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
47
085 FXUS63 KDLH 221819 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 119 PM CDT Sat Jun 22 2024 .KEY MESSAGES... - Periods of rain and some thunderstorms continue through the weekend. Severe weather is not expected. - Severe thunderstorms expected (risk level 2 out of 5) Monday evening and night. - Quieter weather Tuesday and Wednesday before thunderstorm chances return late next week. && .DISCUSSION... Issued at 118 PM CDT Sat Jun 22 2024 Rain showers and embedded thunderstorms in association with a shortwave/MCV across west central Minnesota will continue to propagate east-northeast through the afternoon and into this evening. This will represent the next more widespread round of precipitation for northwest Wisconsin and northeast Minnesota. Buoyancy is modest and severe weather is not expected. A close eye will be kept on rainfall amounts and rates with this round of precipitation given the sensitive hydrologic situation across the Northland. The highest rainfall amounts through this evening are favored across northwest Wisconsin where the shortwave/MCV will track along a 1.5-2.0 inch precipitable water gradient. CAM trends and upstream rainfall analysis suggest 0.5 to 1.0 inches of rainfall across northwest Wisconsin is most likely. Across the Twin Ports one quarter to one half inch of rainfall is the most likely rainfall range through this evening, with amounts decreasing further north across the Iron Range and Borderlands. The axis of heaviest rainfall will have to monitored based on radar and satellite trends through the afternoon. With high pressure in place tonight at the surface with weak winds and plentiful remnant moisture, fog will be likely across most of the Northland tonight into Sunday morning. A Dense Fog Advisory may be needed (30-50% chance) across northwest Wisconsin, the Twin Ports and I-35 corridor. The next wave arrives in northwest flow from Canada late tonight and will propagate across the Northland through Sunday. Numerous rain showers and a few thunderstorms are likely with this wave and its associated cold core aloft with residual precipitable water values around 1 inch. Again, buoyancy is modest so severe weather is unlikely. Although some small hail (half inch or less diameter) is not out of the question with low freezing levels. Attention on Monday turns to the severe thunderstorm threat, especially for Monday evening and Monday night across all of the Northland. SPC has the area in a Slight Risk for severe thunderstorms. How the scenario for Monday evening and night will unfold is somewhat conditional based expected capping in the warm sector, how far north the warm sector is able to establish itself, and subtle forcing in the mid levels with smaller impulses embedded in fast westerly flow aloft south of the more significant wave across Canada. In the warm sector, mid to upper 60s dewpoints beneath steep mid level lapse rates support moderate to strong buoyancy with MLCAPE values of 2000-3000+ j/kg. However, model soundings indicate an appreciable cap through the afternoon and into the early evening that will likely hold until the arrival of the cold front from the west. Like SPC stated, all threats are in play with any supercells that are able to break the cap Monday evening with strong deep layer shear largely perpendicular to the cold front. This includes damaging wind gusts in excess of 70 mph, and a tornadic threat with hodographs with significant low level curvature. This significant low level curvature may limit how large hail is able to grow as initial hail embryos would be quickly removed from the favored hail growth curtain. Still hail to 2 inches is certainly possible. CSU Machine Learning probabilities confirm these threats. Upscale growth into an MCS is possible Monday night into northwest Wisconsin, though that is uncertain based upon how much convective coverage there will be to congeal. The flash flood threat is non-zero, although not as significant as was seen last Tuesday as the overall setup is much different with a lower coverage of storms also expected. Impressive rates are likely where storms track, although the lower coverage makes the widespread flash flood threat much less. A much needed two days of quiet weather is expected on Tuesday and Wednesday with surface high pressure. Thereafter, thunderstorm chances return for late in the week beneath fast zonal flow aloft. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 118 PM CDT Sat Jun 22 2024 Widespread IFR conditions in fog, stratus and rain will continue across northwest Wisconsin, through KDLH and the KBRD area this afternoon and this evening. A few embedded thunderstorms are possible (20-40% chance). For KHIB and KINL, scattered rain showers and isolated thunderstorms will continue this afternoon with occasional MVFR ceilings. Tonight, another round of rain showers and a few thunderstorms will spread across northeast Minnesota and northwest Wisconsin and continue into Sunday. LIFR conditions in fog and stratus are likely at KDLH and KHYR tonight into Sunday morning. Fog coverage will be less, but still present across the remainder of northeast Minnesota and northwest Wisconsin tonight into Sunday morning with remnant moisture and weak surface winds. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 118 PM CDT Sat Jun 22 2024 Dense fog will continue for the Twin Ports and through all South Shore zones through Sunday morning and a Dense Fog Advisory is in effect. Fog may (40-60% chance) expand along the North Shore today, and especially tonight. Northeast winds with gusts around 25 kts and waves of 2-4 feet will continue for Taconite Harbor, through the Twin Ports and along the South Shore through the afternoon, with winds and waves slowly subsiding tonight. Scattered rain showers with a few embedded thunderstorms will continue today through Sunday. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...Beach Hazards Statement until 9 PM CDT this evening for MNZ037. WI...Beach Hazards Statement until 9 PM CDT this evening for WIZ001. MARINE...Dense Fog Advisory until 7 AM CDT Sunday for LSZ121-144>148- 150. Small Craft Advisory until 7 PM CDT this evening for LSZ142>148-150. && $$ DISCUSSION...PA AVIATION...PA MARINE...PA