Day 1 Convective Outlook
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Summary
Severe thunderstorms with potential derechos, large hail, and tornadoes are expected this afternoon and evening across southeastern Montana, the Dakotas, and the northern High Plains. Additionally, isolated tornadoes and damaging wind gusts are possible throughout the Ozarks region today.
Product Text
000 ACUS01 KWNS 072001 SWODY1 SPC AC 072000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Sun Jun 07 2026 Valid 072000Z - 081200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF SOUTHEASTERN MONTANA...EXTREME NORTHWESTERN SOUTH DAKOTA...WESTERN AND CENTRAL NORTH DAKOTA,... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF SOUTHWESTERN MISSOURI AND FAR NORTHWESTERN ARKANSAS... ...SUMMARY... A bow echo with 60-100 mph gusts appears likely over the northern High Plains into the Dakotas this afternoon, with a few instances of severe hail and isolated tornadoes also possible. A couple of tornadoes and isolated damaging gusts are still possible across the Ozarks region. ...20Z Update... A Category 4/Moderate Risk was introduced to portions of the northern High Plains. Confidence is increasing in a well-defined cold-pool-driven bow echo MCS developing across portions of the northern High Plains later this afternoon. A potentially dense swath of 60-100 mph gusts appears likely, and a derecho may occur. Current observations depict a near stationary surface boundary across far southeastern MT northeastward into western ND along an elongated surface trough. High-resolution deterministic and ensemble guidance (including HREF, REFS, and some of the latest WoFS runs) all depict a classic bow echo MCS traversing this surface boundary, accompanied by a widespread severe wind swath and scattered 75+ mph gusts. The MCS would benefit from localized vorticity along this boundary, which in turn could support book-end vortices and the subsequent development and sustenance of a rear-inflow jet, lending plausibility to the guidance consensus. Latest mesoanalysis also shows continued eroding MLCINH and 2500+ J/kg MLCAPE in place. Low- to mid-level lapse rates are already exceeding 8 C/km in some spots, coinciding with 50-60 kts of sfc-8 km bulk shear oriented normal to the anticipated bow echo leading line, which is favorable for derecho development. Alternatively, multiple severe-wind producing multicellular clusters may occur, which would support higher coverage of severe winds (with gusts occasionally exceeding 75 mph). Otherwise, the previous forecast remains on track, with only minor changes made to thunder and severe probabilities to reflect the latest observations. ..Squitieri.. 06/07/2026 .PREV DISCUSSION... /ISSUED 1139 AM CDT Sun Jun 07 2026/ ...MT/WY/Dakotas... Water-vapor imagery late this morning shows a strong upper trough over the northwestern CONUS and it is forecast to pivot eastward through the northern High Plains through tonight. Surface mesoanalysis placed a low near the MT/ND/SD border with a frontal zone draped southwest to northeast from northeastern WY into far western ND. Cyclogenesis and strong heating/moistening of the boundary layer will favor storm development by mid afternoon in the vicinity of the Big Horns. Relatively steep low-level lapse rates on the immediate cool side of the frontal zone and moderate CAPE values will support a risk of large hail and severe wind gusts once storms begin to mature. A linear cluster is expected to evolve during the late afternoon into potentially a bow echo during the early evening with the severe-wind risk notably increasing and becoming more widespread. Have increased the intensity highlight from southeast MT into western portions of ND where it seems increasingly probable a swath of intense gusts ---possibly a bow echo--- is progged by a diverse array of different model cores/runs this morning. This model signal appears reasonable given the co-location of surface features, lapse rates, and upper-level support. It is within this mesoscale corridor that localized peak gusts may range 85-100 mph. Considered an upgrade to Moderate Risk but will defer to the 20 UTC outlook for additional model run-to-run continuity and confidence in mesoscale environmental features. This activity will sweep northeastward during the evening with a gradual lessening of the wind/hail hazard towards the early overnight as it moves east into the eastern half of the Dakotas late. ...Ozarks... A weak trough/low over the central US with embedded disturbances from OK into IA continues to drift northeastward late this morning. An associated band of 30-40 knot southwesterly mid-level winds and deep moisture will lie across the Ozark plateau this afternoon. The 12 UTC Springfield, MO raob sampled this belt of stronger flow with 80-kt at 200 mb. Heating of a very moist airmass with some minor enlargement of low-level hodographs may result a few weak supercells developing coincident with peak heating. A couple of brief tornadoes and isolated damaging gusts are possible with this activity. ...Eastern VA/NC... A weak surface cold front is sagging southward across central VA this morning. A combination of strong heating and frontal forcing will lead to widely scattered thunderstorms this afternoon across southeast VA and northeast NC. The strongest of these cells could produce gusty winds. $$