Alert archive / Michigan / Mesoscale Discussions in 2020

Mesoscale Discussion 1682

September 7, 202028 counties in Michigan

The Storm Prediction Center issued this mesoscale discussion at Sep 7, 2020, 12:20 AM EDT for 28 counties in Michigan. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued
Sep 7, 2020, 12:20 AM EDT (04:20 UTC)
Expired
Sep 7, 2020, 2:15 AM EDT
In force
115 min
Issued by
the Storm Prediction Center
Concerning
Severe thunderstorm watch 488
All 28 counties

Alcona County, MI, Arenac County, MI, Bay County, MI, Clare County, MI, Gladwin County, MI, Gratiot County, MI, Huron County, MI, Iosco County, MI, Isabella 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, Oscoda County, MI, Ottawa County, MI, Roscommon County, MI, Saginaw County, MI, Tuscola County, MI, Wexford County, MI

The radar

The Grand Rapids radar (KGRR), 86 km from the middle of the area, began a volume at 04:23 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.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 00:00Z, 4.3 hours before the alert went out and 250 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.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 00:00Z on 2020-09-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 274 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Green Bay/Straub, WI at 00:00Z on 2020-09-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 403 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
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

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 6, 9:38 PM EDTSevere Thunderstorm WatchSPCAllegan, Arenac, Bay, Benzie, Clare, Clinton and 27 more5 hr

Nearby

Mesoscale Discussions in Michigan, 2020Every mesoscale discussion 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.