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258
FXUS63 KIWX 240548
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
148 AM EDT Fri May 24 2024

.KEY MESSAGES...

- Driest periods of the holiday weekend look to be through
  Friday afternoon and again Saturday into early Sunday.

- Shower and thunderstorm chances return Friday afternoon end
  evening with a strong to possible severe storms west of
  Indiana 15/US 131.

- Greater chances for showers and thunderstorms Sunday
  afternoon and night with both severe storms and possibly heavy
  rain/hydro issues existing.

- Lingering showers may impact activities on Memorial Day and
  Tuesday.

&&

.DISCUSSION...
Issued at 214 PM EDT Thu May 23 2024

An overall active pattern remains in place for the next week or so
with a few quiet periods expected in between systems. The first of
these us underway with high pressure bringing clear skies and
pleasant temperatures/humidity to the area.

The first feature to monitor will be an upper level trough that will
quickly shift east towards the region to start out the holiday
weekend. The trough and associated cold front will spark a line of
strong to severe storms across Nebraska later today which will race
east and reach western IL sometime during the first part of Friday.
From here models diverge on handling of the remnants of the complex
as well as potential new development on the cold front. The MCS will
likely weaken somewhat as it enters IL, but plenty of sunshine ahead
of it and increasing low level moisture should bring in 1K to 2K
J/KG of MUCAPE into eastern IL/western IN by late afternoon to
support re-intensification with a ramp up in the damaging wind
threat if it can organize and possibly be aided by any MCV left
over. Equally plausible is complex moves through faster with
cloud cover holding on and limiting instability over our area.
500/300 mb jet streak remains to the SW and main trough will
eject into WI, limiting overall strength of the line as well.
NAM suite and 12Z HRRR remain the most aggressive on severe
potential with a pronounced rise/fall couplet in the NAM
suggesting strong wind potential. Bit concerned that with the
lack of overall stronger wind fields in place (rather weak
shear) this could be some convective contamination, but could
also be a reflection of an MCV. For the time being, the slight
risk for the western half is warranted with a decreasing trend
likely to happen with eastern extent (unless the line becomes
well established and early enough). Some scattered showers could
occur on the cold front itself overnight. Categorical pops were
inherited and for now will be maintained for collaboration as
well as chance that convection does survive into the area with
great enough coverage to warrant it.

Saturday and Saturday night will be the nicest of the days for this
weekend with a stronger system in the offing for Sunday with some
lingering effects into Monday and Tuesday. Strong trough will move
towards IL Sunday afternoon, deepening further and closing off an
upper low over N WI by 6Z Mon. Low pressure will develop with
original model trends track the low across the NW part of our area
Sunday night. A few of the 12Z solutions track the sfc low a bit
further northwest. Regardless, abundant moisture will be drawn north
into the area with increasing instability and shear to bring a risk
for not only severe weather (possibly all modes), but also hydro
issues. We will continue to monitor trends as models struggling (as
expected) with evolution of convection along the warm front and
eventual cold front.

Clouds may linger on Memorial Day and beyond with the potential for
some showers around as the overall trough remains across the
region.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
-- Changed Discussion --
Issued at 144 AM EDT Fri May 24 2024

Predominantly VFR conditions at the TAF sites outside of
potential MVFR/IFR with any showers and thunderstorms that move
through after 00z. Most of the model guidance keeps KSBN dry
until 2z, but there are a few stragglers that suggest earlier
timing (more like 22-01z). Added VCTS for 1z onward, with a
prob30 to account for potentially impactful showers/storms that
arrive with a frontal boundary. Similarly, most of guidance
(with the exception of the RAP) keep precipitation out of KFWA
until after 3z, so have added VCSH for now. Held off on thunder
mention given low confidence (may be closer to 6-7z when storms
arrive). Otherwise, light and variable flow will strengthen out
of the ESE and gradually shift southward through the evening.
-- End Changed Discussion --

&&

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

&&

$$

DISCUSSION...Fisher
AVIATION...MCD