Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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432 FXUS63 KDLH 220924 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 424 AM CDT Sat Jun 22 2024 .KEY MESSAGES... - Periods of rain and some thunderstorms continue through the weekend. - More showers and storms are possible Monday late-afternoon into early Tuesday morning. Some strong to severe storms are possible. - Active weather with rain and thunder chances persist through next week with occasional breaks of sunshine. && .DISCUSSION... Issued at 423 AM CDT Sat Jun 22 2024 Main concerns this morning is for convection and potential for heavy rainfall in the forecast. Currently, a weak surface low is over Iowa, with a east-west oriented boundary extending fromm Nebraska across Iowa along the WI/IL border. VWP data shows a 40 knot low level jet impinging upon this boundary, explaining the broad area of showers and storms extending from Iowa into southern WI and southeast MN. We also have some weaker showers over northwestern MN, but these appear to be associated with a weak shortwave moving across that area. Hi res models are generating an expanding area of showers and storms mainly over northwest Wisconsin this morning as it gradually pushes east, right on the nose of the low level jet. They keep generating some bands that move up into the Twin Ports and nearby areas, but this is sitting on the far northern fringe of where we may get thunder, up until mid morning today before it pushes east for the remainder of the morning. A potent shortwave will move across the area this afternoon and early evening, and we should build sufficient instability and deep layer shear for new thunderstorm developmet. For now it appears the instability will be the limiting factor, with only enough for general thunder chances, but not enough for severe storms. However, most of the southern CWA should get some afternoon and evening storms, with the precipitation potential decreasing to the north. Northeast winds today along with temperatures already on the cool side will keep high temperatures in the upper 60s to mid 70s for most of the area. The northeast winds will put the "cooler by the lake" into reality today, with temperatures along the Lake Superior shoreline not getting any warmer than the low 60s. Another shortwave will bring shower and storm chances to the forecast area late tonight and Sunday, again with enough CAPE for general thunder chances but not enough for severe storms. Our next time period of concern is Monday and Monday night, with a surge of warm air pushing a surface boundary to over the forecast area, with heat, humidity and significant instability to the south, and sufficient shear for strong to severe storms. SPC has us in a day 3 outlook, as well as the CSU severe weather probability, which support what we`re seeing in the deterministic model runs. Models are generating some pretty incredible instability in the warm sector on Monday, and since it`s not limited to the NAM, it might actually get pretty significant. While we will have to wait and see on these details, this might be another active evening of convection. We currently have max temperatures in the upper 70s to mid 80s, and would not be surprised to see slowly increase as we get closer in time to this event. Shower and storm chances continue into Tuesday and Tuesday night with cyclonic flow continuing behind the main trough axis for Monday evening. The warmer than normal temperatures continue into Tuesday, with highs rising into the 80s once again, which is 5 to 10 degrees above normal for both days. A ridge of high pressure should slide across the area on Wednesday and Wednesday night for a drier day with cooler temperatures, especially as compared to Monday and Tuesday. Precipitation chances return for Thursday into Friday as a fairly large upper level trough axis moves across the area. While timing and strength is not in very good agreement at this point, the ensembles at least show some flavor of this upper level trough moving through the area late in the work week, perhaps continuing into the weekend. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1255 AM CDT Sat Jun 22 2024 Initial VFR conditions with light east winds of less than 10kts. Rain with embedded thunder to spread into the area from the southwest during the early morning, then spread east Saturday morning. For now it appears the lowest conditions are expected for KBRD, KHYR and KDLH, with ceilings lowering to IFR and MVFR visibilities where the heaviest showers pass. MVFR conditions can be expected for KHIB, but conditions to remain VFR for KINL. These lowered ceilings to linger Saturday afternoon and evening, with some sites returning to VFR for the end of the TAF period. Rain chances move back in from the northwest after 00z for KINL. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 423 AM CDT Sat Jun 22 2024 Northeast winds to increase today, with gusts of 20 to 25 knots for several hours from late morning through the afternoon, before decreasing once again for this evening. These winds will help build waves into the southwest arm of the lake, and have continued the Small Craft Advisory that has been issued for today from Taconite Harber through to Saxon Harbor, including the Apostle Islands. Winds decrease for tonight, allowing waves to diminish as well. Conditions on the lake do not get significant again until Monday with the stronger weather system moving through, once again producing stronger northeast winds into the southwest arm of the lake, causing building waves and potentially hazardous conditions. 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...Small Craft Advisory until 7 PM CDT this evening for LSZ142>148-150. && $$ DISCUSSION...LE AVIATION...LE MARINE...LE