Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1246 AM CDT Tue Jun 27 2017 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN COLORADO INTO NORTHERN KANSAS AND NORTHEASTWARD ACROSS IOWA INTO SOUTHERN WISCONSIN... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL HIGH PLAINS INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered severe thunderstorms with large hail and damaging winds are expected mainly from northern Kansas into Iowa, with more isolated activity stretching from Wisconsin to Colorado and eastern Wyoming. A couple tornadoes are also possible mainly northeast of the Missouri river, including Iowa, far southeast Minnesota and southern Wisconsin. ...Synopsis... A belt of relatively strong westerly upper flow for late June will stretch from the central Rockies into the Northeast, with several embedded shortwave troughs. One wave will be located over the upper MS Valley Wed morning, and will move toward Lake Michigan by afternoon. To the west, another wave will affect WY and CO. At the surface, a warm front will lift northeast into WI, with front extending southwest across central IA and into northern KS. Western parts of this front will lift north late into CO. Both these shortwave troughs and boundaries will lead to scattered severe thunderstorms, beginning early in the day across the upper MS Valley, and by late afternoon farther west. ...Northern KS into southern WI... Scattered thunderstorms will be ongoing Wed morning from MN southward into northern MO, aided by strong low-level warm advection and in association with a shortwave trough. Some of this activity may contain severe hail, especially from the MO river into IA where instability will be strongest. This activity should generally weaken during the day but additional storms are expected from southeast MN/southwest WI into IA as destabilization occurs. The early storms may create an outflow boundary in the region, which would serve as a focus for supercell development with the possibility of a couple tornadoes as low-level shear will be favorable. Predictability is a bit low given variance in model output, and this area will experience rising heights in the wake of the shortwave trough. Therefore will defer a possible upgrade to later outlooks. To the southwest, additional activity will form late in the day along the stalled front across northern KS/southern NE, as areas to the south experience strong heating which will erode the cap. Midlevel flow on the order of 40 kt along with MUCAPE in excess of 2000 J/kg will support large hail and damaging winds. ...Eastern WY into CO... Lee troughing will occur during the day with weak surface upslope and convergence initiating storms after 21Z. Strong heating will lead to very steep lapse rates, and substantial mid to high level flow may support a few supercells capable of large hail. With time, activity could merge into an MCS, and continue eastward along the stationary front into western KS with a continued hail and wind threat. ..Jewell.. 06/27/2017Read more
from SPC Forecast Products http://ift.tt/GB0aDL
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