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Just got a report of half dollar sized hail. This corresponds well with the MESH which indicated max of 1.89. Issued another warning upstream now that the storm has taken on a little more supercell type characteristics. Did have a decent low level circ in Wabasha County, but experience today suggests that the storms are elevated in this area.MRD/TY
Again, missing the OUNWRF :,( The recent HRRR runs have kept updraft helicity values pretty low (<100 m2/s2) across the plains and upper midwest. The forecast vertical wind shear and CAPE across MN should be sufficient for supercells, yet the HRRR says “nyet”.
SNELSON/TMT
Updraft strength has increased with storms moving into Northwest Iowa. 3DVAR showed steady increase especially with the storm over Monona County IA. The 1 km Total Wind showed an increase to 50 knots with this storm.
Maximum divergence above 8 km has increased to near 17 /s at 2150z.
Tim/Steve
Very strong storms over Butler county over the last 45 minutes. Have had several reports of hail, most recently under the most intense storm of the day east of Brainard. Suprisingly, the spotter report was only nickel size hail at 2145 UTC. 2142 UTC MESH has showed as high as 2.4 inches in this area. The 2145 UTC 3DVAR composite updraft maximum and max divergence aloft at this location were also high, 23 m/s and 18 s-1, respectively. Not seeing much supercell development or behavior (mesocyclone, right turning or splitting). Updraft helicity has been low. Better vertical wind shear remains to the north over MN. Will continue to watch.
SNELSON/TMT
Mass continuity is still something we can believe in with 3DVAR data. The top right panel shows max divergence above 8km and bottom right panel shows composite updraft maximum. Saw both of these fields increase from 2050 to 2055 UTC. Was waiting to see if MESH or reflectivity would also increase in the subsequent 30 minutes, but as of 2125 UTC, have not seen any sign of this. MESH and storm reports have only yielded hail up to 1.5 inches.
SNELSON/TMT
Went with a SVR for the western storm in Goodhue Co. 3dvar data shows strong updraft close to 17 ms^-1 and updraft helicity close to 150 ms^-2. 3dvar 1km wind also shows 31m/s inflow into the storm. Suspect this developed right on the boundary and may be elevated but will need to watch for a low level circ developing given the proximity to the boundary. MRD/TY
Strongest CTC indication yet on latest pass. Would issue an outlook for strong storms may be developing in the next hour based on environment and what we are seeing in the CTC rates.
Garmon/Skov
The leading storm moving through Goodhue County is starting to diminish, confirmed by weakening updraft and weak storm top divergence in 3dvar. Storm to the west has strengthened slightly over the past 15 min and will need to be watched given the increased updraft and storm top divergence. -MRD/TY
CTC did a good job forecasting 45 minutes out the development of the Polk county cluster that really got going as it crossed over into Butler county in Omaha’s area.
The 2030Z pass of the CTC and CI products are starting to hint at convective initiation across our area in the next hour or so. Here is a look at the regional radar…
Garmon/Skov
Cloud top cooling product shows new potential, if only briefly. Max cooling reached <-22 degrees C. The area of concern is closer to the un-worked over air, but it will be moving into LaCrosse’s CWA soon. Might be able to warn on it before it moves out.
