Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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565 FXUS63 KDLH 262309 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 609 PM CDT Wed Jun 26 2024 .KEY MESSAGES... - Widespread moderate to locally heavy rainfall may return Thursday night and ends Friday midday. The heaviest rainfall is most likely near and north of the Iron Range into the Arrowhead of far northern Minnesota. - Isolated severe thunderstorms in north-central Minnesota late Friday afternoon and evening may (5% chance) move into northeast Minnesota through early Friday night. - Residual showers Saturday in northeast Minnesota give way to a dry Sunday before the next round of moderate to locally heavy rainfall is forecast to return Monday into Monday night. && .DISCUSSION... Issued at 211 PM CDT Wed Jun 26 2024 Satellite imagery shows the partly sunny skies that are being observed across the Northland today as a few elevated showers associated with a very weak mid-level disturbance in Ontario north of Superior moves eastward. Not seeing any indications on surface observations nor forecast model soundings for this dry boundary layer to even support more than a few hundredths of an inch in highly isolated locations in the Arrowhead and Borderlands today so kept with only `Sprinkle` mention in the forecast for now through 10 PM today. Clearing diurnal skies after sunset tonight under surface high pressure and a low to mid-level high-amplitude ridge axis tonight create fair radiational cooling conditions in the Northland. Areas of fog are expected tonight, mainly in the I-35 corridor and across northwest Wisconsin into early Thursday morning. A few cold spots in inland north-central Wisconsin (mainly Price County and far southern Iron County in this case) could (10-20% chance) drop down to 39 F by early Thursday morning. There are zero concerns for frost, but just a note on the seasonally cool temperatures (10 degrees below normal low temperatures on the low side of this forecast). After a dry Thursday daytime, a warm front lifts east- northeastward from the Northern Plains into north-central Minnesota Thursday evening. Precipitation chances increase around sunset for the Brainerd Lakes region first, with northwest Wisconsin closer to the 3-6 AM hours early Friday morning. The moist southerly advection provides the next chance for widespread moderate (mainly northeast Minnesota) to light (northwest Wisconsin) rainfall for that early Thursday night to Friday morning daylight hours. Locally heavier rainfall is most likely (50-70% chance) near and north of the Iron Range in northeast Minnesota. There is a 10-20% chance of exceeding 2 inches of rainfall in the Borderlands, with around an inch favored (50-70% chance) from Grand Rapids to Silver Bay and northward. This rainfall scenario is the most favored (60% chance) solution, but there is also a possibility (40% chance) that the warm front lifts even further northward into Ontario and Manitoba to only leave even the Iron Range northward with moderate rainfall (0.25 to 0.75 inches). An instability axis is expected to setup in northwest Minnesota Friday afternoon, with somewhat favorable mid-level lapse rates aligning along the instability axis to support some isolated severe weather threat into north-central Minnesota by the late afternoon to evening hours. Model forecast soundings show a disorganized shear environment though and CAPE maximized around 800 J/kg in that area of around 7 C/km lapse rates. This setup creates concerns for not much more than scattered strong to near-severe thunderstorms for the Brainerd Lakes to western Iron Range locations into the late evening hours. The furthest east locations for strong thunderstorms currently look to be along a line from Silver Bay to Ely and westward. As the mid- level instability axis shifts into northwest Wisconsin Friday night, a few strong elevated storms may persist into inland northwest Wisconsin, but confidence is very low on that scenario at this point. Lingering showers behind the cold frontal passage in the Arrowhead are favored (40-60% chance), but severe thunderstorms would not be expected for those weekend plans. A dry Sunday and first part of Monday yields to the pattern of moderate to locally heavy rainfall returning for the Monday PM. Long-range ensemble guidance is in low to moderate agreement for a 30% chance of around a half inch to one inch of rainfall again next Monday and Monday night. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 607 PM CDT Wed Jun 26 2024 VFR for most of the period. Some fog could develop overnight though still not sure of the intensity so went with MVFR visibilities at the terminals until confidence increases. Winds generally light and from the northwest though they begin to increase their speeds Thursday afternoon while backing to the south. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 211 PM CDT Wed Jun 26 2024 Northeast winds around 10 knots or less are ongoing this afternoon and shift northwesterly Thursday morning. Those northwesterly winds then shift southerly Thursday afternoon, except northeasterly into the southwestern arm. Thunderstorm chances build back into the region Thursday night and last into Friday afternoon. Heavy rainfall Friday over the North Shore may (20% chance) produce locally dense fog. 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...NLy AVIATION...Wolfe MARINE...NLy