023
FXUS63 KIWX 231735
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1235 PM EST Sun Feb 23 2025

.KEY MESSAGES...

- A warming trend continues early this week with highs in the middle
  40s to lower 50s by Monday and from the middle 40s to mid 50s for
  Tuesday and Wednesday

- A few flurries possible across southern Lower Michigan today, but
  otherwise dry through Monday afternoon. Chances of light rain
  return Monday night (30-40%).

- Greatest chances of light rain for Wednesday/Wednesday
  evening (50-60%).

- Cooling back to near normal for next weekend with just low
  chances of rain/snow showers.

&&

.DISCUSSION...
Issued at 345 AM EST Sun Feb 23 2025

Overall very little change from previous forecast thinking with
mainly quiet weather in the short term period. A series of
short waves will track across the region Monday through
Thursday with periodic chances of rain, but progressive nature
of this pattern will limit rainfall amounts.

A couple of low amplitude short waves noted this morning. The first
of these short waves is progressing across the southern Great Lakes
with a patch of low clouds that will be exiting to the eastern Great
Lakes next few hours. Another upstream short wave is evident on
water vapor imagery from the arrowhead of MN into south central
Ontario. Mid level warm advection forcing is preceding this upper
level wave, and strongest isentropic upglide in 290-285K layer
should work across central/southern Lower Michigan this
afternoon. Low level moisture quality will remain meager
however, so confidence in any precipitation as far south as
southern Lower Michigan remains very low. Given strength of
isentropic upglide and some amplification of mid level wave this
afternoon, there is some potential of a few light snow
showers/flurries across southern Lower Michigan later today.
This may end up being a virga scenario given dry low level
profiles so will continue to keep a dry forecast. Otherwise for
today, mid and high clouds are expected to overspread a good
portion of the area. with a period of mostly cloudy conditions.
Despite the increased cloud cover, strength of low level warm
advection should support highs on the order of 3 to 6 degrees
warmer than yesterday. Low level height gradient will remain
moderately strong today, but mixed layer depths will be more
shallow under the influence of warm advection that should limit
gusts to around 15-20 mph.

The active parade of short wave troughs will continue tonight into
Monday as next disturbance shifts across the northern Great Lakes.
This will allow a cold frontal boundary to settle across the Great
Lakes region into early Monday. A good deal of high clouds are
likely to linger into Monday, but low level thermal ridge preceding
this frontal boundary should be positioned favorably across the
local area for highs from the mid 40s to around 50. If better
insolation can be realized Monday, forecasted highs may be a bit
underdone.

The next chance of rain should arrive for Monday night as a 120 knot
Pacific jet streak noses into the southern Great Lakes. This short
wave will allow a low level trough to interact with the stalled
baroclinic zone for chances of light rain Monday night.
Moisture quality in this highly progressive pattern still looks
on the marginal side which supports only very light QPF for this
period.

Induced short wave upper ridging in advanced of stronger eastern
Pacific wave should allow for warmest days of this forecast period
on Tuesday and Wednesday as low level winds back more southwest.
Still some question as to the exact track and strength of
mid/upper level short wave on Wednesday, but thermally driven
low level height anomaly should track across the southern Great
Lakes during the Wednesday. High chance to low likely (50-65%)
PoPs still appear reasonable Wednesday given more pronounced
low level circulation with this feature providing better
opportunity for brief period of better low level moisture
transport/convergence. Progressive nature of system should limit
rainfall amounts to quarter of an inch or less.

A northwest flow wave is still expected to dig into the region in
the wake of this midweek system with gradual increase in low level
cold advection through next weekend. Departure of lead system
Wednesday night looks to leave limited low level in moisture in
place, so will continue to limit PoPs to slight chance (20%)
for late work week into early next weekend. Will keep trend to
temps back to near seasonable normals for next weekend, although
pattern could be conducive for brief intrusion of colder air
headed toward Sunday-Monday. GEFS large 10 to 90 percentile low
level temperature spreads highlight this uncertainty in
baroclinic zone placement toward the end of this forecast valid
period.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1233 PM EST Sun Feb 23 2025

A shortwave moves through the area early in the forecast period and
that will bring mid level cloud decks into Sunday. Still expecting
VFR through the bulk of that period, though. The one wrinkle will be
if we start getting dew points above 35F, we may be able to generate
some fog as snow melts. Snow could be too crusty and dry to generate
fog and we may be able to ventilate fog out if winds stay around 10
kts as they look to do. As such, given the potential negatives, will
leave this chance out of TAFs at this time. LLWS is generally
marginal and may struggle to occur at all, but wanted to make known
the possibility of it with inclusion in this TAF.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Marsili
AVIATION...Roller