000
FXUS63 KIWX 171039
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
639 AM EDT Sat May 17 2025

.KEY MESSAGES...

- Today will be cool, cloudy, and breezy with highs in the mid
  60s.

- Sunshine returns on Sunday but cool temperatures remain.

- Widespread rain is expected Tuesday and Wednesday.

&&

.DISCUSSION...
Issued at 246 AM EDT Sat May 17 2025

Postfrontal CAA now well underway with 850mb temps dropping into the
low single digits in the wake of slowly departing mid/upper low.
Persistent low level cyclonic flow could support a few sprinkles in
our N/NE zones at times today but expect only trace amounts with
most of our area remaining entirely dry. Biggest sensible weather
impact today will be ample clouds due to residual boundary layer
moisture in CAA regime as well as some gusty winds. Despite expected
cloud cover, still expect decent mixing with momentum transfer from
forecast soundings suggesting frequent 30-35mph gusts. Calendar-day
highs likely already reached with afternoon temps probably topping
out in the mid 60s...roughly 5-10 degrees below normal. Overall not
a great weather day. Sunday will be much better with less clouds,
less wind and highs a few degrees warmer away from the lake.

A large upper low is expected to develop over the Rockies late this
weekend and eventually eject eastward during the middle of next week.
There remain some important track details to work out given a fairly
complicated interaction with persistent Quebec trough/upper low. No
major changes to NBM initialization which was in line with previous
forecast in showing high PoP`s mainly Tue into Wed. A few embedded
thunderstorms remain possible but the risk of severe weather is low
given limited instability north of low track. Exact rainfall amounts
highly uncertain at this range but not expected to cause any
flooding given recent (mainly) dry conditions. This pattern will
also support highs well below normal (low/mid 60s) for much of next
week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 639 AM EDT Sat May 17 2025

An upper low passes by to the north of the area and heads towards
the northeastern US. Behind a cold FROPA, some 850 mb moisture
lingers starting around sunrise into daytime. LAV guidance has some
MVFR CIGs, but the height of the moisture appears to be just a
little too high for complete confidence in MVFR CIGs. Tracing back
the location of MVFR CIGs advecting in does show that those CIGs do
exist across WI so that increases confidence. Therefore, will
include in these TAFs, but there is a chance that they could be
pulled in the 12z TAFs. Otherwise, expect southwest winds to slowly
veer towards westerly by the end of the TAF period and 20 to 30 kt
wind gusts to be experienced.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LMZ043-
     046.

&&

$$

DISCUSSION...AGD
AVIATION...Roller