Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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051 FXUS63 KDLH 201729 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1229 PM CDT Thu Jun 20 2024 .KEY MESSAGES... - Some light showers will occur today over portions of the Northland. - Chances for showers and thunderstorms ramp up tonight into Saturday. There will continue to be a risk for both severe storms (Saturday) and heavy rain (mainly Friday night into Saturday). - There has been a slight southward shift in the greatest risk for heavy rain. && .DISCUSSION... Issued at 350 AM CDT Thu Jun 20 2024 High pressure was over the Northland this morning and it`s forecast to slowly slide east today. Area radars showed light showers/virga moving north into the southwest quarter of the Northland early this morning and chances(20-40%) for light showers will occur over mainly southern portions, from the Brainerd Lakes east northeast to the Twin Ports and northwest Wisconsin today. 00Z Soundings showed plenty of dry air present and that will take some time to saturate. We only expect light rainfall amounts today. The surface high will only move slightly further east tonight but warm air/moisture advection and FGEN with the baroclinic zone lifting north will provide forcing for showers/storms. PWAT values will increase to about 1.6" by 12Z Friday over southern portions of the Northland. There are some limiting factors though for strong storms/heavy rain tonight. Instability is lacking with only ~130j/kg per the RAP with the GFS/ECMWF lower. There isn`t much of a low level jet either with the core of the stronger 850MB winds well off to the southwest in Nebraska. Although the CAMS offer different solutions with placement of showers/storms tonight they mostly agree on keeping any of the stronger storms just south of the Northland. We increase POPS further on Friday, keeping the highest values of 60-90% over the southern half of the Northland. The warm front is forecast to stay in southern Minnesota into central Wisconsin through the day. However, 850MB FGEN will exist over the Northland along with a weak upper shortwave. The CAMS are not as bullish on shower/thunderstorm coverage as our current POPS suggest, especially in the afternoon, but forcing and PWAT values ~1.5" support higher chances. The HREF 24 hour QPF does forecast a narrow band of 1-1.75" of rainfall tonight into Friday over parts of northwest Wisconsin. The ECMWF ensemble and NBM probabilities for 2" of rain or greater are rather low at 15% or lower. A stronger shortwave will cause the surface low to move toward southwest Minnesota by Saturday morning with the low continuing northeast into Wisconsin or Upper Michigan or northern Minnesota by Saturday evening. Confidence in the low track is low as seen in the global model forecasts and from the smattering of low locations from the ECMWF ensemble members. The best chance for heavy rain will occur Friday night into Saturday with plenty of moisture and some increase in instability, especially Saturday. The low level jet is again not very strong and is more southwest, especially on Saturday versus southerly like what occurred earlier this week. Depending on the low track, there will be a severe threat as well on Saturday and the SPC has a Slight Risk (2/5) from east central Minnesota into much of northwest Wisconsin with a Marginal Risk (1/5) over all be western portions of the Northland. The risk of rainfall of 2" or more for a 48 hour period ending Sunday morning is 30-75% from the Brainerd Lakes to the Twin Ports and northwest Wisconsin, with the highest values from east-central Minnesota into northwest Wisconsin. Our total rainfall from today through Saturday night has diminished for most slightly and ranges from 0.75 to 2.5", greatest over northwest Wisconsin. If stronger thunderstorms do develop, there will likely be smaller areas that receive greater amounts. Given soils are saturated in spots and many rivers/streams are running high or will already be in flood, there will be a risk of more flash flooding. There will be periodic chances for more showers/storms beyond this weekend but the upper level flow will favor systems that are more progressive. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1221 PM CDT Thu Jun 20 2024 Lower flight cats will nose in from the south overnight and really make their way north after 12Z as a warm front approaches. Could be some thunderstorms embedded in the advancing nimbostratus. High confidence in IFR or lower conditions but lower confidence in northward extent of these low flight cats. Winds generally remain light ( less than 10 knots ) and easterly. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 350 AM CDT Thu Jun 20 2024 East to northeast winds will occur through Saturday becoming west to northwest Saturday night into Sunday. Speeds today into Friday will be from 5 to 15 knots, with some higher gusts, and be strongest in the Twin Ports area. Winds will be a bit stronger Saturday, mostly from 10 to 20 knots. There will be a chance for thunderstorms Friday into Saturday. Some of the storms Saturday could be strong to severe. An area of low pressure will move through the region and turn winds to west or northwest Saturday night into Sunday. 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...Wolfe MARINE...Melde