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August 22-31 Severe Weather Thread


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DTX's update for tomorrow

THE BIG THING, WHICH WAS DOCUMENTED THOROUGHLY IN THE EARLY MORNING

FORECAST PACKAGE, IS THE INCREASE IN THE MODEL WIND FIELD AND

INSTABILITY PARAMETERS FOR WEDNESDAY AFTERNOON AND EVENING. THIS HAS

CARRIED OVER INTO THE 12Z FORECAST CYCLE ADDING CONFIDENCE TO THE

POTENTIAL FOR SEVERE CONVECTION. THE LATEST FORECAST SOUNDINGS FROM

THE NAM AND GFS SPORT 0-1KM MLCAPE OF 2000-2500 J/KG BY LATE

AFTERNOON VS 1500 COMPARED TO YESTERDAYS DATA. THIS APPEARS TO BE

THE RESULT OF A BETTER HANDLE ON THE EML MIGRATING INTO THE

MIDWEST FROM THE PLAINS. THERE IS ALSO CONSIDERABLY GREATER SHEAR

IN THE LOW LEVELS OF THE WIND PROFILE, DUE TO EXTRA DEEPENING OF

THE SURFACE LOW IN NORTHERN ONTARIO, WITH 0-3KM HELICITY RANGING

FROM 250-300 M2/S2 COMPARED TO VALUES CLOSER TO 150 YESTERDAY. THE

DATA IN YESTERDAY`S MODEL RUNS DEPICTED A SCENARIO SUFFICIENT FOR

SEVERE WEATHER, ESPECIALLY WITH REGARD TO LINEAR CONVECTIVE MODES,

BUT THE NUMBERS THAT HAVE PERSISTED INTO TODAY`S MODEL DATA

INTRODUCE AN EXTRA LAYER OF POTENTIAL THAT INCLUDES SUPERCELL

MODES CAPABLE OF LARGE HAIL AND TORNADO DEVELOPMENT. THE MOST

CHALLENGING ASPECT OF THE FORECAST WILL BE IDENTIFYING THE TIMING

AND LOCATION FOR STORM INITIATION. THIS IS COMPLICATED BY THE LOW

TO MID LEVEL CAPPING INVERSION THAT DEVELOPS ON THE HEELS OF THE

EARLY MORNING ACTIVITY AND STRENGTHENED BY THE INCREASING

SOUTHWEST LOW LEVEL FLOW DURING THE EARLY AFTERNOON. AT THIS

POINT, PREFER TO EXPECT THE CAP TO HOLD INTO THE LATE

AFTERNOON/AROUND 21Z. AFTER THAT, SURFACE CONVERGENCE ALONG THE

PREFRONTAL TROUGH WILL COMBINE WITH MAX TEMPS NEAR 90 AND THE

APPROACH OF THE UPPER TROUGH TO INITIATE STORMS. BY THEN, HOWEVER,

THE ACTIVITY WILL LIKELY DEVELOP RIGHT OVER SE MICHIGAN BEFORE

MOVING OFF TO THE EAST BY MID EVENING. THIS WOULD RESULT IN VERY

LITTLE ADJUSTMENT TO EARLIER EXPECTATIONS FOR SEVERE WEATHER OTHER

THAN POSSIBLY SPARING US THE MORE MATURE ASPECTS OF SQUALL LINE

DEVELOPMENT IN OUR AREA.

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mcd2044.gif

MESOSCALE DISCUSSION 2044

NWS STORM PREDICTION CENTER NORMAN OK

0456 PM CDT TUE AUG 23 2011

AREAS AFFECTED...WI

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 232156Z - 232330Z

LONG LIVED WELL DEFINED MID LEVEL VORT IS DIGGING SEWD ACROSS NRN WI

AT ROUGHLY 35KT. WHILE WEAK CONVECTION HAS BEEN NOTED WITH THIS

FEATURE MOST OF THE DAY...A RENEWED BAND OF TSTMS HAS INTENSIFIED

ALONG LEADING EDGE OF STRONGER FORCING FROM LINCOLN COUNTY TO CLARK

COUNTY. LATEST SATELLITE IMAGERY SUGGESTS CONVECTION IS SLIGHTLY

ELEVATED AS POST MCS AIRMASS OVER MUCH OF CNTRL/SRN WI IS SHROUDED

IN STRATUS. EVEN SO...STRONG...SLIGHTLY ELEVATED UPDRAFTS SHOULD

PRODUCE HAIL AT/ABOVE SEVERE LEVELS. GIVEN CURRENT SPEED/MOVEMENT

THIS DEVELOPING SQUALL LINE SHOULD APPROACH WRN SHORE OF LAKE MI

BETWEEN 00-01Z.

..DARROW.. 08/23/2011

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Interesting what DTX mentioned about things firing up right over SEMI tomorrow. So while things might not be as widespread as a squall line moving through, the tornado threat will probably be enhanced when things are more discrete. Let's just hope the CAP works with us this time...

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Tor watch and first tor warning of the day issued.

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE GREEN BAY WI

520 PM CDT TUE AUG 23 2011

THE NATIONAL WEATHER SERVICE IN GREEN BAY HAS ISSUED A

* TORNADO WARNING FOR...

WESTERN WOOD COUNTY IN CENTRAL WISCONSIN...

* UNTIL 545 PM CDT

* AT 517 PM CDT...LOCAL LAW ENFORCEMENT REPORTED A TORNADO 8 MILES

WEST OF MARSHFIELD...OR 29 MILES NORTHWEST OF WISCONSIN RAPIDS.

DOPPLER RADAR SHOWED THIS TORNADO MOVING SOUTHEAST AT 25 MPH.

* LOCATIONS IMPACTED INCLUDE...

PITTSVILLE...LINDSEY...BAKERVILLE...BETHEL...ARPIN...VESPER AND

DEXTERVILLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TO REPEAT...A TORNADO IS ON THE GROUND. TAKE COVER NOW. MOVE TO AN

INTERIOR ROOM ON THE LOWEST FLOOR OF A STURDY BUILDING. AVOID

WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR OUTDOORS...MOVE TO THE

CLOSEST SUBSTANTIAL SHELTER AND PROTECT YOURSELF FROM FLYING DEBRIS.

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URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 800

NWS STORM PREDICTION CENTER NORMAN OK

520 PM CDT TUE AUG 23 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF

CENTRAL WI WISCONSIN

LAKE MICHIGAN

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 520 PM UNTIL

1000 PM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE

MILES NORTH AND SOUTH OF A LINE FROM 25 MILES WEST NORTHWEST OF

CAMP DOUGLAS WISCONSIN TO 25 MILES EAST OF MANITOWOC WISCONSIN.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU0).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS.

DISCUSSION...SCATTERED THUNDERSTORMS CONTINUE TO INCREASE IN

COVERAGE OVER CENTRAL WI. THESE STORMS ARE EXPECTED TO TRACK

SOUTHEASTWARD ACROSS THE WATCH AREA THROUGH THE EVENING.

STRENGTHENING LOW LEVEL WIND FIELDS AND FAVORABLE MID LEVEL FLOW

SUGGEST THE RISK OF SUPERCELLS CAPABLE OF VERY LARGE HAIL...DAMAGING

WINDS...AND AN ISOLATED TORNADO OR TWO. THE MAIN UNCERTAINTY

REGARDING THE WIND/TORNADO THREAT WILL INVOLVE THE PERSISTENT LOW

CLOUDS AND EXTENT OF REMAINING CAP.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 30030.

...HART

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Interesting what DTX mentioned about things firing up right over SEMI tomorrow. So while things might not be as widespread as a squall line moving through, the tornado threat will probably be enhanced when things are more discrete. Let's just hope the CAP works with us this time...

Maybe things will slow down a bit. Pessimistic that things will get going just to our east.

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Meanwhile to the west:

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE LA CROSSE WI

547 PM CDT TUE AUG 23 2011

THE NATIONAL WEATHER SERVICE IN LA CROSSE HAS ISSUED A

* TORNADO WARNING FOR...

SOUTH CENTRAL CLARK COUNTY IN CENTRAL WISCONSIN...

EAST CENTRAL JACKSON COUNTY IN WEST CENTRAL WISCONSIN...

* UNTIL 630 PM CDT

* AT 544 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

TORNADO 4 MILES SOUTHWEST OF HIGHWAY 95 AND 73...OR 7 MILES

SOUTHWEST OF NEILLSVILLE...MOVING SOUTHEAST AT 30 MPH. THIS TORNADO

WARNING UPGRADES THE PREVIOUS SEVERE THUNDERSTORM WARNING FOR CLARK

AND JACKSON COUNTIES.

* THE TORNADO WILL BE NEAR...

BALLARD ROAD AND PRAY AVENUE AROUND 555 PM...

PRAY AROUND 605 PM...

POTTERS FLOWAGE AROUND 610 PM...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER IN A BASEMENT OR IN AN INTERIOR ROOM ON THE LOWEST FLOOR

AND STAY AWAY FROM WINDOWS! CARS AND MOBILE HOMES SHOULD BE ABANDONED

FOR A STURDY BUILDING. AS A LAST RESORT...LAY FLAT IN A DITCH AND

COVER YOUR HEAD.

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Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 000

NWUS53 KARX 232302

LSRARX

PRELIMINARY LOCAL STORM REPORT

NATIONAL WEATHER SERVICE LA CROSSE WI

602 PM CDT TUE AUG 23 2011

..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...

..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....

..REMARKS..

0530 PM TORNADO CHILI 44.63N 90.35W

08/23/2011 CLARK WI EMERGENCY MNGR

HOUSE OFF FOUNDATION...POWER LINES DOWN...ROOFS OFF

HOUSES...AND BARNS DESTROYED

&&

$$

DAS

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I was in the 50% on the 15z today and it looks like I won't even get any storms as they start to weaken, to illustrate how the SREFs can go wrong.

We've already had an apparent tornado and the window probably isn't closed yet. I like seeing the high probs on multiple runs but it's never a substitute for looking at each ingredient and the overall setup.

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