797
fxus63 kiwx 211142
afdiwx
area forecast discussion
national weather service northern indiana
642 am est wed jan 21 2026
.key messages...
- light snow moves out this morning. then, after a brief break,
some more snow showers will be possible this evening. gusty
winds between 20 and 30 mph will be possible, especially
southeast of us-24 today. there is a 15% to 30% chance that
winds may exceed 35 mph tonight. these winds could cause
blowing and drifting snow making driving hazardous.
- after a brief warm-up today, a bitterly cold arctic air mass
is poised to return later this week through the weekend. there
is a high probability (greater than 70% north of us-24 friday
and north of us-30 on saturday) that daytime highs on friday
and saturday will remain in the single digits. some areas may
struggle to get above zero.
- there will be periodic chances for lake enhanced snow showers
tonight through the weekend. an additional 1-2 inches of snow
is possible in far southwest lower mi tonight. less than 1
inch expected elsewhere.
&&
.discussion...
issued at 252 am est wed jan 21 2026
a couple things that may ultimately restrict the amount of snow that
falls out of this morning`s clipper include dry low levels allowing
evaporation and a little bit of a mismatch in the omega/moisture/dgz
leading too less (not an elimination) dendrites being formed and
lowering slrs. dry air on the back end of the lake effect snow
and the sunny skies we got on tuesday probably contributed to
this with the moisture plume arriving late to contribute to a
juicy low. the hi-res models began picking up on this last night
whereas the low-res models continued to maintain a lower
gradient in snow totals for this event.
moving forward, the vort max from this system rises northward today
and gives way to another clipper system for this evening. today`s
fight south of us-30 between the cooler moist air and the drier
potentially warmer air will affect how warm temperatures get
today. would guess 10 degree td depressions would make it harder
to precipitate and make that area able to warm into the mid to
upper 30s for highs today.
for tonight`s system, a worse moisture plume than this morning`s
system allows for a thinner moisture profile, but the air is cold
enough that it`s still enough for snow. omega appears to be in the
dgz, but is below the moisture so that cross-hair is offset
contributing to lower ratios. while the vort max pinwheels around
the base of the trough, the general motion once it reaches lake mi
is more towards our north. it does bring a cold front through the
region between 3 and 9z this evening. the nam is highlighting
this with the snow squall parameter and there are some better
low level lapse rates with it, which would bring to mind some
more gusty snow showers. will include some pops for this, but
there may be some low level moisture problems with this system
again leaving widely scattered snow showers. as this second
clipper moves through, snow showers will be most likely in our
mi counties where some lake enhancement is possible after 3z and
continuing into early thursday morning. given weak delta ts,
dry low levels, and shallow inversion heights, only have up to
an additional inch from this second clipper system tonight. at
the very least, the increased lapse rates today allow mixing
but it never really gets high enough to tap into the 40 to 45 kt
llj with the early departure of the jet before lapse rates get
high enough. this does leave the possibility for 30 to 40 mph
gusts today, with the highest south of us-24. when the second
clipper system moves in, it actually appears that better lapse
rates will be able to continue into the overnight period.
however, it still appears to struggle with rising into the llj
again. 30 to 40 mph gusts will be possible with the highest
gusts occurring along the front.
mid level height rises take over and surface high pressure
nudges in, tending to suppress weather for thursday as
trajectories become more southerly. another weak system does
appear to come in for thursday evening and a brief uptick in
moisture along the boundary may be enough to supply some
scattered snow showers. the nam snow squall parameter is
lighting this up and there`s some adequate sbcape and low level
lapse rates to supply a gusty snow shower/ snow squall
situation. gusts during this time could reach 30 to 40 mph and
potentially 45 mph along the front as it swings through.
a vigorous shortwave follows for later thu night/friday and this
looks to invigorate the lake effect belts again. initially, it
appears that inversion heights are back up to around 7500 to 8500
ft, but nam profiles have dry low levels. i`d be curious if that
moistens up in the future runs. better low level moisture arrives
early friday morning, but by that point, inversion heights appear to
be more down around 5000 ft. delta t values are between 25 to 30c
indicating enough temperature differential and instability.
the other talking point for friday will be the cold as a 1050 mb
high drops south from canada and -25 to -30c at 850 mb temperatures
swing through the area. friday morning lows drop to the single
digits and highs struggle to get much higher than 10 degrees. we`ll
also have a bit of a breeze to work with with these temperatures to
make -10 to -20f wind chills possible again. with high pressure
moving in for saturday and sunday, high temperatures are able to
trend warmer with highs either side of 10 degrees on saturday and
mid teens on sunday. sometimes, the low temperatures can lag the
warming at the low levels of the atmosphere evidenced by some
warming noticeable by 12z saturday with -20 to -25c around instead
of securely around -25c at 850 mb.
we`ll need to watch the placement of the high pressure system, which
may shunt the moisture plume from a developing low across the
south/southeastern us just to our south. models currently depict the
moisture plume arriving sunday with snow. however, adjustment in
models has already happened and will continue to happen with this
dynamic system so it`s too early to lock in anything at this
point.
&&
.aviation /12z tafs through 12z thursday/...
issued at 635 am est wed jan 21 2026
predominantly vfr to mvfr conditions, with potential for ifr
conditions within snow showers this morning into early
afternoon. ceilings should linger around 5kft through late
morning when we see additional snow showers/mvfr ceilings with
a cold front through early/mid afternoon (ksbn to kfwa). s-sw
winds shift west through the period, with gusts up to around
25-30kts possible at times. suspect visibilities will remain
between 2-5sm for the most part during snow-with potential to
drop to around 1sm briefly at ksbn (especially if wind leads to
blowing/drifting in addition to falling snow). llws this morning
and then again later tonight at kfwa during periods of
decoupling.
&&
.iwx watches/warnings/advisories...
in...none.
oh...none.
mi...winter weather advisory until 10 am est this morning for
miz078>081-177-277.
marine...gale warning from 4 pm this afternoon to 7 am est thursday for
lmz043-046.
&&
$$
discussion...roller
aviation...mcd