860 FXUS63 KMPX 121738 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 1138 AM CST Tue Nov 12 2019 .UPDATE... Issued at 1112 AM CST Tue Nov 12 2019 Updated for the 18Z aviation discussion below. && .SHORT TERM...(Today through Wednesday) Issued at 408 AM CST Tue Nov 12 2019 A sprawling 1040+ mb high sits over the middle of the CONUS this morning, leading to a frigid night for most of the country east of the Rockies. Winds have been light overnight, but not calm, which has prevented radiational cooling from reaching its full potential. Expect lows to end up within a few degrees of zero, with below zero readings most likely across central Minnesota where winds are more calm, and southern Minnesota where some snow remains on the ground. The rest of the day looks dry, with southerly winds picking up on the back side of the departing high and ahead of an approaching clipper. Temperatures look to warm into the mid 20s across western Minnesota where warm advection will be strongest, but remain in the teens across eastern Minnesota ands west-central Wisconsin. Warm advection increases into Wednesday as the clipper passes through the region, with temperatures warming onto the mid 20s to low 30s by Wednesday afternoon. Cloud cover will be on the increase during the day as forcing aloft increases ahead of an approaching clipper out of the northern plains. The atmosphere is bone dry ahead of this system (0.07" of PW on last night's sounding, a new record low for Nov 11) so it'll take time for any precipitation to develop despite increasing ascent aloft and frontogenesis in the mid and low levels. expect light snow to hold off until early tomorrow morning across west-central Minnesota, and spread east into west-central Wisconsin through the morning. Light snow is expected to continue into the afternoon, tapering off from west to east during the late afternoon and evening. Precipitation amount look to remain light given the dry airmass in place and typical low PW amounts associated with clippers, but pinning down accumulations and where snow is most likely remains tricky, primarily due to differences int he models with where the best frontogenesis sets up. Leaned closest to the HREF, which shows probability-matched QPF amounts of 0.1-0.2 inches primarily east of I-35, and generally less than 0.1 inch elsewhere. With snow ratios generally expected to be around 12-14:1, this would place amounts around 2 inches for west- central Wisconsin and around an inch or less elsewhere. .LONG TERM...(Wednesday night through Monday) Issued at 408 AM CST Tue Nov 12 2019 Progressive westerly flow through the long term forecast period will bring multiple precipitation chances, but also help temperatures to return back to near or slightly above normal values. Wednesday night snow will taper off over west central Wisconsin. In the wake of the clipper system, broad surface high pressure will build in for several days, as mid-level ridging pushes into the central CONUS. This combination will bring several dry days, with high temperatures moderating from the low/mid 30s on Thursday into the 35-45 degree range for the weekend. By Saturday the aforementioned ridge will have shifted to the eastern CONUS and a surface trough will have entered the Dakotas. Resultant southerly flow over the area will help facilitate the warming, but also usher moisture into the area ahead of the next trough. Both GFS and ECMWF deterministic models indicate precipitation in the late Saturday- Sunday time frame, although onset timing differs by about 6 hours. Therefore POPS for the weekend will likely end up being higher than the 30 percent currently included once temporal certainty improves. At this point a mix of rain and snow looks to be the most likely scenario for precipitation type. The start of next week features northwest mid/upper flow. The GFS has another wave passing over us, following on the heels of the weekend system. However, the ECMWF is less amplified with the shortwave and keeps it farther north with less impact on the area. Therefore have only included 20 POPS at this point until agreement improves. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1112 AM CST Tue Nov 12 2019 VFR conditions will continue through the night, before an approaching weak system will bring light snow and MVFR cigs to the area tomorrow. The forecast has trended more optimistic in terms of the morning rush, with guidance suggesting it will take quite a while to saturate the atmosphere. This makes sense given how dry the atmosphere is currently. Southerly flow has developed across the area and will continue through the night before shifting northwesterly tomorrow. KMSP...main change was to delay onset of light snow. The morning rush prior to 14-15Z looks to see minimal impacts. /OUTLOOK FOR KMSP/ THU...VFR. Wind WNW 5-10 kts. FRI...VFR. Wind NE 5-10 kts. SAT...MVFR psbl. Wind S 10-20 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ UPDATE...SPD SHORT TERM...ETA LONG TERM...LS AVIATION...SPD