102
FXUS63 KIWX 131731
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
131 PM EDT Mon May 13 2024

.KEY MESSAGES...

- Showers and scattered storms arrive late today and persist
  Tuesday.

- Short break in the rain with dry weather Wednesday night and
  early Thursday followed by more chances for showers and storms
  through the weekend.

- Very warm Sunday with highs around 80, possibly reaching the
  mid 80s.


.DISCUSSION...
Issued at 335 AM EDT Mon May 13 2024

Mild but relatively dry low level flow early today at the onset will
become slightly more moist later today. Weak upper support and very
weak fgen/low level convergence was just enough to trigger/support
isolated showers/storms north of the Michigan border. High resolution
models/CAMs were having a hard time picking up this activity. Expect
the showers and isolated storms will move out of the area before
daybreak.

An upper level system had moved out of Colorado over the weekend and
was over Kansas early this morning. This upper low will drift east
ahead of an increasing moist environment. Precipitable water values
will rise to around 1.40". Very limited instability and lack of
low level shear will greatly limit any severe storm risk. The
activity should arrive late today and early tonight and persist
through Tuesday. A second upper level system will arrive later
in the week and bring additional chances for showers and storms
in generally the same environment of high precipitable water
values, low CAPE and limited shear. Locally heavy rain is likely
at times which will bring rises on rivers and possibly bring a
few of the more flashy rivers into action stage or minor flood
stage like North Manchester, Portland and Spy Run. The latest
OHRFC ensemble river forecasts using the GFS model favor several
rivers exceeding the action stage by late Sunday. Otherwise,
did raise blend highs for Sunday to around 80 with the potential
for highs to reach the mid 80s supported by the EC and GFS.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 123 PM EDT Mon May 13 2024

Steep lapse rates and influx of elevated moisture has resulted
in an expanding cu field across mainly western IN back into IL.
Handful of cells have managed to gain some strength and even
produce some lightning, but weak shear is setting the stage for
rather pulsy storms that are difficult to capture in TAFs. KSBN
seems to be in the favored path of development, resulting in a
continuation of a tempo group for thunder with mainly brief MVFR
vsbys. Will need to monitor trends prior to 00Z for possible
ramp up to more of a predominate forecast for the activity.
Leaving KFWA dry for now through 00Z, but will monitor trends as
well.

Past 00Z, better coverage should begin to materialize across
the area with tempo thunder at KSBN maybe more questionable
given loss of heating and potential that any storms this
afternoon could reduce instability and limit lightning. No
changes for now.

Confidence is not overly high on how low cigs will drop late
tonight into Tuesday or if showers will last beyond 8 or 9Z.
Minor tweaks made but will let later forecasts hone in on
things.



&&

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

&&

$$

DISCUSSION...Skipper
AVIATION...Fisher