Alert archive / Michigan / Special Weather Statements in 2021

Special Weather Statement, NWS Grand Rapids, MI

September 12, 2021Isabella County, Michigan

NWS Grand Rapids, MI issued this special weather statement at Sep 12, 2021, 4:29 PM EDT for Isabella County, Michigan. It was in force for 31 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 12, 2021, 4:29 PM EDT (20:29 UTC)
Expired: Sep 12, 2021, 5:00 PM EDT
In force: 31 min
Issued by: NWS Grand Rapids, MI
Hail: 0.75 in
Wind: 30

County Isabella County, MI

The radar

The Grand Rapids radar (KGRR), 98 km from the middle of the area, began a volume at 20:32 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, 8.5 hours before the alert went out and 128 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.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Grand Rapids, MI wrote its last area forecast discussion before this special weather statement went out at Sep 12, 3:30 PM EDT, 59 minutes earlier.

Area forecast discussion, Sep 12, 3:30 PM EDT, 59 minutes before

Area Forecast Discussion
National Weather Service Grand Rapids MI
330 PM EDT Sun Sep 12 2021

LATEST UPDATE...
Synopsis/Discussion/Marine

.SYNOPSIS...
Issued at 330 PM EDT Sun Sep 12 2021

-Rounds of showers and storms through Tuesday

-Above normal temp pattern next 7 to 10 days

&&

.DISCUSSION...(This evening through next Sunday)
Issued at 330 PM EDT Sun Sep 12 2021

--Rounds of showers and storms through Tuesday--

The pattern tonight and Monday features a fast zonal flow aloft
with a sharp surface frontal zone draped across or just south the
area. A corridor of strong deep layer shear of 50-70 kts exists
near the front along with MUCapes of 1500-2500 J/JG. Several fast
moving shortwaves within the zonal flow will support periodic
showers and storms tonight and Monday, generally elevated and
near/north of the frontal boundary.

The first shortwave, now moving into NW Lwr MI, zips through this
afternoon and brings a batch of strong storms to areas north of
I-96. The regional radar/satl shows another shortwave upstream
near LaCrosse WI which should fuel additional showers and storms
later tonight. These should be a bit farther south than the
current batch since the sfc front continues sagging south tonight.
Yet another wave, now in NE CO, appears to be an impetus for more
storms on Monday.

on Monday night and early Tuesday the boundary lifts north as a
warm front as another shortwave tracks from SD to Upr MI. A
deepening sfc low tracking across the Straits of Mackinac on
Tuesday sends a cold front through the area during pk heating
which will lead to another round of storms, possibly severe,
for Tuesday afternoon/evening. Dry weather settles in behind that
front for the mid week period.

--Above normal temp pattern next 7 to 10 days--

As Tropical Storm Nicholas makes landfall in the wrn Gulf mid
week, heights rise over the GrtLks Rgn and we stay in a warmer
than normal pattern for the foreseeable future. Convective threat
toward the end of the week into next weekend is uncertain pending
behavior of remnants of the tropical system lifting north.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 141 PM EDT Sun Sep 12 2021

The main concern for the forecast period is a front that will drop
south today into tomorrow. This front is expected to stall around
GRR, MKG, and LAN, resulting in lower ceilings as well as
scattered showers and storms along that line. The main time frame
for storm potential looks to be this afternoon/evening between
20z and 0z. Confidence is also low on the possibility of IFR
ceilings, but they will be possible early Monday particularly for
more inland sites such as LAN and JXN. Otherwise expect MVFR
ceilings in the proximity of this front.

&&

.MARINE...
Issued at 330 PM EDT Sun Sep 12 2021

Will let the beach hazard statement/small craft advisory south of
Muskegon expire soon. Frontal boundary continues sagging south so
winds and waves are subsiding in the south. However waves will be
building near Big and Little Sable Points over the next few hours
due to increased northerly flow behind the front. Conditions in
the north should remain below advisory criteria.

Marine headlines will be needed again on Tuesday due to a period
of strong southerly flow which shifts northwesterly behind a cold
front later in the day.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 4 PM EDT this afternoon for MIZ056-
     064-071.

LM...Small Craft Advisory until 4 PM EDT this afternoon for
     LMZ844>846.

&&

SYNOPSIS...Meade
DISCUSSION...Meade
AVIATION...Thielke
MARINE...Meade

Hazardous weather outlook, Sep 12, 4:10 PM EDT, 19 minutes before

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In the hours before

Special weather statement, Sep 12, 3:50 PM EDT, 39 minutes before

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Local storm report, Sep 12, 4:01 PM EDT, 28 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
401 PM EDT SUN SEP 12 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0353 PM     HAIL             BIG RAPIDS              43.70N 85.49W
09/12/2021  E0.25 INCH       MECOSTA            MI   TRAINED SPOTTER

            HAIL FOR TWO MINUTES. SIZE WAS PEA-SIZED TO
            SLIGHTLY LARGER.

&&

HLO

Local storm report, Sep 12, 4:09 PM EDT, 20 minutes before

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Local storm report, Sep 12, 4:20 PM EDT, 9 minutes before

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Local storm report, Sep 12, 4:25 PM EDT, 4 minutes before

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Special weather statement, Sep 12, 4:29 PM EDT, 0 minutes before

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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, 4:56 PM EDT	Severe Thunderstorm Warning	GRR	Gratiot	34 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

Special Weather Statements in Michigan, 2021 Every special weather statement 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.