8/3 NOW: Upper Midwest

[Jeff Snyder]

Intense bow echo continues near FSD currently. Reported gusts near 90 mph and numerous other svr wind reports. Radar shows a relatively compact convective system now, though radial velocities from FSD are very intense! SPC just issued a PDS Severe weatch for widespread winds to 90mph... RUC indicates extreme CAPE will build into northern IA through the afternoon, ahead of the current complex. This instability should maintain and strengthen the system with time... Additionally, the system will likely increase in size as it tracks into far southern MN and into northern IA.

 

[Glen Romine]

There is also increasing convective coverage along the outflow boundary from the SD/MN MCS extending south and southwestward toward the surface low just east of Broken Bow. Convection was also starting to develop southeastward along the other residual outflow boundary that runs from ~ SUX to SPI. SPC RUC Mesoanalyses suggest the atmosphere is still capped strongly in these areas - so convection could currently be elevated in nature - but sufficient shear exists along the northern extent of this convection to allow for storm organization, and persistent upper level divergence over eastern NE should continue to promote additional convective development and cap erosion - perhaps allowing a few cells to tap into the boundary layer by early afternoon. Areas from SUX to Ft. Dodge look worth watching for the next few hours. Anyone else have thoughts on this?

Glen

 

[Dan Cook]

Newest Day 1 extended Mod risk through N. IL.

 

[rdale]

Dan: No need to repost SPC stuff without adding any info...

Anyways -- GREAT images from http://www.schoolnet8.com/camera/viewer.phtml if you click on the Jefferson site, it's a weathernet station & webcam just south of the massive hook echo near DSM!

- Rob

 

[Zach Bailey]

TOR warning up for what appears to be a tail-end charlie storm riding an OFB (maybe?). Strong velocity couplet seen on radar and a hint of a hook on BREF. This storm is currently WNW of Ames, IA.

 

[mikegeukes]

Interesting Severe Weather Statement out of Des Moines at 4:02pm CDT
this is for Greene County Iowa, currently has a tornado warning for it.

AT 356 PM...NWS SPOTTERS REPORTED A FUNNEL CLOUD NEAR CHURDAN...BUT
AS OF 402 PM AMATUER RADIO SPOTTERS DID NOT SEE A FUNNEL.

WW 698 TORNADO IA IL 032125Z - 040300Z
WW 699 SEVERE TSTM WI LM 032145Z - 040300Z just been issued.

Mike

 

[rdale]

Level II data shows 64.5dbZ up to 28K just over Dana so there's plenty of hail ready to fall out... Rotation not as good as before with outflow racing ahead of storm. Temps dropping nearly 20 degrees with passage.

 

[Glen Romine]

So, SPC just issued a T box for much of e IA into nw IL - bit of a surprise move in my opinion - I don't really see much of a tornado threat developing in that area. Plenty of instability - but still somewhat capped, and heating for the day is coming to a close. Helicity is currently pretty lame in the region boxed - though the RUC forecast suggests this will change over the next few hours. Upstream convection is looking pretty linear already, so it will be interesting to see if this box verifies.

Glen

 

[Robert Dewey]

So, SPC just issued a T box for much of e IA into nw IL - bit of a surprise move in my opinion - I don't really see much of a tornado threat developing in that area. Plenty of instability - but still somewhat capped, and heating for the day is coming to a close. Helicity is currently pretty lame in the region boxed - though the RUC forecast suggests this will change over the next few hours. Upstream convection is looking pretty linear already, so it will be interesting to see if this box verifies.

Glen

I agree - The southern most storm (tail end charlie) just threw out an outflow, so I don't see any significant potential there (its weakening now, probably due to the cap you mention - which is probably weakening the cold pool)... The middle storm (between the tail end charlie and the stuff in extreme northern IA/southern MN) looks like its now beginning to bow out...

 

[Zach Bailey]

Plenty of CAPE (I'm looking at SBCAPE of 7000+ on SPC's hourly meso analysis page on the border between IA and MO) with a weak to non-existant CIN can do amazing things, even with little to marginal helicities/shear. If some storms can fire along that OFB that tail-end charlie just laid out, we might be seeing something...

 

[mikegeukes]

Updated: 508 PM CDT

-Report of 80 mph winds out of Iowa Falls in Hardin County
-Tornado warning: Iowa for Marshall County
-Tornado warnings Wisconsin for Sauk Counties
nice little boundary moving west on MKX radar

-Storms just popped up in Dodge County Nebraska
WW 700 TORNADO IA NE 032200Z - 040300Z

Mike

 

[Dan Cook]

Is that boundary on MKX and LOT's radar from the lake or an outflow boundary?

 

[nickgrillo]

It's an outflow boundary (from the previous convection)....

 

[Jamie Lahowetz]

I decide to take a look at the weather cause im bored and look what i find, a CAPE of 4885 and a CINH of 0029 wow. I hope these stormes get going before sunset so that I can use my camera some more... and my roommates Rav4 hehe.

 

[Glen Romine]

The cell just west of OMA - if you are within an hours drive from it I'd seriously consider giving this cell a visit. the intersection of the outflow with the line in IA might get it done - but the motion of E @ 55 would make for a difficult chase.....

Glen