Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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
895 FXUS63 KDTX 051924 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 324 PM EDT Wed Jun 5 2024 .KEY MESSAGES... - Widespread showers and thunderstorms this afternoon, ending early this evening. Some of these storms may be strong to marginally severe. - Localized rainfall totals of 1 to 2 inches are possible for areas that see multiple storms this afternoon. - Pattern shift for the latter half of the week brings below normal temperatures through at least the end of the week along with periodic chances of rain. && .DISCUSSION... Showers and thunderstorms have blossomed this afternoon over southeast Michigan, and are tracking through a touch faster than most hires solutions. Surface dew pts mostly in the 68-70 degree range with MLcapes 1000-1500 J/kg per SPC mesoscale analysis. Better shear (~35 knots effective shear) attempting to catch up to continue to support isolated marginally severe storms. Regardless, some storms will be strong producing wet micro-burst winds of 50+ mph. Pronounced mid level dry slot arrives early this evening, ending shower/thunderstorm activity (23-2z), with 850 MB Theta-E dropping close to 20 K. Mid level cold pool (-22 C at 500 MB) will be pushing into northern lower Michigan by Thursday morning, and lapse rates look to be quickly steepening up with a narrowing moisture plume streaming in from the Midwest, generating some modest cape in the mid levels. Expecting scattered showers/isolated thunderstorms as showalter index reaches at or slightly below zero. Yet another mid level dry slot moving through during the afternoon hours, making activity difficult with limited coverage at best. Increased mixing depths expected to product breezy conditions, with westerly wind gusts aoa 30 mph. 850 MB temps progged to bottom out in the mid single numbers Friday morning, but with the slow movement of the large 500 MB low exiting the northern/eastern Great Lakes, still probably enough marginal instability to produce isolated-scattered shower activity, especially over the Thumb region. Short lived confluent upper level flow/shortwave ridging for the first half of the weekend, before yet another upper level wave/re- enforcing cold shot arrives for the second half of the weekend. 850 MB temps forecasted to bottom our in the 3-5 C range Monday morning. Another upper level ridge, a bit more pronounced, is then expected to build in for Tuesday, supporting temps slightly above normal. && .MARINE... The ongoing passage of a cold front will bring a line of showers and thunderstorms across the Great Lakes through the afternoon and evening. Some isolated development ahead of this main line is possible. There will be a marginal risk for severe weather across all of the eastern Great Lakes given the building instability, where wind gusts in excess of 30 knots and hail to an inch will the most likely hazards with the strongest storms. While much less likely, an isolated waterspout cannot be ruled out with the thunderstorms. Passage of the front will veer wind direction from the southeast to the southwest. A cooler air mass will then gradually setup over the Great Lakes into the end of the week. The enhanced mixing depths will bring some breezy conditions, particularly for the nearshore zones. A Small Craft Advisory has been issued for the Saginaw Bay tomorrow as a smaller window for southwest fetch will enhance wind gusts potential to around 25 knots, which would produce wave heights to or in excess of three feet. Wind speed and gust potential will then reduce in magnitude overnight. && .HYDROLOGY... Showers and thunderstorms around this afternoon will taper off early this evening. The airmass is seasonably warm and moist. Thus storms are efficient rain makers with widespread rainfall amounts up to half inch expected. Localized higher amounts are possible in the stronger thunderstorms, with potential storm total rainfall amounts in the 1 to 2 inch range. Minor flooding of prone urban and low-lying areas, ponding of water on roadways, and rises in area rivers will all be possible. && .PREV DISCUSSION... Issued at 148 PM EDT Wed Jun 5 2024 AVIATION... Convection has begun to perk up this afternoon ahead of the approaching cold front. Will include a VCTS for the scattered activity from 18-20Z before a convection cluster over northern Indiana brings a more solid line of storms which a tempo will cover for now. Biggest risk with these storms will be heavy rainfall, wind gusts to 50-60 mph and large hail. Some question as to whether there could be redevelopment behind the leading storms or not. Will keep a couple hours of showers lingering and adjust as needed. An additional period of showers will be possible from about 06-10Z overnight as a secondary cold front drops through. For DTW/D21 Convection...Scattered showers and thunderstorms are ongoing as of 18Z around the area but the better coverage remains off to the west and southwest. A cluster of storms currently lifting into MI will impact DTW generally 20-23Z. Storms will be moving NE at 30 mph while the cold front pushes everything east over time. Storms will be capable of brief heavy downpours reducing visibilities, strong winds to 50-60 mph and some large hail. DTW THRESHOLD PROBABILITIES... * Moderate in thunderstorms this afternoon/evening. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Small Craft Advisory from 10 AM to 10 PM EDT Thursday for LHZ421- 422. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...SF MARINE.......AM HYDROLOGY....SF AVIATION.....DRK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.