475 FXUS63 KMPX 130016 AAA AFDMPX Area Forecast Discussion...UPDATED National Weather Service Twin Cities/Chanhassen MN 616 PM CST Tue Jan 12 2021 .SHORT TERM...(This evening through Wednesday night) Issued at 253 PM CST Tue Jan 12 2021 Primary concern comes at the end of the period as an upper trough moves in from the northern Plains and a cold front works its way across Minnesota. Prior to then things will be relatively benign as we see mid and high clouds stream into the area with west northwest upper flow. Weak warm advection doesn't look like it will be able to generate much if any precipitation Wednesday into Wednesday night, so most of the area will need to wait until the cold front arrives to see a period of precipitation. Guidance still differs quite a bit on some of the details with this upcoming system, although the cold frontal timing is fairly consistent. It should reach the far western part of Minnesota just after midnight Wednesday night, then work its way to near I-35 by daybreak. .LONG TERM...(Thursday through Tuesday) Issued at 253 PM CST Tue Jan 12 2021 The main focus of the long term will be the continuation of the system that begins moving into the area Wednesday night. Most of the precipitation looks to be post-frontal given where front relative flow is leading to lift, and the moisture columns looks to saturate quickly and nearly at the same time throughout its depth. This means there could be some window of mixed precipitation (rain or freezing rain depending on near surface temperatures), but that window should be short with things changing over to snow as the entire column cools behind the front. Snowfall rates with the frontal forcing could get above a half inch per hour, but the snow shouldn't last more than a few hours, so at this point it looks like just an inch or two would be possible Thursday morning. Guidance continues to exhibit substantial spread on forecast details Thursday through Friday, but there is general consensus on a surface low intensifying some as it moves across Minnesota Thursday, before it slowly occludes and fills Friday into Friday night. It will be very slow to move out of the area, so after a general lull in precipitation post cold front, we will see a prolonged period of light snow from late Thursday into Friday night. The ECMWF continues to be the most bullish in terms of total precipitation, but there is general consensus on amounts from a quarter to a half inch during this second phase of the event, so a drawn out accumulation of 4+" looks to be a safe bet across much of the area. The main question is whether we'll see a band of moderate snow Friday as a broad TROWAL feature reaches in from the northeast (and we see somewhat rare warm advection from the north). If a moderate band is able to develop along the periphery of the TROWAL then some locations could see upwards of 8", but at this point there is too much uncertainty to have any confidence on if and where that will occur. There is much more confidence on a long duration of breezy conditions from Thursday through Friday. An initial burst of higher northwest winds with gusts above 35 mph will occur behind the front Thursday, then another window of higher winds with gusts above 40 mph seems likely on Friday as we get into the tighter pressure gradient. However, the combination of a weakening low (which will counteract any isallobaric contribution) and warm advection (which works against mixing) should keep the winds somewhat in check. Colder but mostly benign weather looks to prevail across the region in the wake of the Thursday-Friday system, with northwest upper flow in place. The best chance for another round of snowfall looks to be Monday when a weak clipper will drop southeast through the region. It will be moving quickly and will have minimal moisture with which to work, so any snowfall from it should be fairly light. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 616 PM CST Tue Jan 12 2021 MVFR/IFR conditions will likely develop across western WI again this evening with light winds and few high clouds. Thicker mid level clouds will arrive area wide overnight, which could limit the further deterioration across WI. VFR and light winds expected in MN through the period. KMSP...The fog and stratus tonight should remain east. /OUTLOOK FOR KMSP/ Thu...MVFR. -FZRA/-RA/-SN mix likely early bcmg -SN. Wind bcmg NW 15G25kts. Fri...MVFR/IFR. -SN likely. Wind NNW 15G25 kts. Sat...MVFR. Wind NW 5-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ SHORT TERM... LONG TERM... AVIATION...Borghoff