[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 291200
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED AUG 29 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 HURRICANE ISAAC AT 29/1200 UTC IS NEAR 29.4N
90.5W. THIS POSITION IS NEAR GALLIANO LOUISIANA. THIS IS ALSO
ABOUT 20 MILES SOUTHEAST OF HOUMA LOUISIANA AND ABOUT 50 MILES
SOUTH-SOUTHWEST OF NEW ORLEANS LOUISIANA. ISAAC IS HAS BEEN
STATIONARY DURING THE PAST HOUR...BUT A GENERAL MOTION TOWARD
THE NORTHWEST NEAR 5 KT IS EXPECTED TO RESUME LATER THIS
MORNING. ISAAC IS PRODUCING A DANGEROUS STORM SURGE. FLOODING
FROM RAINFALL ALSO IS EXPECTED. THE MINIMUM CENTRAL PRESSURE IS
970 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 70 KT WITH GUSTS
TO 85 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 A 45 NM RADIUS OF 29N90W. THIS MEANS
THAT RAINFALL IS REACHING INLAND AREAS BETWEEN SOUTHWESTERN
GEORGIA AND THE FLORIDA PANHANDLE AND SOUTHEASTERN LOUISIANA.
ALL RESIDENTS FROM THE FLORIDA PANHANDLE 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 HURRICANE ISAAC.

THE CENTER OF TROPICAL STORM KIRK AT 29/0900 UTC IS NEAR
24.3N 45.3W. KIRK IS MOVING WEST-NORTHWESTWARD 8 KNOTS.
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 40 KT WITH GUSTS TO 50 KT. PLEASE
READ THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/WTNT21 KNHC AND THE PUBLIC ADVISORY...MIATCPAT1/
WTNT31 KNHC FOR MORE DETAILS. THE CLOUD TOP TEMPERATURES IN
THE PRINCIPAL AREA OF CONVECTIVE PRECIPITATION HAVE BEEN
WARMING DURING THE LAST SIX HOURS. REMAINING SCATTERED MODERATE
TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS FROM 24N TO 26N
BETWEEN 44W AND 46W. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND
POSSIBLE PRECIPITATION ARE ELSEWHERE FROM 20N TO 31N BETWEEN
25W AND 49W. COMPARATIVELY DRIER AIR IN SUBSIDENCE IN WATER
VAPOR IMAGERY COVERS THE ATLANTIC OCEAN TO THE SOUTH OF 30N
BETWEEN 40W AND 60W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 32W/33W...FROM 20N TO A
1009 MB LOW PRESSURE CENTER THAT IS NEAR 12N33W. THE SHOWER
ACTIVITY AROUND THE CENTER HAS INCREASED COMPARED TO
OBSERVATIONS 24 HOUR AGO. ENVIRONMENTAL CONDITIONS ARE EXPECTED
TO BE CONDUCIVE FOR SLOW DEVELOPMENT DURING THE NEXT FEW DAYS.
THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD 13 KNOTS.
CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS STRONG FROM 8N
TO 11N BETWEEN 36W AND 40W...SCATTERED MODERATE TO STRONG FROM
11N TO 16.5N BETWEEN 27W AND 39W.

...TROPICAL WAVES...

NO OTHER TROPICAL WAVES ARE INCLUDED IN THE 29/0600 UTC
SURFACE MAP ANALYSIS. PLEASE REFER TO THE SPECIAL FEATURES
SECTION FOR DETAILS ABOUT THE 32W/33W TROPICAL WAVE.

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

THE MONSOON TROUGH IS INDISTINCT TO THE EAST OF THE 32W/33W
TROPICAL WAVE AND ACCOMPANYING LOW PRESSURE CENTER. THE MONSOON
TROUGH HAS BEEN DISRUPTED BY THE LARGE-SCALE WIND FLOW THAT IS
MOVING AROUND THE WAVE AND LOW CENTER FEATURE. THE MONSOON
TROUGH EVENTUALLY IS ALONG 9N34N 8N40W 10N49W 13N55W. THE ITCZ
ALSO IS INDISTINCT. CONVECTIVE PRECIPITATION...SCATTERED STRONG
FROM 10N TO 13N BETWEEN 18W AND 20W...SCATTERED MODERATE TO
ISOLATED STRONG ELSEWHERE FROM 5N TO 15N TO THE EAST OF 24W.
RAINSHOWERS ARE POSSIBLE FROM 10N TO 15N BETWEEN 50W AND 60W.

...DISCUSSION...

THE GULF OF MEXICO...

HURRICANE ISAAC IS MOVING SLOWLY ALONG THE COAST OF SOUTHEASTERN
LOUISIANA. ISAAC IS PRODUCING A DANGEROUS STORM SURGE. FLOODING
FROM RAINFALL ALSO IS EXPECTED. PLEASE REFER TO THE SPECIAL
FEATURES SECTION FOR DETAILS ABOUT THIS CYCLONE.

THE UPPER LEVEL ANTICYCLONIC OUTFLOW FROM ISAAC COVERS
FLORIDA...THE SOUTHWESTERN HALF OF GEORGIA...THE SOUTHERN
TWO-THIRDS OF ALABAMA AND MISSISSIPPI...THE SOUTHEASTERN HALF
OF LOUISIANA...AND THE GULF OF MEXICO TO THE NORTH OF 24N.
THE OUTFLOW EVEN REACHES THE YUCATAN CHANNEL. COMPARATIVELY
DRIER AIR IN SUBSIDENCE SHOWS UP IN WATER VAPOR IMAGERY
IN MOST OF 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 24N.

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

FROM THE ATLANTIC OCEAN...INTO THE CARIBBEAN SEA...

A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS ALONG 26N75W...ACROSS
SOUTHEASTERN CUBA...TO A CYCLONIC CIRCULATION CENTER THAT IS
ON TOP OF JAMAICA...TO THE GULF OF URABA OF COLOMBIA. SCATTERED
STRONG CONVECTIVE PRECIPITATION IS IN EASTERN HONDURAS...
NORTHEASTERN NICARAGUA AND SOUTHEASTERN COASTAL NICARAGUA.
SCATTERED MODERATE CONVECTIVE PRECIPITATION IS BETWEEN 80W
AND 85W...AND IN THE ATLANTIC OCEAN TO THE SOUTH OF 26N BETWEEN
70W AND 76W.

THE REST OF THE CARIBBEAN SEA...

THE MONSOON TROUGH IS ALONG 9N73W IN COLOMBIA...THROUGH 9N80W IN
PANAMA...BEYOND WESTERN COSTA RICA. SCATTERED STRONG CONVECTIVE
PRECIPITATION IS ALONG THE COLOMBIA EASTERN PACIFIC COAST FROM
3N TO 6N BETWEEN 77W AND 80W. SCATTERED STRONG CONVECTIVE
PRECIPITATION IS FROM 8.5N TO 10N BETWEEN 77W INCLUDING IN THE
GULF OF URABA AND 80W. THE BASE OF THE MIDDLE LEVEL TO UPPER
LEVEL TROUGH THAT PASSES OVER SOUTHEASTERN CUBA IS IN THE GULF
OF URABA.

ISOLATED MODERATE CONVECTIVE PRECIPITATION IS FROM THE VENEZUELA
COAST TO 15N BETWEEN 62W AND 67W. BROKEN MULTILAYERED CLOUDS
COVER THE WATERS FROM 15N TO 18N BETWEEN 60W AND 68W. THE CLOUDS
AND PRECIPITATION HAVE BEEN MOVING WESTWARD DURING THE LAST FEW
DAYS...ORIGINALLY FROM THE ATLANTIC OCEAN...AFFECTING BARBADOS
POSSIBLY DURING THE LAST 24 TO 48 HOURS.

BROAD UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE CARIBBEAN
SEA THAT IS TO THE EAST OF THE SOUTHEASTERN 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 11 FOOT SEA HEIGHTS FROM
11N TO 18N BETWEEN 68 AND 80W.

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.

ONE SURFACE RIDGE PASSES THROUGH 32N20W TO 28N25W 26N35W. BROAD
SURFACE ANTICYCLONIC WIND FLOW MOVES AROUND A 1020 MB HIGH
PRESSURE CENTER THAT IS NEAR 26N63W. THIS AREA GOES FROM 15N TO
20N BETWEEN 50W AND 60W...AND TO THE NORTH OF 20N TO THE WEST OF
TROPICAL STORM KIRK.

PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...FOR DETAILS
ABOUT TROPICAL STORM KIRK. A SECOND FEATURE OF INTEREST IS
A 1009 MB LOW PRESSURE CENTER THAT STARTS AS A POSSIBLE TROPICAL
CYCLONE 12 HOURS FROM NOW NEAR 13N37W...AT 24 HOURS 1008 MB
POSSIBLE TROPICAL CYCLONE NEAR 13N41W...AND AT 48 HOURS 1008 MB
POSSIBLE TROPICAL CYCLONE NEAR 14N46W.

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

$$
MT



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