508
FXUS63 KGRR 272311
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
711 PM EDT Tue Oct 27 2026
.KEY MESSAGES...
- Brief warmup expected Wednesday
- Weak cold front brings light showers Thursday
- More chances for rain over the weekend and into next week
&&
.DISCUSSION...
Issued at 255 PM EDT Tue Oct 27 2026
- Brief warmup expected Wednesday
In spite of the continued presence of a broad upper level ridge
aloft, and low level winds that are slowly veering to the
southeast, temperatures today are largely similar to what they
were yesterday at the same time, if not a couple of degrees
cooler even. This is largely due to the fact that notable warm air
advection ahead of Thursday`s cold front has yet to take place,
and mid/high clouds have likely stunted daytime heating at least
somewhat.
Throughout the day tomorrow though, a shortwave and associated
surface low pressure system will round the top of the ridge
across Minnesota and Ontario, and breezy south to southwest winds
will develop locally in response. The resulting warm air advection
from these increasing winds will produce a noticeable jump in
temperatures tomorrow, likely around 5 to 8 degrees, bringing
afternoon highs to near and slightly above 70 degrees and about 15
degrees above daily averages. While we will also see a modest
increase in dewpoints, precipitation is expected to remain to our
west for at least one more day, although we are likely to see a
bit more cloud cover.
- Weak cold front brings light showers Thursday
As the shortwave/surface low moves off to the northeast into
Quebec Thursday, it will drag a weakening cold front through the
Great Lakes, which is expected to produce at least some shower
activity across much of the lower peninsula during the day
Thursday. The model depiction of this "event" has been relatively
consistent over the past couple of days, with a narrow plume of
increasing moisture (near 1 inch precipitable water) and meager
elevated instability (100-200 J/kg of MUCAPE). While most areas
will see at least some very light rain, our northwestern lakeshore
counties are favored for more meaningful amounts, although even
here there is only a 30-40% chance of exceeding 1/4 inch.
Meanwhile, we still cannot completely rule out a few lightning
strikes here and there, although model soundings do not suggest
that this will be common. Showers are favored Thursday morning and
afternoon, and should move southeast and diminish during the
evening and overnight as the weakening cold front sweeps through
the area.
- More chances for rain over the weekend and into next week
Temperatures Friday are expect to dip back down to near or
slightly above average, resulting in another pleasant fall day
similar to the last few. However, a model guidance continues to
depict another shortwave attempting to climb the crest of the
upper ridge over the weekend, bringing additional chances for
showers at various times. While timing details remain nebulous, it
appears that chances are focused over two rough windows: light,
spotty showers sometime during the day Saturday (Halloween), and
potentially more widespread showers late Sunday/early Monday. The
lack of timing specificity and ensemble spread continues to limit
precipitation probabilities to only around 20-40% at any given
time, but late Sunday continues to be the most favored period for
rain over the weekend.
Meanwhile, there continues to be a consistent long-range model
signal for a more substantial southern-stream trough and low
pressure system early next week, with the potential to bring
widespread rain to the Great Lakes. While ensemble spread remains
significant at this time range, the ceiling of this event is a bit
higher than its predecessors when it comes to the potential for a
more soaking rain. Meanwhile, the potential for this system to
produce early-season snow also appears to be low, with almost no
representation in long range ensemble members and continued warm
temperatures.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 710 PM EDT Tue Oct 27 2026
Sct-bkn mid/high clouds will continue to move over the terminals
through the period. As high pressure drifts to the east, winds
will gradually turn from the SE to the SW by the end of the
period.
&&
.MARINE...
Issued at 255 PM EDT Tue Oct 27 2026
While wind speeds remain elevated (10 to 20 kt at times), they
have turned out of the southeast and largely offshore, allowing
waves to settle to near or below 2 feet throughout the nearshore
waters. This will continue through the night and into Wednesday
morning, but winds will slowly veer to the southwest and increase
to between 15 and 25 kt by tomorrow evening. This will drive
steep, building waves into the nearshore waters Wednesday night
through Thursday, reaching heights of 4 to 6 feet. Winds will
weaken and become westerly, then northerly, behind a cold front
Thursday afternoon and overnight, allowing waves to settle.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
DISCUSSION...BRC
AVIATION...04
MARINE...BRC
NWS GRR Office Area Forecast Discussion
