Alert archive / Michigan / Mesoscale Discussions in 2018

Mesoscale Discussion 1405

September 1, 201820 counties in Michigan

The Storm Prediction Center issued this mesoscale discussion at Sep 1, 2018, 6:57 PM EDT for 20 counties in Michigan. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued
Sep 1, 2018, 6:57 PM EDT (22:57 UTC)
Expired
Sep 1, 2018, 8:00 PM EDT
In force
63 min
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Allegan County, MI, Barry County, MI, Calhoun County, MI, Clinton County, MI, Eaton County, MI, Genesee County, MI, Gratiot County, MI, Ingham County, MI, Ionia County, MI, Jackson County, MI, Kalamazoo County, MI, Kent County, MI, Livingston County, MI, Montcalm County, MI, Oakland County, MI, Ottawa County, MI, Shiawassee County, MI, Van Buren County, MI, Washtenaw County, MI, Wayne County, MI

The radar

The Grand Rapids radar (KGRR), 46 km from the middle of the area, began a volume at 22:58 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

Detroit, MI (KDTX), launched 12:00Z, 11.0 hours before the alert went out and 130 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, Detroit, MI at 12:00Z on 2018-09-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 214 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, Detroit, MI at 12:00Z on 2018-09-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 33 square meters per square second.193958Sfc1 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
214 J/kg
Mixed-layer CIN
-143 J/kg
Mixed-layer LCL
1058 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
33 m²/s²
0-3 km storm-relative helicity
-12 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.2

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 1, 1:53 AM EDTMesoscale DiscussionSPCBaraga, Gogebic, Houghton, Keweenaw, Marquette, Ontonagon2 hr

Nearby

Mesoscale Discussions in Michigan, 2018Every mesoscale discussion in 2018

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.