Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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795 FXUS63 KDLH 162347 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 647 PM CDT Mon Sep 16 2024 .MESOSCALE UPDATE... Issued at 647 PM CDT Mon Sep 16 2024 Showers and a few thunderstorms over northern St. Louis and Lake counties continue to percolate along a remnant outflow boundary from this morning`s convection under a zone of 850-750 mb isentropic ascent. This nebulous area of convection has demonstrated a backbuilding tendency and additional convection has developed farther south toward Hibbing while propagating northward. Think this area of precipitation will persist for several more hours. Southerly low-level flow into this zone of focused ascent is forecast to increase over the next several hours as a southerly to southwesterly low-level jet develops. Radar- estimated precipitation totals have ranged from a trace up to nearly 3 inches so far today and early this evening. As precipitation continues, the risk of minor flooding will gradually increase. If a few stronger cells can develop and train over the same location, additional flood products may be needed tonight. Later tonight the convection over North Dakota and northwest Minnesota may advance into north-central Minnesota with a risk of damaging wind gusts and perhaps a few quarter-size (1 inch) hailstones. Favorable low-level shear is forecast for supercells as the LLJ develops, though weaker mid-level winds should limit updraft speed in the hail growth zone. Time will tell whether much of a severe weather risk develops over Koochiching County. && .KEY MESSAGES... - Scattered thunderstorms into this evening mainly north-central MN and the Arrowhead. - A 5-10% chance of a strong to severe thunderstorm and a 5-15% chance of heavy rainfall in north-central Minnesota and the Arrowhead tonight. - Warm temperatures continue through mid-week before gradually cooling to normal by this weekend. && .DISCUSSION... Issued at 345 PM CDT Mon Sep 16 2024 Low pressure deepening over the northern high plains is expected to trigger strong to widely scattered severe thunderstorms over the northern plains this evening. As the storms move northeastward, a few stronger thunderstorms could (5-10% chance) move through just east enough to impact far north-central Minnesota later this evening as a result. If any stronger thunderstorms do realize into an isolated severe thunderstorm, hail around the size of a quarter would be the primary expected hazard type. The seasonably moist airmass over the Northland keeps concerns for heavy rainfall in the region too, so any strong to severe thunderstorm could (5% chance) be accompanied by heavy rainfall as well into early Tuesday morning. As the low moves eastward Tuesday, general thunderstorm chances (30-40% chance) are forecast into tomorrow morning. A stalled boundary along the Borderlands could (20-30% chance) also promote further general thunderstorms into Tuesday night. Drier weather looks likely (90% chance) on Wednesday as a drier air mass may promote decreased relative humidity from a drop in dew points into the 50 degree F range behind the passing low pressure. A western trough begins to breakdown Wednesday and low pressure lifts into the northern high plains to deepen into Thursday. A cold front passes over the region later Thursday. This Thursday night time period looks to be the best chances for more widespread rainfall (light to moderate) as the western low pressure centered in south-central Canada brings in cooler westerly air behind the front. This late work week into weekend time period looks to be the first time of returning to normal to below normal temperatures this fall! Stratiform and widespread rainfall returns later Saturday and into Sunday. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 647 PM CDT Mon Sep 16 2024 A few storms may move over INL tonight while additional convection persists north of HIB into the MN Arrowhead. A somewhat tight pressure gradient will remain over the region tonight and should keep winds in the 5 to 10 knot range overnight. If winds go calm for an hour or so, a brief period of IFR visibility in fog may develop. For now think that chance is too low to include with this forecast. A strong south to southwesterly low-level jet will develop tonight and aid storm development near INL. LLWS will be a concern at BRD, INL, HIB, and DLH overnight. HYR appears to be east of the strongest winds aloft, so no LLWS concerns there. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 256 PM CDT Mon Sep 16 2024 Light winds generally less than 15 knots are forecast outside of scattered thunderstorms where gusty, erratic winds may occur this evening and again Tuesday on the North Shore. Dry weather is forecast on Wednesday over the lake. 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. && $$ UPDATE...NLy DISCUSSION...NLy AVIATION...Huyck MARINE...NLy