166
FXUS63 KGRR 242330
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
730 PM EDT Sun May 24 2026
.KEY MESSAGES...
- Fog Likely Tonight, Locally Dense Fog Possible
- Warmup into Wednesday With Low Rain Chances Mid-week
- Dry and Cool Late Week
&&
.DISCUSSION...
Issued at 152 PM EDT Sun May 24 2026
- Fog Likely Tonight, Locally Dense Fog Possible
Rain showers and isolated thunderstorms associated with an occluded
front crossing the area should exit by early evening. Concern then
develops for fog overnight given low-level moisture from today`s
rain. Winds subside and skies begin to clear as high pressure
moves in tonight, with a favorable environment for fog development
resulting. Signals are present in guidance that pockets of
locally dense fog could develop depending on the extent of
clearing overnight and to what extent any sunshine today can mix.
Climatology suggests that given a strong sun angle in late May,
widespread dense fog is unlikely, matching the picture guidance
shows. We will continue to monitor trends going into tonight.
- Warmup into Wednesday With Low Rain Chances Mid-week
West Michigan sets up on the periphery of a large scale ridge
starting later Monday into Tuesday with the development of an omega
blocking pattern over the central CONUS. 850 mb temps warm into the
mid teens Celsius resulting in highs in the 80s. There are two low
chances of rain for the first half of the week. First is Monday
where convergence off Huron may pop an isolated shower across our
northeast CWA. Confidence is low, with PoPs 10% or less. Second is
Wednesday with the arrival of a backdoor cold front. Moisture
quality is marginal so only light precipitation is expected. Medium
range model guidance suggests enough MUCAPE will be present thunder
to be in play.
- Dry and Cool Late Week
The post backdoor cold frontal environment will be slightly
cooler than the first half of the week, with highs in the upper
70s likely. Compared to yesterday, guidance has trended towards
the warmer solution with 850mb temps in the low teens. The omega
blocking persists with a surface ridge in place across the region.
This keeps the forecast dry for the later portions of the week.
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 730 PM EDT Sun May 24 2026
Mixture of flight categories currently as clouds after the rain
have varied between IFR or MVFR ceilings, to scattered or few.
After a wet day, the scattering of clouds this evening going into
a calm night is a recipe for fog. Dense fog has been present over
portions of the Lake Michigan shoreline, and is expected to
spread over MKG later this evening. IFR to LIFR visibility,
ceilings or vertical visibility is favored to develop over much of
the area between 03 and 06 Z. Visibility may be near minimums
late tonight. Fog will mix out with drier air above between 12 and
14 Z, then the rest of Memorial Day is likely to be VFR.
&&
.MARINE...
Issued at 238 PM EDT Sun May 24 2026
Webcams show that fog has already developed across the nearshore
waters as of 230 pm Sunday afternoon and is already dense. Have
moved up the Dense Fog Advisory to start immediately.
--- Original Discussion ---
Primary concern for marine interests is the potential development
of fog across the waters tonight. Ample low-level moisture paired
with a approaching high pressure system looks to calm winds
enough for fog development overnight. Climatologically, the cooler
waters favor fog development, which is also supported by model
guidance. As a result, will be issuing a Marine Dense Fog Advisory
from late this evening through mid Monday morning.
As for winds and waves, Time/Height wind overviews suggest largely
that light winds and sub-advisory waves are expected over the next
several days. Winds in the 1-3kft range look to approach 30-35 kts
later Monday into Tuesday, however the strong warm air advection in
place suggests these winds won`t mix down. Other than the
aforementioned Marine Dense Fog Advisory, headlines are not
anticipated over the next week.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Dense Fog Advisory until 10 AM EDT Monday for LMZ844>849.
&&
$$
DISCUSSION...Thomas
AVIATION...CAS
MARINE...Thomas
NWS GRR Office Area Forecast Discussion
