8/25/04 NOW: Midwest/Plains.

Blue Box out for SOUTHWEST IOWA, NORTHEAST KANSAS, NORTHWEST MISSOURI, and SOUTHEAST NEBRASKA.

Also upgrade needed for this area at 1630: ERN KS...MO...SE IA
AND PART OF IL. THE CATEGORICAL RISK FOR SEVERE STORMS
WILL BE UPGRADED TO MODERATE RISK AT 1630Z.

Looks to be a very active day.
 
new outlook shows a 15% hatched area across norther MO, southern iowa and western ill. and also the same area has hatched wind and hail.

STWs coming out for storms Ill, but they are nothing compared to what seems possible later.
 
FYI: "NOW (nowcast) is only for discussion of storm character after convective initiation has occurred" -- looks like your stuff would go in a FORECAST section but it's just reposting of SPC info anyways. (Severe Thunderstorm Warning is abbreviated SVR)

Two nice squall lines ongoing, one through central IL but it's moving through a fairly cloud-covered airmass with temps low-70's. The big one appears to be just getting underway in NW Missou / SW Iowa with 85/77 air coming in from the south - I imagine that's going to be the newsmaker of the day.
 
I've been watching the cells near Columbia, MO try to get going - and slowly but surely echoes have been intensifying. This is right on the edge of the outflow boundary - so definitely worth keeping an eye on. Farther east, a persistent mesocyclone has been present with the IL cell west of Jacksonville - which is getting close to the outflow boundary from the earlier passing convective line. Instability and shear aren't as ideal with this cell - but it hass been improving in structure over the last hour or so.

Glen
 
Interesting on the 18Z sounding how great the profile looks - if you ignore the area from 800mb down to surface! Great lightning but surface temps are only in the upper-60's / low-70's with the heat a bit south.

Also nice 3-body scatter from 3.5* scan with TVS algorithm very excited... If only it wasn't elevated!
 
The wind profiles in the lower troposphere over Missouri are largely unidirectional, so I think the short line segment mode we see now on radar will continue. Wouldn't be surprised, with local pockets of backed surface winds remaining, to see a few tornadoes. I would lower the tornado probabilities to 5% unhatched on the afternoon update, centered on COU/STL.
 
3 tornado warnings are now in effect for the SW part of michigan, law enforcement reported a tornado 10 miles south of portland.

Radar doesn't show tons of shear, but none the less there is some.

EDIT: Damage being reported with storm:

0550 PM TSTM WND DMG VERMONTVILLE 42.63N 85.03W
08/25/2004 EATON MI LAW ENFORCEMENT

SEVERAL STRUCTURES DAMAGED IN THE CITY


It says tstm winds, but i wouldn't doubt it was a tornado. Cells firing ahead of line, could get interesting.
 
Not too often you see a SVR watch in an area of 25% hatched tornado probability... :? ... This seems to be a case of understable disconnect between the Day1 writer (Darrow) and the watch issuer (Thompson). Interesting none-the-less.

Edit: I'm referring to watch 786, btw.
 
The storm southeast of Topeka:

" AT 658 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A TORNADO NEAR OVERBROOK...OR ABOUT 18 MILES NORTHWEST OF OTTAWA...MOVING EAST AT 15 MPH."

Radar-indicated rotation has been decent with this storm, though not overly impressive on tilt 1. Low-level flow is weak in the area of the storm, and not overly backed. Instability remains strong (~4000 J/KG SBCAPE), though low-level shear remains weak in eastern KS (0-3km SRH ~100), though does increase markedly as one moves into MO with better 700-850mb flow...
 
I've been watching the "Ottawa" storm on radar for over an hour, and I have yet to see a velocity scan that did NOT have a coupling. Echo tops have consistently been >50K feet.

Yikes.

12,000 people in Ottawa....look out!

Bob
 
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