Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 121033
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
633 AM EDT Tue Mar 12 2024

.KEY MESSAGES...

- Mild temperatures continue, with highs in the 50s and 60s
  through Friday, and then drop into the 40s and 50s on the
  weekend.

- Chances for showers and thunderstorms starting later tonight
  and continuing into Friday. A few strong to severe storms are
  possible on Thursday, mainly west of US 31. Confidence is low
  at this time.

- Colder temperatures with chances for snow return for the start
  of next week.

&&

.DISCUSSION...
Issued at 451 AM EDT Tue Mar 12 2024

Dry and breezy today, with partly to mostly sunny skies and highs in
the mid to upper 60s. Clouds will increase overnight into Wednesday,
with chances for showers and even a few thunderstorms late tonight
into Wednesday. Confidence in this period is extremely low--models
are really struggling with a little shortwave that makes a run at
our upper level ridge tonight/Wed. Models suggest anything from
completely dry all day to cloudy with numerous rain showers. I
suspect that the moisture is slightly overdone with the NAM (which
seems most aggressive in precipitation Wed, along with the FV3), and
that the shortwave may be weaker than it suggests-but think there
was enough confidence to warrant at least a 20-30 percent chance for
showers and some thunderstorms. If we do manage to pop some showers
as the NAM suggests, we`ll have around 300-600 J/kg sfc cape and 6.5-
7 C/km mid level lapse rates, so kept low chances for thunderstorms
in. Otherwise, expect another day with highs in the mid-upper 60s
(upper 50s near Lake MI), with partly to mostly cloudy skies.

Wednesday night into Thursday a warm front will lift northward
and settle somewhere over our CWA, with rain overspreading the
area. Steep mid level lapse rates and MUCAPE around 700 J/kg
warrant a chance for some thunder with this. By the afternoon
our area should be at least half way (if not completely) in the
warm sector ahead of the approaching surface low, with dewpoints
in the WSW reaching around 59-60 degrees. Our area remains at
the nose of strong moisture transport, with consistent ascent
through at least 15z on the 295K sfc. Models are still bouncing
around as to the exact evolution of the system, with some
lifting the warm front out of our area (and then having the
surface low/cold front into our western CWA by Thu eve) and
others keeping it anchored over our central CWA and having the
surface low move into the central CWA by early evening. I`m
uncertain if we will be unstable enough at the surface to get
any strong to severe storms with this-but we do have steeper mid
level lapse rates and a warm front, with 40-60 knots of bulk
effective shear (0-6km), and reasonable moisture, so it`s not
out of the question. I suspect if we do get any severe storms,
they will be west of US 31 further southwest in the late
afternoon/early evening hours-where the better surface
instability appears to materialize in many of the models
(400-800 J/kg)around the 18-21z time frame. Highs Thursday will
range from the mid-upper 50s and 60s.

Thursday night into Friday we will see continued chances for showers
and non-severe thunderstorms as the low exits the area, with
Thursday night lows in the 40s and Friday highs in the 50s. Winds
shift NW during the day on Friday, with gusts up to 25 mph possible.

A surface high will keep conditions dry on Saturday, with breezy
southwest winds and highs in the low to mid 50s. An upper low will
drop from northern Ontario into the Great Lakes starting Sunday and
lingering through Tuesday, bringing rain chances in for Saturday
night and Sunday. By Monday into Tuesday, highs will be in the 40s
and lows in the upper 20s and low 30s, so we`ll see chances for
snow.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 632 AM EDT Tue Mar 12 2024

VFR conditions will continue for this forecast period. KIWX VAD
profile indicates some weakening of low level west-
southwesterlies over the past few hours suggesting increasingly
more marginal LLWS setup. A few gusts to 20 knots will be
possible early this morning before gusts increase mid-late
morning to around 25 knots. Filling low pressure across the
Great Lakes this evening will continue to slacken low level
height gradient, with a rapid decrease in sfc wind gusts after
23Z. Passing high clouds today will transition to some mid level
cloudiness tonight as a mid/upper level short wave approaches
the Ohio Valley on Wednesday. Some elevated instability will
develop downstream of this feature which could promote a few
showers late tonight across NW IN, but will maintain dry TAFs
through this period as greater potential will likely remain
west/southwest of the local area.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 11 AM this morning to 8 PM EDT this
     evening for LMZ043-046.

&&

$$

DISCUSSION...MCD
AVIATION...Marsili


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