Indystorm

At least Ricky is using observations rather than relying on CAMS As had noted in earlier update, the MCV slowly pushing east from the Quad Cities area will be the trigger mechanism for convection the rest of this afternoon into the evening. A small cluster initiated right over the Quad Cities within the past hour. Aside from near the new CI, the cumulus over most of the area isn`t all that impressive with the exception of a more congested look near the lake breeze convergence. Possible that the Quad Cities activity just pushes east with CI near it or the ascent from the MCV gradually triggers widely scattered convection through the late afternoon. Had noted a modest wind response from 850 mb up to 500 mb on the DVN VWP, so deep layer shear as the MCV transits the area could sneak up to as much as 20-25 kt. The CAMs have once again no help in the forecast, so utilizing observational trends for the most part. The anticipated scattered convection that develops should gradually building/spreading southeast through the evening. Main threat from the tallest cores will be localized wind gusts strong enough to down tree limbs (level 1 severe threat). PWATs up in the 1.7-1.9" range will certainly yield efficient rainfall rates, so a localized flooding threat is there as well.

Why is SPC relying on CAMS in this meso discussion when CAMS have been horrible recently?

mesoanalysis indicates 2000-3000 J/kg of MLCAPE is present across much of Illinois owing to strong heating and surface dewpoints in the 70s F. As the cluster of storms east of Davenport continues south and east, strong buoyancy will continue to support vigorous updrafts with occasional hail or damaging gust potential. CAM guidance is not overly bullish with any organization of the ongoing convection. However, hints at a weak cold pool developing suggest some clustering may occur as storms move southeastward. Across far western Indiana and eastern Illinois, a westward propagating cluster of storms may also pose an isolated risk for downbursts this evening. Little vertical shear is in place with multicell storms exhibiting pulse characteristics. However, as additional development takes place, collapsing storms may produce a few strong wind gusts into this evening.

ED AUG 25 2021 ILC073-252115- /O.CON.KDVN.SV.W.0097.000000T0000Z-210825T2115Z/ HENRY IL- 403 PM CDT WED AUG 25 2021 ...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 415 PM CDT FOR SOUTHERN HENRY COUNTY... AT 402 PM CDT, A SEVERE THUNDERSTORM WAS LOCATED NEAR WOODHULL, OR NEAR CAMBRIDGE, MOVING EAST AT 20 MPH. THIS IS A DESTRUCTIVE STORM FOR ULAH...BISHOP HILL...NEKOMA AND GALVA. HAZARD...BASEBALL SIZE HAIL AND 60 MPH WIND GUSTS. SOURCE...RADAR INDICATED. IMPACT...PEOPLE AND ANIMALS OUTDOORS WILL BE SEVERELY INJURED. EXPECT SHATTERED WINDOWS, EXTENSIVE DAMAGE TO ROOFS, SIDING, AND VEHICLES. LOCATIONS IMPACTED INCLUDE... KEWANEE, CAMBRIDGE, GALVA, WOODHULL, ALPHA, ANDOVER, LYNN CENTER, BISHOP HILL, OPHIEM, NEKOMA, KEWANEE MUNICIPAL AIRPORT AND ULAH.

BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE QUAD CITIES IA/IL 343 PM CDT WED AUG 25 2021 THE NATIONAL WEATHER SERVICE IN THE QUAD CITIES HAS ISSUED A * TORNADO WARNING FOR... CENTRAL HENRY COUNTY IN NORTHWESTERN ILLINOIS... * UNTIL 400 PM CDT. * AT 343 PM CDT, A CONFIRMED TORNADO WAS LOCATED NEAR GENESEO, OR 7 MILES NORTH OF CAMBRIDGE, MOVING EAST AT 20 MPH. HAZARD...DAMAGING TORNADO. SOURCE...LAW ENFORCEMENT CONFIRMED TORNADO. IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE TO ROOFS, WINDOWS, AND VEHICLES WILL OCCUR. TREE DAMAGE IS LIKELY. * THE TORNADO WILL BE NEAR... GENESEO AROUND 350 PM CDT.

I am wondering if these multiple t storm clusters will morph into more of an east-west oriented band later this evening along the OFB and would produce training of heavy rains. Maybe I am just reacting to what happened in TN although I don't expect anything near that amount of precip.

I wonder where that OFB will eventually settle for tonight before it moves back north tomorrow with hot and muggy conditions predicted once again. That location might be the focus for heavier rains overnight.

Flash flood warning for parts of Boone and McHenry counties. I am concerned with training storms over certain areas this evening given multiple bands extending west into Iowa.

I am rooting for the development of a good cold pool to push the storms se.

UL 29 2021 WIC079-101-127-133-290715- /O.CON.KMKX.TO.W.0006.000000T0000Z-210729T0715Z/ MILWAUKEE WI-WALWORTH WI-RACINE WI-WAUKESHA WI- 144 AM CDT THU JUL 29 2021 ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 215 AM CDT FOR MILWAUKEE...NORTHEASTERN WALWORTH...RACINE AND WAUKESHA COUNTIES... AT 142 AM CDT, TORNADO PRODUCING STORMS WERE LOCATED ALONG A LINE EXTENDING FROM NEAR WAUKESHA TO POTTER LAKE TO NEAR ELKHORN, MOVING SOUTHEAST AT 50 MPH. HAZARD...DAMAGING TORNADO. SOURCE...RADAR CONFIRMED TORNADO WEST OF WAUKESHA. IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE TO ROOFS, WINDOWS, AND VEHICLES WILL OCCUR. TREE DAMAGE IS LIKELY. LOCATIONS IMPACTED INCLUDE... MILWAUKEE, RACINE, WAUKESHA, WEST ALLIS, WAUWATOSA, NEW BERLIN, BROOKFIELD, GREENFIELD, OAK CREEK, MOUNT PLEASANT, MUSKEGO, SOUTH MILWAUKEE, CUDAHY, WHITEFISH BAY, GREENDALE, PEWAUKEE, ST. FRANCIS, HARTLAND, HALES CORNERS AND MUKWONAGO.

Storm with rotation and history of producing tornadoes moving directly for Milwaukee and suburbs.

LOT issues its first warning of the episode for 70 mph winds for McHenry Boone and Winnebago counties.

SOURCE...MULTIPLE RADAR CONFIRMED TORNADO IN EASTERN JEFFERSON COUNTY. IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE TO ROOFS, WINDOWS, AND VEHICLES WILL OCCUR. TREE DAMAGE IS LIKELY. LOCATIONS IMPACTED INCLUDE... WATERTOWN, WHITEWATER, FORT ATKINSON, HARTLAND, JEFFERSON, DELAFIELD, LAKE MILLS, WALES, OKAUCHEE LAKE, OCONOMOWOC, OTTAWA, MERTON, JOHNSON CREEK, DOUSMAN, NORTH PRAIRIE, PALMYRA, LAC LA BELLE, LAKE RIPLEY, LAKE KOSHKONONG AND IXONIA. PRECAUTIONARY/PREPAREDNESS ACTIONS... TO REPEAT, A TORNADO IS ON THE GROUND.

EVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 114 AM CDT THU JUL 29 2021 WIC055-133-290645- /O.CON.KMKX.TO.W.0005.000000T0000Z-210729T0645Z/ WAUKESHA WI-JEFFERSON WI- 114 AM CDT THU JUL 29 2021 ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 145 AM CDT FOR WESTERN WAUKESHA AND JEFFERSON COUNTIES... AT 113 AM CDT, TORNADO PRODUCING STORMS WERE LOCATED ALONG A LINE EXTENDING FROM NEAR LAC LA BELLE TO 6 MILES EAST OF JOHNSON CREEK TO NEAR JEFFERSON, MOVING EAST AT 50 MPH. HAZARD...DAMAGING TORNADO. SOURCE...RADAR CONFIRMED TORNADO SOUTH-SOUTHWEST OF WATERTOWN. IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE TO ROOFS, WINDOWS, AND VEHICLES WILL OCCUR. TREE DAMAGE IS LIKELY. LOCATIONS IMPACTED INCLUDE... WATERTOWN, WHITEWATER, FORT ATKINSON, HARTLAND, JEFFERSON, DELAFIELD, LAKE MILLS, WALES, OKAUCHEE LAKE, OCONOMOWOC, OTTAWA, MERTON, JOHNSON CREEK, DOUSMAN, NORTH PRAIRIE, PALMYRA, LAC LA BELLE, LAKE RIPLEY, LAKE KOSHKONONG AND IXONIA.

Svr storm watch coming soon for Chi town area and environs per SPC meso discussion.

Just like Alek said this morning that the complex would go much farther west than the models predicted and be an I-90 special.

Trees and powerlines reported down throughout the city.

Skilling said trees and powerlines were down in Tomahawk WI.

That is where the greatest helicity has been located.

With svr storms forming as far west as Itasca I am not so sure that western areas will escape unscathed. I-90 special in a broad arc from east of Green Bay in Lake Michigan down through Madison and west to LaCrosse IMHO.

With CAPE values as high as what we are seeing when these storms form they will certainly explode as they move south/se. Not very often do we get a PDS svr storm watch particularly for the night hours.

When in doubt go big. Almost all of WI is included in the watch. I know the focus has been rightly upon svr wind and possible derecho, but those helicity values in certain locations on SPC meso concern me.

SPC meso page for what it is worth

700mb temps still 10-12 in the affected area where we anticipate a watch. Cap?

I'm tending to agree with Purduewx here and thinking the CAMS might be off a bit and too far ne. As I look at current satellite, radar, and SPC meso values I'm leaning to a more north south orientation as well a bit farther west. The instability gradient will be all important in its location for what transpires this evening and tonight in the affected areas.