080 FXUS63 KBIS 022343 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 643 PM CDT Mon Jun 2 2025 .KEY MESSAGES... - Near to slightly below normal temperatures expected this week, with a slight warmup heading into the weekend. - Daily low to medium chances for showers and thunderstorms through the weekend, lowest on Tuesday (around 10 percent) and highest on Saturday (around 40 percent). && .UPDATE... Issued at 641 PM CDT Mon Jun 2 2025 Cyclonic flow aloft across the Northern Plains, with an area of showers across eastern MT and another area over parts of eastern North Dakota. Extensive cloud cover at the moment early this evening across western and central ND, with clouds forecast to decrease tonight as diurnally driven cloud/precip development decreases. Only some minor edits to the inherited forecast were needed with this update/product issuance, mainly based on latest observations. && .DISCUSSION... Issued at 356 PM CDT Mon Jun 2 2025 North Dakota sits under southwest flow aloft associated with a closed upper low spinning just west of Hudson Bay this afternoon. The surface air mass is post-cold frontal with a southwest-northeast oriented surface ridge dividing gusty northerly winds to the south and lighter northwesterly winds to the north. Strong DCVA eminating from the base of an upper trough over the Montana Rockies as well as a 700 mb trough cutting from northeast to southwest North Dakota continue to promote areas of light rain showers this afternoon, with the greatest concentration from the south central to northeast as of 330 PM CDT. Both satellite imagery and SPC mesoanalysis suggest it has now become too stable to support any more thunderstorms in our forecast area. The showers are forecast to dissipate and shift eastward through the rest of the afternoon, but a separate area of more popcorn-type showers in southern Saskatchewan that are associated with another surge of DCVA could move into northwest North Dakota this evening. A quiet but seasonably cool overnight period is expected as surface high pressure expands across Montana. Lows tonight will mainly be in the 40s. A quasi-zonal cyclonic flow pattern is forecast over the Northern Plains Tuesday through Thursday. The NBM shows high confidence in high temperatures in the upper 60s to mid 70s and low temperatures in the 40s over this time period. Daily low chances for rain (10 to 30 percent) are in the forecast Tuesday through Thursday, which should mostly come in the form of scattered afternoon showers initiated by destabilization of the boundary layer underneath the cyclonic flow. Tuesday has the lowest chances for showers, and any that do develop are likely to be limited to northern parts of the state. There may be enough buoyancy to support a few isolated thunderstorms Wednesday and Thursday during the afternoon and early evening, but widespread organized convection is not expected. A subtle shift in the upper level pattern to a slightly amplified northwest flow is being advertised for Friday and Saturday. This brings a slight warmup to the ensemble temperature distribution, with the latest NBM favoring highs around 75 to 80 on Friday and 80 to 85 on Saturday. There is increasing ensemble support for a potent shortwave/closed low digging into the Upper Midwest by Sunday. 3 out of 4 ensemble clusters composing 80 percent of the total ensemble membership support the closed low solution vs. a weaker open wave, albeit with spatial and temporal disparities. Prior to the arrival of the upper wave/low, there is higher forecast confidence that it will drive a surface cold front across the region on Saturday, but with timing uncertainty. The NBM has accordingly increased chances for showers and thunderstorms to around 40 percent on Saturday. Prospects for severe convection remain low at this time, with the current suite of ensembles projecting marginally sufficient CAPE but weak shear. The cold frontal passage and arrival of the upper wave/low may cool temperatures back to below average for Sunday, but there is a considerable increase in ensemble spread compared to the preceding days && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 641 PM CDT Mon Jun 2 2025 Lingering chances for showers will continue this evening over mainly western ND. Ceilings/visibility expected to prevail at VFR levels through the 00Z period. Southern and eastern North Dakota will continue to see gusty northerly winds through early this evening, with lighter and more variable winds to the north. For tonight through Tuesday morning, expect west- northwest winds around 10 kts. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...NH DISCUSSION...Hollan AVIATION...NH