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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Friday, June 11, 2021

SPC Jun 11, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Fri Jun 11 2021 Valid 112000Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN KS...NORTHEAST OK...FAR WESTERN MO... ...SUMMARY... Scattered severe thunderstorms (some of which may be significant) with damaging winds as the primary hazard, along with large hail, are expected through this evening. The most likely corridor is across eastern Kansas and adjacent western Missouri through parts of north-central and northeast Oklahoma. ...20Z Update... ...Lower MO Valley to the Ozarks... Current trends with the ongoing organized convective system across the Lower MO Valley suggest the potential for strong wind gusts will likely extend into more of west-central MO, with the corridor of weak surface winds from DMO through TBN acting as an the eastern bound. Portions of the line along and just east of the KS/MO border have begun to surge southward (recent observation at STJ reported 55 kt) and the air mass downstream remains strongly unstable and moderately sheared. ...Upper MS Valley and WI.... Only changes over this area was to trim up wind probabilities based on current trends. Additional thunderstorm activity remains possible tonight, with an associated threat for isolated hail. ..Mosier.. 06/11/2021 .PREV DISCUSSION... /ISSUED 1109 AM CDT Fri Jun 11 2021/ ...Lower MO Valley to the Ozarks and OK... An MCS near the NE/IA/MO/KS border is expected to persist south across much of eastern KS and far western MO this afternoon into north-central and northeast OK by evening, around the eastern periphery of a mid-level ridge over the southern High Plains. For near-term forecast information, please see MCD 922. Though vertical shear will remain rather modest, there could be mesoscale enhancement due to MCV formation within the MCS as it develops southward through the afternoon. Large to extreme buoyancy with MLCAPE of 3000-5000 J/kg is expected in advance of the convective cluster, owing to robust heating of a very moist boundary layer (mid 70s dew points), beneath steep mid-level lapse rates. These thermodynamic profiles will favor intense updrafts along the southwest flank of the cluster where transient supercell structures will be capable of large hail. The overall primary threat should be damaging winds with a series of downbursts given heavy precipitation loading. The cluster/MCS is expected to move across eastern KS during peak heating with the largest buoyancy and steepest low-level lapse rates, when the severe wind and large hail threat should be greatest. Some severe threat will likely persist across at least northern OK through this evening, where lift along the front/outflow and residual large CAPE should support additional storm development to the south and southwest. ...Upper MS Valley and WI... Outflow associated with pre-frontal convection is moving eastward across northwest WI and southeast MN, while a separate/weak baroclinic zone oriented will also persist from northwest to east-central WI. These boundaries should help focus thunderstorm development this afternoon. Despite modest vertical shear, moderate buoyancy (MLCAPE of 1000-2000 J/kg) will favor storms with isolated damaging downbursts and marginally severe hail through about sunset. Read more LIVE: