073 FXUS63 KFGF 211834 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 1234 PM CST Mon Dec 21 2020 .UPDATE... Issued at 1234 PM CST Mon Dec 21 2020 Light snow has finally ended across our eastern counties, and there has been some clearing in portions of eastern ND although more clouds have been moving into the Devils Lake Basin. A brief area of clearing behind that, then more high clouds further west. Cloud cover will be all over the place this afternoon, but with continued cold advection there will be not much rising for temperatures. Continued to keep temps steady, maybe rising a few degrees, and colder than most guidance as we head into this evening. UPDATE Issued at 943 AM CST Mon Dec 21 2020 Light snow continues near Lake of the Woods, and a band has developed all the way back to TVF to Fosston to Park Rapids. Adjusted POPs up in that area for the next few hours, but otherwise still think snow will taper off around noon. Plenty of wind and cold air advection, so will continue to keep temp trends we have going. UPDATE Issued at 653 AM CST Mon Dec 21 2020 Not much has changed with light snow still falling near LOW. Some additional very light precipitation lingers in portions of northwest Minnesota. Gusty winds are also making their further into the southern Valley. && .SHORT TERM...(Today through Tuesday) Issued at 407 AM CST Mon Dec 21 2020 An exiting clipper lingers light snow through mid morning near the Lake of the Woods to the Red Lakes area. This may continue hazardous travel conditions during the morning commute in this location. The cold front assoc with the clipper will also elevate northwest winds gusting up to 40 mph. Winds are expected to gradually decrease west to east through the afternoon. A pocket of colder air behind the clipper will also envelope a good portion of the CWA, mainly within the Valley into Minnesota, which will cause a general decreasing trend in temperatures throughout the day in these locations. Temperatures dip into the teens within northwest Minnesota by afternoon. The next surface low begins to track into the Northern Plains on Tuesday. A swath of warm advection will push across the FA from west to east. At this point, there is essentially no precipitation associated with this warm advection. The precipitation the models show is mainly around the 700mb low...which is across southern Manitoba and Saskatchewan. So basically just expect decreasing winds as the low approaches, and another mild day. .LONG TERM...(Tuesday night through Sunday) Issued at 407 AM CST Mon Dec 21 2020 The main focus in the long term is the potential snow/wind event late Tuesday night into Wednesday. Being one of the first snow/wind events of the season, and it occurring during a busy holiday travel period...it naturally would bring the greatest impacts. So what exactly is this expected to bring? At this point, both snowfall amounts and wind speeds have been trending upwards. So let's take a look at each individually. Starting with wind speeds, seeing the main wind speed indicators coming together for strong winds. To start off, the direction is a favorable northwest-north direction. There is also good cold advection. 850mb temperatures drop from -8C at Grand Forks at 06z Wednesday to -17C by 18z Wednesday. There is good linkage from the surface up to 850mb, with unidirectional flow. Also seeing nice pressure rises moving through. Wind speed meteograms are indicating a nice cluster of winds in the 30 to 35 mph range, with peaks in the 45 to 55 mph range. So feel pretty confident on wind speeds with this system. Now for snow amounts. In prior days, the models have had issues dealing with splitting the energy of this system into a southern and northern area, or having one main system. On this shift, there is better consistency in depicting one system. However, blended precipitation amounts still favor the old split solution. This left a big discrepancy between WPC and our model blended guidance (WPC precipitation amounts were about 3 times less than the model blended guidance). Coordinated with WPC to raise their guidance a little more to catch up, but that still resulted with lower precipitation amounts for this event (over our blended solution). Big differences like this do reflect the high amount of uncertainty in expected snowfall amounts. Have followed the WPC precipitation amounts, but if the higher amounts do pan out, confidence would increase even more on a wind/snow event with high impacts for a good portion of the FA. The wind/snow should impact the Devils Lake region first, likely around midnight Tuesday night. The Valley proper would be later than that, more likely in the hours prior to sunrise Wednesday morning. The winds last all day on Wednesday. There will no snow on the ground to blow around, any impacts from snow/blowing snow with this system would be from falling snow, or snow that accumulates with this system. So any impactful low visibilities from snow/blowing snow would last when the falling snow overlaps with the strong winds. This could be a period of only 6 hours (maybe even less)...or it could be longer (12 hours). After discussing headlines with the neighboring offices, have elected to go with a winter storm watch for late Tuesday night into Wednesday. Could see several potential outcomes with this system. If there is less snow than expected, it may only be a winter weather advisory. High wind warning criteria could also be met in some areas. If the winds/snow link up as strong or stronger than expected, there could be low visibilities due to snow/blowing snow. At this point, do not expect winter storm category snow amounts. But feel confident enough due to the high impact time (the holiday) and the significantly warm December we have had so far, to highlight this potential event with a watch. This will bring a blast of cold air and wind chills well below zero. After the initial cold blast, temperatures do look to moderate by late week into the weekend. && .AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon) Issued at 1139 AM CST Mon Dec 21 2020 MVFR conditions across most of the area, with some IFR at KBJI. There should be some improvement a bit later this afternoon to VFR as more high and mid level clouds move in. VFR conditions for tonight and the rest of the period. Winds gusting from the northwest at near 30 kts at KFAR will slowly diminish this afternoon, becoming light and variable by evening. Southeasterly winds will pick up by the end of the period and start gusting around 20 kts by mid day Tuesday. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...Winter Storm Watch from late Tuesday night through Wednesday afternoon for NDZ008-016-027-029-030-038-039-049-052-053. Winter Storm Watch from late Tuesday night through Wednesday afternoon for NDZ006-007-014-015-024-026-028-054. MN...Winter Storm Watch from late Tuesday night through Wednesday afternoon for MNZ001>005-007-008-013>015-022-027-029>031- 040. $$ UPDATE...JR SHORT TERM...CJ/Godon LONG TERM...Godon AVIATION...JR