286
FXUS63 KGRR 100813
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
413 AM EDT Wed Jun 10 2026
.KEY MESSAGES...
- Areas of dense fog this morning
- Heat concerns across Southern Lower Michigan today
- Chances for severe thunderstorms this afternoon and evening
- Chances for severe thunderstorms Thursday evening/night
&&
.DISCUSSION...
Issued at 413 AM EDT Wed Jun 10 2026
- Areas of dense fog this morning
We have issued a Dense Fog Advisory for this morning for northwest
portions of the forecast area including Grand Haven, Muskegon,
Ludington, Baldwin and Newaygo. Cooler air being pushed inland by
westerly winds in the lowest 100mb is resulting in dense fog given
the high dew point air in place. Other areas remain above advisory
levels and we will monitor for any expansion to the Dense Fog
Advisory. We feel by mid to late morning that conditions should
improve to above advisory conditions.
- Heat concerns across Southern Lower Michigan today
After coordination with surrounding offices we have issued a Heat
Advisory for our southern row of counties (the I-94 row). The heat
is a bit borderline, but we thought it was close enough to match
up with neighbors to the south and east. Jackson County probably
stands the best chance at seeing triple digit max apparent
temperatures. With highs around 90 to the low 90s and dew points
rising into the lower 70s its going to be hot. There is a chance
we may need another heat headline on Thursday especially towards
Jackson once again.
- Chances for severe thunderstorms this afternoon and evening
All Southwest Lower Michigan counties are in a slight risk for
severe thunderstorms today via the Storm Prediction Center. Per
the latest HREF we expect storms to approach mid Lake Michigan in
the 400pm hour and sweep through the forecast area between roughly
500pm and 1000pm this afternoon and evening. There are signals in
the HREF that damaging winds are the primary threat with 10m AGL
ensemble max gusts exceeding 60 mph, especially over the western
half of the forecast area. MUCAPE values will likely exceed 3,000
j/kg today which will be coincident with a 850mb LLJ increase to
30-40 knots. DCAPE values near the convection this evening are
forecast to be in excess of 1,000 j/kg which is a good indicator
for damaging winds. Some lingering convection is expected into the
overnight, but a downward trend in intensity is expected given the
stabilizing affect of the evening rain.
- Chances for severe thunderstorms Thursday evening/night
There will likely be a lull in the activity Thursday morning and
for much of the day for that matter. While today`s storms will be
largely thermodynamically driven, Thursday`s storms will get more
of a synoptic scale boost from a sharp shortwave trough sweeping
in at 500mb. The low level jet Thursday evening is forecast by all
of the models to at least be in the 40-50 knot range which is
substantial for mid summer. Winds in the mid levels will be
equally as strong with a 100 knot jet core at 500mb noted just
upstream over WI/MN. Suffice it to say Thursday`s convection has
some dynamics associated with it. MUCAPE values will exceed 3,000
j/kg again with much stronger deep layer shear of around 40 knots.
All hazards are in play on Thursday evening, but again this looks
to be another damaging wind event. Max gusts in the HREF are
increasing as the storms are approaching from the west at the end
of the current 48hr time window of the model. SPC has us in an
enhanced for Thursday which looks warranted.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 200 AM EDT Wed Jun 10 2026
Two concerns over the next 24 hours for aviation purposes are
fog/low clouds this morning and chances for thunderstorms this
afternoon and evening.
As for the fog and low clouds...low ceilings have spread into West
Central Lower Michigan as of 06z...essentially from GRR and BIV to
the north. We expect these low clouds (IFR/LIFR) to expand to the
east and south encompassing almost all areas near and north of
I-96 by 10z to 11z. Visibilities will be worst near Lake Michigan.
The low clouds and fog should lift through the course of the
morning hours. VFR weather should prevail into the afternoon.
Focus in the afternoon shifts to thunderstorm potential. While
some scattered storms are possibly in the 18z to 21z time frame we
expect a surge of storms to move in after 21z from the west. These
storms will be capable of wind gusts to 35 knots, with isolated
gusts to 50 knots.
&&
.MARINE...
Issued at 413 AM EDT Wed Jun 10 2026
We have a Marine Dense Fog Advisory out this morning and that is
working out well looking at shoreline webcams. We expect the fog
to lift in the mid to late morning hours with mixing. Focus is on
the chance of a Small Craft Advisory and Beach Hazards Statement
for tonight. At this point the event looks confined to the night
hours between 8pm this evening and 8am Thursday. Holding off for
now and will let the day crew look at it. 3-5 footers look
possible north of Holland.
Mariners will need to be prepared for high winds both this
afternoon and evening and again Thursday evening associated with
strong to severe thunderstorms sweeping across the lake from the
west. Wind in excess of 50 knots will be possible.
&&
.HYDROLOGY...
Issued at 413 AM EDT Wed Jun 10 2026
We have had some heavier rain fall across the forecast area in the
past couple of days. Radar estimates from MRMS indicate that it is
the northwest CWA from Muskegon and Newaygo northward through
Hart and Scottville that has seen the most rainfall. 1-3 inches or
rain in this area has been common with some isolated areas of 4+
which has been backed up by rainfall reports. Most of the
remainder of the area has seen less than an inch.
An anomalously high moisture content is expected through the
depth of the atmosphere over the course of the next 2 days with
PWAT values of 1.5 to 2.0 inches today and exceeding 2.0 inches on
Thursday. Sounding climatology for Detroit shows the daily max
value for this evening of 1.90 inches. We will be near or above
daily max values for the next 48 hours.
Forecast precipitation amounts range from 0.75 to 1.50 inches
across almost the entire area via WPC. HREF 48 hour max values
which normally equates well to the heaviest swaths show that 1.50
to 3.00 inches is possible. The HREF only goes through 00z
Thursday evening at this point, so with additional precipitation
expected with the storms Thursday evening/night it is possible we
will see some amounts toward 4.00 inches in the heaviest swaths.
Good news is that area rivers are well within bank and near
normal values. We should be able to absorb most of this rain
without significant issues on mainstem rivers. That said, short
term hydro issues are a concern. Once PWAT values approach and
exceed 2.0 inches localized flooding is very possible given the
strong convection we are expecting. Local short term flood
advisories and warnings are possible over the next 48 hours due to
urban and small streams not being able to keep up with and drain
the amount of rain falling in short durations. 1-2 inch per hour
rainfall rates are expected in the heaviest cells.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 11 AM EDT this morning for MIZ037-038-
043-044-050-056.
Heat Advisory from noon today to 8 PM EDT this evening for
MIZ071>074.
MARINE...Dense Fog Advisory until 11 AM EDT this morning for LMZ844>849.
&&
$$
DISCUSSION...Duke
AVIATION...Duke
MARINE...Duke
HYDROLOGY...Duke
NWS GRR Office Area Forecast Discussion
