734 FXUS63 KBIS 221706 AFDBIS Area Forecast Discussion National Weather Service Bismarck ND Issued by National Weather Service Grand Forks ND 1206 PM CDT Tue Oct 22 2019 .UPDATE... Issued at 1205 PM CDT Tue Oct 22 2019 Updated temperatures to reflect a slower warming response this morning. Otherwise, the forecast remains on track for mostly sunny skies through much of the day with increasing clouds this afternoon from the southwest. UPDATE... Issued at 620 AM CDT Tue Oct 22 2019 Updated PoPs early this morning to add in a very small area of light snow that developed over Dickinson. It appears this is in association with weak lift aided by a vort lobe across western ND. This area continues to shift away, closer to southern border and have a mention of light snow through 12z. Otherwise expect a mostly sunny morning and afternoon for central ND, while clouds will increase west this afternoon with a chance of rain late. SHORT TERM...(Today and tonight) Issued at 320 AM CDT Tue Oct 22 2019 Rain, some thunder, and light snow accumulations highlight the short term period across western and portions of south central ND. Nothing is anticipated across the north central and the James River Valley through tonight. Latest water vapor imagery shows a northwest flow aloft with a shortwave/vorticity center noted over southern Saskatchewan. An area of weak 3hr surface pressure falls continues to push through western North Dakota, now nudging into central North Dakota. Pockets of mid level clouds out ahead of this shortwave can be seen on satellite moving from northwest to southeast. Expect scattered clouds through the morning as this shortwave progresses through, otherwise mostly sunny with increasing clouds west later this afternoon. Highs today will be in the 40s to around 50 west. Our next vigorous upstream shortwave trough is now located over British Columbia, and this will support the development of an Alberta Clipper type cold front this morning. As the entire system pushes into eastern Montana and western North Dakota this evening/tonight, the potential for a couple thunderstorms are possible given the instability and large scale ascent that is forecast to slide across western and portions of south central ND tonight. An 850mb baroclinic zone really tightens up by 06z Wednesday across the west. On the warmer side of the baroclinic zone, mainly southwest and far south central ND, SPC continues to advertise a General Thunderstorm area for this evening through most of tonight. The SPC 03z SREF 3hr calibrated thunderstorm probabilities do show a weak signal for thunderstorms across far southwest and far south central between 00z and 09z Wednesday. Our gridded data picked this up based on the steep mid level lapse rates that are forecast. Both the GFS and NAM show strong ascent, steep mid level lapse rates, and low level frontogenesis between 00z and 12z Wednesday for western and portions of south central ND. The RAP13 Bowman BUFKIT forecast sounding at 03z Wednesday shows potential for thunder. Low level lift/Omega is maximized around 4000ft, which is the level where parcels need to get. Most Unstable CAPE is very narrow, around 200 J/Kg per NAM12, and weaker per GFS. At the same time, on the colder side of the baroclinic zone, expect a quick transition from rain to snow later this evening with snowfall accumulations of between 1 and 2 inches by daybreak Wednesday from Williston to Killdeer, Dickinson to Elgin and to Selfridge in Sioux County. The area of snowfall lines up well with a sharp 700mb shortwave trough and 700mb low which tracks from McKenzie County southeast into Stark and Grant counties 06z-12z Wednesday. Bismarck/Mandan will remain on the far eastern fringes of little or no snowfall accumulation. North central and the James River Valley will not be impacted with this clipper system. LONG TERM...(Wednesday through Monday) Issued at 320 AM CDT Tue Oct 22 2019 Precipitation from the departing clipper lingers Wednesday through Wednesday night across southwest North Dakota. Expect chances of snow in the morning and night, with a mix of rain/snow Wednesday afternoon. Any accumulations at this point will be light. It will be dry but colder across the rest of western and central ND Wednesday with highs in the upper 30s to lower 40s. Warm air advection kicks in later in the day Thursday west, then propagates across central ND Thursday night through Friday. Dry Thursday and Friday with highs in the lower 40s Thursday, then mid to upper 50s Friday. A strong clipper swings through Saturday, mostly with an increase in northwest winds, and some chances of rain/snow. Highs will once again be in the 50s Saturday, then the colder air arrives Sunday and Monday with high temperatures dropping back into the 30s. AVIATION...(For the 18Z TAFS through 18Z Wednesday) Issued at 1200 PM CDT Tue Oct 22 2019 Look for VFR conditions to prevail through much of the day at all TAF sites with northwest winds. Gusts of 20 to 30 knots will continue through the afternoon at KJMS and KMOT before tapering off this evening. Rain chances increase this evening at KXWA, KDIK, and eventually KBIS. This shower activity will mix with snow later in the evening with the better chances remaining west of Bismarck. CIGs will be reduced accordingly as precipitation impacts the region, with MVFR to IFR conditions likely. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...99 LONG TERM....99 AVIATION...FGF