565 FXUS63 KDLH 091714 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1214 PM CDT Tue Oct 9 2018 .UPDATE... Issued at 653 AM CDT Tue Oct 9 2018 Update for new 12Z Aviation Discussion below. && .SHORT TERM...(Today through Wednesday) Issued at 448 AM CDT Tue Oct 9 2018 A powerful fall storm will move across the region tonight through Wednesday night, bringing more rainfall, strong winds, and snow to the region. Today though, we remain in what has been a rather persistent plume of warm moist advection riding up over the cold front draped from eastern Kansas northeast across Iowa and Wisconsin to eastern Upper Michigan, and ascending along the 850mb baroclinic zone farther north over Minnesota and Lake Superior. This has produce widespread rainfall over the area overnight, with rainfall amounts in the last 24 hours as much as three quarters of an inch in Price county Wisconsin, to only a few hundredths in northwestern parts of the forecast area. The precipitation is fairly light at the moment, and we can expect this to continue most of today, with mainly light to perhaps moderate rain through the day. Highs today will be cooler than yesterday, ranging from the 40s to low 50s. The main storm system is still an upper level trough axis over the Four Corners region, which is expected to advance northeast out of the Rockies today and interact with the baroclinic zone, which extends from eastern Colorado northeast to over the forecast area. I expect development of a surface low this morning over northern Texas, and intensification as it sweeps northeast today and tonight, arriving over Iowa by 12z Wednesday morning. Ahead of it another wave of rain will push into the forecast area this afternoon, bringing moderate to even heavy rainfall tonight and Wednesday. Rainfall amounts for tonight and Wednesday should range in the 1 to 2 inch range in the flood watch area, and while I am not terribly concerned for flash flooding as we just aren't looking at much convection, river rises could be quite significant and have maintained the flood watch as is. This storm has wrapped enough cold air into the back side that the precipitation will become mixed with snow late tonight and early Wednesday over mainly Koochiching county, with only minor snow accumulations expected due to the recent rainfall and relatively warm temperatures. These accumulations are only expected on grassy surfaces, and roads are likely still too warm for any accumulation there. Overnight lows will be in the mid 30s to mid 40s. As the low advances towards the area, I expect northeast winds to strengthen considerably by this afternoon and evening, and with fairly deep mixing over the lake, winds will be even stronger there. Areas near the lake shore will also experience these strong winds, so have issued a wind advisory for the head of the lake and east along the south shore where the strong winds will continue inland from the lake far enough to cause some hazards. These strong winds and the resulting large waves will cause some lakeshore flooding as well, and have continued the lake shore flood watch for now as I have some uncertainty over how far up the north shore an eventual advisory will be needed. If the wind direction is more parallel to the shoreline, the risk may be less, but a small change to a more onshore direction and consequences could be significant. Late Wednesday and Wednesday night the main surface low finally moves northeast across Wisconsin and Upper Michigan to eastern Lake Superior by early Thursday morning. This should finally allow our winds to ease off and turn more northwesterly as the pressure gradient weakens with the low moving somewhat away from the forecast area. However, this does bring more cold air into the area, and turns our precipitation over to more snow than rain, mainly over northern Minnesota. Snowfall amounts along the Canadian border should range from 2 to 4 inches, with lighter amounts to the south, with less than a half inch expected south of the Iron Range, and none for northwest Wisconsin. For now, with the wet, warm ground and recent rain, this should be very similar to our snow event last weekend, with few/no reported road impacts. However, this may change and we may need an winter weather advisory for parts of the area tomorrow night and early Thursday. .LONG TERM...(Wednesday night through Monday) Issued at 448 AM CDT Tue Oct 9 2018 Drier and continued cool Thursday through Saturday morning, then a chance of rain and snow returns to the Northland for the bulk of the weekend into early next week. After the prolonged period of semi-blocked and meridional flow from the first half of the week, Thursday and beyond features a more progressive pattern. The upper-level trough and associated surface low will continue its trek into Quebec Thursday with rain and snow showers across the north tapering off during the morning. Clouds are forecast to linger thanks to considerable moisture trapped below a thermal inversion as surface high pressure moves into the region. The clouds will begin to part in the late afternoon and evening hours with a few peeks of sunshine possible for Friday. With clouds and cold air aloft, Thursday high temperatures will be around 20 degrees below normal for the period. Readings will be in the middle 30s to near 40 degrees. Temperatures moderate some for Friday and Saturday, but remain much below normal. Highs for the final day of the work week will reach the upper 30s to middle 40s and trend even warmer on Saturday in the low to upper 40s. Another trough of low pressure aloft will dive into the Canadian Prairies and Upper Midwest by Saturday and deepen through the weekend. Cold air advection and cyclonic flow aloft, along with falling mid-level heights, will support cyclogenesis over the Northern Plains and Canadian Prairies. Temperatures will be cold enough with this system for a rain/snow mix changing to snow in the overnight periods. Moisture will be somewhat limited for the weekend system and snow accumulation on grassy areas and elevated surfaces is possible. The best chance of precipitation through the weekend will be over northern Minnesota and portions of northwest Wisconsin. Central and east-central Minnesota may see rain and snow showers Saturday and Saturday evening, but may wind up dry for Sunday into Monday. Showers may loiter over north- central Wisconsin and the northeastern portions of the Arrowhead Monday with the remainder of the Northland staying dry. Another system will begin to make its presence known Monday night as rain/snow shower chances notch upward once again over the International Border areas. Temperatures will trend a bit colder on Sunday with highs in the middle 30s to low 40s with similar readings for Monday. && .AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon) Issued at 1213 PM CDT Tue Oct 9 2018 Continued poor flight cats as a storm system approaches. Do not expect much in the way of improvement through the period. TAFs are probably on the optimistic side as some really low crud should move through as the system gets closer. && .PRELIMINARY POINT TEMPS/POPS... DLH 43 39 41 31 / 90 100 90 90 INL 42 34 36 28 / 50 100 100 90 BRD 44 38 41 30 / 90 100 90 80 HYR 47 43 47 34 / 90 100 90 70 ASX 45 43 45 36 / 90 100 90 80 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Flood Watch through late Wednesday night for WIZ001>004-006>009. Wind Advisory from 10 PM this evening to 4 PM CDT Wednesday for WIZ001>003. Lakeshore Flood Watch from 10 PM CDT this evening through Wednesday afternoon for WIZ001>003. MN...Flood Watch through late Wednesday night for MNZ020-021-037-038. Wind Advisory from 10 PM this evening to 4 PM CDT Wednesday for MNZ020-037. Lakeshore Flood Watch from 10 PM CDT this evening through Wednesday afternoon for MNZ020-037. LS...Small Craft Advisory until 10 PM CDT this evening for LSZ121- 140>148. Gale Warning from 10 PM this evening to 10 PM CDT Wednesday for LSZ121-140>148. && $$ UPDATE...Huyck SHORT TERM...LE LONG TERM...Huyck AVIATION...Wolfe