648
FXUS63 KGRR 060930 CCA
AFDGRR
Area Forecast Discussion...CORRECTED
National Weather Service Grand Rapids MI
430 AM EST Fri Nov 6 2026
.KEY MESSAGES...
- Cooler today, with lake effect showers near the lakeshore and far
north.
- Much more typical temperatures and dry Saturday onward
&&
.DISCUSSION...
Issued at 321 AM EST Fri Nov 6 2026
- Cooler today, with lake effect showers near the lakeshore and far
north.
Now that the cold front has passed through the area, attention
turns to the establishment of lake effect rain (mostly) bands
along the immediate lakeshore and the northern lower peninsula.
Cold air advection has begun in earnest with north-northwesterly
cyclonic flow, and 850 mb temperatures have fallen to between -2
and -4C already as of 3am, and may drop another 1-3 degrees over
the next few hours. With lake temperatures still quite warm
(12-15C), this is producing a temperature difference of 14-16C,
which may reach as high as 19C when the core of the cold air
moves overhead. Meanwhile, inversion heights are expected to rise
to around 8k-9kft, and a prominent lake effect rain band has
already formed along the immediate lakeshore in an area of
enhanced convergence. Further north, numerous additional lake
effect bands are also forming downstream of the northern lakes,
and one particular band emanating from Grand Traverse Bay may be
relevant to us later this morning.
In any case, these lake effect showers will mature this morning,
continue through the day, and diminish gradually this evening.
Temperatures currently are still too warm for snow where
precipitation is falling (low 40s near the lakeshore), and we
remain confident that the vast majority of this will fall as rain,
particularly within the primary band along the lakeshore.
Instead, expect another 1/4-1/2 inch of rain in western
Mason/Oceana counties, and possibly western Allegan/Van Buren
counties as well. Lighter amounts are also possible across our
northern row of counties as the remnants of lake effect bands from
the northern lakes expand further downstream, but precipitation
rates with these bands should be much lower than the lakeshore
band. We may also be grazed in our northeast by more synoptically
driven, lake enhanced precipitation as the upper low moves along
the length of Lake Huron, but this would likely be very light as
well.
We will also need to keep an eye out for a few wet snowflakes with
this activity later this morning as cold air deepens and the upper
part of the cloud layer cools to near -10C (enough for cloud ice
formation). If this occurs at all, it will be most plausible in the
higher terrain of Lake/Osceola counties if the previously
mentioned Grand Traverse Bay lake effect band can become
established. Even if this occurs, about the most we could expect
with this band would be a thin layer of slushy snow almost
exclusively on grassy surfaces, due to a combination of warm
surface temperatures, modest precipitation rates that far inland,
and very low snow-liquid ratios. More likely is that snow will
melt before accumulating at all.
- Much more typical temperatures and dry Saturday onward
Once lake effect showers diminish this evening, a dry pattern will
become established for the foreseeable future, with little
opportunity for precipitation of any variety. This weekend will see
cool, but near seasonal average temperatures, with morning lows near
or slightly below freezing both Saturday and Sunday, and highs
rising from the low 50s Saturday to the mid/upper 50s Sunday. A
modest shortwave passes the area to the northeast Sunday, but again
is not expected to produce precipitation. Transient upper ridging
is expected to boost temperatures slightly above average
early/mid week.
In the longer range, ensemble guidance has trended toward the
development of a longwave trough across the eastern CONUS late in
the week, opening the door for cooler air to return south into the
Great Lakes. Ensemble temperature spreads remain large during this
period, but the overall trend back toward cooler (or at least near
average) temperatures is clear nonetheless.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1244 AM EST Fri Nov 6 2026
Low ceilings will continue to impact local terminals to varying
degrees, along with occasional lake effect showers. Once overnight
showers move east of the area over the next few hours, MKG has
the highest chance for additional rain today, although there is a
lower probability of a few showers at LAN/JXN during the day.
Elsewhere, the main concern is low ceilings, which will be quite
variable. at GRR/AZO/BTL, some improvement is likely tonight
through tomorrow afternoon, but MVFR ceilings are expected to move
back in late afternoon/evening. At other terminals clouds are
more likely to persist, and a longer period of MVFR categories is
expected throughout the day.
&&
.MARINE...
Issued at 321 AM EST Fri Nov 6 2026
Northerly gales or near-gales are expected to persist through the
day today in the nearshore waters north of Whitehall, with the
strongest winds and largest waves (perhaps as high as 10 feet)
near Big and Little Sable points. Small Craft Advisory conditions
will also persist in the remainder of the nearshore waters,
although there is the possibility for sporadic near-Gale force
gusts in the waters south of South Haven as well. Waves are also
expected to become particularly large here due to the northerly
winds, and may reach 10-12 feet during the afternoon today. Winds
will slowly subside this evening, allowing waves to settle
overnight.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 7 PM EST this evening for LMZ844>847.
Gale Warning until 7 PM EST this evening for LMZ848-849.
&&
$$
DISCUSSION...BRC
AVIATION...BRC
MARINE...BRC
NWS GRR Office Area Forecast Discussion
