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
46
462 FXUS63 KDLH 040538 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 1238 AM CDT Tue Jun 4 2024 .KEY MESSAGES... - Dense fog will form over Lake Superior tonight and may impact areas along it`s shores. - A line of showers and thunderstorms will develop and move eastward across the Northland Tuesday afternoon and evening. A few storms may be strong to severe. Locally heavy rainfall is possible and could lead to localized minor flooding. - Rain and storm chances will continue each afternoon and evening Wednesday through the end of the week. && .DISCUSSION... Issued at 452 PM CDT Mon Jun 3 2024 A stationary front loitered over northwest Wisconsin and portions of the Minnesota Arrowhead late this afternoon. Meanwhile a weak cool front stretched from near International Falls to near Brainerd to southwest Minnesota. In the warm sector between these two fronts, isolated to scattered showers and a few thunderstorms developed over the past several hours. Weak deep layer shear and limited instability means most of the storms have been short lived. The exception is a cell over west- central Wisconsin, northeast of Eau Claire. We expect a few additional storms to develop through early evening. Areas of fog may develop tonight, particularly over portions of the I-35 corridor and northwest Wisconsin where heavy rain fell earlier this morning. Another cold front will propagate eastward across northern Minnesota and northwest Wisconsin Tuesday and Tuesday night. Southerly flow aloft and mainly clear skies ahead of the front are forecast to provide MLCAPE values of 1000-2500 J/kg by late afternoon. Deep layer shear of around 30 knots is forecast ahead of the front with straight to cyclonically curved hodographs below 3 km becoming shorter above 3 km. The limited shear and hodograph presentation raises questions about storm modes. We expect widespread convection along the front as it progresses eastward through the afternoon. At the moment, shear parameters and limited moisture aloft seem to limit the hail potential with storms. It seems penny to half-dollar size hail is probably the top end of the hail potential, with most storms producing smaller hail. The low-level wind shear seems favorable for rotating storms, although dry air entrainment and shortening hodographs with height would suggest difficulty maintaining updraft strength. It would seem the tornado risk is somewhat mitigated by these factors. Think the SPC Marginal and Slight Risk areas are appropriate based on the 12Z guidance. Storm motions and orientation to the front raise concerns about training storms and locally heavy rainfall. With recent heavy rain and localized minor flooding today, and more rain coming tomorrow, think the risk of additional minor flooding is high enough to support a Flood Watch from the Brainerd Lakes east including northwest Wisconsin. For Wednesday and Thursday an upper level low will be in place across the western Great Lakes. This will continue the potential for numerous rain showers and thunderstorms, especially during peak daytime heating through sunset each day. Severe threats like hail, tornadoes, and strong winds appear to be minimal, as CAPE values are expected to not exceed more than 1000 J/kg with weak shear. While these rain showers and thunderstorms do not have the flood concerns of Tuesday and Tuesday night, areas in NW Wisconsin already wet from the rain on Sunday night and Monday morning, especially the Knife, St. Croix, Namekagon, and Bois Brule River basins should expect continued higher water levels. For Friday into the weekend, an upper level ridge will attempt to build in the western CONUS, but does not appear to be very strong. Thus the Upper Midwest is expected to remain in northwest flow, with winds exceeding 100 kts at the 300 mb. However, the moisture from the Gulf might not be as strong as it will be for Tuesday-Wednesday. While daily rain shower and thunderstorm chances are inevitable, uncertainties remain into the weekend due to the timing of possible shortwaves embedded within the fast flow. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1238 AM CDT Tue Jun 4 2024 Conditions varied widely across the Northland. Fog was developing and stratus was expanding. IFR conditions will expand over northwest Wisconsin and around Lake Superior with some fog further inland as well. IFR or lower visibility and ceilings will occur at KHYR/KDLH/KHIB and could occur at KBRD but higher clouds moving in there should lower the chances some. The fog and stratus will lift for most through the day but take longest around Lake Superior which will see off lake winds through most of the day which won`t help matters. A cold front will push through the Northland Tuesday afternoon and evening bringing with it showers and thunderstorms. Some of the storms during the afternoon and evening could be severe with large hail and damaging wind both threats. Showers and some isolated thunderstorms will continue after the main line of storms push through but will eventually end from west to east. Gusty southerly winds will occur prior to the front with decent mixing leading to gusts of 20 to 25 knots. Winds will switch to west or southwest behind the front and be quite a bit lighter through Tuesday night. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 452 PM CDT Mon Jun 3 2024 Light winds this evening will turn northeasterly and increase slightly overnight to around 10 to 15 knots. With heavy rainfall over the waters early Monday, dense fog may redevelop over the lake. Fog lingered near Grand Marais as of 3 PM and thus we extended the Marine Dense Fog Advisory until late Tuesday morning. The advisory may need to be expanded should the dense fog redevelop elsewhere. A cold front will move across the region from west to east Tuesday. Showers and thunderstorms are forecast late Tuesday afternoon through early Wednesday morning. A few storms may be strong to severe with large hail and wind gusts of 30 to 45 knots possible. Fog may redevelop once again Tuesday night. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...Flood Watch from this afternoon through Wednesday afternoon for MNZ034-036-038. WI...Flood Watch from this afternoon through Wednesday afternoon for WIZ001>004-006>009. MARINE...Dense Fog Advisory until 10 AM CDT this morning for LSZ140>143. && $$ DISCUSSION...Huyck AVIATION...Melde MARINE...Huyck