FXUS63 KUNR 090354 AFDUNR Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 954 PM MDT Wed Jul 8 2026 .KEY MESSAGES... -Unsettled through Thursday as a series of disturbances move through the region -Sufficient moisture and shear is in place to support a few strong to severe storms -Very hot this weekend into early next week with record high temps possible and dangerous heat && .UPDATE... Issued at 950 PM MDT Wed Jul 8 2026 Convection continues this evening across portions of northeastern Wyoming, northwestern South Dakota, and southwestern South Dakota. The severe threat has largely ended. No major changes to the forecast. Meager westerly flow coupled with weak large-scale ascent will limit overall coverage and a more widespread severe threat. Expect convection initiation on the Black Hills after 1200-1300 Thursday afternoon, where marginal effective bulk shear will be in place (~25-30 knots). A few strong to severe storms are possible; large hail is a threat with any supercellular structures that can sustain themselves. Similar to the past few days, up to golf ball sized hail are possible with the strongest transient single cells. Beyond the severe threat tomorrow, building heat will become the dominant weather story along with worsening fire weather conditions through the weekend into next week. && .DISCUSSION...(This Afternoon Through Tuesday) Issued at 1103 AM MDT Wed Jul 8 2026 Impulse filled westerly flow remains in place over the FA. Daily chances for thunderstorms can be expected with strong to severe storms possible at times, through Thursday. Weak impulse will advect through the SW third this afternoon and support TS clusters. Ample LL moisture in place combined with sufficient deep layer shear will support a few strong to severe storms, with large hail and damaging wind the main threats, mainly INVOF of the Black Hills. Given ML CAPE of 1-2 KJ/KG, deep bulk layer shear of 35 to 40 knots expect isolated supercells to be possible, capable of producing large hail and damaging winds. Storms will carry SE across the SW FA through the evening. More storms are expected Thur as sufficient LL moisture will be in place with weak stability and another impulse. Best chances for storms will be in the afternoon/evening. Similar CAPE/shear parameters will be in place to again support a few strong to severe storms, esp over the SW third. Upper ridge builds into the region this weekend, with dry and hot conds expected. Hot temps around 35C at h85 with close to 6000m H5 heights over WY, will offer record to near record highs well into the 100s with some areas seeing readings around 110 on portions of the Plains, esp Sunday and Monday. However, given how dry the BL will be with dewpoints falling into the 20s in the west to the 50s east, apparent T's will only top out in the upper 90s to lower 100s, highest on the SD Plains, supporting adv level numbers. Ridge begins to retrograde the middle of next week, with storm chances returning as the active northern periphery of the ridge settles back south. && .AVIATION...(For the 06Z TAFS Through 06Z Thursday Night) Issued At 954 PM MDT Wed Jul 8 2026 Thunderstorms will continue move across portions of western South Dakota through the overnight hours. Transient MVFR conditions are still possible around any heavier precipitation cores. Conditions will begin to improve between 09/08-10z as storms diminish and move out of the region. Another round of storms will begin to develop over northeast Wyoming and western South Dakota around 09/18z and lasting through the remainder of the forecast period. Hail, frequent lightning, and gusty/erratic winds can be expected with any stronger convective cores. Transient MVFR/IFR conditions also expected around any heavier precipitation cores. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ UPDATE...SE DISCUSSION...JC AVIATION...Schultz