[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 312357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN AUG 31 2008

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

HURRICANE GUSTAV CENTERED NEAR 26.9N 87.7W AT 01/0000 UTC OR
ABOUT 260 MILES SSE OF NEW ORLEANS LOUISIANA MOVING NW AT 15 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 952 MB. MAXIMUM SUSTAINED
WIND SPEED IS 100 KT WITH GUSTS TO 120 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
FOR MORE DETAILS. GUSTAV IS EXPERIENCING ABOUT 20 KT OF
SOUTHERLY SHEAR AND WATER VAPOR IMAGERY INDICATES DRYING/
SUBSIDENCE OVER THE SW SEMICIRCLE. HOWEVER GUSTAV IS EXPECTED TO
STRENGTHEN SLIGHTLY AS IT APPROACHES THE LOUISIANA COAST AND IS
BEING STEERED BY A MIDDLE LEVEL RIDGE OVER THE EASTERN UNITED
STATES. THE LATEST VISIBLE IMAGERY INDICATES THE EYE IS FILLING
AND THE DEEPEST CONVECTION IS LOCATED OVER THE S QUADRANT.

TROPICAL STORM HANNA CENTERED NEAR 23.5N 71.6W AT 01/0000 UTC OR
ABOUT 140 MILES NNW OF GRAND TURK ISLAND MOVING W AT 8 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. MAXIMUM SUSTAINED
WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. HANNA IS EXPERIENCING NORTHERLY SHEAR AND THIS
WILL INHIBIT SIGNIFICANT STRENGTHENING OVER THE NEXT TWO DAYS.
THE STORM IS BEING STEERED BY A MIDDLE/UPPER LEVEL RIDGE OVER
THE WESTERN ATLANTIC. A BURST OF DEEP CONVECTION HAS FORMED S OF
THE CENTER AND SCATTERED MODERATE CONVECTION IS LOCATED OVER THE
SOUTHERN BAHAMAS.

A TROPICAL WAVE IS ALONG 34W FROM 11N TO 22N WITH AN EMBEDDED
1006 MB SURFACE LOW ALONG THE WAVE AXIS AT 17N. THE WAVE HAS THE
POTENTIAL TO DEVELOP INTO A TROPICAL CYCLONE OVER THE NEXT 48
HOURS AND THE FLOW ALOFT AS INDICATED BY WATER VAPOR IMAGERY IS
ANTICYCLONIC. THE WAVE IS MOVING W 10 TO 15 KT. THE CIRCULATION
COVERS A LARGE AREA AND THE LATEST INFRARED SATELLITE IMAGERY
INDICATES SCATTERED MODERATE TO STRONG CONVECTION FROM 16N TO
22N BETWEEN 32W AND 38W.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 50W FROM 14N TO 25N WITH AN EMBEDDED
1010 MB SURFACE LOW ALONG THE WAVE AXIS AT 21N. THE WAVE IS
MOVING WNW ABOUT 10 KT AND THE LOW IS DEFINED BY A SWIRL OF LOW
LEVEL CLOUDS. WINDS ALOFT DO NOT SUPPORT TROPICAL CYCLONE
DEVELOPMENT. A LARGE AREA OF LAYERED CLOUDS WITH EMBEDDED
SHOWERS AND THUNDERSTORMS ARE LOCATED UP TO 300 NM E OF THE WAVE
AXIS FROM 20N TO 28N.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED ALONG 10N14W 13N26W 09N40W 11N50W
10N62W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS LOCATED
FROM 10N TO 14N E OF 20W TO THE AFRICAN COAST AND FROM 07N TO
11N BETWEEN 30W AND 41W.

...DISCUSSION...

GULF OF MEXICO...
LOW SURFACE PRESSURES...AT OR BELOW 1012 MB...COVER THE ENTIRE
GULF THIS EVENING. GUSTAV IS A CATEGORY THREE HURRICANE ON THE
SAFFIR-SIMPSON SCALE AND IS FORECAST TO MAKE LANDFALL ALONG THE
NORTHERN GULF COAST ON MONDAY. STORM SURGE OF 10 TO 14 FEET
ABOVE NORMAL TIDAL LEVELS IS EXPECTED NEAR AND TO THE E OF WHERE
THE CENTER OF GUSTAV CROSSES THE NORTHERN GULF COAST AND
RAINFALL TOTALS MAY BE AS HIGH AS 20 INCHES. THE HIGHEST
SEAS FROM BUOY REPORTS IN THE NORTHERN GULF IS FROM STATION
42039 AND MEASURES 19 FEET. OUTER RAIN BANDS FROM GUSTAV ARE AS
FAR N AS THE CENTRAL PARTS OF ALABAMA AND MISSISSIPPI. AN
EAST-WEST RIDGE ALOFT IS FORECAST TO DEVELOP IN THE SOUTHERN
GULF ALONG 22N/23N ON MONDAY AND TUESDAY.

CARIBBEAN SEA...
WINDS ALOFT OVER THE CARIBBEAN ARE MOSTLY EASTERLY TO
NORTHEASTERLY EXCEPT FOR SE TO S WINDS OVER THE NW PART. WATER
VAPOR IMAGERY INDICATES SUBSIDENCE OVER THE CENTRAL CARIBBEAN.
AN AREA OF DEEP CONVECTION IS LOCATED ALONG THE COLOMBIA COAST
BETWEEN 72W AND 75W. AT THE SURFACE WINDS ARE EASTERLY AND
MEASURE NO HIGHER THAN 15 KT. THE SOUTHERN EXTENSION OF A
MIDDLE/UPPER LEVEL TROUGH OFF THE E COAST OF THE UNITED STATES
IS FORECAST OVER THE N CENTRAL CARIBBEAN.

ATLANTIC OCEAN...
A MIDDLE LEVEL RIDGE IS LOCATED OVER MOST OF THE AREA W OF ABOUT
55W. A SHARP MIDDLE/UPPER LEVEL TROUGH HAS ITS AXIS ALONG 52W N
OF 15N. AN EMBEDDED MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION IS
LOCATED WITHIN THE TROUGH AND CENTERED NEAR 27N52W...MOVING N 10
TO 15 KT. OVER THE E PART OF THE DISCUSSION AREA A MIDDLE/UPPER
LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 19N35W AND A
MIDDLE/UPPER LEVEL TROUGH COVERS THE AREA N OF 24N BETWEEN 15W
AND 35W WITH THE AXIS ALONG 26W. A MORNING QUIKSCAT PASS
INDICATES THE RIDGE AXIS JUST N OF THE DISCUSSION BOUNDARY FROM
34N30W TO NEAR BERMUDA.

$$
CAB


This weather bulletin was brought to you by:
www.nashvilleweather.net