Moderate risk coming to Midwest...

[PurdueWx80]

today, and further north tomorrow. See http://www.spc.noaa.gov/products/outlook/. One MCS after another keeps hitting the same areas of KS, MO, IA and IL, so look for lots of flash flooding as well. Models have had a horrible time the past couple of days. Tomorrow's outbreak looks like a more serious situation, and I wouldn't be surprised to see an upgrade to high risk in tomorrow's day1 outlook. Excellent chance of tornadoes and large hail evolving into a derecho.

The MCS across IL and MO this morning should stabilize much of the atmosphere in this region, but as long as it clears out behind this, there should be sufficient helicity and CAPE along the outflow boundary to initiate supercell development. There is not a tremendous amount of directional shear from 850-500, but the speed shear is there, and low level winds will be easterly along and north of the outflow. Look for supercells w/ a tornado and hail threat (not tremendously large but up to 2" possible). I think it will evolve into another MCS that will travel along the old boundary this evening.

[WXBUFFJIM]

It's definitely looking to be a busy time period ahead for eastern KS through southeastern Iowa today. By tomorrow, it could get worse with a good chance for tornadoes, some strong, and hail up to baseball-softball sized. A derecho setup is possible as this situation evolves from supercellular to more of a bow echo later in the evening Thursday.

Also latest tornado count for the month preliminarily is 128. the old record for August is 126. We'll add alot more to this between now and tomorrow night. Definitely a very busy tornado season and August is following suit.

Jim

[TexasStooge]

All I can say is look out!!!

[PurdueWx80]

Severe weather outbreak continues. I would not be at all surprised if some MAJOR flooding occurs in IA, MO and IL today. There are storms training over the exact same areas, and I could see as much as 6-8" of rain falling in some locations, w/ a few seeing as much as 10" (including this morning's rain). Precip water is between 1.7 and 2". The ground is already saturated so it won't take much for flash flooding. Again, this morning's models are failing to see much of the current activity, although the Eta is generally better than RUC or GFS. The mesoscale environment is really quite impressive and conducive to supercell development ahead of the currently forming MCS in western IA. Surface based CAPE's are up to 5500 at noon across northern and central MO - more than enough to fuel the fire. I look for a number of tornadoes this afternoon. Those CAPE's may mean hail could be up to baseball size in the strongest updrafts.

Tomorrow is quite scary as well. I still feel pretty confident in a high risk at some point, particularly across MN and WI, where the upper jet is most conducive to upper level divergence. I agree that a derecho setup looks likely with winds up to 100 mph once the supercells congeal into a bow echo. Look for widespread wind damage with even a few F3's possible.

[frankthetank]

i'm in SouthWest WI--right next to the mississippi...i'll be on the lookout! with my camera handy...

[NWIASpotter]

Indeed, very dangerous situation. Bad news for me, I'm stuck in school, not being able to go out. And what is probable good news/bad news, it is not over my area, just a lil to far to the east.

[PurdueWx80]

Outbreak just beginning, albeit a bit further south than what I thought yesterday. Turns out the rich moisture (dewpoints above 70) didn't quite make it into MN. Still, supercells forming rapidly in north central IA. Best tornado chance would be closer to WI and IL borders, but hail can reach baseball size or larger over the next couple of hours.

[NWIASpotter]

Not a great tornado outbreak at all. Preliminary report has only 5 tornadoes that thouched down. There has been wind gusts up to 70 mph, and hail that has reached 3 inches in diameter. This stretched from around Fort Dodge, IA, to near Omaha, NE. I barely recieved any rain at all today, and it was from this morning's rain shower that came through. I was able to get several pictures of the cloud tops, which were indeed spectacular.

[PurdueWx80]

Not a great tornado outbreak at all. Preliminary report has only 5 tornadoes that thouched down. There has been wind gusts up to 70 mph, and hail that has reached 3 inches in diameter. This stretched from around Fort Dodge, IA, to near Omaha, NE. I barely recieved any rain at all today, and it was from this morning's rain shower that came through. I was able to get several pictures of the cloud tops, which were indeed spectacular.

SPC shows hail reports up to 5.5" in diameter...very impressive. Tornado risk didn't pan out because moisture didn't make it up further north where best dynamics were. 850 flow was also much too weak over IA. Still a sizeable "outbreak" for late August.

[NWIASpotter]

That is true purduewx80, it was a sizable outbreak for this time in August. Those storms have continued through Iowa, and now through Illinois as well. What is left of these storms should be going through parts on Indiana already this morning.