Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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682 FXUS63 KDLH 121134 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 634 AM CDT Mon Aug 12 2024 .KEY MESSAGES... - Scattered rain showers and isolated thunderstorms are possible (15 - 30 percent chance) Monday and Tuesday in the afternoon and evening. - Rain chances increase to 50 - 70 percent later Wednesday and last into Friday - Temperatures in the upper 70s to low 80s through Wednesday decrease into the low to mid 70s Thursday onward. && .DISCUSSION... Issued at 405 AM CDT Mon Aug 12 2024 Water vapor satellite imagery early this morning shows an upper-level boundary draped over northwest Minnesota into north- central Wisconsin and extending through southern parts of Lower Michigan. Surface high pressure immediately under this boundary is promoting very little winds aloft and clear skies overnight tonight. A plume of more moist air will remain situated over the Borderlands, Arrowhead and into the South Shore during the daytime today. After morning diurnal destabilization, anywhere from 300-700 J/kg of CAPE build into that more moist airmass aloft part of the Northland to kick off another round scattered rain showers and isolated thunderstorms later today. The 10 knots or less of low to mid-level flow will allow for pulse general thunderstorms that can break a mid- level cap. This very weak steering flow will also mean that storms stall out over locations and could bring some moderate rainfall along and northeast of US Hwy 2 in northeast Minnesota. Very localized amounts of 0.25-0.5 inches of rainfall are expected for a few locations from late afternoon to early evening today. A drier airmass is progged to move over the rest of the Northland from tonight into Tuesday and further limit the already widely scattered shower potential on Tuesday. Temperatures under a seasonal airmass will be in the upper-70s to low-80s for the first few days of this work week. The ridge axis that is slowly moving through the Northern Plains today and Tuesday passes east of the Upper Midwest Tuesday evening to setup southerly return flow. The more moist airmass helps to limit overnight surface temperatures from dropping out later this week compared to the upper-40s and fifties that are being observed and expected for the first couple of night this week. Low pressure centered in the Central Canadian Prairies Wednesday drapes a warm front over the northern US Plains Wednesday that moves the Northland beginning Wednesday night. In the meantime, an area of surface low pressure deepens over the Lower Midwest Thursday morning and further increases the chances of moderate rainfall in the Northland by Thursday afternoon. The highest chances of any very localized heavy rainfall would be northwest Wisconsin into east-central Minnesota along an occluded front. Temperatures decrease by late this work week down into the low to mid-70s F. As the Central Canadian deeper low passes to the north of the Northland, a trailing cold front helps to decrease rainfall chance Friday night onward as the low pressure to the south moves eastward. Wrap around cold core rain showers remain possible (20-30 percent chance) though into the weekend under northerly flow aloft. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 625 AM CDT Mon Aug 12 2024 Localized LIFR to MVFR fog burns off by 13Z this morning to create widespread VFR conditions this morning. Daytime heating by early afternoon will prompt a round of afternoon and early evening rain showers and isolated thunderstorms. The best chance of localized visibility restrictions are in northeast Minnesota near and northeast of a line from Bemidji to Grand Rapids to Moose Lake through 03Z Tue. Expect localized mist/fog again after 06Z Tue. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 320 AM CDT Mon Aug 12 2024 Southwest winds 5 to 15 knots today and Tuesday are forecast with afternoon scattered rain showers and isolated thunderstorms. Winds shift to easterly Wednesday and are expected to build to 15 to 20 knots at the head of the lake by later Wednesday and create wave heights around 2 feet. 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...NLy MARINE...NLy