Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
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183 ACUS01 KWNS 190531 SWODY1 SPC AC 190529 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1229 AM CDT Thu Sep 19 2024 Valid 191200Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM MINNESOTA...IOWA AND WESTERN WISCONSIN SOUTHWARD INTO EASTERN KANSAS AND WESTERN MISSOURI... ...SUMMARY... Scattered severe thunderstorms are possible across central/eastern Minnesota, Iowa, and western Wisconsin. A couple tornadoes, isolated large hail, and damaging winds may occur. An area of locally severe gusts and hail may also develop over parts of eastern Kansas, southwest Missouri, and into northeast Oklahoma. ...Synopsis... A negatively tilted shortwave trough will move across the Dakotas and MN during the day, with veering midlevel winds into western MN by late afternoon. Farther south, moderate west/southwest winds in the midlevels will extend into NE and IA, with weaker west to northwest winds around a southern Plains upper high from KS/OK into MO and AR. In the high levels, flow will be strongest across the central Plains, with weakening winds over the northern Plains/upper MS Valley. At the surface, the primary low will move into southern MB, with a cold front moving into MN and western IA by mid afternoon. A wind shift/surface trough will also extend southward across eastern KS and into northern OK at that time. Southerly surface winds will set up a plume of mid to upper 60s F dewpoints east of the front/surface trough, and this will aid moderate destabilization across the length of the front, with scattered severe storms from MN to perhaps OK. ...Upper MS Valley... Scattered early day elevated storms are likely to dissipate by midday as they move out of MN/IA into WI, with destabilization in their wake. Strong heating near the surface trough/front along with cool temperatures aloft will yield MUCAPE to around 3000 J/kg, beneath 35-40 kt 500 mb winds. A broken line of storms including supercells are expected after 21Z over much of central and eastern MN and into IA. A couple tornadoes are most likely from IA into southern MN and southwest WI where effective SRH may exceed 200 m2/s2. Given the northward lifting of the shortwave trough, and increasing inhibition east of the MS River, the primary threat are may remain relatively narrow. ...Eastern KS into western MO and into OK... A few thunderstorms may be ongoing early this morning from IA into northwest MO, near the 850 mb theta-e plume and beneath subtle height falls. A cell or two may persist into the afternoon, likely translating southeastward across western MO. A greater risk of locally severe wind gusts or hail will then develop near and just west of the early day activity, as a plume of steep lapse rates develops out of OK into KS. While midlevel subsidence may limit instability somewhat, plenty of CAPE will be present at or above 2000 J/kg, with a lengthy mid to upper level hodograph by virtue of northwest flow aloft. As such, hail may still occur with the cellular storm modes, and favorable time of day and hot surface conditions will favor locally strong to damaging gusts. ..Jewell/Weinman.. 09/19/2024 $$