830 FXUS63 KDLH 180910 AFDDLHArea Forecast Discussion National Weather Service Duluth MN 410 AM CDT Thu Sep 18 2025
.KEY MESSAGES...
- Off and on rain chances increase today and tonight and will persist through the weekend.
- A few thunderstorms will be possible through the weekend but no severe weather is expected at this time.
- Temperatures turn cooler for today with easterly winds returning. Highs will be in the 60s and 70s with some 50s by the Lake.
- Increased risk of rip currents in the Twin Ports for today and Friday.
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.DISCUSSION... Issued at 407 AM CDT Thu Sep 18 2025
A slow moving upper low over the northern High Plains will slowly spin over the Dakotas the next couple days, keeping the Northland in on and off rain chances through the weekend under gloomy skies. There will be shortwaves embedded within this upper low, that will rotate across the region today through Saturday. These waves, in combination with a plume of Gulf moisture and broad isentropic lift extending all the way up to here will help to push waves of precipitation across the forecast area for the next few days. Digging into the details this morning, moisture is still being pushed into the area, as is being shown by the difference in available moisture between the 00z sounding at KMPX with a PWAT values of 1.50in vs KINL with a PWAT of 0.88in, and a large dry layer between 400 and 700mb. We expect the moisture available for precipitation to gradually increase through the day today, with precipitation chances gradually increasing from south to north today and tonight. The main upper low is a bit too far west for a coherent wave of precipitation, but with the consistent warm moist advection going on, I expect scattered showers and isolated storms to move across the forecast area from south to north today through tonight. Friday the upper low gets a little closer and our moisture will be much higher, so I expect the highest precipitation chances on Friday through Saturday, with precipitation chances likely for a large portion of the forecast area. This upper low finally eases off to the east on Sunday, allowing the precipitation chances to decrease on Sunday. The cloud cover, precipitation chances and easterly flow off Lake Superior will keep our temperatures near to below normal values for this time of year, with highs only in the 60s today and Friday, with some 50s along the North Shore. Temperatures will moderate through the weekend as the upper low moves northeast of the area. This will also keep overnight lows on the above normal side, with only the tip of the Arrowhead dipping into the 40s and the remaining areas staying in the 50s.
As we get into early next week, the upper low will get pushed off to the east by a short ridge, even as another upper low moves across the northern Rockies and dives southeast into the Mid Mississippi River Valley by the middle part of next week. This will leave us with the in-between troughing with small precipitation chances for Monday and Tuesday, then transitioning into mostly dry conditions for Wednesday and Thursday of next week. Temperatures return to near to above normal for early next week.
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.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1246 AM CDT Thu Sep 18 2025
Currently VFR conditions will begin to deteriorate overnight as an area of showers and storms spreads towards the area from the southwest. Ceilings will remain VFR through 12Z before decreasing to MVFR as the next round of rainfall lifts northward again for Thursday daytime rain showers. Ceilings should lift back to VFR for KHIB, KINL, KBRD and KHYR around 21z. Easterly winds quickly increase for KDLH beginning around 09z, becoming gusty to around 25 knots through the rest of the TAF period. The other terminals will also be gusty out of the east, but should stay under 20kts.
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.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 407 AM CDT Thu Sep 18 2025
Northeast winds will gradually increase today as a low pressure system advances towards the area, then slowly lifts north across western Minnesota today through Saturday. This will keep winds on the lake out of the northeast to east during this time frame. The strongest winds will be found as the low center moves towards the area today and again on Friday, with wind gusts approaching gale force where winds accelerate into the southwest arm of the lake around the Twin Ports. Short term Gale Warnings may be needed this afternoon.
For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.
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.DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...Small Craft Advisory until 7 AM CDT Friday for LSZ121-148. Small Craft Advisory until 1 AM CDT Saturday for LSZ140-141. Small Craft Advisory until 1 AM CDT Saturday for LSZ142>147- 150.
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DISCUSSION...LE AVIATION...LE MARINE...LE
NWS DLH Office Area Forecast Discussion