textproduct: Bismarck

KEY MESSAGES

- Numerous severe thunderstorms are possible through tonight. Expected hazards include damaging winds to 80 mph, along with a few tornadoes possible. Hail up to tennis ball sized is possible with any discrete storms that form.

- Additional isolated to scattered severe thunderstorms are possible Sunday through Monday.

- Near to above normal temperatures are favored this weekend through the middle of next week, warming to well above normal heading into the Forth of July holiday weekend.

UPDATE

Issued at 755 PM CDT Sat Jun 27 2026

** Mesoscale Update **

The risk of 70-90+ mph winds is rapidly increasing in southwest ND and is forecast to rapidly expand east-northeast across west central, the rest of southwest, and into parts of central ND in the next 1-2 hours.

Merging supercells and an increasingly-linear convective mode is occurring in an environment characterized by strong bouyancy and deep-layer shear, and 0-3-km bulk shear on the order of 30 kt in the face of large DCAPE. The requisite environmental and storm mode considerations for a bow echo are becoming realized. Forward-propagating Corfidi vectors suggest the linear, bowing complex will rapidly move east-northeast with a forward speed on the order of 50 kt. Recent WoFS runs suggest the damaging to destructive wind risk will continue, with potential for localized gusts up to around 100 mph possible in western ND the next 1-2 hours.

CJS

UPDATE Issued at 657 PM CDT Sat Jun 27 2026

** Mesoscale Update **

The severe storm risk is rapidly increasing in western ND and is expected to spread eastward the next several hours, with an initial risk of large to very large hail and tornadoes, and a transition in mid-late evening to the main hazards being from damaging winds and potential line-embedded tornadoes.

Thunderstorms are rapidly developing from northeastern MT into southwestern ND and northwestern SD as of 2345z, with additional upstream convection in southeastern MT also approaching and merging into this activity. These storms are forming along a surface trough and as stronger forcing for ascent approaches. Earlier attempts at convective initiation in west central ND, e.g., McKenzie and Billings Counties, failed multiple times, likely as a result of a residual warm nose aloft shown on RAP/HRRR forecast soundings. That will be eroded with the approaching forcing for ascent as CAMs have long been forecasting, and as even recent WoFS cycles have supported.

Deep-layer shear on the order of 40-50 kt and strong bouyancy with MLCAPE on the order of 3000-4000 J/kg supports rotating and intense updrafts in western ND this evening. Backed southeast flow has resulted in low-level hodographs becoming more curved in the last hour, which is beginning to and will continue to favor right-moving supercells in western ND. Occasional left-moving splits may continue to survive, but may be less prevalent than they were in southeastern MT 1-2 hours ago given the recent trends in hodograph shapes. Given the supercell-favorable setting, rich boundary layer moisture along/north of a triple point in far northwestern SD into southwestern ND, a tornado risk is present and is expected to increase the next few hours as storms move further east- northeast into an environment that contains greater low-level SRH and related higher effective STP values. This same theme will be present with storms that move into west central and northwestern ND into an environment that contains increasing amounts of low-level shear and related SRH.

Large to very large hail is expected with supercells through mid-evening, though gradual upscale growth will result in a shift toward damaging winds at some point by around 9 pm CDT. CAMs and recent WoFS cycles continue to suggest one or more bowing segments with damaging winds will develop in western ND by mid evening. Some tornado risk is apt to occur even with upscale growth and more linear structures given the CAPE-shear and low-level shear setting.

CJS

UPDATE Issued at 414 PM CDT Sat Jun 27 2026

Winds in the southcentral and southeast remain breezy, yet below Wind Advisory criteria. Abundant cloud cover should limit mixing for the rest of the afternoon. Thus will cancel the Wind Advisory.

A Tornado Watch is now in effect for portions of western North Dakota From 4 PM CDT / 3 PM MDT to midnight CDT / 11 PM MDT. Destabilization is taking place across western ND with clearing skies. Cumulus clouds are starting to form, although billow clouds still showing signs of a stable PBL. In far southeastern MT, slightly more cu agitation is being noted, with some orphan anvils. Overall this western and especially southwestern area will be the area to monitor for the next few hours. Any discrete cells that form in this area will be capable of all hazards including tornadoes and large hail. The watch does reach to the Canadian border. The northwest has more of a conditional threat for supercells, although parameters for tornadogenesis are quite concerning. Overall a tornado threat is anticipated for the next few hours. Convection further into MT will be the next area to monitor as the wave producing this could lead to more linear convective threat this evening into tonight. The alternate is any discrete cells that form also go linear this evening. Overall an active severe weather even is expected and most will want to stay weather aware.

DISCUSSION

Issued at 122 PM CDT Sat Jun 27 2026

Wind Advisory remains for southcentral and southeastern portions through this afternoon. This is mainly for sustained winds around 30 mph with gusts up to 45 mph. Isolated to scattered showers will linger through this afternoon. Highs today are forecast to warm into the upper 70s to upper 80s for most areas, although could be slightly lower than forecast to areas with abundant cloud cover.

We continue to monitor for the threat of severe weather later this afternoon through tonight. SPC's latest update keeps the outlooks for severe weather similar to this morning, although there are some updates to the hazard threats. SPC has increased the tornado probabilities to 5 to 10 percent in the west with an Intensity Level 1 now in place. Meanwhile the hail and wind threats remain elevated, with the an Intensity Level 1 wind threat expanded across much of the west. Shear and instability remain abundant today through tonight. The concerns will be storm mode, some initial capping, and timing of the low. Latest CAMs predicting two scenarios. Scenario 1 sees the capping breaking down around mid to late afternoon, allowing a supercell threat to flourish in the west before storms quickly become linear. This scenario would be the most concerning as supercells would be in a favorable environment for tornadoes and large hail up to the size of tennis balls. Linear mode would take over in the evening with this scenario with winds in excess of 80 mph as the storms move from west to east. The second scenario has less supercell development late this afternoon and has storms going linear quicker this evening. There still would be a brief tornado and large hail threat, yet the bigger threat would be wind gusts of 80 mph or higher. Which scenario ends up playing out is still uncertain. 18z sounding at WFO Bis showing a stout cap in place currently. SPC Meso analysis page showing this cap lessoning in the Highway 85 corridor later this afternoon. Thus it'll come down to the timing of the wave in this area. Of note is some convection starting to develop with this wave in Montana. Will continue to monitor and all should prepare for the threat of severe weather through tonight as once the line of strong convection forms it will push eastward through the night. WPC also showing a Marginal to Slight Risk for excessive rainfall through tonight. There could be some lower clouds and fog tonight behind the mentioned thunderstorms especially in the west. Confidence was not high enough to include fog at this time.

Today's upper wave moves east for Sunday, although the broad upper low will linger across the region. Some morning convection may linger, with enough elevated instability and shear around to make for an isolated strong to severe thunderstorm threat with hail and wind the main threat. An axis of instability then returns Sunday afternoon and evening mainly along Highway 83 and eastward. Ample shear will also be in place. Lift for thunderstorms will be the limiting factor for Sunday afternoon and evening as the upper low may be to far west or northward. However, given the general unsettled pattern chances for showers and thunderstorms will continue. SPC has maintained a Marginal to Slight Risk in these areas for severe weather wind large hail and winds the main threat. SPC has added a Intensity Level 1 for hail for Sunday in their afternoon update today. CSU-MLP does have some low tornado risk tomorrow, more so in eastern ND. LCLs may be a tough high for this threat. Otherwise look for breezy winds to continue for Sunday with high temperatures in the mid 70s to mid 80s. A secondary wave may rotate through Sunday night, perhaps bringing another round of elevated thunderstorms to the area. An isolated severe threat is possible with these nighttime storms given a strong shear, increasing low level jet, and modest instability. Lows Sunday night will be in the 50s west to 60s east.

Broad upper low remains to our west for Monday, while a surface low kicks out of the southern Rockies and tracks north northeast through the region. The result will be continued unsettled weather with showers and thunderstorms likely. SPC has a broad Marginal risk across the area for isolated severe weather. Shear and instability will once again be high, although the timing of the strongest shear and instability remains uncertain. This is mainly dependent on the track of the surface low. Current forecast has this low tracking through earlier in the day Monday, which may limit the severe weather threat for our CWA and shift the afternoon and evening threat eastward. All hazards are possible for these eastern areas, although much the Marginal Risk is for a hail and wind threat. The early passage of a cold front could bring cooler temperatures Monday, with highs in the 70s west to 80s east. Precipitation chances are then more confined to the north Monday night, with lows in the 50s to lower 60s. Upper low and surface low look to become well stacked in southern Canada for Tuesday, bringing cooler and breezy to windy conditions to the state. Shower and thunderstorm chances will be limited and mainly in the north and southeast as a result. Lower instability will limit the severe weather threat, although some higher amounts of shear will remain.

Upper low moves north mid week with a broad area of high pressure settling in across the eastern US. As a result unstable and warming southwest flow will be found starting mid week. Look for temperatures to start warming back into the 80s to lower 90s for most areas. Winds will generally be light with this pattern. CSU-MLP showing at least an isolated threat for severe weather each day with this pattern. Looking ahead to the 4th of July Holiday weekend, clusters indicate a secondary building of the mentioned broad ridge could move into the area. Where clusters differ is how far east a Pacific Northwest trough moves into the interior US. Further eastward will bring more unsettled southwest flow to the region, while further westward brings more ridging and less chances for precipitation. Either way the forecast will maintain slight to chance PoPs for afternoon and evening thunderstorms each day. CSU-MLP also showing at least an isolated threat for severe weather as well through the weekend. There remains moderate to high confidence in above normal temperatures for the Holiday Weekend with highs currently forecast in the 80s and 90s. NBM temperature spreads start getting slightly more broad during the holiday weekend, although even the 25th percentile is right around normal for this time of year. Heat Risk products showing at least moderate heat impacts possible and will be worth monitoring closer to next weekend.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 705 PM CDT Sat Jun 27 2026

Tonight: Main concern in the short term will be for scattered to widespread storms to roll through from W to E, some of which will likely be severe. See update section above for detailed threats. The primary window for severe storms looks to be 01-06Z from W to E. Flight category reductions into MVFR and even IFR (both CIGs and VSBYs) will be possible in the strongest storms. Even out ahead of the storms will be some MVFR CIGs. Most of the stronger storms will be out of the area by 07Z, but some of the CAMs have isolated weaker redevelopment off and on for mainly XWA MOT and perhaps BIS through dawn. Behind these showers and thunderstorms will be some lower clouds - generally in the MVFR to perhaps IFR range for CIGs, but confidence in exact coverage is low due to the effects the convection could have on this development. Winds will be breezy out of the ESE-SE ahead of and behind the main line of storms.

Sunday: MVFR to IFR CIGs may continue into Sun AM, but again, confidence on exact coverage/persistence remains uncertain. Any low clouds should gradually lift and scatter late AM into early aftn. Winds will gradually turn from SE to SSW through the day and remain on the breezy side, esp. for the afternoon.

BIS WATCHES/WARNINGS/ADVISORIES

None.