Special Weather Statement, NWS Grand Rapids, MI

Area Forecast Discussion
National Weather Service Grand Rapids MI
223 PM EDT Tue Jun 22 2021

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 257 AM EDT Tue Jun 22 2021

- Scattered Thunderstorms Today

- Potential for Heavy Rain Late Week

&&

.UPDATE...
Issued at 1148 AM EDT Tue Jun 22 2021

I have increased the risk of showers and thunderstorms to likely
over our northeast CWA (North and East of GRr actually) for this
afternoon. The NAMNESt forecast surface based cape is in the 600
to 800 j/kg range over our NE CWA this afternoon as the short
wave moves through. There is a significant risk for small hail
since the cape is in the -10 to -20 range. Also freezing levels
are around 6000 ft. Expect gusty winds with these storms too since
there is an inverted "v" look to the model sounding too. Beside
all of that we have storms on our radar now and HTL has heavy rain
with winds gusting to 27 knots as a storm is moving through that
area. There was a confirmed water spout near Manitou Passage a few
minutes ago. The bottom line is these thunderstorms will have
gusty winds, locally heavy rainfall and small hail. Even so, I
would expect the area south and west of GRR should be mostly dry
this afternoon even so.

Tomorrow looks rather wet actually. We have a northern stream
shortwave interacting with a moist southwesterly flow at low to
mid levels. This results in a 40 to 45 knot low level jet aimed at
Mount Pleasant at 4 pm Wednesday. There is also decent warm
advection occuring in the lower to mid levels Wednesday. There is
decent isentropic lift during the day Wednesday (30 knots
perpendicular to the isentropic surfaces near 700 mb).
Condensation pressure deficits fall to near 5 mb over our western
and southern CWA by early Wednesday afternoon. However there is
not much instability. So, it seems to me we are looking at a
cloudy day with widespread showers for Wednesday.

&&

.DISCUSSION...(Today through next Monday)
Issued at 257 AM EDT Tue Jun 22 2021

- Scattered Thunderstorms Today

Unseasonably strong shortwave trough axis approaches Lower
Michigan this morning with vort max rounding the base. Model
soundings show mid-level lapse rates providing potential for some
low-topped convection developing by noon. The freezing level is
around 5 kft today so, even though the updraft depth is expected
to be limited...at least pea-sized hail is possible with
thunderstorm updrafts. The storms should decrease by late
afternoon with the trough axis moving east and diminishing
insolation.

- Potential for Heavy Rain Late Week

Still looking at a slow-moving front being the focus for
convection by Thursday night into Friday and Saturday. Deep
moisture pools ahead of the front with precipitable water over 1.8
inches. Training of heavy rain could cause localized flooding by
late Friday. Given the recent rains, this event could finally
result in some rises on the mainstem rivers where heavy rains have
occurred recently such as the St. Joseph and Kalamazoo river
basins.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 222 PM EDT Tue Jun 22 2021

Showers and a few thunderstorms with small hail will continue to
move through mid-Michigan this afternoon. Cloud bases are
generally VFR but a heavier downpour may create temporary IFR
visibility, though the probability of this is low at any
particular location. Winds gusting from the west today will go
light and variable around sunset then trend more from the south-
southeast early in the morning. Rain showers from mid-level
moisture streaming in Wednesday morning are expected, with a
trend toward MVFR ceilings near and north of MKG, GRR, and LAN.

&&

.MARINE...
Issued at 257 AM EDT Tue Jun 22 2021

Winds and waves will be relatively light today then increase again
on Wednesday into Thursday when another Small Craft Advisory will
be needed.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

UPDATE...WDM
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...CAS
MARINE...Ostuno

Hazardous Weather Outlook
National Weather Service Grand Rapids MI
1156 AM EDT Tue Jun 22 2021

MIZ037>040-043>046-050>052-056>059-064>067-071>074-231600-
Mason-Lake-Osceola-Clare-Oceana-Newaygo-Mecosta-Isabella-Muskegon-
Montcalm-Gratiot-Ottawa-Kent-Ionia-Clinton-Allegan-Barry-Eaton-
Ingham-Van Buren-Kalamazoo-Calhoun-Jackson-
1156 AM EDT Tue Jun 22 2021

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

.DAY ONE...This Afternoon and Tonight

Scattered thunderstorms with small hail, gusty winds and locally
heavy rain are expected this afternoon, mostly north and east of
Grand Rapids.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Thunderstorms with heavy rain are possible on Friday and
Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

LMZ844>849-231600-
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-
1156 AM EDT Tue Jun 22 2021

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

.DAY ONE...This Afternoon and Tonight

Isolated thunderstorms are possible north of Grand Haven this
afternoon. Small hail, gusty winds, cloud to water lighting and
even a water spout are possible with these storms.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

Conditions will become hazardous to both small water craft and
beach goers Wednesday and that will continue into Thursday.

Thunderstorms are expected Friday into Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

wdm

Special Weather Statement
National Weather Service Grand Rapids MI
142 PM EDT Tue Jun 22 2021

MIZ052-059-221830-
Clinton-Gratiot-
142 PM EDT Tue Jun 22 2021

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN GRATIOT AND NORTHERN
CLINTON COUNTIES...

At 140 PM EDT, a strong thunderstorm was located near Hubbardston,
or 13 miles northeast of Ionia, moving east at 20 mph.

Winds in excess of 40 mph and penny size hail are possible with this
storm.

Locations impacted include...
St. Johns...           Elsie...               Eureka...
Ovid...                Fowler...              Maple Rapids...
Ashley...              Perrinton...           Hubbardston...
Pompeii...             Middleton...           Bannister...

If outdoors, seek shelter inside a building to protect yourself from
lightning.

LAT...LON 4300 8484 4320 8484 4319 8437 4293 8437
TIME...MOT...LOC 1740Z 276DEG 18KT 4310 8485

CAS

Special Weather Statement
National Weather Service Grand Rapids MI
250 PM EDT Tue Jun 22 2021

MIZ052-221930-
Gratiot-
250 PM EDT Tue Jun 22 2021

...A DEVELOPING THUNDERSTORM WILL AFFECT CENTRAL GRATIOT COUNTY...

At 250 PM EDT, a strong thunderstorm was located southwest of
Ithaca, moving east at 20 mph.

Winds in excess of 40 mph and half inch hail are possible with this
storm.

Locations impacted include...
Ithaca...              North Star...          Ashley...
Perrinton...           Pompeii...             Bannister...

If outdoors, seek shelter inside of a building to protect yourself
from lightning.

LAT...LON 4312 8444 4320 8475 4331 8473 4332 8437
      4312 8437
TIME...MOT...LOC 1848Z 277DEG 18KT 4325 8468

CAS