[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 290604
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

...SPECIAL FEATURES...

THE CENTER OF HURRICANE ISAAC AT 29/0600 UTC IS NEAR
29.0N 90.0W. THIS POSITION IS ABOUT 51 NM TO THE SOUTHEAST
OF HOUMA LOUISIANA...AND ABOUT 61 NM TO THE SOUTH OF NEW ORLEANS
LOUISIANA. ISAAC IS MOVING SLOWLY ALONG THE COAST OF
SOUTHEASTERN LOUISIANA. ISAAC IS PRODUCING A DANGEROUS STORM
SURGE. FLOODING FROM RAINFALL ALSO IS EXPECTED. ISAAC IS MOVING
WEST-NORTHWESTWARD 6 KNOTS. THE MINIMUM CENTRAL PRESSURE IS
976 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 IS FROM 27.5N TO 31N BETWEEN
87W AND 91W. THIS MEANS THAT RAINFALL IS REACHING INLAND BETWEEN
THE FLORIDA PANHANDLE BORDER WITH MISSISSIPPI 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 29/0300 UTC IS NEAR
23.9N 45.0W. KIRK IS MOVING WESTWARD 10 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.
NUMEROUS STRONG CONVECTIVE PRECIPITATION IS FROM 24N TO 26N
BETWEEN 43W AND 46W. BROKEN TO OVERCAST MULTILAYERED CLOUDS
AND POSSIBLE PRECIPITATION ARE ELSEWHERE FROM 20N TO 31N
BETWEEN 25W AND 48W. COMPARATIVELY DRIER AIR IN SUBSIDENCE
IN WATER VAPOR IMAGERY COVERS THE ATLANTIC OCEAN TO THE SOUTH
OF 30N BETWEEN 40W AND 60W. BROAD UPPER LEVEL ANTICYCLONIC WIND
FLOW COVERS THE ATLANTIC OCEAN TO THE NORTH OF 20N BETWEEN 25W
AND 40W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 20N26W 16N29W...
TO A 1010 MB LOW PRESSURE CENTER THAT IS NEAR 12N30W.
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 7.5N TO
10.5N BETWEEN 36W AND 40W...SCATTERED MODERATE TO ISOLATED
STRONG FROM 13N TO 16N BETWEEN 30W AND 37W.

...TROPICAL WAVES...

NO OTHER TROPICAL WAVES ARE INCLUDED IN THE 29/0000 UTC
SURFACE MAP ANALYSIS. PLEASE REFER TO THE SPECIAL FEATURES
SECTION FOR DETAILS ABOUT THE 20N26W 12N30W TROPICAL WAVE.

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

THE MONSOON TROUGH IS INDISTINCT TO THE EAST OF THE 20N26W
12N30W TROPICAL WAVE...AS IT HAS BEEN DISRUPTED BY THE
LARGE-SCALE WIND FLOW THAT IS MOVING AROUND THE 1010 MB LOW
PRESSURE CENTER THAT IS NEAR 12N30W AND THE TROPICAL WAVE.
THE MONSOON TROUGH EVENTUALLY IS ALONG 9N BETWEEN 33W AND 50W.
THE ITCZ IS ALONG 13N55W 10N61W. CONVECTIVE PRECIPITATION...
SCATTERED STRONG IN TWO CLUSTERS FROM 10N TO 15N BETWEEN 15W
AND 18W IN COASTAL AFRICA...ISOLATED MODERATE TO LOCALLY STRONG
FROM 5N TO 10N TO THE EAST OF 30W.

...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 THE
SOUTHERN HALF OF LOUISIANA...AND IT REACHES CENTRAL MISSISSIPPI
AND CENTRAL ALABAMA. THE OUTFLOW MOVES EASTWARD COVERING THE
FLORIDA PANHANDLE AND THE EASTERN HALF OF THE GULF OF MEXICO
INTO THE YUCATAN CHANNEL. COMPARATIVELY DRIER AIR IN SUBSIDENCE
SHOWS UP IN WATER VAPOR IMAGERY IN PARTS 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 23N.

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 AND ITS
COASTAL WATERS BETWEEN 83W AND 85W. RAINSHOWERS ARE POSSIBLE
ELSEWHERE IN THE CARIBBEAN SEA TO THE NORTH OF 14N BETWEEN 78W
AND 85W...AND IN THE ATLANTIC OCEAN TO THE SOUTH OF 26N BETWEEN
68W AND 76W.

THE REST OF THE CARIBBEAN SEA...

THE MONSOON TROUGH IS ALONG 8N75W IN COLOMBIA...THROUGH 9N80W IN
PANAMA...BEYOND 9N84W IN COSTA RICA. SCATTERED STRONG CONVECTIVE
PRECIPITATION IS FROM 8N TO 9N BETWEEN 74W AND 77W INCLUDING IN
THE GULF OF URABA. THE BASE OF THE MIDDLE LEVEL TO UPPER LEVEL
TROUGH THAT PASSES OVER SOUTHEASTERN CUBA IS IN THE GULF OF
URABA.

BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE RAINSHOWERS
ARE FROM 12N TO 17N BETWEEN 63W AND 66W. THIS AREA OF CLOUDS
AND POSSIBLE PRECIPITATION HAS 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
12N 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 30N BETWEEN 20W AND 70W.
COMPARATIVELY DRIER AIR IN SUBSIDENCE COVERS THE AREA...EXCEPT
FOR THE CONVECTIVE PRECIPITATION THAT ACCOMPANIES T.S. KIRK.

ONE SURFACE RIDGE PASSES THROUGH 32N23W TO 27N36W. BROAD
SURFACE ANTICYCLONIC WIND FLOW MOVES AROUND A 1020 MB HIGH
PRESSURE CENTER THAT IS NEAR 27N63W. THIS AREA GOES FROM
13N 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...POSSIBLE TROPICAL CYCLONE...
AT 24 HOURS NEAR 13N36W...AND 1009 MB POSSIBLE TROPICAL CYCLONE
NEAR 14N42W IN 48 HOURS.

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

$$
MT





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