textproduct: Bismarck

KEY MESSAGES

- High chances across the western half of the state Thursday through Friday.

- Temperatures remain closer to normal through Friday, then warm to well above normal by the end of the holiday weekend.

UPDATE

Issued at 151 AM CDT Thu May 21 2026

Shower activity has greatly diminished over the last few hours, with little to no lightning being observed. Still tracking the remnants of mid-evening convection that flared up in southwest North Dakota, which has now shifted closer to Lake Sakakawea. Only light amounts of rain less than a tenth of an inch are anticipated through the rest of the night, and most areas will remain dry.

UPDATE Issued at 936 PM CDT Wed May 20 2026

For the late evening update we expanded the pops in time and areal extent. A narrow line of thunderstorms have recently developed over southwest ND in an area of focused warm advection, moderate 850mb FG forcing and a narrow band of steep low level lapse rates. The steep low level lapse rates should subside pretty quickly as CIN increases over the area, but the FG forcing and warm advection may persist for at least a few more hours, keeping scattered showers and isolated thunderstorms through the evening hours. Elsewhere, not much lightning any more but there are a few strikes occasionally. Will keep a mention of thunder through midnight, and linger showers activity into the overnight hours. Otherwise, there is a local area of heavier showers around the Turtle Mountains. This should lift northeast of that area shortly, but the area from southwest ND into the Turtle mountains will see warm advection through the night, thus kept at least a little activity here through the night. Updated text products out shortly.

UPDATE Issued at 535 PM CDT Wed May 20 2026

Updated pops based on latest radar. Showers have spread into central ND and have pulled slight chance pops farther east. There is some occasional lightning, so for this afternoon and evening utilized coverage terms for shower and thunderstorm activity. Williston picked up just over a quarter inch of rain and gust to around 35 mph. Updated text products will be transmitted shortly.

DISCUSSION

Issued at 208 PM CDT Wed May 20 2026

High temperatures are forecast to warm into the 60s and 70s this afternoon. Surface high pressure has shifted off to the southeast over Minnesota as surface low pressure moves into eastern Montana. This has lead to breezy to windy conditions across the central and eastern half of the state due to a tighter north south orientated pressure gradient. An upper level low is forecast to move into southern Saskatchewan tonight. This low has brought two upper level waves to the region. Water vapor imagery shows the first wave which is moving across the north central into the northeast while the second wave is forecast to move through eastern Montana into the west this afternoon and evening. Majority of the precipitation will remain scattered to isolated across the west from the second wave.

The aforementioned upper level low is forecast to stall out over southern Saskatchewan Thursday and Friday. Hi-Res models are showing a band of precipitation that will traverse west to east Thursday into Friday. However, the HREF has this banded precipitation stalling across the west maybe barely making it to the HWY 83 corridor. Storm total qpf on the HREF is up to around an 1.5 inches in some areas with locally higher amounts possible this is supported by decent rainfall rates and residence time of banded precipitation. This mean central and eastern North Dakota will likely miss out on the majority of rain the next two days. This cooler pattern will keep temperatures in the 60s to 70s Thursday and Friday until warming up by the weekend. Saturday morning there is a chance of some patchy frost in the southwest. The NBM 25th begins to push the high temperatures into the upper 70s to lower 80s and the 75th percentile has the lower 90s by early next week. There is fairly high confidence for warm weather to start off next week. The pattern could shift again by the end of next week as an upper level troughing could return to Western CONUS.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 151 AM CDT Thu May 21 2026

A few light rain showers will continue to meander about western and central North Dakota through the night and into Thursday morning, with VFR conditions expected. From Thursday afternoon through Thursday night, a significant increase in showers is expected across western and into north central North Dakota, with embedded thunderstorms in the late afternoon and evening. Ceilings could fall to MVFR levels under rain, and the heaviest showers and storms could briefly reduce visibility to IFR levels. Western North Dakota will see variable winds around 5-10 kts through the forecast period, while central North Dakota maintains a southerly breeze overnight, increasing back to around 15-25 kts Thursday afternoon.

BIS WATCHES/WARNINGS/ADVISORIES

None.