037 FXUS63 KBIS 170518 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND 1218 AM CDT Thu Apr 17 2025 .KEY MESSAGES... - 60 percent chance for rain tonight through Thursday southwest through central. - Rain may mix with or change to snow in the southwest late tonight through early Thursday morning with some light accumulations possible southwest. - Windy and colder Thursday and Friday with highs mainly in the 40s. The strongest winds will be on Thursday in the James River Valley. - Trending warmer for the weekend and the start of next week. && .UPDATE... Issued at 1208 AM CDT Thu Apr 17 2025 Some shower shower activity approaching southwest ND at this time. Will trim the eastward extent of pops back a bit during the overnight hours. Otherwise no significant changes. UPDATE Issued at 1000 PM CDT Wed Apr 16 2025 A few showers have developed over south central North Dakota this evening, broadly along the cold front trawling across the northern Plains. An isolated rumble of thunder or two have also been observed with a few of these showers as they roll over a pocket of 100-200 J/KG MLCAPE. These showers and any thunder associated with them are anticipated to diminish over the next hour or so. For this update, have added PoPs and a slight chance for thunder across portions of south central North Dakota into the James River Valley. Otherwise, north winds have remained gusty behind the cold front across western and portions of central North Dakota, with speeds generally from 15 to 20 MPH and gusts up to around 25 mph. UPDATE Issued at 625 PM CDT Wed Apr 16 2025 Surface analysis places a low pressure center over northern North Dakota this evening, and with it an associated cold fron draped over a rough NNE-SSW axis. With it, increasing cloud cover and weak reflectivities can be found over the forecast area this evening. With these clouds well elevated about 19000ft, and with a significantly dry layer near the surface, little to no precipitation associated with these reflectivities have or are expected to reach the ground. Along and behind this front, winds are reorienting from the south to become out of the north. Further behind this front, well into eastern Montana, precipitation has begun to be reported this afternoon. This precipitation will begin to move into southwestern North Dakota early tonight. Otherwise conditions are relatively quiet at the time of this update. No major changes to the forecast were performed, as it remains broadly on track. && .DISCUSSION... Issued at 150 PM CDT Wed Apr 16 2025 Currently a surface low pressure is moving through North Dakota, with a warm front moving through the eastern half, and a backdoor cold front moving across the west. With the warm front, winds are from the south, and behind the cold front winds are turning to the north. Aloft, a medium sized positive tiled trough is across the Northern Plains. The rest of this afternoon winds will go calm as the front moves over, then will be a little breezy. Forecast highs across the south and central will still be in the 70s. In the northwest, highs stay in the 50s, as they are behind the cold front already. With this cold front tonight, precipitation, mainly as rain, will fall. There is very strong 700mb frontogenesis from the southwest to Devil`s Lake. This area is where the highest QPF will fall. Cloud bases will start around 10kft which may be hard for the rain drops to not evaporate, so QPF could end up lighter. Clouds will lower through the night however. With the frontogenesis, this area could shift slightly, it already has since this morning. On the backside of the front, cooler air will make the rain turn to snow early Thursday morning. No accumulation is expected, however the southwest has a low probability of less than an inch. The GEFS and NBM plumes vary for QPF tonight but there is some agreement that it will likely be below 0.25 inches. The rain/snow will tapper off to the east through Thursday morning. Highs will be cooler Thursday. Winds will remain breezy through Friday in the east. Friday another small trough will move through with a very slight chance of some rain in the afternoon. Temperatures will be even cooler with this. Highs will only reach into the 40s. Through the weekend highs will recover back into the 50s and 60s. Saturday relative humidities will drop into the 20s across the winds with slightly breezy winds. This will create some fire weather concerns. Saturday will be quiet otherwise, under a shortwave ridge. Then a trough will move in Sunday and remain through Wednesday as multiple lows move in, we will have a medium chance (40%) of rain these days. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1208 AM CDT Thu Apr 17 2025 An area of light rain will spread from southwest to northeast ND through the overnight hours. Rain may mix with or change to snow in southwest around 12 UTC Thu. Expect mostly VFR ceilings through the period. Perhaps a period of MVFR ceilings/vsbys in the southwest this morning. Northerly surface flow expected across western and central ND today generally 15 to 25 knots, diminishing after 00Z Friday. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...TWH DISCUSSION...Smith AVIATION...TWH