539
FXUS63 KIND 210712
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
312 AM EDT Sat Mar 21 2026

.KEY MESSAGES...

- Above normal temperatures through the weekend, with near record
  highs on Sunday

- Showers and thunderstorms possible on Sunday, a few strong to
  severe storms cannot be ruled out.

- Mostly dry and warmer than average conditions expected next week.

&&

.SHORT TERM (Today and tonight)...
Issued at 312 AM EDT Sat Mar 21 2026

A cold front passed through yesterday evening with brisk northerly
winds. These winds are already diminishing as surface high pressure
moves in overhead. By morning, high pressure will already be passing
to our east with winds becoming southerly.

A surface low, embedded within northwesterly flow aloft, approaches
from the northwest this afternoon. An increasing MSLP gradient ahead
of this feature should promote increasing winds and warm air
advection through the day today.

High cloud cover associated with a subtle vort max aloft may linger
into the morning hours, but should diminish with time. Mainly clear
skies are anticipated during the afternoon hours. This should allow
for efficient diurnal mixing. Combined with the warm air advection,
temperatures likely trend higher than guidance similar to previous
days. Our forecast will reflect this, with highs in the mid to upper
70s for the majority of our CWA.

A potent low-level jet develops overnight as the aforementioned low
makes its approach. A persistent breeze at the surface likely limits
the effectiveness of radiational cooling overnight. With continued
warm air advection, low temperatures are expected to be quite warm
with readings falling to near 60 for most.

&&

.LONG TERM (Sunday through Friday)...
Issued at 312 AM EDT Sat Mar 21 2026

Our attention continues to be focused on Sunday with the surface low
mentioned in the short term. This system becomes rather disorganized
as it moves southeastward, elongating into a broad surface trough
extending from Texas to Pennsylvania. Of particular interest is the
system`s cold front which may be quite strong.

SUNDAY TEMPERATURES

Focusing on the cold front first, we`ll take a look at expected
temperatures on Sunday. The air mass ahead of the front is warm with
850mb temps near 18-20 degrees. Assuming ideal adiabatic mixing,
this would place high temperatures into the 80s. However, the high
temperature forecast tomorrow is tricky due to the approaching
front. Guidance has trended a bit faster with the front arriving
across our northern counties as early as 21z.

This would limit how long these locations have to warm up before the
front arrives. In the scenario of a faster front, temperatures
failing to climb out of the 60s is possible. The greatest likelihood
of high temperatures below 70 are from Lafayette to Kokomo and
points northwestward. Further south, a rapid warm up under mostly
sunny skies is expected. Diurnal mixing may be very efficient, with
surface temperatures reaching their full potential. As such, highs
in the 80s are likely. A few locations may even climb into the mid
to upper 80s, especially further south and west.

SUNDAY THUNDERSTORM POTENTIAL

Next, we will take a look at the potential for showers and
thunderstorms with the approaching front. Since guidance has trended
towards a slightly faster front, our threat for storms has shifted
southward. The threat remains conditional, as forcing aloft is
subtle at best...confined to slightly favorable jet dynamics. At the
surface, the strong cold front will act at the primary forcing
mechanism. However, this brings about its own problem as the mean
flow is east-southeasterly and the front is moving due south. Given
the strength of the front, it may quickly undercut developing
updrafts and prevent them from reaching maturity.

However, given tall and wide CAPE profiles, this may not be a huge
issue for storm potential. As long as a few updrafts can sustain,
they may simply become elevated and continue to mature within the
unstable air above the shallow surface front. Storms that do form
would have ample shear to work with, and so severe weather would be
possible even with elevated storms. Shear profiles show long curved
hodographs. However, if storms are not surface based then the
effective shear profile becomes rather straight. As such, large to
very large hail would be the primary hazard. Strong wind gusts are
possible as well, since downdrafts may still be able to penetrate
the shallow surface cold layer via momentum. The most probable
timing would be late afternoon into the early evening hours.

Gusty gradient winds between 25-35 mph are expected behind the
front.

NEXT WEEK

Anomalous ridging out west continues to dominate the large-scale
pattern. Our weather is therefore expected to be similar to recent
days with broad northwesterly flow aloft and southerly flow at the
surface. Overall, warmer-than-average temperatures and dry
conditions are favored. Occasional systems embedded within the
northwesterly flow may periodically drag a cold front across the
region leading to brief cool-downs. Showers and thunderstorms may
accompany these fronts but that depends on the quality of moisture
return prior.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 134 AM EDT Sat Mar 21 2026

Impacts:

- Generally light winds veering from NNE to ESE by 14Z Saturday
- Winds continuing to veer through midday/afternoon hours, to SSW,
  while increasing slightly

Discussion:

VFR conditions to prevail through Saturday night over central
Indiana terminals.  TAF period starts with weak cool frontal zone
stretched over the region...which overall zonal pattern will quickly
return northward during morning and midday hours.  Mainly dry column
and better Gulf moisture staying south of the Ohio River will
promote mainly high cloud into late Saturday night.

Generally lighter winds will veer from north-northeast to easterly
by 13Z and southerly by 18Z...with 190-230 degrees prevailing
Saturday evening and overnight.  Winds sustained around 5-10KT on
Saturday after 14Z.


&&

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

$$

SHORT TERM...Eckhoff
LONG TERM...Eckhoff
AVIATION...AGM