095
FXUS63 KIND 211800
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
200 PM EDT Sat Mar 21 2026

.KEY MESSAGES...

- Above normal temperatures through Sunday

- Showers and thunderstorms possible on Sunday night mainly south of
  I-70. Isolated severe storms cannot be ruled out.

- Cooler on Monday with a warming trend through the workweek.

&&

.SHORT TERM (This evening through Monday Night)...
Issued at 159 PM EDT Sat Mar 21 2026

Surface Analysis early this afternoon shows high pressure over the
eastern Ontario and Western Quebec. Low pressure was found over MN.
Another area of high pressure was found over the gulf coast. A weak
frontal boundary over northern KY was pushing northward. This was
resulting a cool SE flow across central Indiana, for the moment, but
winds were expected to become southwesterly later this afternoon.
Satellite imagery shows mainly high clouds due to Pacific moisture
streaming across Indiana from the NW, but these clouds were exiting
east as ridging over the western CONUS was shifting east and
flattening somewhat.  High clouds were following the upper jet as
seen on water vapor. Dew points across Indiana were in the 40s.

Tonight...

Quiet weather is expected tonight as the low pressure system to the
north is expected to continue east, reaching the eastern Great Lakes
by Sunday morning. A trailing cold front will begin to sag into NW
Indiana by Sunday morning. Warm southwest flow is expected to remain
in place overnight, as models show a thermal ridge settling across
Indiana. Forecast soundings remain dry through and skies should
remain mostly clear. Good mixing due to pressure gradient winds will
prevent radiational cooling. This along with the thermal ridge in
place will result in lows in the upper 50s to around 60.

Sunday and Sunday Night...

The day will remain dry on Sunday, however showers and thunderstorms
will be possible across the southern half of Central Indiana on
Sunday night. The previously mentioned cold front will sag across
Indiana through the day, reaching south of I-70 by Sunday night.
Prior to the is time, little to no upper support is found within the
flow aloft. This will lead to much of Sunday just remaining partly
sunny, and still warm as the thermal ridge will be slowly edging
southward through the day ahead of the cold front. Looks for a wide
range of high temperatures across Indiana on Sunday, ranging from
the upper 60s across the northwest to around 80 southeast.

By Sunday night, a broad upper level wave is expected to arrive
within the NW flow aloft. This will act as an additional trigger for
forcing across the area. At that point the cold front and warm
sector will be found just south of I-70, and evening showers and
thunderstorm chances will be found there. HRRR shows Storm
development during the early evening hours as the front sags
southward. Forecast soundings suggest shallow CAPE but pwats remain
over 1.3 inches. Thus chances will be needed on Sunday evening ahead
of the cold front. Dry weather will arrive overnight in the wake of
the front as subsidence arrives and the upper forcing departs to the
east. Strong cold air advection will remain a factor on Sunday night
as 850 mb temps fall to near 2C by 12Z Monday. This will result in a
much colder Monday morning with lows in the low to middle 30s. Thus
Pops will only be included in the south half of Indiana in the
evening. Isolated Severe storms cannot be ruled out at this point on
Sunday night with damaging wind and large hail the main threats.

Monday and Monday Night...

Dry and more seasonable weather is expected on Monday and Monday
night. NW flow looks to remain predominate within the upper levels
with little to no forcing passing. This will be a continuation the
mild Pacific air streaming to Indiana aloft, keeping any arctic
intrusions at bay. Meanwhile within the lower levels subsidence is
predominate, with ridging in the mid levels and high pressure
arriving at the surface. Thus this will lead to a mostly sunny
Monday and mostly clear Monday night.

&&

.LONG TERM (Tuesday through Saturday)...
Issued at 159 PM EDT Sat Mar 21 2026

Tuesday Through Saturday.

The long term period for the central Indiana is characterized by a
transition from an unseasonably warm, ridge-dominated pattern to a
more active, progressive synoptic regime. By Tuesday night into
Wednesday, the dominant upper-level ridging currently over the
central U.S. begins to deamplify and shift eastward. While this
transition initially maintains above-normal 500mb heights and mild
surface temperatures, it opens the door for a series of shortwave
troughs embedded within the broad northwesterly to zonal flow aloft.

Surface conditions on Wednesday and Thursday will be defined by
persistent southerly flow on the western periphery of a departing
surface high, leading to efficient WAA. Forecast guidance suggests
temperatures will remain well above seasonal normals, with highs
potentially reaching back into the 70s depending on the degree of
boundary layer mixing and cloud cover. However, a more potent mid-
latitude cyclone is progged to track from the Pacific Northwest
toward the Great Lakes by late Thursday or early Friday.

The primary scientific challenge in this timeframe involves the
timing and moisture recovery associated with an approaching cold
front late in the week. By Friday into Saturday, as the surface low
reinvigorates over the Great Lakes and Ohio Valley, a tightening
baroclinic zone will drive a significant cold front through central
Indiana. Atmospheric profiles indicate that while deep-layer shear
will be ample for organized convection, the quality of low-level
moisture return from the Gulf remains a point of uncertainty. If
sufficient dewpoint recovery occurs ahead of the frontal passage, a
round of showers and perhaps isolated thunderstorms would be likely.

Alternate scenarios center on the exact speed and depth of this late-
week trough. A faster, more progressive solution favored by some
ensemble members would limit the duration of the pre-frontal warm
sector, resulting in a drier and quicker transition to cooler air by
Saturday. Conversely, a slower, more amplified trough would allow
for more substantial moisture flux and potentially a more robust
severe weather threat, given the favorable kinematic environment
often present in these late-March transitions. Regardless of
precipitation, a notable airmass change is expected by Saturday,
with temperatures trending back toward or slightly below
climatological normals as surface high pressure descends from Canada.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 1246 PM EDT Sat Mar 21 2026

Impacts:

- VFR Conditions this TAF period

Discussion:

VFR conditions are expected this TAF period. Surface low pressure is
expected to push across the Great Lakes as high pressure remains
across the deep south. Meanwhile the upper flow is expected to
flatten, allowing only high Pacific moisture across our area.

Thus only some passing high clouds will be expected this afternoon
as the lower level flow becomes more westerly.

A cold front trailing the low will pass across Indiana on Sunday.


&&

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

$$

SHORT TERM...Puma
LONG TERM...White
AVIATION...Puma