Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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116 FXUS63 KDLH 211800 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 100 PM CDT Fri Jun 21 2024 .KEY MESSAGES... - Chances for showers and thunderstorms increase today, especially over northwest Wisconsin, with chances continuing into Saturday. Little rainfall is expected over far northern Minnesota today. - There will be a threat for heavy rain today into Saturday morning, although it has decreased and shifted south again. Portions of northwest Wisconsin have the highest chance at seeing 1-2"+. - The threat for severe storms has diminished Saturday but there remains a Marginal Risk (1/5) from east-central Minnesota into much of northwest Wisconsin. The window for severe is narrow and dependent on sufficient clearing to build instability. && .DISCUSSION... Issued at 358 AM CDT Fri Jun 21 2024 A stalled frontal boundary remained well south of the Northland this morning and the latest guidance has it moving slightly north into southern Minnesota into southern Wisconsin today. Showers and thunderstorms were moving along and north of this front early this morning from eastern South Dakota through southern Minnesota and northern Iowa. This activity will continue to move east-northeast and most of the heavy rain this morning will remain south of the Northland. However, high PWAT air will move north with values over the southern half rising to 1.5-1.8" today into tonight. 850-700MB FGEN will increase through the day and combine with a shortwave to provide lift for showers/storms further north into northern Minnesota. Instability will be meager at best today and tonight with the RAP forecasting a few hundred j/kg over the south half of the Northland. The threat for severe storms today/tonight is low and the SPC keeps the Marginal Risk just south of northwest Wisconsin. Confidence is not very high on POPS, especially tonight. CAM guidance suggests showers/storms will move north today especially over northwest Wisconsin and we have the highest POPS there. Most then bring a lull in coverage this evening before another shortwave moves in later tonight and the surface low lifts northeast. We didn`t buy in completely to the majority of the CAM guidance given the very moist airmass and FGEN but it trends hold, we may be able to reduce chances later this afternoon/tonight, especially over central into northern Minnesota. We do have more confidence that the heavy rain threat has shifted south but does remain over portions of northwest Wisconsin. HREF 24 hour QPF does show the potential for a narrow band of 1-2" from Washburn to Price Counties in northwest Wisconsin today into tonight and the WPC has a Slight Risk of excessive rainfall in that area. The ECMWF ensemble guidance paints a more bullish picture for heavy rain with probabilities of 60-90% for rainfall of 2" or greater from east-central Minnesota into northwest Wisconsin. However, we think the ECMWF is too far north with the surface low/warm front. The latest guidance does show it has shifted south compared to 24 hours ago and we think that trend will continue so feel it`s too high on its QPF. We have chances for showers/thunderstorms continuing Saturday, highest over northwest Wisconsin and in the morning. Instability is again meager, especially in the morning. Thunderstorm coverage will be low over central to northern Minnesota. CAM guidance suggests a lull in shower/storm coverage will develop Saturday morning overnight/early morning convection moves off. It`s possible we may too high with POPS Saturday morning. The threat for heavy rain is low on Saturday and the Northland has been removed from the latest excessive rain outlook. We remain in a Marginal Risk (1/5) for severe thunderstorms Saturday over east- central Minnesota into northwest Wisconsin and the main threat will be hail to 1" in diameter and damaging wind to 60 mph. The window for severe will be narrow and dependent on some clearing occurring to boost CAPE. Winds today into Saturday will be off Lake Superior and they will be stronger Saturday compared to today. There will be a HIGH risk for rip currents on Saturday. A shortwave in northwest flow aloft will bring more chances for showers/thunderstorms Sunday. Widespread heavy rainfall and severe storms are not expected. There will be periodic chances for more showers/storms next week but the upper flow will be more progressive diminishing the heavy rain threat. The best bet for a dry day will occur Wednesday with high pressure over the region. Temperatures will trend warmer Sunday-Tuesday then cool slightly. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 100 PM CDT Fri Jun 21 2024 Mostly clear skies and VFR conditions are expected to persist for most of the period at HIB/INL. Further south, a broad shield of clouds (MVFR to IFR) are expected to continue impacting HYR/BRD/DLH. Rain chances for the next 6 hours are looking quite low, but chances increase from south to north tonight. IFR ceilings are expected tonight and into Saturday morning. There could be a stray embedded thunderstorm or two as well, mainly at HYR/BRD. MVFR visibilities are likely at times with showers and perhaps some fog potentially developing later tonight, mainly at HYR. Winds remain below 20 kt from the east to northeast through the period. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 1007 AM CDT Fri Jun 21 2024 With this update, Small Craft Advisories have been issued for most nearshore zones for Saturday with gusty northeast winds to 25 kt and wave heights 2 to 5 ft expected. No other changes since the last update. 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...Small Craft Advisory from 7 AM to 7 PM CDT Saturday for LSZ142>147-150. && $$ DISCUSSION...Melde AVIATION...JDS MARINE...JDS