Damaging Wind in Wisconsin, September 6, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
313 PM CDT THU SEP 6 2001

SEVERAL SIGNIFICANT SYSTEM WILL AFFECT THE FORECAST AREA TONIGHT
THROUGH THE WEEKEND.  THIS WILL RESULT IN A SIGNIFICANT CHANGE TO
THE WEATHER.  MAIN FORECAST PROBLEM IS RESOLVING THESE FEATURES AND
THEIR TIMING/AFFECT ON THE FORECAST AREA.

MORNING ANALYSIS SHOWS A SIGNIFICANT UPPER LEVEL DISTURBANCE
(DISTURBANCE NUMBER 1)...WHICH AT 250 MB IS CENTERED OVER
SOUTHEASTERN IDAHO.  SHORTWAVE TROUGHS EXTENDS FROM THIS DISTURBANCE
SOUTHEAST INTO TEXAS...AND SOUTHWEST THROUGH CALIFORNIA.  THIS SYSTEM
IS BECOMING MORE CLOSED OFF THROUGH TIME...GRADUALLY BECOMING REMOVED
FROM THE MEAN FLOW.  DISTURBANCE NUMBER 2...WHICH IS OF MORE
SIGNIFICANCE...RESIDES ACROSS THE YUKON AND CONTINUES TO MOVE
SOUTHEAST AND GAIN STRENGTH AS A STRONG JET MOVES ALONG ITS SOUTHWEST
PERIPHERY.  A THIRD DISTURBANCE IN EASTERN KANSAS IS ALONG THE
SHORTWAVE TROUGH EXTENDING SOUTHEAST FROM THE DISTURBANCE ACROSS
SOUTHEASTERN IDAHO.  THIS SYSTEM IS MOVING NORTHEAST.

IN THE LOWER LEVELS...A STRONG TROUGH EXTENDS FROM THE HIGH PLAINS
SOUTHWEST TO THE 4 CORNERS REGION.  STRONG BAROCLINICITY NOTED AT
850 MB NEAR THIS SYSTEM.  SOUTHERLY MOISTURE IS BEING TAPPED...
PRODUCING 850 MB DEWPOINTS 12C AND HIGHER ALL THE WAY NORTH THROUGH
KMPX.  A COLD FRONT EXTENDS FROM EAST OF CYWG...SOUTHWEST THROUGH
EAST OF KRAP.  TEMPERATURE CHANGE NEARLY 20 DEGREES BEHIND THE FRONT.

REGIONAL RADARS SHOWING PRECIPITATION INCREASING ACROSS THE UPPER
MISSISSIPPI RIVER VALLEY.  THIS IS FROM DISTURBANCE 3...WHICH
EXHIBITS STRONG LOW LEVEL MOISTURE TRANSPORT AND FAVORABLE UPPER
LEVEL DIVERGENCE.

MODELS INITIALIZED ADEQUATELY...WITH THE AVN BETTER WITH THE LOW
LEVEL MOISTURE AND STRENGTH OF THE DISTURBANCES.  MAIN DIFFERENCE
BETWEEN THEM IS THEIR FORECAST OF DISTURBANCE 2.  THE ETA DIGS IT
FURTHER TO THE SOUTH.  THIS CAUSES THE SURFACE SYSTEM TO BE FURTHER
SOUTH AND SLOWER TO EJECT ACROSS THE FORECAST AREA THAN THE AVN. THIS
SEEMS REASONABLE GIVEN THE TREND TOWARD A STRONGER...MORE CLOSED
SYSTEM.

AS THE SHORTWAVE (DISTURBANCE 3) MOVES NORTHEAST TONIGHT...SHOWERS
AND THUNDERSTORMS WILL MOVE ACROSS THE FORECAST AREA.  THIS SHOULD
MOVE OUT EARLY FRIDAY MORNING.  SOUTHWESTERLY WINDS WILL KEEP LOW
TEMPERATURES UP TONIGHT.

FRIDAY SHOULD BE DRY FOR A PERIOD DURING THE MORNING.  DISTURBANCE 1
AND 2 WILL MOVE SOUTHEAST.  DURING THE DAY FRIDAY...AN AXIS OF
DEFORMATION DEVELOPS AS THESE TWO DISTURBANCES BEGIN TO INTERACT WITH
EACH OTHER.  AT THE SURFACE...THE COLD FRONT WILL MOVE SOUTHEAST...
PROVIDING A FOCUSING MECHANISM TO ENHANCE PRECIPITATION IN THE LOWER
LEVELS. PRECIPITATION SHOULD MOVE BACK IN DURING THE DAY FRIDAY.

THIS SHOULD CONTINUE AS DISTURBANCE 2 BEGINS TO BE PULLED NORTHEAST
BY DISTURBANCE 1.  THIS DEVELOPS INTO QUITE A DYNAMIC SITUATION...
RESULTING STRONG FRONTOGENESIS AND A WELL DEVELOPED SYSTEM MOVING
THROUGH THE FORECAST AREA SATURDAY.  THIS WILL CONTINUE THE
EXTENDED PERIOD OF PRECIPITATION.

ON SUNDAY...DISTURBANCE 1...WHICH IS RATHER CLOSED BY THIS TIME...
SLOWLY MAKES ITS WAY THROUGH THE UPPER MISSISSIPPI RIVER VALLEY.
ANOTHER SYSTEM IS RIGHT ON THIS ONES HEELS...WHICH SHOULD MOVE INTO
THE REGION DURING THE MONDAY/TUESDAY TIME FRAME.  THIS WILL CONTINUE
THE UNSTABLE/CLOUDY/COOL CONDITIONS THROUGH THIS TIME.

AM HESITANT IN BRINGING BACK RIDGING AS SUGGESTED BY THE 06/00Z
MRF.  MEANS SUGGEST MORE TROUGHING ACROSS THE NORTHERN PORTION OF
THE COUNTRY.  AS A RESULT...WILL CONTINUE FORECAST OF COOL AND
CHANCE OF PRECIPITATION.

COORDINATED WITH DVN...MPX/MKX/GRB VIA OZF.

.LSE...NONE.

KRC

WIZ029-032>034-041>043-053-062130-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LA CROSSE WI
313 PM CDT THU SEP 6 2001

...HEAVY RAINS MOVING THROUGH WESTERN WISCONSIN...

A CLUSTER OF THUNDERSTORMS WAS MOVING THROUGH WEST CENTRAL WISCONSIN
DROPPING VERY HEAVY RAIN IN THE LA CROSSE...SPARTA AND BANGOR AREAS.
THE FAST RAINFALL RATE MAY LEAD TO MINOR STREET AND SEWER
FLOODING...ESPECIALLY IN URBAN AREAS...SO WATCH FOR HIGH WATER.

THE NATIONAL WEATHER SERVICE OFFICE JUST EAST OF LA CROSSE PICKED UP
JUST OVER THREE QUARTERS OF AN INCH OF RAIN IN A VERY SHORT PERIOD
AS THESE STORMS MOVED THROUGH.

THIS HEAVY RAIN IS HEADING TOWARD THE BLACK RIVER FALLS AND
NEILLSVILLE AREAS BY 345 PM.

SHEA