670
FXUS63 KIWX 250732
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
232 AM EST Mon Nov 25 2024

.KEY MESSAGES...

- Rain showers and drizzle will likely be scattered throughout
  the day today, with the best chances for widespread showers
  in the afternoon/evening.

- Becoming much colder and windy on Tuesday in the wake of a
  cold front.

- Additional chances for rain/snow will be possible mid to late
  week around Thanksgiving. There is considerable uncertainty
  in precipitation type(s) but minor impacts to travel could be
  possible.

- Lake effect snow chances and much colder air follows for the
  weekend after Thanksgiving; highs in the 20s and lows in the
  teens are likely.


&&

.DISCUSSION...
Issued at 230 AM EST Mon Nov 25 2024

An area of low pressure is situated over northern Missouri, with the
attendant warm/stationary front draped over northern Indiana.
Current radar imagery shows a few areas of patchy drizzle/light rain
starting to develop. As the front lifts northward, southerly WAA
and shallow increases in low level moisture will aid in the
development of drizzle/light rain showers throughout the day
today. Moisture will be slow to increase, so precipitation will
remain light throughout the morning. It is also worth noting
that the best forcing will likely be displaced from the highest
moisture, so this disjointment will likely keep rain on the
lighter side today. Forecast soundings also depict some mid
level dry air working in this morning and afternoon, which will
limit rain amounts. As the attendant cold front moves through
the area Monday afternoon/evening, some additional light
scattered showers will be possible. Overall, rainfall totals
should be between 0.10"-0.20" today.

A tightening pressure gradient on the backside of the departing low
will yield breezy conditions for the latter half of the day today
into Tuesday with gusts to 30 mph possible. Enjoy the highs in the
low to mid 50s today because this is likely the last day it will be
this mild for the next 7 to 10 days! Drier, colder air quickly
filters behind the cold front in with highs only in the upper 30s
Tuesday.

Mid and long range model guidance continues to pick up on chances
for snow during the day Wednesday. A deepening theta-e gradient
lends itself to the potential for some WAA and/or frontogenesis-
driven snow during this timeframe. A slushy inch or so of snow
accumulation is possible in the afternoon/evening. Slick spots are
possible for the PM commute/any Thanksgiving travel across the area
on Wednesday. Give yourself extra time and take it slow on the
roads!

Confidence is low in the Wednesday night to Thursday timeframe; It
still too far out to determine impacts, if any, for the Thanksgiving
travel period. At the time of this writing, all scenarios are still
on the table as a system will likely move through the Midwest/Ohio
River Valley. There are two scenarios at play on Wednesday/Thursday;
we are watching to see if a northern stream shortwave approaching
the Great Lakes on Wednesday merges with a southern stream wave. As
noted by the previous shift, guidance is handling strength/timing of
northern/southern streams differently. Should this merger occur,
which is depicted by the ECMWF and NAM, the result would be a phased
low pressure system centered over Tennessee/Kentucky, with a
few inches of slushy snow possible in our forecast area and
potential for travel impacts. If these two pieces of energy do
not merge, or are displaced, which are solutions shown in the
GFS, then the result would be that precipitation would stay
further south and thus, we would be mainly dry. Further
complicating the forecast is that temperatures will be in the
upper 30s to low 40s Thursday...with uncertainty as to how much
cold air there will be to work with, it is possible we end up
with a rain/snow mix or a slushy few inches of accumulating
snow. We should have a better grasp on the track, intensity,
timing, and precipitation type(s) with this system 48 to 72
hours out. For now, will stick with the NBM PoPs for the
Wednesday to Friday timeframe, which are 30-60%.

There is high confidence in very cold air intruding for the end
of November and into the start of December. While temperature
records are not in jeopardy, the cold will be unusual for this
early in the season. High temperatures this weekend into early
next week could be limited to the 20s with lows in the teens.
Stay tuned for updates! With such cold air moving over the
unfrozen, relatively mild waters of Lake Michigan, there is also
increasing confidence in lake effect snow potential. Travel
impacts and accumulating snow are possible in areas downwind of
Lake Michigan (especially Berrien County, MI, La Porte County,
IN, and St Joseph County, IN).

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1152 PM EST Sun Nov 24 2024

Weak sfc low over wrn IL in reflection of larger scale shortwave
disturbance ejecting out of the nrn Rockies. Delayed moisture
entrainment into this sys and nrn track through the nrn lakes
calls into question threat for showers later this morning into
this afternoon. Given generally poor model based signals opted
for vcsh mention. Nonetheless gradual but accelerating downturn
in cloud cigs expected toward and after daybreak within emerging
warm sector bulge progressing across the terminals.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 3 PM this afternoon to 7 PM EST
     Tuesday for LMZ043-046.

&&

$$

DISCUSSION...Johnson
AVIATION...T