8/9/05 FCST: MN, IA

Joined
Jul 23, 2004
Messages
497
Location
Iowa City, IA
Chase target:
Worthington, MN.

Timing:
4 PM CDT.

Storm type:
A few discrete storms early in storm evolution, transitioning into a linear complex through 6 PM, at which time the leading edge of the storms will extend along a Rochester to Albert Lea to Estherville line. Hail to 1â€￾ will be possible between 4PM and 6PM, and then during the evening the severe threat will transition to that of winds to 60 MPH.

Discussion:
An MCS in CNTRL MN has pushed an outflow boundary to an EAU-FBL-MWM-PQN-MHE line in WI/MN/SD through 14Z. In MN, this feature appears to be moving SWRD at 25-30mph. Also associated with this MCS is an extensive CI shield covering much of MN and the ERN Dakotas, although thinning/clearing is taking place in SWRN MN. Meanwhile, the synoptic picture shows a surface CF from near DLH to ATY to a developing low pressure near VTN. Upstairs, a couple of vorticity lobes were sagging slowly S along the SRN edge of a 40-60kt ULVL flow.

Later this afternoon, the CF will make a strong push into SWRN/CNTRL MN; and the intersection of it and the outflow boundary will provide the focus for renewed convective development near Worthington as a potent piece of energy at the mid-levels approaches. By 21Z, convective temperatures around 92-94F should be easily reached where clearing has taken place. The synoptic forcing mode suggests that storms will evolve into a linear complex early in evolution and dive S into NRN IA where it will outrun the mid/upper-level support, limiting the SVR potential there after dark.

- bill
 
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