Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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166 FXUS63 KDLH 090856 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 356 AM CDT Thu May 9 2024 .KEY MESSAGES... - The potential for frost in the interior Arrowhead persists through 7-8 AM this morning as temperatures remain at or a few degrees above freezing. - Another period of sub-freezing temperatures (northwest Wisconsin and the Arrowhead) sets up again Thursday night, with frost also possible for east-central Minnesota and northward throughout Carlton and St. Louis Counties. - Scattered thunderstorms are expected to form Friday afternoon, with isolated strong thunderstorms possible in the late afternoon to mid-evening hours Friday. Severe storms are not currently expected. - Temperatures around sunrise on Saturday are forecast in the low-40s and increasing to low to mid-60s F by early afternoon under mostly sunny skies. Precip chances build in Saturday evening, with thunderstorms on Sunday. && .DISCUSSION... Issued at 356 AM CDT Thu May 9 2024 Surface temperatures right around to a few degrees above freezing are being observed early this morning in the interior parts of the Arrowhead where winds are generally calm to only a few mph from the northeast. Where winds are 4-5 mph or more the surface temperatures have remained around 40 to mid-40s helping inhibiting frost potential within about ten miles of Lake Superior. Temperatures remain within the frost-tolerance threshold through 7-8 AM this morning so the Frost Advisory remains in effect. A couple of locations where dewpoints have been observed into the upper-20s even dropped to 29 F so far in far eastern interior Cook County. Quiet weather is expected today outside of some breezy morning northeasterly winds near Lake Superior. A very dry airmass aloft is forecast to help to drop surface RH down to 25-30% in north-central MN, but light winds limit any general fire weather concerns and no less the gradual green-up and recent rainfall. Surface high pressure allowing for calm winds under a mid-level ridge aloft creating a very dry and cool airmass creates an 80-90% chance of sub-freezing surface temperatures for nearly all of northwest Wisconsin beginning late this evening through Friday morning. A Freeze Watch has been issued for all but Burnett County from 10 PM to 9 AM as a result. At to slightly above freezing temperatures remain very likely (70% chance) from Aitkin to eastern Itasca to eastern Koochiching Counties and eastward into the Arrowhead tonight, including nearly of the Twin Ports. Frost Advisories very easily could be again needed in future forecast updates to cover these low to mid-30 F low temperatures expected by early Friday morning. A building pressure gradient allowing for light southwesterly winds to persist overnight in the Brainerd Lakes and northward into western Koochiching County highly limits any frost/near-freeze potential for this part of the Northland. Today during the daytime is the time to prep those early uncovered gardens, flower beds, outdoor plants for these freezing temperatures expected tonight. A shortwave trough digs southeastward early Friday morning over southern Manitoba to create the next round of rainfall for Friday morning over north-central Minnesota and later northeast MN. One to two tenths of an inch of rainfall is the most likely rain amounts expected currently. As the trough moves into the Borderlands Friday late morning though, increased mid-level lapse rates, greater saturation and CAPE up to 800-1000 J/kg are very likely to create scattered thunderstorms Friday afternoon through Friday evening. Wind shear around 25 knots could support stronger thunderstorms in the late afternoon to early evening time period Friday across the region. Small hail and wind gusts of 40-50 mph are the primary hazard threats at this time. While CAPE decreases in the late evening hours, lingering isolated thunderstorms and rain showers exit the Arrowhead and northwest Wisconsin last Friday night. Temperatures around sunrise on Saturday are forecast in the low-40s with west to northwest winds around 5 mph. By early afternoon, temperatures increase to to low to mid-60s F under mostly sunny skies with westerly winds around 7-10 mph. There is a 40% chance of temperatures in north-central Minnesota reaching 70 F. Not a bad day for the boat eh? Speaking of boating though, keep in mind wearing life jackets even with these pleasant air temperatures, the water temperatures remain fairly cold compared to the air temperature. Cold water safety! By Saturday evening, there is a 20% chance of rain showers building into the Northland though, which further builds to 30-40% chance by Sunday (best chances in the Arrowhead and northwest Wisconsin). Keep in mind rain gear for the second half of the weekend and having an alternative plan if out on the water and thunderstorms begin to approach those inland lakes Sunday. A dry start to the next work week with temperatures about 5 to 10 degrees above normal may (20% chance) lead to rainfall by next Tuesday PM. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1226 AM CDT Thu May 9 2024 VFR conditions prevail under light northeast winds away from the lake shoreline and around 10-15 knots for shoreline terminals. Scattered MVFR ceilings in north-central Wisconsin may (50% chance) impact HYR overnight into early Thursday morning. Winds shift to south-southeasterly around 5 knots from 00-06Z Fri. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 301 AM CDT Thu May 9 2024 Today will be another day of gusty northeast winds creating elevated wave heights from 3 to 5 feet in the southwestern arm and along the South Shore through this afternoon. Small Craft Advisories are in effect. Winds decrease in the early to mid- afternoon hours today though and shift southwesterly tonight. Southwesterly winds 10-15 knots, locally gusting to 20 knots north of Grand Marais on Friday build wave heights again of 2-4 feet along the North Shore. An approaching shortwave trough from the north creates thunderstorm chances Friday afternoon and evening. Local outflow driven erratic wind gusts to 35 knots are possible from any stronger thunderstorms. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...Frost Advisory until 9 AM CDT this morning for MNZ011-012-019. WI...Freeze Watch from this evening through Friday morning for WIZ001>004-007>009. MARINE...Small Craft Advisory until 1 PM CDT this afternoon for LSZ142- 143. Small Craft Advisory until 1 PM CDT this afternoon for LSZ144>148-150. && $$ DISCUSSION...NLy AVIATION...NLy MARINE...NLy