Plaincast

Messages

There is a 1 of 5 risk for severe storms this evening and overnight across northeast North Dakota and northwest Minnesota.

Heat impacts continue across portions of the area through today.

Wildfire smoke continues to affect air quality.

Discussion

The upper level ridging has flattened/weakened a bit, but additional upper waves are rounding the upper ridge. Ensemble guidance agrees that through the weekend and into early next week the upper ridge axis will be west of the region and then flatten early next week as a stronger system propagates through Canada, bringing cooler temperatures to the northern plains. There does not appear to be any stronger synoptic signals for rainfall/storms given the anticipated pattern, although mesoscale forcing could provide scattered storms here or there.

Interesting set up is developing for severe potential this evening, with what appears to be a triple point across northcentral North Dakota. MLCAPE near 3000 J/KG and effective bulk shear 30-35 knots will lead to organized storms. Storm mode expected to be discrete given lack of strong synoptic forcing and limited threat area. CAM guidance indicates convective initiation 5-7p. Initial development will likely be supercellular along with all associated supercell hazards (hail, wind gusts, tornado). Regarding tornado potential, the triple point plus any storm that anchors to the warm front should experience increased SRH favorable for tornado development. Uncertainty increases with how the event will evolve after initial development, although in these situations storm tipsily attempt to work into the stronger instability meaning the threat area for the surfaced based severe potential will remain across northeast North Dakota - and be mainly diurnally driven with weakening toward 11p or so. The 1 of 5 risk from SPC is based on anticipated coverage.

Later into the night, an area of strong synoptic forming/warm air advection will bring an elevated severe hail threat to northwest Minnesota (likely after midnight).

Frontal boundary has set up from west to east across the region, with temperatures low-mid 70s to the north of the boundary and low 90s to the south of the boundary. With dew points around 70F south of the boundary, heat impacts will continue into the evening. After today, temperatures will be a bit cooler (although limited heat impacts will remain for sensitive groups).

As winds become southerly and then westerly overnight, smoke should move out of the area. That said, forecasting where wildfire smoke will go is pretty difficult, and as the flow turns from the north tomorrow, smoke could return, although not sure how impactful it would be if it does.