Area Forecast Discussion
Issued by NWS Duluth, MN
Issued by NWS Duluth, MN
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
893 FXUS63 KDLH 210546 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1246 AM CDT Sat Sep 21 2024 .KEY MESSAGES... -Quiet conditions are expected this evening into tonight with mostly clear to clear skies. -Showers and thunderstorms develop late tonight into Saturday morning. Severe weather is not expected Saturday morning. -A second round of thunderstorms are likely Saturday afternoon and evening, mainly over northwest Wisconsin. A few storms may become strong to severe, capable of producing damaging winds and large hail. -Quiet and dry weather returns on Sunday and is likely to persist through this upcoming week. && .DISCUSSION... Issued at 324 PM CDT Fri Sep 20 2024 Compared to the active conditions that were seen yesterday, today has been much more benign as high pressure briefly builds in a post- frontal environment. A stratus deck that advected into the CWA earlier this morning has been gradually scattering out this afternoon. Expect mostly clear to clear skies overnight with low temps cooling into the mid 40s to mid 50s. Localized areas of fog will be possible tonight, but the potential is low (25% chance). A strong southerly LLJ of around 35-40 knots is expected to develop tonight ahead of approaching low pressure, which will result in WAA and moisture advection into the CWA. Scattered showers and isolated thunderstorms are likely to develop in the morning hours on Saturday along a warm front, which will be lifting northward through the area. This morning round of convection is expected to remain sub- severe as CAPE will be minimal around 100-200 J/kg. Following the warm frontal passage in the morning, temperatures will be warming into the low to mid 70s on the Minnesota side of the CWA and the upper 70s to low 80s on the Wisconsin side. A second, stronger, round of convection is likely to develop on Saturday afternoon along a cold front that will be sweeping through. Ahead of this cold front, mid-level lapse rates will be increasing to around 7-8 degC/km on Saturday afternoon. Since this cold frontal passage will be coinciding around the time of peak diurnal heating, MUCAPE is progged to increase into the 1500-1800 J/kg range over northwest Wisconsin by mid-afternoon. 0-6km bulk shear will also be favorable tomorrow at around 30-35 knots. These favorable convective parameters support the potential for a few strong to severe storms in northwest Wisconsin. The one potential mode of failure to mention for tomorrow`s severe weather chance is a moderately strong warm nose appearing in CAM soundings around 750mb. This warm nose, resulting from the strong LLJ, may limit vigorous updraft development and winnow the potential for severe weather. SPC currently has portions of northwest Wisconsin under a Marginal Risk for severe thunderstorms tomorrow. Potential hazards tomorrow include damaging winds up to 60 mph and large hail up to 1 inch in diameter. Following the cold frontal passage on Saturday afternoon and evening, a quiet pattern will settle over the CWA with high pressure building on Sunday. The only notable feature in the extended period is a shortwave trough that will be propagating east on Monday. This shortwave may bring a slight chance of rain to the area as a cutoff low develops over the northern Plains and quickly dives south. Otherwise, little to no other chances for precip are expected. Looking out over the next 2 weeks, the Northland is favored to have above-normal temperatures and below-normal precipitation. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1246 AM CDT Sat Sep 21 2024 Area radar shows scattered showers/thunderstorms from near the Brainerd Lakes east southeast into northwest Wisconsin. This activity was occurring with warm air advection and a low level jet. The showers/storms should impact or be near all TAF sites tonight. The low level jet will lead to some low level wind shear into Saturday morning. The showers/storms tonight will eventually lift north and east of the area but more will be possible along and ahead of a cold front today into this evening. Instability will build, especially from east-central Minnesota into northwest Wisconsin this afternoon. A few strong to severe thunderstorms will be possible this afternoon into early evening over parts of northwest Wisconsin. Winds will switch behind the front to west then northwest and become gusty. There are some indications that some lower ceilings, MVFR, will occur right along or behind the front for a time. For now, we left these low ceilings out of the forecast. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 324 PM CDT Fri Sep 20 2024 Breezy southwest winds observed over western Lake Superior this afternoon are expected to ease over the next couple hours. Winds will be shifting to the northeast on Saturday morning with speeds around 5 to 10 knots with gusts up to 15 knots. Scattered showers with isolated thunderstorms will be possible on and off through the day Saturday over the lake. Expect another wind shift to occur on Saturday evening with winds becoming northwesterly. A tightening pressure gradient will increase wind gusts up to around 25 knots across much of western Lake Superior on Saturday night into Sunday morning. Small Craft Advisories will likely be needed. Waves will be highest on Saturday night in the outer Apostle Islands with heights around 2-4 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...Unruh AVIATION...Melde MARINE...Unruh