MNstorms Posted July 16, 2019 Share Posted July 16, 2019 Some scattered severe storms yesterday and today across the upper midwest. Tomorrow could be huge in Minnesota if morning convection doesn't interfere and the cap breaks. So far the SPC only has a slight risk. The models are going crazy. Link to comment Share on other sites More sharing options...
MNstorms Posted July 18, 2019 Author Share Posted July 18, 2019 Northern MN had tornadoes yesterday. Perhaps Southern MN today. Tomorrow looks interesting. Link to comment Share on other sites More sharing options...
MNstorms Posted July 19, 2019 Author Share Posted July 19, 2019 Tomorrow looks to be a tornado outbreak in Minnesota and Wisconsin. Quote ...Upper Midwest...Upper Great Lakes... Showers and isolated thunderstorms will likely be ongoing at the beginning of the period over portions of the Upper Great Lakes, supported by a modest low-level jet. These showers and thunderstorms are expected to dissipate by the early morning as the low-level jet weakens. A very moist air mass is currently in place over the Upper Midwest/Upper Great Lakes, with even better moisture upstream across the Middle MS Valley. This air mass will remain over the region today with some modest moist advection possible. As a result, dewpoints are expected to be mid to upper 70s across a large portion of the Upper Midwest and Upper Great Lakes. Dewpoints around 80 may be realized across southern MN near a weak surface low. Surface temperatures are also expected to climb into the 90s as the boundary layer mixes. These very warm and moist conditions will exist beneath relatively cool mid-level temperatures, resulting in very steep (i.e. 8-8.5 deg C per km) mid-level lapse rates. As a result, an extremely buoyant thermodynamic environment (i.e. 4000+ J/kg of MLCAPE) will be in place. Highest buoyancy will likely occur across northern IA, southern MN, and west-central WI. In these areas MLCAPE could exceed 6000 J/kg this afternoon and evening. In addition to this extreme buoyancy, seasonally strong westerly flow aloft will extend from the northern High Plains through Upper MI. Generally southerly low-level flow beneath these westerlies results in effective bulk shear values of 45-55 kt across much of MN and northern WI today afternoon and evening. Link to comment Share on other sites More sharing options...
mob1 Posted July 19, 2019 Share Posted July 19, 2019 Upgraded to Moderate and they introduced a 15 percent TOR contour. Link to comment Share on other sites More sharing options...
yoda Posted July 19, 2019 Share Posted July 19, 2019 47 minutes ago, mob1 said: Upgraded to Moderate and they introduced a 15 percent TOR contour. Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0736 AM CDT Fri Jul 19 2019 Valid 191300Z - 201200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS EAST-CENTRAL MN AND NORTHERN WI... ...SUMMARY... A regional outbreak of severe thunderstorms with strong tornadoes and potentially widespread significant wind damage may occur from central Minnesota across northern Wisconsin during the mid-afternoon to evening. ...Upper Midwest/Great Lakes... Upgrading to Moderate Risk this outlook for the potential threats of multiple strong tornadoes and a derecho later this afternoon and evening. CAPE/shear/SRH parameter space in this region is forecast to be exceptionally rare for mid July amid a predominately zonal flow regime across the northern states. A convective cluster is ongoing across north-central SD aided by warm/moist advection around 700 mb along a pronounced baroclinic zone. 00Z CAM guidance had a decent handle on this activity earlier this morning and are consistent with a decaying trend through late morning as advection shifts east amid pronounced MLCIN as sampled by the 12Z Aberdeen sounding. There is a low confidence scenario that a strong enough cold pool is becoming established with this early-day cluster such that total decay does not occur. If this occurs, robust boundary-layer heating downstream may be sufficient for an increasing threat during the afternoon of strong to severe wind gusts. This could still yield a scattered to widespread damaging wind scenario, albeit in an earlier time frame than progged by guidance. The more probable scenario is for an extremely unstable air mass (MLCAPE > 4000 J/kg) to become established to from southeast SD through central/southern WI as the elevated mixed-layer overspreads surface dew points rising into the mid to upper 70s. A surface cyclone over central SD should track towards the Twin Cities through early evening. Strong low-level convergence near/northeast of this cyclone along the warm front should sustain surface-based storm development across central into east-central MN. Once initiation occurs, intense supercells will develop rapidly, with an attendant threat for all severe hazards including strong tornadoes amid 50-60 kt effective shear and 0-3 km SRH > 300 m2/s2. The very warm/moist thermodynamic profiles will also support generation of strong cold pools which should eventually yield a bowing, forward-propagating MCS across northern WI into parts of northern Lower and Upper MI. Strength of the vertical shear suggests the potential for intense bowing segments capable of yielding a derecho with significant severe wind gusts. Link to comment Share on other sites More sharing options...
Indystorm Posted July 19, 2019 Share Posted July 19, 2019 Amazing soundings for any time of year, let alone mid July. Going to be a dangerous situation for MN and WI later today if that first complex this morning decays as expected and these parameters verify this afternoon and evening. Link to comment Share on other sites More sharing options...
Windspeed Posted July 28, 2019 Share Posted July 28, 2019 Link to comment Share on other sites More sharing options...
Windspeed Posted July 29, 2019 Share Posted July 29, 2019 1 Link to comment Share on other sites More sharing options...
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