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Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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712 FXUS63 KDLH 172030 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 330 PM CDT Tue Sep 17 2024 .KEY MESSAGES... - Muggy, much above normal temperatures persist through the week, with the hottest temperatures and highest dewpoints through Thursday. - Scattered showers and thunderstorms are possible today into Wednesday, primarily across north-central MN and the MN Arrowhead. Some severe storms are possible Thursday with a passing cold front. - Seasonable temperatures may return through the weekend and into next week. && .DISCUSSION... Issued at 329 PM CDT Tue Sep 17 2024 Another hot and muggy day has developed across the Northland with southwesterly flow bringing temperatures in the 80s and dewpoints in the mid 60s. A front draped just north of the border continues to spur areas of thunderstorms, but much of the CWA was clear this morning. A few areas of cumulus fields have developed early this afternoon, out of which some afternoon showers and an isolated thunderstorm are possible. With as much moisture as we have hanging around at the moment, some small areas of heavy rain are possible if thunderstorms develop but coverage should be very minimal. Overnight, an area of showers may develop along the front edge of a zippy LLJ building along a frontal zone. These showers are most likely over north-central and northeast Minnesota and are generally expected to dissipate through the morning as the support from the LLJ wanes. Wednesday, a stacked upper level low is progged to push out of the Rockies and into the northern Plains and southern Manitoba, dragging a cold front over the Upper Mississippi and northern Great Lakes Wednesday afternoon and through the day Thursday. Along this front, a narrow corridor of 1000-1500 J/kg of MLCAPE, up to 40 knots of bulk shear, and steep lapse rates is expected to build, which could be enough to spur a some scattered severe thunderstorms. CAMs and global models generally suggest two different periods of possible storms, one in the morning with elevated convection along the overnight LLJ, and the second in the afternoon and early evening from the combination of a front and surface-based instability. The second is the more likely candidate for any severe storms. Morning showers could lead to some widespread mid to high clouds which leads to a little uncertainty regarding the potential for afternoon convection to redevelop. However, synoptic forcing is good and may be enough to overcome a lack of instability. Currently, the SPC has portions of the Northland outlooked in a Slight risk (level 2 out of 5), but there is still some discrepancy on frontal placement by Thursday afternoon, with the latest suite of models being slightly more progressive with the front and initiation of afternoon storms. In addition to the severe threat, some quick downpours and locally heavy rain is possible, thanks to our very moist environment. However, no widespread heavy rainfall coverage is expected. Beyond Thursday, the Northland finds itself stuck between a high pressure over the southern Plains and an upper level trough bearing down from Canada. Embedded within that all could come some cut off lows and shortwave troughs. This should generally bring some cooler temperatures to the region, but our current above normal temperature situation may dally on it`s way out, with high temperatures not expected to reach their climatological normal of high 60s until Sunday. All the action in the upper levels may also keep chances for rainfall around. However, global ensembles have backed off slightly in their widespread washout precipitation chances they were showing a couple runs back, so there could be some sunshine scattered in there as well. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1220 PM CDT Tue Sep 17 2024 Predominantly VFR conditions continue through the TAF period. INL may see some isolated showers and thunderstorms late this afternoon or early this evening, but latest trends have pushed the best chance of precipitation north of the border. Overnight, expect an area of showers and thunderstorms to build along a low level jet which may impact INL and BRD, with a slight chance that showers reach HIB. The low level jet may lead to some LLWS at DLH overnight. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 329 PM CDT Tue Sep 17 2024 Through Wednesday, expect a similar wind pattern as the last couple days. Southerly winds along the South Shore turn and become onshore for the Twin Ports and North Shore, with some gusts of 10-15 knots possible in the afternoon. Thursday, slightly strong south to southeast winds are possible, sustained around 10-15 knots and some gusts near 20 knots in the Twin Ports and Chequamegon Bay. Some rain showers and thunderstorms are possible Thursday, which may contain strong winds and some larger hail in the afternoon and evening. Friday, expected southwesterly winds with some strong afternoon gusts behind Thursday`s cold front. 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...Levens AVIATION...Levens MARINE...Levens