Area Forecast Discussion
Issued by NWS Duluth, MN

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000 FXUS63 KDLH 041147 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 547 AM CST Thu Mar 4 2021 .DISCUSSION...(Today through Wednesday) Issued at 349 AM CST Thu Mar 4 2021 Main forecast concerns this morning include the stratus and the effect they will have on max temps today, with similar concerns for the next couple days with a ridge of high pressure over the area. A shortwave moving through Manitoba and Ontario on Sunday will produce our warmest day of the week. We have also been watching the potential for a spring storm system in the Tuesday- Thursday time frame. Stratus clouds at less than 1 thousand feet have spread onto the land from Lake Superior, and are affecting a large portion of the MN Arrowhead as well as parts of NW WI this morning. I expect this stratus to continue to expand or at least maintain through at least sunrise, and from past experience is unlikely to clear until late morning given the strength of the surface ridge axis, light winds and steep low level inversion that is depicted on model soundings. Models are not handling these clouds well, and worked more with the 925-975mb RH off the NAM12 and RUC13 as a better guide for what should happen with the stratus. This is going to stifle the morning temperature rise, and have kept temperatures cooler than yesterday where I expect the clouds to be most persistent, but put more warming where there should be more sunshine. There is a risk of having this stratus form and move inland once again tonight but the wind trajectory may not work out properly with the surface ridge axis shifting more directly over the area and have decided to leave the stratus out for tonight and early Friday and we will have to play things by ear tonight to see if this changes. This should allow temperatures to get warmer on Friday, and with the same pattern again on Saturday, high temperatures both days should get into the mid 30s-mid 40s Friday and slightly warmer Saturday. The ridge axis shifts east late Saturday, and the strong upper level ridge that we have for the latter part of the work week flattens enough to allow a strong shortwave to move along the US/Canada border for Sunday. A surface low develops over eastern MT, moving east-northeast into Manitoba and then Ontario during the day. This brings a surge over warm moist air into the area, but with all the stronger dynamics up into Canada, the chances for getting precipitation into the forecast area are pretty minimal and have kept the forecast dry for now. However, if we get enough moisture into the area from the south there may be some afternoon showers. We will have to wait and see on this for now. The strong surge of warm air should produce the warmest day of the week though, and have put in high temperatures in the mid 40s to mid 50s for Sunday, which is on the high end of guidance. Our next chance for precipitation moves into the area in the Tuesday through Thursday time frame as the models are beginning to show some consensus as bringing a strong deep trough axis across the Rockies on Tuesday, moving east through the work week. For now there is only general agreement on the 500mb heights, but the details and lower levels still have pretty large spread and I cannot say much more than we have a chance at some much needed precipitation in the midweek time frame. For now, from the amount of warm air pushed this direction, Tuesday and even Wednesday will be on the warm side and the precipitation should start out with rain, gradually switching over to snow before the system moves out on Thursday. We will have to keep a close eye on this system, as we could have some flooding concerns with precipitation falling on top of the snowpack we have, even after we melt some of it off this weekend. && .AVIATION...(For the 12Z TAFS through 12Z Friday morning) Issued at 547 AM CST Thu Mar 4 2021 IFR to low end MVFR stratus has overspread KDLH, KHIB and is approaching KBRD as of issuance time. KDLH and KHIB should remain in the stratus for at least the first few hours of the forecast before the stratus lifts and dissipates, returning both sites to VFR by 17z. The stratus should move into KBRD between 13z and 14z, only to dissipate again around 16z. The stratus should stay out of KINL and KHYR. Light winds of less than 10 knots and VFR conditions are expected for much of the remainder of the time range. With the warm conditions, light winds and melting snow, I expect fog development tonight, and have included MVFR visibilities for the most likely sites beginning at 10z, though lower visibilities are possible. && .PRELIMINARY POINT TEMPS/POPS... DLH 34 19 39 17 / 10 0 0 0 INL 42 15 40 15 / 0 0 0 0 BRD 45 21 43 22 / 0 0 0 0 HYR 43 14 42 14 / 0 0 0 0 ASX 35 16 38 14 / 0 0 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ DISCUSSION...LE AVIATION...LE

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