Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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086 FXUS63 KDLH 111145 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 645 AM CDT Sat May 11 2024 .KEY MESSAGES... - Chilly through early morning, with Frost Advisories in portions of the Arrowhead and north-central MN. - Warm this weekend with a chance for rain showers today into tonight and then some afternoon thunderstorm chances (20-40%) Sunday in NW WI. - A few of the Sunday afternoon storms may become strong in NW WI. Primary hazards would be wind gusts to 50 mph and penny size hail. - Very dry afternoon relative humidity expected today and especially on Sunday, particularly across NE MN. && .DISCUSSION... Issued at 449 AM CDT Sat May 11 2024 Early this Morning: Aside from a few mid-level clouds in the Arrowhead this morning, skies remain clear across the Northland. This, combined with light winds, has allowed for another efficient radiational cooling setup leading to some isolated pockets of patchy fog in areas that saw rain yesterday. Additionally, temperatures have dropped into the low to mid 30s across the interior Arrowhead and far north-central MN, where Frost Advisories are in effect. Pockets of mid-30s are also expected for portions of NW WI, but these aren`t expected to result in more than some patchy frost in the coldest locations. Today: We see northwest flow some weak shortwave ridging sets up for today, resulting in high temperatures warming into the 60s to low/mid 70s, warmest across north-central MN. Northeast MN should also see the development of a narrow band of light rain showers later this morning into the afternoon, though deep mixing to 750 mb and drier low levels should keep most of this precipitation from hitting the ground. As a result, only expect a few hundredths of an inch of rain at best with the showers. Otherwise, the deeper mixing today will lead to lower relative humidity values this afternoon dropping to around 25-35% for most of the Northland, though some values down to 20% will be possible in north-central MN. Winds will be weaker than yesterday, turning southwesterly during the afternoon with gusts up to 15 to 18 mph. The strongest gust are also expected in the region of lowest humidity, so near-critical fire weather conditions are expected for north-central MN. Relative humidity will quickly increase this evening. This evening - Sunday: A closed upper-level low/associated surface low treks across northern Manitoba and Ontario from this afternoon through Sunday. This system will bring scattered showers and a few non- severe storms southeastwards across the Northland this evening and tonight ahead of a progressive cold front. Rainfall amounts look light, with spottier amounts of 0.05-0.2". Some locations will not see any rain since precipitation will not be widespread. By Sunday afternoon, some redevelopment of showers and thunderstorms is likely in the warm sector just south of the front. Higher-res model guidance has been trending faster with the southeastward progression of the cold front Sunday afternoon, so the window of space and time for the redevelopment of thunderstorms in NW WI before the front pushes south of our forecast area is relegated to a 2 PM - 5 PM window at best. Most of this higher-res model guidance actually develops storms just south of our southern tier of NW WI counties. The FV3 and RAP are slightly slower with the front progression, and would give areas southeast of a Siren to Hayward to Hurley line a 20-40% chance to see some brief, scattered thunderstorms. If this slower solution were to occur, warm sector SBCAPE of 500-1200 J/kg, steep low- and mid-level lapse rates, and deep layer shear vectors of 25-35 knots would be sufficient to produce a few strong storms with wind gusts up to 50 mph and up to penny size hail, and localized rainfall amounts of 0.1-0.3". However, a faster moving front would have any storms develop south of our area. Another concern on Sunday will be much drier air advecting in behind the cold front, particularly across northeast MN where deep mixing will be taking place. High temperatures in the 70s, relative humidities dropping into the upper-teens to mid-20s, and breezy northwest winds will likely lead to near-critical fire weather conditions and possibly Red Flag Warning criteria for north-central and Northeast MN. Relative humidity values for Sunday afternoon have been trending lower, though the wind/gust forecast has been trending ever-so-slightly weaker to 15 to 20 mph for most of north-central and northeast MN, but some locations near the International Border are still forecast to see wind gusts up to 25 mph. Next Week: High pressure moves into the Upper Midwest for Monday and Tuesday, leading to mainly sunny skies and drier conditions. Slightly cooler temperatures in the 60s (even cooler near Lake Superior) should keep afternoon relative humidities from getting too low and wind gusts will be generally under 20 mph, as well. Parts of the Arrowhead and NW WI may even need some Frost Advisories Monday and Tuesday nights due to temperatures dipping into the mid-30s. Ensembles point to shortwave troughing Wednesday-Thursday and more shortwaves late next week into next weekend bringing periodic shower and thunderstorm chances with them. Still looking at 40-60% chances for >0.25" of rain with the midweek system, with a 20-40% chance for greater than 0.5". High temperatures remain mostly in the 60s during this timeframe, as well. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 646 AM CDT Sat May 11 2024 Some very patchy fog across parts of the Northland will burn off by 13-14Z. Calm to light winds back to westerly this morning and northwesterly in NW WI, then to southwesterly this afternoon and southerly this coming evening. Afternoon winds pick up to around 8-10 knots with gusts up to 12-18 knots, strongest at KBRD and KINL. A few showers will be possible over northern and northeast Minnesota this afternoon, with an additional round of scattered showers and a few embedded thunderstorms moving northwest to southeast across the Northland later this evening into tonight ahead of an approaching cold front. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 639 AM CDT Sat May 11 2024 Southwesterly winds this morning turn southerly this afternoon with gusts up to around 15-18 knots. Some stronger gusts to 20 knots develop very near land along the South Shore Saturday night. Additionally, some showers and isolated thunderstorms are expected Saturday night. Winds turn northwesterly on Sunday, with warmer temperatures leading to most of the stronger winds remaining over land. Some gusts to 20 knots are possible along the North Shore Sunday afternoon into evening, however. As of now, Small Craft Advisory-level winds are not expected for Sunday afternoon. Northeasterly winds develop for Monday and Tuesday, with some funneling into the Twin Ports pushing afternoon gusts up to around 20 knots. 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 8 AM CDT this morning for MNZ010>012-018- 019-026. WI...None. MARINE...None. && $$ DISCUSSION...Rothstein AVIATION...Rothstein MARINE...Rothstein