Alert archive / Michigan / Severe Thunderstorm Watches in 2020
Severe Thunderstorm Watch 488
The Storm Prediction Center issued this severe thunderstorm watch at Sep 6, 2020, 9:38 PM EDT for 33 counties in Michigan. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 6, 2020, 9:38 PM EDT (01:38 UTC)
- Expired
- Sep 7, 2020, 3:00 AM EDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 33 counties
Allegan County, MI, Arenac County, MI, Bay County, MI, Benzie County, MI, Clare County, MI, Clinton County, MI, Crawford County, MI, Gladwin County, MI, Grand Traverse County, MI, Gratiot County, MI, Huron County, MI, Ionia County, MI, Iosco County, MI, Isabella County, MI, Kalkaska County, MI, Kent County, MI, Lake County, MI, Manistee County, MI, Mason County, MI, Mecosta County, MI, Midland County, MI, Missaukee County, MI, Montcalm County, MI, Muskegon County, MI, Newaygo County, MI, Oceana County, MI, Ogemaw County, MI, Osceola County, MI, Ottawa County, MI, Roscommon County, MI, Saginaw County, MI, Tuscola County, MI, Wexford County, MI
The radar
The NCL Michigan radar (KAPX), 113 km from the middle of the area, began a volume at 01:41 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 10%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Green Bay/Straub, WI (KGRB), launched 00:00Z, 1.6 hours before the alert went out and 239 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 274 J/kg
- Mixed-layer CIN
- -198 J/kg
- Mixed-layer LCL
- 946 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 403 m²/s²
- 0-3 km storm-relative helicity
- 401 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.6
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 7, 12:20 AM EDT | Mesoscale Discussion | SPC | Alcona, Arenac, Bay, Clare, Gladwin, Gratiot and 22 more | 115 min |
Nearby
Severe Thunderstorm Watches in Michigan, 2020Every severe thunderstorm watch in 2020
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.