Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
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545 FXUS63 KDLH 100323 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1023 PM CDT Thu May 9 2024 .UPDATE... Issued at 1022 PM CDT Thu May 9 2024 Temperatures have fallen into the mid-thirties at Grand Marais and Two Harbors so we added the Coastal Cook and Lake Counties to the Frost Advisory tonight. && .KEY MESSAGES... - An active spring weather pattern persists through the next 7-10 days with continued chances for showers/thunderstorms most days and seasonable temperatures. A few stronger thunderstorms could produce small hail and gusty winds on Friday afternoon (northeast Minnesota) and again on Sunday afternoon (mainly northwest Wisconsin). - Temperatures will fall below the freezing mark in much of inland northwest Wisconsin overnight. A Freeze Warning is in effect for most of northwest Wisconsin, with a Frost Advisory for parts of northeast Minnesota. && .DISCUSSION... Issued at 157 PM CDT Thu May 9 2024 On the synoptic scale a very spring-like weather pattern continues, with many chances for precip but no particular day looking like a complete washout. Mainly sunny skies today with a weak area of high pressure over Lake Superior causing a lake breeze/lake influence well inland, with north-northeast winds gusting to around 20 knots this afternoon for areas near the lake and into parts of northwest Wisconsin. Temps will fall below freezing given clear skies tonight, with a freeze in northwest Wisconsin and frost (temps in the 33-36 range) in northeast Minnesota. Increasing clouds in northern Minnesota will prevent a freeze, though some higher elevations of the Minnesota Arrowhead region may reach below freezing. On Friday a fairly fast-moving mid-level shortwave trough will move from almost north to south from Manitoba/northern Ontario down through the Upper Mississippi River Valley. While the thermal fields don`t reflect much of a gradient ahead of this wave, the broad-scale lift from the approaching wave combined with steep low level lapse rates will lead to scattered showers and a few thunderstorms, though the limited instability (perhaps 200-400 j/kg SBCAPE) and dry air at low levels will mean the amount of precip that falls will be limited and individual showers/storms will be fairly short-lived. Gusty winds likely to be the main threat from the strongest storms - perhaps producing 40-45 mph gusts at most, with some pea-size hail also possible. Precipitation will be mainly diurnally-driven, with showers/storms diminishing towards sunset and skies clearing out on Friday night. The shortwave trough is followed by some mid-level ridging over northern Ontario into the Upper Great Lakes, with otherwise northwest flow at mid levels and warm air advecting in from the west at lower levels. Sunny skies to start on Saturday with diurnally driven cumulus in the afternoon given some residual moisture in the column, with a spotty shower possible Saturday afternoon/early evening across northern Minnesota (15-25 percent chance) but nothing to ruin a great day to get outside as highs reach into the 60s to as warm as the low 70s for parts of north-central Minnesota. Late weekend into early next week a slower-moving upper low with an associated surface low deepening over far northern Ontario/Hudson Bay will draw down a surge of unseasonably cooler air at low levels, with a strong surface cold front moving from north to south across the region late Sunday into Monday. In the warm sector ahead of this cold front another round of diurnally-driven showers and thunderstorms are expected on Sunday afternoon, mainly in east- central Minnesota and northwest Wisconsin. With two days of west winds at low to mid levels ahead of this front, a decent EML will be present - nothing to write home about but still favorable mid-level lapse rates, strong surface heating leading to steep low level lapse rates, and a decent amount of moisture in the column will lead to instability on the order of 500-1200 j/kg. While deep-layer shear will be weak (15-20 knots), some stronger thunderstorms producing heavy rainfall rates are possible in northwest Wisconsin, and a few of the first storms could produce gusty winds and small hail depending on the the timing of the arrival of the large-scale lift from the cold front moving in from the north. While the closed mature low briefly pauses over northern Ontario a weak mid-level shortwave embedded in the northwest flow over southern Manitoba into the Dakotas late Sunday moves across the region on Monday leading to yet another round of precipitation on Monday afternoon. Through the rest of the work week it`s much more of the same - a longwave trough enters southern Canada and the Pacific Northwest early in the week then slowly tracks eastward into the Great Plains and Midwest mid-week leading to more widespread precipitation, with a 60-70% chance for at least a tenth of an inch of precipitation across the Northland mid-week, with some ensemble guidance solutions producing as much as a half inch or more (10-20% chance). Highs in the 60s to low 70s most days, cooler near Lake Superior. Lows in the 40s with little to no chance for frost/freeze late weekend through next week. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 629 PM CDT Thu May 9 2024 Mostly clear skies will occur well into tonight with mid-clouds moving in from the northwest late tonight into Friday morning along and ahead of a cold front. Winds will diminish tonight and become light or calm for most. Some patchy fog is possible in spots but chances are too low to include a mention at this time. Showers will develop from northwest to southeast through the Northland on Friday with a few thunderstorms in the afternoon and evening. Forecast soundings show drier low levels so we expect VFR conditions for most with the showers. Some brief dips to MVFR will be possible with any of the stronger showers or thunderstorms. Gusty and erratic winds and small hail will also be possible with any thunderstorms. Winds will veer through the day Friday as the cold front moves through. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 1021 PM CDT Thu May 9 2024 East-northeast winds diminish this evening, with winds becoming westerly at 5 to 10 knots on Friday as a weak cold front moves across Lake Superior bringing with it scattered showers and an isolated thunderstorm. Southwest winds through the weekend, around 10 knots on Saturday then stronger Sunday at 15-18 knots. Conditions are not anticipated to reach Small Craft Advisory level through the weekend. Next week a prolonged period of easterly winds will lead to gradually building waves across western Lake Superior, but hazardous marine conditions are not anticipated. 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 Friday for MNZ012-019>021-037- 038. WI...Frost Advisory until 8 AM CDT Friday for WIZ006. Freeze Warning until 9 AM CDT Friday for WIZ001>004-007>009. MARINE...None. && $$ UPDATE...Melde DISCUSSION...JJM AVIATION...Melde MARINE...JJM