[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 281157
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 28 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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 1045 UTC.

...SPECIAL FEATURES..

THE CENTER OF POTENTIALLY CATASTROPHIC CATEGORY FIVE HURRICANE
KATRINA IS NEAR 25.7N 87.7W AT 28/1200 UTC...OR ABOUT 275 MILES
SOUTH-SOUTHEAST OF THE MOUTH OF THE MISSISSIPPI RIVER. IT IS
MOVING WEST-NORTHWEST 11 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 908 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE NEAR
140 KT WITH GUSTS TO 170 KT. PLEASE READ THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
AND THE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32
KNHC FOR MORE DETAILS. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS
SURROUND KATRINA...WITHIN 100 NM FROM THE CENTER IN THE NORTHERN
SEMICIRCLE AND WITHIN 180 NM FROM THE CENTER IN THE SOUTHERN
SEMICIRCLE. ONE THIN BAND OF SHOWERS/THUNDERSTORMS STILL IS
SOUTH OF KATRINA FROM WESTERN CUBA TO CENTRAL BELIZE.

AN ATLANTIC OCEAN TROPICAL WAVE ALONG 43W/44W WITH A SURFACE
1010 MB LOW PRESSURE CENTER ALONG THE WAVE NEAR 12.5N. IT IS
POSSIBLE THAT THIS LOW CENTER MAY BECOME A TROPICAL CYCLONE
DURING THE NEXT 24 HOURS. THIS SYSTEM IS REMAINS WELL ORGANIZED
AND UPPER LEVEL WINDS APPEAR TO BE SOMEWHAT FAVORABLE FOR
DEVELOPMENT. SCATTERED STRONG SHOWERS AND THUNDERSTORMS ARE
FOUND FROM 14N TO 17N BETWEEN 43W AND 46W. ISOLATED TO WIDELY
SCATTERED MODERATE SHOWERS/LOCALLY STRONG THUNDERSTORMS ARE
ELSEWHERE FROM 8N TO 18N BETWEEN 41W AND 52W.

...TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 56W/57W SOUTH OF 19N
MOVING WEST 15 KT. A 1011 MB SURFACE LOW PRESSURE CENTER IS
NORTH OF THE WAVE ALONG 22N55W. SCATTERED STRONG SHOWERS AND
THUNDERSTORMS ARE FOUND FROM 24N TO 27N BETWEEN 48W AND 51W.
ISOLATED MODERATE SHOWERS ALSO ARE FOUND FROM 19N TO 23N
BETWEEN 50W AND 52W. THIS ASSOCIATED SHOWER ACTIVITY REMAINS
POORLY ORGANIZED...AND UPPER-LEVEL WINDS ARE EXPECTED TO
REMAIN UNFAVORABLE FOR TROPICAL CYCLONE FORMATION. THE
SURFACE LOW PRESSURE CENTER IS NOT CLOSE TO THE CONVECTIVE
ACTIVITY AT THIS TIME.

...THE ITCZ...

ITCZ 13N16W 9N24W 11N40W...11N46W 11N54W...11N59W 11N66W.
ISOLATED MODERATE TO LOCALLY STRONG SHOWERS AND THUNDERSTORMS
IN A CIRCULAR PATTERN FROM 7N TO 13N BETWEEN 12W AND 21W.

...DISCUSSION...

THE GULF OF MEXICO...
HURRICANE KATRINA IS THE MAIN FOCUS OF WEATHER IN THE
ATLANTIC BASIN...IT IS NOW A CATEGORY FOUR HURRICANE ON THE
SAFFIR-SIMPSON SCALE. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS
SURROUND KATRINA...WITHIN 100 NM FROM THE CENTER IN THE NORTHERN
SEMICIRCLE AND WITHIN 180 NM FROM THE CENTER IN THE SOUTHERN
SEMICIRCLE. ONE THIN BAND OF SHOWERS/THUNDERSTORMS STILL IS
SOUTH OF KATRINA FROM WESTERN CUBA TO CENTRAL BELIZE.
A HURRICANE WARNING IS IN EFFECT FOR THE NORTH CENTRAL GULF
COAST FROM MORGAN CITY LOUISIANA EASTWARD TO THE ALABAMA/
FLORIDA BORDER...INCLUDING THE CITY OF NEW ORLEANS AND LAKE
PONTCHARTRAIN. A HURRICANE WARNING MEANS THAT HURRICANE
CONDITIONS ARE EXPECTED WITHIN THE WARNING AREA WITHIN
THE NEXT 24 HOURS. PREPARATIONS TO PROTECT LIFE AND PROPERTY
SHOULD BE RUSHED TO COMPLETION.

THE CARIBBEAN SEA...
ONE THIN BAND OF SHOWERS/THUNDERSTORMS STILL IS SOUTH OF KATRINA
FROM WESTERN CUBA TO CENTRAL BELIZE. UPPER LEVEL NORTHEASTERLY
WIND FLOW...THE RESULT OF THE UPPER LEVEL ANTICYCLONIC OUTFLOW
FROM HURRICANE KATRINA...COVERS MOST OF THIS AREA WEST OF 70W.
A MIDDLE TO UPPER LEVEL TROUGH RUNS FROM THE ATLANTIC WATERS
THROUGH 32N61W THROUGH 20N62W INTO THE MONA PASSAGE. AN UPPER
LEVEL RIDGE IS WEDGED INTO THE REST OF THE EASTERN CARIBBEAN
SEA. MIDDLE TO UPPER LEVEL DRY AIR IS SOUTHEAST OF 20N60W
15N75W. SOME UPPER LEVEL DIFFLUENT FLOW IN AN AREA OF ISOLATED
MODERATE SHOWERS FROM 15N TO 20N BETWEEN 70W AND 80W.

THE ATLANTIC OCEAN...
UPPER LEVEL ANTICYCLONIC FLOW...SEPARATE FROM THE FLOW ON TOP
OF HURRICANE KATRINA...EXTENDS FROM THE SOUTHEASTERN U.S.A.
CURVING INTO THE ATLANTIC OCEAN SOUTHEASTWARD AS IT COMBINES
WITH THE FLOW FROM THE MIDDLE TO UPPER LEVEL 32N61W 26N61W
MONA PASSAGE TROUGH. A SURFACE STATIONARY FRONT IS ALONG 33N
BETWEEN 55W AND 65W. INSTABILITY FROM THE REMNANTS OF THIS FRONT
IS HELPING TO KEEP ALIVE ISOLATED MODERATE SHOWERS AND
THUNDERSTORMS FROM 30N TO 35N BETWEEN 60W AND 80W. ISOLATED
MODERATE SHOWERS AND THUNDERSTORMS CONTINUE IN AN AREA OF SOME
UPPER LEVEL DIFFLUENT FLOW...NORTHWEST OF THE 32N61W-MONA PASSAGE
TROUGH...ALL THE WAY TO THE BAHAMAS ISLANDS. ISOLATED MODERATE
SHOWERS ARE IN THE AREA OF THE CYCLONIC FLOW OF THE TROUGH FROM
20N TO NORTH OF 32N BETWEEN 46W AND 62W. BROAD UPPER LEVEL
ANTICYCLONIC FLOW IS IN BETWEEN THE 34N23W CYCLONIC CENTER AND
THE 32N61W-TO-MONA PASSAGE TROUGH. MIDDLE TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER IS NEAR 34N23W WITH NO SURFACE
REFLECTION. MIDDLE TO UPPER LEVEL CYCLONIC FLOW COVERS THE
ATLANTIC WATERS NORTH OF 27N BETWEEN 10W AND 32W. SURFACE HIGH
PRESSURE AND ANTICYCLONIC WIND FLOW COVER THE ATLANTIC WATERS
NORTH OF 23N BETWEEN AFRICA AND 50W.

$$
MT


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