA
PANHANDLE. LIFE-THREATENING HAZARDS FROM STORM SURGE...INLAND
FLOODING...AND TORNADOES ARE OCCURRING STILL...EVEN THOUGH ISAAC
IS NOT A HURRICANE ANYMORE. STORM SURGE...THE COMBINATION OF A
STORM SURGE AND THE TIDE...WILL CAUSE NORMALLY DRY AREAS NEAR
THE COAST TO BE FLOODED BY RISING WATERS. ALL RESIDENTS IN
LOUISIANA AND MISSISSIPPI AND SURROUNDING STATES SHOULD CONTINUE
TO MONITOR ALL BULLETINS THAT ARE ISSUED BY THE NATIONAL
HURRICANE CENTER AND THE LOCAL NATIONAL WEATHER SERVICE OFFICES
FOR UPDATES ABOUT TROPICAL STORM ISAAC.

THE CENTER OF TROPICAL STORM KIRK AT 30/0900 UTC IS NEAR
26.5N 49.0W. KIRK IS MOVING NORTHWESTWARD 9 KNOTS. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 997 MB. THE MAXIMUM SUSTAINED WIND
SPEEDS ARE 55 KT WITH GUSTS TO 65 KT. PLEASE READ THE NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
AND THE PUBLIC ADVISORY...MIATCPAT1/WTNT31 KNHC FOR MORE
DETAILS. SCATTERED MODERATE TO STRONG CONVECTIVE PRECIPITATION
IS FROM 26N TO 28N BETWEEN 48W AND 50W. COMPARATIVELY DRIER AIR
IN SUBSIDENCE IN WATER VAPOR IMAGERY COVERS THE ATLANTIC OCEAN
TO THE SOUTH OF 20N TO THE WEST OF 50W...AND TO THE NORTH OF 20N
TO THE WEST OF 50W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 40W/41W FROM A 1007 MB
LOW PRESSURE CENTER THAT IS NEAR 14N ALONG THE WAVE TO 20N.
CONVECTIVE PRECIPITATION...NUMEROUS STRONG FROM 13N TO 15N
BETWEEN 42W AND 44W...SCATTERED MODERATE TO ISOLATED STRONG
FROM 10N TO 13N BETWEEN 43W AND 47W...ISOLATED MODERATE FROM
16N TO 20N BETWEEN 31W AND 42W AND FROM 7N TO 10N BETWEEN 40W
AND 50W. SATELLITE IMAGES INDICATE THAT A TROPICAL DEPRESSION IS
LIKELY DEVELOPING AND ADVISORIES WILL PROBABLY BE INITIATED
LATER THIS MORNING. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

NO OTHER TROPICAL WAVES ARE INCLUDED IN THE 30/0600 UTC
SURFACE MAP ANALYSIS. PLEASE REFER TO THE SPECIAL FEATURES
SECTION FOR DETAILS ABOUT THE 40W/41W TROPICAL WAVE AND
THE ACCOMPANYING 1007 MB LOW PRESSURE CENTER.

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

THE MONSOON TROUGH IS INDISTINCT TO THE EAST OF THE 40W/41W
TROPICAL WAVE. THE MONSOON TROUGH HAS BEEN DISRUPTED BY THE
LARGE-SCALE WIND FLOW THAT IS MOVING AROUND THE WAVE AND
LOW CENTER FEATURE. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTIVE PRECIPITATION IS FROM 3N TO 11N TO THE EAST OF 32W.

...DISCUSSION...

THE GULF OF MEXICO...

THE UPPER LEVEL ANTICYCLONIC OUTFLOW FROM ISAAC COVERS
THE SOUTHEASTERN U.S.A. AND MUCH OF THE GULF OF MEXICO...
EXCEPT FOR THE SOUTHWESTERN CORNER OF THE AREA.
COMPARATIVELY DRIER AIR IN SUBSIDENCE SHOWS UP IN WATER
VAPOR IMAGERY IN THE SOUTHWESTERN CORNER OF THE
GULF OF MEXICO.

THE SURFACE PRESSURE PATTERN IN THE EASTERN GULF OF MEXICO
IS MADE UP OF THE CLOSED ISOBARS THAT SURROUND ISAAC.
THESE ISOBARS COVER THE AREA THAT IS TO THE NORTH OF 25N.

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

FROM THE FLORIDA KEYS AND THE STRAITS OF FLORIDA...
INTO THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS ALONG 23N82W IN WESTERN
CUBA...TO 16N8W...INTO NORTHWESTERN COLOMBIA. NUMEROUS STRONG
CONVECTIVE PRECIPITATION COVERS THE AREA FROM 6N74W IN COLOMBIA
TO 12N ALONG THE SOUTHEASTERN COAST OF NICARAGUA. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION ALSO
IS IN THE COASTAL WATERS AND COASTAL PLAINS FROM EASTERN
HONDURAS TO EAST CENTRAL NICARAGUA.

THE REST OF THE CARIBBEAN SEA...

SCATTERED STRONG CONVECTIVE PRECIPITATION IS IN THE ATLANTIC
OCEAN...JUST TO THE EAST OF THE EASTERN CARIBBEAN SEA ISLANDS...
FROM 13N TO 15N BETWEEN 58W AND 60W...INCLUDING IN BARBADOS.
IT IS POSSIBLE THAT A SURFACE-TO-LOW LEVEL TROUGH IS MOVING
WESTWARD WITH THIS PRECIPITATION.

THE MONSOON TROUGH IS ALONG 8N73W IN COLOMBIA...THROUGH 8N81W
IN PANAMA...BEYOND WESTERN COSTA RICA. NUMEROUS STRONG
CONVECTIVE PRECIPITATION COVERS THE AREA FROM 6N74W IN COLOMBIA
TO 12N ALONG THE SOUTHEASTERN COAST OF NICARAGUA. THE BASE OF
THE MIDDLE LEVEL TO UPPER LEVEL TROUGH THAT PASSES OVER
NORTHWESTERN CUBA IS IN THE GULF OF URABA.

BROAD UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE CARIBBEAN
SEA THAT IS TO THE EAST OF THE CUBA-TO-GULF OF URABA MIDDLE
LEVEL TO UPPER LEVEL TROUGH. UPPER LEVEL NORTHEASTERLY WIND
FLOW IS ON THE WESTERN SIDE OF THE TROUGH.

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 FROM 12N TO 18N
BETWEEN 69W AND 81W. A SECOND AREA OF INTEREST IS TO THE SOUTH
OF 18N TO THE WEST OF 85W WITH 20 TO 25 KNOT WINDS.

THE REST OF THE ATLANTIC OCEAN...

BROAD MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS
THE ATLANTIC OCEAN TO THE SOUTH OF 20N BETWEEN 20W AND 70W.
MIDDLE LEVEL NORTHERLY WIND FLOW COVERS THE AREA TO THE NORTH
OF 20N BETWEEN T.S. KIRK AND 60W. COMPARATIVELY DRIER AIR IN
SUBSIDENCE COVERS THE AREA...EXCEPT FOR THE CONVECTIVE
PRECIPITATION THAT ACCOMPANIES T.S. KIRK.

BROAD SURFACE ANTICYCLONIC WIND FLOW MOVES AROUND
A 1019 MB HIGH PRESSURE CENTER THAT IS NEAR 27N65W...
FROM 20N TO 30N BETWEEN T.S. KIRK AND 80W.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...FOR DETAILS
ABOUT TROPICAL STORM KIRK. A SECOND FEATURE OF INTEREST IS
A 1007 MB LOW PRESSURE CENTER THAT STARTS NEAR 14N41W...AT
24 HOURS 1006 MB POSSIBLE TROPICAL CYCLONE NEAR 15N46W...
AND AT 48 HOURS 1005 MB POSSIBLE TROPICAL CYCLONE NEAR 17N52W.

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

$$

MT




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