textproduct: Bismarck

KEY MESSAGES

- Well above average temperatures through Monday, then a cooling trend through the end of the week.

- Dry weather through Tuesday, then low to medium chances for rain and snow Wednesday and Friday through Saturday.

UPDATE

Issued at 1135 AM CST Sun Nov 15 2026

Fog across portions of western North Dakota has fully lifted by the time of this mid day update. Patchy fog will again be possible across portions of southwestern into south central North Dakota overnight, though a very shallow saturated layer at the surface will limit this to where winds become very light. Have added chances for fog across the south central with this update, otherwise the forecast remains in good shape.

UPDATE Issued at 915 AM CST Sun Nov 15 2026

Patchy fog, occasionally dense, can be found over portions of far southwestern and northwestern North Dakota at the time of this mid morning update. Fog is anticipated to rapidly lift over the next few hours as boundary layer mixing increases. No major adjustments to the forecast were performed with this update.

UPDATE Issued at 540 AM CST Sun Nov 15 2026

Patchy dense fog has developed in Slope and Bowman Counties, and rapid-refresh guidance insists that dense fog in northeast Montana could soon spread into Divide and Williams Counties. Do not anticipate dense fog will become widespread enough for an advisory. A Special Weather Statement has been issued in the far southwest, and the need for one in the northwest will be monitored closely. Otherwise, the only notable change to the forecast for this update was to drastically reduce sky cover in alignment with satellite observations and trends.

DISCUSSION

Issued at 300 AM CST Sun Nov 15 2026

An omega blocking pattern is in the process of breaking down early this morning as it is being undercut by a progressive closed low over the Texas Panhandle. A lower amplitude mid level shortwave is also preparing to eject off the Northern Rockies early this morning and will cross the region today, producing no precipitation and not even much in the way of cloud cover. An underlying surface trough will also meander eastward into western North Dakota this afternoon, with breezy southerly winds ahead of through and lighter westerly winds behind. Highs this afternoon should mostly be in the 50s. Upper level ridging is forecast to resume over the Northern Plains on Monday as a trough digs into the western CONUS. This should give us the warmest day of the forecast period with highs mostly in the mid 50s to lower 60s. The western trough approaches the Rockies on Tuesday, turning flow aloft over the Northern Plains to the southwest. It will remain dry on Tuesday, but increased cloud cover and surface flow becoming southerly to easterly are projected to cool high temperatures into the mid 40s to mid 50s.

There is strong ensemble consensus that the upstream trough will eject into the Northern Plains on Wednesday, but there is still considerable uncertainty on its strength and to some extent, the trajectory of strongest forcing. Ensemble clusters are heavily separated by system core. Key takeaways from cluster analysis are that the GEFS strongly favors a more potent and progressive wave through the Dakotas, while the ECMWF ensemble prefers a lower amplitude wave with the strongest forcing closer to Nebraska. All solutions want to bring light precipitation across the state Wednesday through Wednesday night, with higher chances north than south. Mean maximum QPF within the state is only around 0.1" for ECMWF- heavy clusters, but closer to 0.25" in their counterparts. It should be noted that even though 6-hourly NBM PoPs are only 10 to 50 percent, raw ensemble probabilities for measurable precipitation in a 24-hour period are closer to 50 to 90 percent. As the wave and its attendant surface low progress northeastward, cooler air will be dragged into the state. Highs on Wednesday are only forecast to reach the mid to upper 30s in the northwest, but could still approach 50 in the southern James River Valley. A transition from rain to snow could begin as early as late Wednesday afternoon in the far west, with the rain/snow transition line progressing eastward through Wednesday night, but perhaps not as quickly as the departure of precipitation. The progressive nature of the system should greatly limit accumulating snow potential. Probabilities for measurable snowfall with this system range from around 10 percent from southwest to north central North Dakota to near 50 percent in the far northwest corner of the state, and the lowest membership cluster (less than 20 percent of the total membership) is far more aggressive with snow probabilities than the other 3.

Ensembles are in agreement with a transitory ridge keeping Thursday dry, but it will remain cooler with highs only projected in the upper 30s to mid 40s. Attention then turns to the next western CONUS trough and its evolution Friday through the weekend. The GEFS is nearly unanimous that the trough will translate through the Northern Plains as an open, progressive wave Friday into Saturday. This solution (hereafter referred to as Scenario 1) is favored by 60-65 percent of the total ensemble membership, as the ECMWF and Canadian ensembles are much more dispersive. The other, lower membership outcome (Scenario 2) brings a slower, deeper, and more southerly wave into the Northern/Central Plains late Friday through Saturday. But there are two distinct potential outcomes within Scenario 2: an ECMWF-only solution that would keep the highest QPF south of North Dakota (Scenario 2a), and a slightly lower probability outcome mostly driven by Canadian ensemble members that would bring much higher QPF across much of the state (Scenario 2b). Scenario 1 would favor higher QPF in eastern North Dakota compared to the west, but still with lower maxima than Scenario 2b. NBM-based high temperatures are still in the mid 30s to mid 40s on Friday, then lower to upper 30s on Saturday. But raw ensemble probabilities for sub-freezing temperatures at midday Saturday are medium to high (except for the dry Scenario 2a). This means that precipitation from this system could fall more as snow than rain, but it is still difficult to draw any conclusions on potential snow amounts given the forecast time range and uncertainty, especially with a 20 percent chance of little to no precipitation at all (Scenario 2a). Scenario 1 places low to medium chances for at least an inch of snow (using a 10:1 snow-to-liquid ratio) across much of the area, and also has temporally higher chances for precipitation Friday night when temperatures are more strongly favored to fall below freezing. Scenario 2b, which again has less than 20 percent support from the total ensemble membership and barely any support from the GEFS or ECMWF ensemble, would be a much more problematic outcome from a winter weather impacts perspective.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1135 AM CST Sun Nov 15 2026

VFR ceilings and visibility are generally expected at all terminals throughout the 18Z TAF period. Patchy, shallow fog will be possible over portions of southwestern and south central North Dakota late tonight into Monday morning, though confidence in visibility reductions is low at this time. Light winds across the west and north central, and gusty south winds over south central North Dakota, will become very light and variable overnight, before reorganizing out of the south to southwest through Monday morning.

BIS WATCHES/WARNINGS/ADVISORIES

None.