078
FXUS63 KIWX 191142
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
642 AM EST Sun Jan 19 2025

.KEY MESSAGES...

- Lake effect snow gets going in southwest Lower Michigan and northwest
  Indiana today and especially on Sunday. A Winter Weather
  Advisory is in effect from now to 7 PM EST Monday for Berrien
  and Cass counties. Snow accumulations of 3 to 7 inches
  expected.

- Gusty winds of 20 to 30 mph may cause some blowing and drifting
  snow early in the week, especially closer to Lake Michigan.

- Dangerous cold begins filtering into the area Sunday and lasts into
  the middle of next week. A Cold Weather Advisory will be in
  effect from tonight through Wednesday morning. Wind chills as
  low as 25 below zero are expected at times.

- Temperatures return to near normal by the end of the week.

&&

.DISCUSSION...
Issued at 248 AM EST Sun Jan 19 2025

Lake effect snow showers have been slow to start up this morning
thanks to low level dry air. However, the current Winter Weather
Advisory for Berrien and Cass counties is in good shape as lake
effect snow showers are expected to intensify this evening and into
the day on Monday. Negative theta e lapse rates, less dry air, and a
500 mb shortwave that pivots through the area tonight will all aid
in the intensification of lake effect snow in southwest Lower
Michigan. As the winds shift to become northwesterly later today,
this may also help push scattered lake effect snow showers into
northern Indiana. In southwest Lower Michigan, reduced visibilities
are expected and travel will be hazardous, especially along the I-94
corridor. Gusty northwest winds will also lead to some blowing snow.
Hi res model guidance depicts that as the winds shift on Monday to
become more westerly and a ridge builds to the southeast of our
forecast area, the lake effect snow bands will finally shift out of
our area. The only change made to the Winter Weather Advisory was to
extend it until 7 PM EST Monday to account for a longer duration of
lake effect snow. Snow accumulations of 3 to 7 inches are expected.
After Monday, lake effect snow will be limited by the approaching
dry, Arctic airmass.

A large area of high pressure will allow for bitterly cold Arctic
air to spill into the central CONUS and Midwest starting tonight and
lasting through Wednesday morning. With wind gusts between 20 to 25
mph at times, minimum wind chill values will be as low as -15 to -20
degrees (possibly as low as -25 at times) from Sunday night through
Wednesday morning. The Extreme Cold Watch has been upgraded to a
Cold Weather Advisory area-wide from 7 PM EST tonight to 10 AM EST
Wednesday. Monday and Tuesday will be the coldest days of week with
highs only in the single digits. Lows will be in the single digits
below zero tonight, Monday night, and Tuesday night. As the area of
high pressure expands and moves east, it will centered over our area
on Wednesday morning. Some cloud cover on Sunday and Monday nights
may aid in wind chills being slightly `warmer`, with Tuesday
night/Wednesday morning having the coldest wind chills (as low as 25
below zero) of the Arctic blast. Regardless of what the wind chills
end up being (as there`s not much difference between -20 and -25),
this dangerous cold will be brutal. Several days of prolonged bitter
cold will take a toll on anyone outdoors, with frostbite possible in
as little as 30 minutes! Limit exposure outdoors and take
precautions to protect pets and exposed pipes from this bitter cold.

Temperatures will begin to warm up back towards seasonable levels
(but still below freezing) by mid to late next week. As the Arctic
air and high pressure system exit to the east, it could be windy at
times with a passing area of low pressure across the northern Great
Lakes and a tight pressure gradient across our forecast area. The
latest long range guidance favors near normal temperatures and a
mostly dry pattern for the end of next week and into next
weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 640 AM EST Sun Jan 19 2025

Lake effect snow showers are beginning to become better
organized across west central Lower Michigan early this morning.
The lake response has been somewhat delayed from earlier
indications with dry subcloud layer being a limiting factor.
Land breeze development has also been less pronounced than
earlier high resolution guidance was indicating. Southeast
advance of arctic low level boundary will allow for continued
strengthening of lake induced instability this morning and
likely sharpening of thermally induced low level convergence.
Development should also be aided by a synoptic short wave trough
moving in from the west. Any dominant single band will likely
become more progressive as this trough swings through later this
morning/early afternoon. Some IFR vsbys with the lake effect
cannot be ruled out today, particularly mid morning to mid
afternoon. Gradual backing of low level winds tonight should
confine lake effect snow showers to KSBN, and by Monday most
favored areas for lake effect snow should be across southern
Lower Michigan. Steep low level lapse rates under influence of
cold advection should support gusts to 25 knots today, and
these lapse rates and gusts will persist into tonight.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Cold Weather Advisory from 7 PM EST /6 PM CST/ this evening to
     10 AM EST /9 AM CST/ Wednesday for INZ005>009-012>015-017-
     018-020-022>027-032>034-103-104-116-203-204-216.
OH...Cold Weather Advisory from 7 PM this evening to 10 AM EST
     Wednesday for OHZ001-002-004-005-015-016-024-025.
MI...Cold Weather Advisory from 7 PM this evening to 10 AM EST
     Wednesday for MIZ078>081-177-277.
     Winter Weather Advisory until 7 PM EST Monday for MIZ078-177-
     277.
MARINE...Small Craft Advisory until 5 PM EST Tuesday for LMZ043-046.
     Heavy Freezing Spray Warning from 1 PM this afternoon to 5 PM
     EST Tuesday for LMZ043-046.

&&

$$

DISCUSSION...Johnson
AVIATION...Marsili