013
FXUS63 KGRR 050449
AFDGRR
Area Forecast Discussion
National Weather Service Grand Rapids MI
1149 PM EST Sun Jan 4 2026
.KEY MESSAGES...
- Round of Snow Tonight with Potential for Freezing Rain
- Rain/Freezing Rain Tuesday into Tuesday Night
- Warmer with Periods of Rain Thursday into the Weekend
&&
.DISCUSSION...
Issued at 229 PM EST Sun Jan 4 2026
- Round of Snow Tonight with Potential for Freezing Rain
Satellite water vapor and airmass RGB imagery show an upper PV
maximum has ejected eastward into the northern plains with an
attendant closed surface low crossing SD at this time. As noted
before, this PV feature will cross central/northern Lower MI
overnight, with the best timing for mid-tropospheric upward
vertical motion in the 03-06Z Monday timeframe. We are still
looking at greater than 50 percent chances of one inch per hour
snow accumulations around the US-10 corridor east of Baldwin.
Desaturation of the DGZ will occur in the wake of the upper PV
maximum. Additionally, we see a signal for the surface low to cross
the northwest CWA, which will contribute sufficient low level
isentropic lift and surface convergence to induce freezing drizzle
for a brief period. Given that the best signal for at least a glaze
of ice extends south and west of the current advisory area, we have
expanded the advisory to encompass our two northern tiers of
counties to address travel hazards for the Monday morning
commute.
Agree with previous thinking about fog/freezing fog being a
concern Monday night into Tuesday so have included this in the
forecast.
- Rain/Freezing Rain Tuesday into Tuesday Night
Another PV maximum and associated surface low will cross Lower MI
Tuesday with a slightly more southern track compared to the
Sunday night (tonight`s) system. The surface low moves east across
southern Lower MI and the swath of heaviest precipitation will be
just north of the low track in an area of maximized low level
isentropic ascent. There could be a quick accumulation of 0.05 to
0.10 inches of ice east of a Reed City to Big Rapids line on
Tuesday morning thanks to a very sluggish diurnal climb in
temperatures. This scenario would warrant another advisory for
this area if forecast trends hold. Eventually, temperatures should
warm enough Tuesday afternoon to result in a transition to rain.
- Warmer with Periods of Rain Thursday into the Weekend
The overall pattern transitions to phased troughing over the western
CONUS. This introduces deep southwesterly flow to the western
Great Lakes, which tends to be a wet pattern. The mean trough
position crosses the intermountain west and reaches the plains
early Friday. This will allow lee cyclogenesis to take shape and
bring precipitation to the area Friday night. Most recent
available guidance indicates most of this will fall as rain, but a
transition to snow is likely to occur at some point overnight
into Saturday morning. Any impacts during this time would most
plausibly be from excessive runoff due to rain; however, even this
is a limited threat given that NBM v5.0 guidance indicates just
roughly a 30 percent chance of exceeding one inch or rain
accumulation during this time. Heavier rain is more probable south
of Lower Michigan near a stationary front, and we will have to
monitor whether this threat area shifts north with subsequent
forecasts.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1149 PM EST Sun Jan 4 2026
The latest trends in upstream observations and model data
indicates that the threat of any freezing drizzle at the forecast
terminals has trended down. We are looking at 2-3 hours of precip
chances at the I-96 terminals, and too small of a chc at the I-94
terminals to mention at this time. The precip type at the I-96
terminals looks like either snow or ice pellets/sleet.
Once this precip moves by toward 09z, we may even partially clear
out at the the terminals. Winds will stay up some, and winds
aloft at the I-94 terminals will be high enough (40-45 knots) to
mention low level wind shear.
We will see low clouds move in during the late morning to early
afternoon hours. There is no concern with freezing drizzle as
temps will be above freezing by then. The low clouds will lower a
bit then toward the end of the forecast period, along with some
light fog developing.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 10 AM EST Monday for MIZ037>040-
043>046.
MARINE...Small Craft Advisory until 3 PM EST Monday for LMZ844>849.
&&
$$
DISCUSSION...TJT
AVIATION...NJJ
NWS GRR Office Area Forecast Discussion
