10/04/05 NOW: Central Plains/Mississipi Valley

[nickgrillo]

SFC analysis indicates a decelerating frontal boundary across Nebraska, and then curving northeastward into Wisconsin. Strong diurnal heating has occured across the warm sector, which has allowed for temperatures to rise into the 80-90f range.

Southerly low-level flow and enlarged hodographs should remain most pronounced across northwestern IA into southern MN - consident with SFC moist axis containing mid-upper 60 Tds. These factors combine with destabilizing boundary layer and steep midlevel lapse rates to yield 2000-3000 SBCAPE and rapidly weakening CINH. Strong SFC moisture convergance along the frontal boundary/weakening inhibitation indicates deep convection should develop within the next couple hours... 150-250 0-1km SRH and 50kt effective shear and very favorable moist low-level inflow supports supercells with large hail and perhaps a couple tornadoes.

EDIT: TOR just issued for activity in northwest WI (what a shock, huh? LOL) - not too sure how it will verify, thou. Low-level shear is rather meager in the region, with "doable-ish" LCLs in the 1200m~ area...

 

[Andrew Khan]

There has been a tornado warning issued for WI. The latest velocity scan shows strong rotation near the meso. There is SBCAPE of about the highest 3500 J/KG Along the IA/MN Border. Supercells look very good to develop along northern IA, and Southern MN. I think there is an isolated threat for tornadoes along the MN/WI border...you may even see some moderate size hail along the IA/MN border as well. There are some pretty awsome backing/veering winds along this area as well.

 

[Brett Adair]

Stronger deep layer shear is advecting into the SRN MN region and allowing for some storms to currently sustain there cellular nature while toward the south frontal forcing is stronger and allowing for a more linear nature to activity across SW IA into NE. MPX VWP indicates backed SFC flow, but not a very strong one so meso organization looks rather meager unless it is boundary induced. There could be a short lived twister or two, but not highly likely.