Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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759 FXUS63 KDLH 160800 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 300 AM CDT Mon Sep 16 2024 .KEY MESSAGES... - The late season warmth continues with highs 10 to around 15 degrees above normal through at least Thursday. - Chance for showers and thunderstorms today, mainly over northern Minnesota with a better chance tonight, especially in far northern Minnesota. Storms late today/tonight could be strong and produce localized heavy rain over far north- central/northwest Minnesota. - Periodic chances for more showers/storms through the week. && .DISCUSSION... Issued at 300 AM CDT Mon Sep 16 2024 The upper pattern featured a West Coast upper low with high pressure over the Northeast. The Northland remained under southwest flow aloft with very warm temperatures and plenty of moisture. Area radars showed isolated to scattered showers and thunderstorms across far northern Minnesota into the Apostle Islands as of 0800Z. Chances for showers/storms will continue this morning, sagging south possibly to the Twin Ports and northern Wisconsin. Most of the guidance forecasts a lull occurring by late morning but chances won`t end. However, focus will shift north this afternoon into tonight into far northern Minnesota. A shortwave will lift northeast through the Northern Plains brushing northwest Minnesota. Low level convergence is forecast around a trough over far north-central Minnesota or just northwest of there. A very warm airmass will remain in place with highs in the lower to mid-eighties away from Lake Superior today with surface dewpoints in the sixties. MUCAPE values will rise to 1500-2000 J/kg this afternoon. However, shear will be lacking with effective shear at or less than 20 knots this afternoon and evening. Mid-level lapse rates will be from 6.5-7 C/km with steep low level lapse rates into early evening. The CAMS are in general agreement developing strong thunderstorms late this afternoon or early evening near/over Koochiching/northern Itasca Counties and the SPC has a Marginal Risk (level 1/5) for that area. Storm mode is expected to become messy with clusters of storms and the lack of shear will limit organization. Severe threats will be hail to one inch in diameter, especially with more isolated storms earlier in their formation, and damaging wind to 60 mph. Another threat will be localized heavy rain due to expected training thunderstorms into the overnight hours. PWAT values will rise to about 1.3" which is above the 90th percentile for this time of year. The HREF supports the heavy rain potential with 24 hour LPMM forecast showing amounts of 2-3" across Koochiching County. We thought about a small Flood Watch for Koochiching, northern Itasca, and perhaps northern St. Louis Counties but the area has been quite dry and FFG remains rather high. There is also a chance the storms may occur a bit further north of the current forecast. Storms will decrease in coverage late tonight into Tuesday morning and be confined to far northern Minnesota on Tuesday. Much above normal temperatures will continue with highs again in the eighties. There will be periodic chances for more showers/storms through the week but widespread significant rainfall looks low through Friday. Much above normal temperatures will continue into Thursday. Taking a look well into the future, there is some hope for a larger system next weekend into early next week as a stronger shortwave lifts into the region. There is potential for more widespread rainfall but there remains significant timing and track differences among the global models and among their ensemble members so stay tuned for updates as we progress through the next several days. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 1229 AM CDT Mon Sep 16 2024 Area radars showed isolated showers and thunderstorms dotting northern Minnesota late this evening. The higher res models forecast an increase in coverage overnight with KHIB most likely to see a shower/storm. We have a mention there overnight and left out of KINL for now. Fog may again form in spots tonight but much of the guidance isn`t forecasting much but we`ll continue some visibility reductions under this warm and humid airmass. The fog will lift around or before 14Z Monday morning for most with prevailing conditions remaining VFR. Additional showers/storms will develop Monday afternoon and night, especially across far northern Minnesota. There is pretty good agreement that several rounds of thunderstorms will affect far northern Minnesota and especially KINL. A few strong storms may occur as well. Conditions will drop to MVFR or lower with the thunderstorms. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 300 AM CDT Mon Sep 16 2024 Winds today into Tuesday will be from 5 to 15 knots. Wind direction will be variable across the lake this morning, becoming onshore for most this afternoon into the evening. On Tuesday, winds will be more southerly along the South Shore, and more easterly from the Twin Ports up along the North Shore. There will be a few thunderstorms possible today. Storm chances will continue tonight but mainly be confined to the North Shore. 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...Melde AVIATION...Melde MARINE...Melde