271
fxus63 kiwx 171112
afdiwx
area forecast discussion
national weather service northern indiana
612 am est sat jan 17 2026
.key messages...
- additional isolated to scattered snow showers are possible
early this morning, but little to no snow accumulation is
expected.
- lake effect snow chances will increase again later saturday
afternoon into saturday night with some light snow
accumulations possible.
- much colder temperatures are in store for the weekend with
another clipper system bringing renewed light snow and lake
effect snow chances sunday into monday.
- dangerous wind chills around 15 below zero are expected both
sunday night and monday night.
&&
.discussion...
issued at 311 am est sat jan 17 2026
a large sprawling upper troughing will be maintained across the area
between this weekend and early next week. underneath it, we`ll
continue to look for passing shortwaves to identify potential for
precipitation and subtle mid level ridging to identify dry periods.
as a cold front moves through early this morning, continued
scattered snow showers also move through. low level lapse rates (0-3
km) even at 4z last night were still around 7-7.5c west of i-69 and
were also maintained by some large scale ascent and vort maxes/f-gen
areas moving through in the flow. these are on track to move into nw
oh by 10z or so this morning and should depart that area before
midday. given these showers` scattered nature and their general
weakness as well as temps right around freezing, little if any snow
accumulation is expected.
behind this area of showers, an area of mid level deformation
pinwheels southeast through the tear drop of lake mi today into
tonight. that area of deformation eventually folds into the area of
vorticity southeast of the forecast area into tonight. however, as
it does so, the remaining low level moisture pairs with theta-e
instability and low level convergence in the vicinity of berrien
county, mi along with southwest winds to continue to allow for lake
enhancement. low level inversions up to around 4 kft and delta t
values between 15 and 20c indicate the weak environment for lake
effect snow even with surface temperatures in the teens f. 1 to
3 inches appears most likely in berrien county, mi through
tonight.
trajectories turn more southerly on sunday and the low level
moisture dries out along with a weakening of the theta-e instability
sunday allowing for a period of dry weather across the area sunday
morning.
then, a fairly vigorous shortwave rounds the base of the trough
through the area sunday afternoon and night bringing a clipper
system through the area. moistening of the low levels and
cooling aloft during this period especially allows for a wrap
around lake effect signal as southwest winds become northwest
behind the cold front. as is the case with these clipper
systems, they often lean dry (unless they have a baroclinic
boundary or some gulf connection), this is once again the case.
the gfs/aigfs get started on the early side with snow showers
along the warm front, but it`s probably going to wait until
after 00z sunday night to bring in some isolated to scattered
snow showers, more in line with the nam/ecmwf pairing. once, the
cold front arrives, better lake enhanced instability, low level
moisture, and low level wind convergence reinvigorates the lake
effect snow machine. it does take some time to get the theta-e
instability set up just right even with stout lake enhanced
inversions up to around 700 mb initially. but those descend
through the night even as delta ts increase above 20c. wnw winds
contain the 2"+ snow plumes to north of us-6 and currently have
a 3 to 6 inch total across berrien and cass, mi from sunday
through monday (a 36 hr period). a sliver of nw st joseph, mi as
well as northern st joseph, in county is also in the 3 inch
contour. our model certainty tool using the latest overnight
models indicates a 15 to 30 percent potential for 8 inches in
northern berrien county.
the cold air behind this clipper system, which ushers in -20c at 850
mb overhead of the area monday. surface temperatures fall from the
upper teens and low 20s to the single digits above zero monday
morning, and that along with 20 to 30 mph wind gusts creates wind
chills in the -10 to -20f range for monday, the lower 5 degrees of
which is cold advisory threshold here. highs struggle to reach 15f
on monday. monday night is also pretty cold with surface
temperatures at zero or a couple degrees above. slightly less gusty
winds combined with those temps still allow for chills in the -10 to
-20f range. 850 mb temperatures warm 5 degrees tuesday afternoon and
that`ll allow highs to reach the teens and low 20s.
models begin to diverge on what happens for the midweek period next
week. the ecmwf has its jet axis much farther west than the gfs and
a much better gulf connection with a low developing along a
baroclinic zone right overhead. the aigfs/gfs/gem are all in their
own camp away from the ecmwf right now though, and keep
precipitation east away from the area during this time period. it is
possible precipitation falls wed and again thu night/fri in this
pattern.
&&
.aviation /12z tafs through 12z sunday/...
issued at 612 am est sat jan 17 2026
cold front has cleared the terminals and residual flurries at
kfwa will end in another 1-2 hours. mvfr ceilings are still
possible at kfwa at times through the morning but upstream obs
point heavily toward general vfr ceilings and will hold with
that in the 12z taf. another weak shortwave will arrive this
evening and may bring light snow/mvfr ceilings at ksbn but kfwa
is expected to remain dry/vfr given displacement from better
forcing and lake contribution.
&&
.iwx watches/warnings/advisories...
in...none.
oh...none.
mi...none.
marine...small craft advisory until 1 am est monday for lmz043-046.
gale watch from late sunday night through monday evening for
lmz043-046.
&&
$$
discussion...roller
aviation...agd