-- Discussion containing changed information from previous version are highlighted. --
706
FXUS63 KIND 120103 AAA
AFDIND

Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
903 PM EDT Sat May 11 2024

.KEY MESSAGES...

- Wind gusts of 30-35 mph diminish by early evening
- Showers and storms return Monday into Monday night
- Near normal temperatures for next week

&&

.FORECAST UPDATE...
-- Changed Discussion --
Issued at 903 PM EDT Sat May 11 2024

Minimal changes for the evening update. Split flow pattern with
progressive low-amplitude shortwave troughs is in place. Modest high-
level moisture within the northern stream over us will be
responsible for some thin cirrus tonight. On the northern periphery
of MSLP high, radiative conditions will be enough for a shallow
inversion. High res models are a little colder, naturally in this
setup, so we`ve nudged temperatures downward slightly tonight.
-- End Changed Discussion --

&&

.SHORT TERM (This evening through Sunday)...
Issued at 258 PM EDT Sat May 11 2024

Rest of This Afternoon...

Breezy conditions will persist as steep lapse rates allow for good
mixing. Gusts up to around 35 mph will gradually diminish late as
mixing begins to wane.

Cumulus will continue, especially north in the cooler air aloft. The
clouds will spread out and gradually start to dissipate late this
afternoon.

Mixing will keep dewpoints near the model 10th percentile leading to
low relative humidity, but a moist ground will limit fire weather
concerns.

Tonight...

Quiet weather will continue tonight with surface high pressure
nosing into the area from the south. Winds will diminish with
loss of mixing and with the high nosing in.

Leftover cumulus will gradually dissipate this evening. There may be
a few passing mid or high clouds, but the night should average out
mostly clear.

The mostly clear skies and light winds will allow temperatures to
fall into the upper 40s and lower 50s for lows.

Sunday...

The high pressure ridge will slide to the east, allowing winds to
become southwest. This will allow some increase in low level
moisture, but models are likely overdoing it since there will be
continued good mixing in the afternoon.

Even with the mixing, winds will not be as strong as Saturday with
lighter winds aloft and a more relaxed pressure gradient.

Some models are seeing the steep lapse rates and low level moisture,
perhaps along with some weak upper energy, and are producing some
showers late Sunday afternoon. As noted earlier, believe models are
overdoing the moisture return, so will keep a dry forecast for now.

Sunshine plus the return of southwest flow will lead to highs in the
mid 70s to around 80.

&&

.LONG TERM (Sunday night through Saturday)...
Issued at 258 PM EDT Sat May 11 2024

An active weather pattern continues into next week with multiple
chances for additional rain and thunderstorms. It won`t be a
complete washout of a week though with a couple dry days in between
systems. While there will be rain and storm chances throughout the
extended, the threat for severe weather appears much lower than it
has been over the past week.

Monday and Tuesday...

Another warm day expected Monday; however an approaching trough and
associated surface low over Kansas will bring the next chance for
rain across the region. Increasing moisture advection through the
column and lift ahead of the system will result in increasing clouds
Monday with rain beginning to develop during the afternoon and
evening hours. Currently some discrepancies among guidance with
timing of arrival for precipitation with the GFS bringing in rain by
early Monday afternoon and the EC holding off until Monday night.
Will have to watch how much dry air mixes down to the surface Sunday
and how quickly the column saturates on Monday. Historically, models
are too quick to saturate the column after a few days of dry weather
and bring in rainfall too early at times. This would also affect
high temperatures, with a later arrival of rain allowing for more
daytime heating. With what said, latest model trends have slowed
down the time of arrival for rainfall across Central Indiana.
Confidence is rising in a drier, yet still cloudy, forecast for
Monday with heavier, more widespread showers moving in late
afternoon and into the evening hours.

Model soundings show very skinny, elevated CAPE Monday night with
better instability values on Tuesday in the immediate vicinity of
the surface low. Lightning will likely be few and far between
initially with the best chance for any thunder and lightning closer
to the surface low Tuesday afternoon in South Central Indiana.

Model soundings show PW values rising to between 1.25 and 1.50
inches late Monday night into Tuesday with deep moisture present
throughout the depth of the column. The setup supports the potential
for non-uniform pockets of moderate to heavy rainfall, particularly
on Tuesday with any slow moving convection. Ensemble means show
around an inch of rainfall is possible through late Tuesday night
across Indiana with 90th percentile totals nearing 1.80" across
portions of Western and SW Indiana. So values over an inch appear
certainly probably in this scenario, especially for areas that get
repeated heavier showers. South Central Indiana looks to have a
better potential for those higher rainfall totals being closer to
the low and having better moisture advection and higher instability
values.

Despite increased clouds, warm air advection ahead of the system
will support highs in the 70s on Monday, with the potential for a
few areas to near the 80 degree mark if rain holds off until the
evening and nighttime hours. Expect Tuesday to be a little cooler in
the mid 60s to lower 70s due to more widespread showers and storms.

Wednesday and Thursday...

Troughing begins to slide eastward on Wednesday while ridging builds
back in over the Midwest. With high pressure settling in from the NW
Wednesday morning and the trough still influencing weather locally,
low stratus and fog may stick around through at least Wednesday
morning as moisture is trapped under a subsidence inversion. Expect
a drying trend through the day Wednesday persisting into Thursday
with highs still near to above average in the low to mid 70s.
High
pressure centered over Southern Canada and the Northeast CONUS will
result in another mainly dry day on Thursday for Indiana. Went below
guidance for PoPs Thursday afternoon as the NBM brings in low
chances for precip too early with the best forcing and moisture
return well west of the state in Missouri. Going with a drier and
warmer forecast for Thursday with highs potentially reaching the 80
degree mark once again for South Central Indiana.

Friday into Next Weekend...

Another deep trough and potent storm system is expected to develop
and push into the region Friday into Saturday bringing another round
of unsettled weather conditions. Longer range guidance diverges
quite a bit on the exact evolution of the system, timing, and track.
Despite lower confidence in details, ensembles have been consistent
in showing signals for a strong storm system during this time frame
potentially leading to another round of showers and thunderstorms
and cooler weather on the backside of it. Will be watching this
timeframe closely through the week as details become clearer on the
evolution of things and associated impacts.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 724 PM EDT Sat May 11 2024

Impacts:

- Trend toward southwesterly winds tomorrow

Discussion:

VFR conditions will prevail. Cumulus and wind gusts are decreasing
now with decreasing diurnal heating/mixing. Some cirrus may move in
tomorrow (Sunday) and winds will shift to southwesterly but be
lighter than we experienced today.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

UPDATE...BRB
SHORT TERM...50
LONG TERM...CM
AVIATION...BRB