Alert archive / Michigan / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 93, NWS Grand Rapids, MI

September 12, 2021Gratiot County, Michigan

NWS Grand Rapids, MI issued this severe thunderstorm warning at Sep 12, 2021, 4:56 PM EDT for Gratiot County, Michigan. It was in force for 34 min. 7 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Sep 12, 2021, 4:56 PM EDT (20:56 UTC)
Expired: Sep 12, 2021, 5:30 PM EDT
In force: 34 min
Issued by: NWS Grand Rapids, MI
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

County Gratiot County, MI

The radar

The Grand Rapids radar (KGRR), 87 km from the middle of the area, began a volume at 21:00 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 was reported inside it

Time	Report	Where	Remark
Sep 12, 4:56 PM EDT	HAIL 0.25	5 Nw Saint Louis, MI
Sep 12, 5:00 PM EDT	TSTM WND DMG	1 Nne Saint Louis, MI	POCKETS OF TREES DOWN. RELAYED VIA SOCIAL MEDIA TIME APPROXIMATE.
Sep 12, 5:00 PM EDT	HAIL 1	5 S Breckenridge, MI	RELAYED VIA SOCIAL MEDIA. TIME ESTIMATED.
Sep 12, 5:01 PM EDT	HAIL 1.25	Saint Louis, MI
Sep 12, 5:10 PM EDT	HAIL 2.25	5 S Breckenridge, MI	LOCATION APPROXIMATE. SOCIAL MEDIA PHOTOS FROM SOUTH OF BRECKENRIDGE.
Sep 12, 5:12 PM EDT	HAIL 2.25	5 E Ithaca, MI	PHOTOS FROM SOCIAL MEDIA.
Sep 12, 5:15 PM EDT	HAIL 2.5	8 E Ithaca, MI	SEVERAL MEASURED HAILSTONES BETWEEN 2 AND 2.5 INCHES. IN THE SICKLES AREA NEAR FILLMORE ROAD AND RANSOM ROAD. DENTED VEHICLES.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Detroit, MI (KDTX), launched 12:00Z, 8.9 hours before the alert went out and 125 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 677 J/kg
Mixed-layer CIN: -369 J/kg
Mixed-layer LCL: 734 m above ground
0-6 km bulk shear: 53 kt
0-1 km storm-relative helicity: 157 m²/s²
0-3 km storm-relative helicity: 299 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

As transmitted.

518 
WUUS53 KGRR 122056
SVRGRR
MIC057-122130-
/O.NEW.KGRR.SV.W.0093.210912T2056Z-210912T2130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Grand Rapids MI
456 PM EDT Sun Sep 12 2021

The National Weather Service in Grand Rapids has issued a

* Severe Thunderstorm Warning for...
  Northern Gratiot County in central Michigan...

* Until 530 PM EDT.

* At 455 PM EDT, a severe thunderstorm was located near Alma, moving
  east at 65 mph.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vehicles is expected.

* This severe thunderstorm will be near...
  Alma and St. Louis around 500 PM EDT.
  Ithaca around 505 PM EDT.
  Breckenridge around 510 PM EDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Large hail and frequent cloud to ground lightning is occurring with 
this storm. Move indoors immediately. Lightning is one of nature's 
leading killers. Remember, if you can hear thunder, you are close 
enough to be struck by lightning.

&&

LAT...LON 4332 8485 4340 8485 4347 8484 4346 8437
      4326 8437
TIME...MOT...LOC 2055Z 277DEG 56KT 4341 8474 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

CAS

2 follow-up statements

214 
WWUS53 KGRR 122102
SVSGRR

Severe Weather Statement
National Weather Service Grand Rapids MI
502 PM EDT Sun Sep 12 2021

MIC057-122130-
/O.CON.KGRR.SV.W.0093.000000T0000Z-210912T2130Z/
Gratiot MI-
502 PM EDT Sun Sep 12 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 530 PM EDT
FOR NORTHERN GRATIOT COUNTY...

At 501 PM EDT, severe thunderstorms were located along a line 
extending from near St Louis to 5 miles west of Ithaca, moving east 
at 60 mph.

HAZARD...Golf ball size hail.

SOURCE...Radar indicated.

IMPACT...People and animals outdoors will be injured. Expect damage 
         to roofs, siding, windows, and vehicles.

These severe storms will be near...
  Breckenridge around 505 PM EDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Prepare immediately for large hail and deadly cloud to ground
lightning. Seek shelter inside a well-built structure. Stay away from
windows.

&&

LAT...LON 4346 8437 4326 8437 4331 8479 4347 8466
TIME...MOT...LOC 2101Z 278DEG 54KT 4345 8459 4332 8470 

THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

CAS

414 
WWUS53 KGRR 122123
SVSGRR

Severe Weather Statement
National Weather Service Grand Rapids MI
523 PM EDT Sun Sep 12 2021

MIC057-122131-
/O.EXP.KGRR.SV.W.0093.000000T0000Z-210912T2130Z/
Gratiot MI-
523 PM EDT Sun Sep 12 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN GRATIOT COUNTY WILL
EXPIRE AT 530 PM EDT...
    
The storms which prompted the warning in Gratiot County have moved 
out of the area. Therefore, the warning will be allowed to expire.

A Severe Thunderstorm Watch remains in effect until 1100 PM EDT for
portions of central Michigan.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Grand Rapids.

LAT...LON 4346 8437 4326 8437 4331 8479 4347 8466
TIME...MOT...LOC 2121Z 277DEG 56KT 4341 8419 4328 8430 

$$

CAS

The office that day

Everything else NWS Grand Rapids, MI issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 12, 6:01 AM EDT	Small Craft Advisory	GRR		10 hr
Sep 12, 6:03 AM EDT	Beach Hazards Statement	GRR	Allegan, Ottawa, Van Buren	10 hr
Sep 12, 2:29 PM EDT	Special Marine Warning	GRR		61 min
Sep 12, 2:42 PM EDT	Special Weather Statement	GRR	Lake, Mason, Newaygo, Oceana	63 min
Sep 12, 3:50 PM EDT	Special Weather Statement	GRR	Isabella, Mecosta	40 min
Sep 12, 4:29 PM EDT	Special Weather Statement	GRR	Isabella	31 min
Sep 12, 5:31 PM EDT	Special Marine Warning	GRR		82 min
Sep 12, 6:22 PM EDT	Special Weather Statement	GRR	Muskegon, Ottawa	53 min
Sep 12, 6:40 PM EDT	Severe Thunderstorm Warning	GRR	Muskegon, Ottawa	35 min
Sep 12, 7:16 PM EDT	Severe Thunderstorm Warning	GRR	Gratiot, Montcalm	45 min

Nearby

Severe Thunderstorm Warnings in Michigan, 2021 Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.