Severe Thunderstorm Warning 76, NWS Grand Rapids, MI

Area Forecast Discussion
National Weather Service Grand Rapids MI
718 PM EDT Thu Aug 24 2023

LATEST UPDATE...
Aviation

.UPDATE...
Issued at 604 PM EDT Thu Aug 24 2023

Updated the forecast to feature a higher potential for storms and
severe weather. Parameters continue to become increasingly
favorable for numerous storms, with an increased potential for
higher end severe weather.

We did let the marine dense fog advisory expire.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 206 PM EDT Thu Aug 24 2023

- Risk for Severe Weather This Afternoon into Early Tonight

The region has been placed in an enhanced risk for severe weather.
An unusual set of parameters were coming together here in Lower
Michigan. From SPC's meso page, strong instability was building
over the area with MUCAPE values topping 2000 J/kg, which are
forecast to increase over the next few hours to 5000 J/kg. Also a
mid level jet max in MN and western WI shifts into the CWA this
evening enhancing the vertical shear. This feature does show up on
the upstream VWP's. DCAPE values become rather favorable(greater
than 1200 J/kg) for enhanced winds with the convection ahead of
the approaching mid level speed max. Models are coming together in
showing the 23z to 04z period as the highest potential for storm
to develop over or track through the CWA. Satellite imagery shows
skies now clearing steadily from Holland to near Kalamazoo. Based
on trends, this should be the case for much of the CWA over the
next few hours. It has not taken long for the temperatures to
increase rapidly once the clearing occurs, so it looks like the
models are on the right idea, especially with the old outflow
boundary stalled out near I-96.

.LONG TERM...(Saturday through Thursday)
Issued at 244 PM EDT Thu Aug 24 2023

-- Dry weekend overall still expected --

As noted previously, Saturday morning could begin with some
cloudiness and accompanying drizzle/light rain, but this should be
short-lived. Drier air will result in more noticeable diurnal
temperature swings over the weekend compared to what we've been
experiencing lately.

-- Unsettled with rain Monday/Tuesday --

Forecast scenario looks similar to what was advertised 24 hours ago
in terms of an upper jet digging down the back side of a sharp
upper trough over the western Great Lakes beginning Monday. This
will yield a good coverage of precipitation starting late Monday
and lasting through much of Tuesday. Cold air aloft and strongly
cyclonic flow looks supportive of lake effect rain that may linger
into early Tuesday night.

-- Growing confidence for a dry second half of the work week --

As already noted, Wednesday looks to be our coolest day thanks to
low level thermal troughing associated with the upper trough. As
this trough moves east of the area, we will have confluent
northwest flow aloft favorable for growing surface high pressure.
The resulting surface high will remain centered over the Great
Lakes thanks to reinforcement from an upstream shortwave ridge
aloft over the Northern Plains.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 714 PM EDT Thu Aug 24 2023

A developing line of storm just west of KMKG is forecast to fill
in and track through the TAF sites through 03z. The main risk will
be strong shifting winds that may top 50 knots. Behind the line
of convection, a lower deck of clouds is forecast to arrive by 08z
and persist into Friday morning. A gradual trend of VFR looks
likely for the afternoon.

&&

.MARINE...
Issued at 1016 AM EDT Thu Aug 24 2023

Added a marine dense fog advisory based on webcams and anticipated
very humid air in light winds prior to cold frontal passage
commencing this evening.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Heat Advisory until 9 PM EDT this evening for MIZ066-067-071>074.

LM...None.
&&

UPDATE...MJS
SHORT TERM...MJS
LONG TERM...TJT
AVIATION...MJS
MARINE...TJT

Hazardous Weather Outlook
National Weather Service Grand Rapids MI
1048 AM EDT Thu Aug 24 2023

MIZ037>040-043>046-050>052-056>059-064>067-071>074-251500-
Mason-Lake-Osceola-Clare-Oceana-Newaygo-Mecosta-Isabella-Muskegon-
Montcalm-Gratiot-Ottawa-Kent-Ionia-Clinton-Allegan-Barry-Eaton-
Ingham-Van Buren-Kalamazoo-Calhoun-Jackson-
1048 AM EDT Thu Aug 24 2023

This hazardous weather outlook is for portions of southwest Lower
Michigan.

.DAY ONE...Today and Tonight

There is a risk of severe storms this afternoon and evening. The
greatest threats will be damaging wind gusts, large hail and
flooding rains.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.

LMZ844>849-251500-
St Joseph to South Haven MI-South Haven to Holland MI-
Holland to Grand Haven MI-Grand Haven to Whitehall MI-
Whitehall to Pentwater MI-Pentwater to Manistee MI-
1048 AM EDT Thu Aug 24 2023

This hazardous weather outlook is for portions of southwest Lower
Michigan.

.DAY ONE...Today and Tonight

Dense fog is expected much of the day. This will be followed
thunderstorms this evening and tonight with the potential to
produce damaging winds and large hail.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.

Preliminary Local Storm Report
National Weather Service Grand Rapids MI
804 PM EDT Thu Aug 24 2023

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

0750 PM     Tstm Wnd Gst     2 W Grand Haven         43.05N 86.26W
08/24/2023  M41 MPH          LMZ846             MI   Mesonet

&&

EO

Preliminary Local Storm Report
National Weather Service Grand Rapids MI
842 PM EDT Thu Aug 24 2023

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

0821 PM     Tstm Wnd Dmg     2 WNW Belmont           43.08N 85.65W
08/24/2023                   Kent               MI   Emergency Mngr

            Tree on house. Possible tornado. Radar
            showed debris signature in this area.

&&

EO

Preliminary Local Storm Report
National Weather Service Grand Rapids MI
852 PM EDT Thu Aug 24 2023

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

0818 PM     Tstm Wnd Dmg     2 NNW Comstock Park     43.07N 85.69W
08/24/2023                   Kent               MI   Trained Spotter

            Trees across M37 at 7 Mile. Possible
            tornado. Possible damage to structures. Time
            estimated from radar.

&&

EO