Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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236 FXUS63 KDLH 140847 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 347 AM CDT Fri Jun 14 2024 .KEY MESSAGES... - Sunny and mild weather today. - Rain and thunderstorm chances return Saturday and linger into next week. - There`s a chance (~5%) for strong to severe thunderstorms on Sunday and potential for heavy rain at times Sunday through Tuesday that could lead to some flooding issues. && .DISCUSSION... Issued at 244 AM CDT Fri Jun 14 2024 Today _______________________________________________________________ Skies are mostly clear out there this morning except for an area of clouds in northwest Wisconsin, which will move southeast through the morning. There is some patchy fog out there, which will diminish shortly after sunrise. With high pressure in place, we`re looking at a sunny day with mild high temperatures in the 70s. Some afternoon cumulus clouds will probably develop, but it should be too dry for any showers today. Today will be a good day for everyone to take a few deep breaths as we enjoy some sunshine and a brief break from all the showers and thunderstorms! Tonight _______________________________________________________________ Tonight, expect increasing clouds from southwest to northeast as we get southerly flow and an upper-level wave promoting some showers and storms. With this initial round of rain out ahead of a warm front well to the southwest, there won`t be much instability to work with, so this is more likely to be a synoptically-driven rain (~80% chance) with perhaps some embedded thunder here-and-there, but certainly no storms strong to severe. PWATs will be increasing to around 1.25", and this borders around 90th percentile of climatology. With this potentially being a somewhat long duration (~12 hour) rainfall for many areas, there`s a ~5-15% chance for excessive rainfall (per WPC) that could lead to some flooding issues (most likely minor) Saturday afternoon and night, mainly in northwest Wisconsin. Sunday _______________________________________________________________ The trough aloft and attendant rainfall will continue east Sunday morning. There are timing differences in the models on how quickly this rain could move out, and this will have potential implications on how storm chances end up for Sunday afternoon. Right now, there are a few ingredients in favor of and in opposition of the potential for some strong to severe storms popping up Sunday afternoon. Let`s talk about the less- favorable ingredients first. The upper level pattern does not appear to be very supportive for convection overall with potentially weak ridging aloft and an upper level jet to the west, putting the Northland in the less-favorable right exit region (i.e. sinking air). Model soundings also suggest potential for a pretty strong capping inversion aloft with an elevated mixed layer, and if the timing of the morning rain`s exit is later, it`ll be more difficult to bust the cap in the afternoon. With all that said, the warm air advection regime won`t be going away, and in fact we will have some steep mid to upper level lapse rates and potentially 2k+ J/kg of MUCAPE to work with. 0-6 km shear may be offset with higher values to the west, but perhaps 30-40 kt of shear in the highest instability, which would be enough to promote strong to severe storms if they can bust that aforementioned cap. With all that said, there`s a lot of uncertainty for Sunday, and something we`ll have to keep an eye on. There`s certainly a marginal chance for some severe weather (right now ~5% per SPC`s Day 3 outlook), mainly in northwest Wisconsin. Sunday night into Tuesday _______________________________________________________________ There may be somewhat of a break in precipitation Sunday night, but things get more interesting Monday into Tuesday as a large upper-level trough deepens over the western CONUS and a warm front sets up over the northern Plains. Strong warm air and moisture advection will set up in this period, and the pattern is looking increasingly favorable for a warm front to become nearly stationary Monday into Monday night. Severe weather potential for Monday seems to have dropped off some with higher stability and moisture near the surface ahead of the warm front. Nevertheless, there should be at least some instability for storms, though severe threat is marginal at best. Instead, the heavy rain threat for this period seems the most concerning. Models are all over the place for where this warm front and attendant rain could settle, ranging roughly from southern MN to eastern ND. Those details will have to be worked out in the next few days, but for now, there`s increasing concern that PWAT values rising up into the 1.5"-1.75" range for a good portion of the region (between 90th and 99th percentile of climatology) could combine with a potentially stalled front to bring some locally heavy rainfall and perhaps some flooding or flash flooding. Again, there`s a lot of disagreement among models yet, but enough to at least bring up the discussion for the potential for heavy rainfall. Tuesday through Friday _______________________________________________________________ The warm front is expected to eventually lift north through Tuesday with low pressure developing somewhere in the northern Plains. Storm chances will likely continue into Tuesday, and potentially a cold front moving through going into Wednesday to clear most rainfall out of the region briefly. Models become increasingly divergent from Wednesday onward, but the upper- level pattern looks to remain somewhat amplified, so rain/thunder chances will probably continue through the late- week. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1235 AM CDT Fri Jun 14 2024 The main challenge through the night is fog potential. We have mostly clear skies and nearly calm winds, which are ideal for fog formation. Temperature and dew point depressions are still a few degrees apart around the region, so fog has been slow to develop. Models are not in good agreement for any particular terminal, with most suggesting no fog (which doesn`t seem likely given current conditions). The best potential may be at HIB/DLH, and possibly at INL/HYR where some models suggest at least some fog. Most likely, for terminals that see fog develop over the next few hours, visibility will likely jump up and down between VFR/MVFR/IFR over short durations. After sunrise, fog should quickly diminish, leading to very quiet and sunny weather. There will be potential again for fog Friday night, but confidence is too low to include in any TAFs at this time. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 244 AM CDT Fri Jun 14 2024 Light and variable winds become northeast this afternoon from 5-10 kt, gusting perhaps up to 15 kt late in the afternoon. Winds decrease in speed tonight, then increase again Saturday from the east to southeast from 5-15 kt, gusting to 20 kt especially around the head of the lake. Winds remain east to southeasterly Saturday night with rain and storms moving in (70-80% chance). For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...None. && $$ DISCUSSION...JDS AVIATION...JDS MARINE...JDS