IND issues Area Forecast Discussion (AFD) at Jul 21, 9:16 AM EDT752
FXUS63 KIND 211316
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
916 AM EDT Tue Jul 21 2026
.KEY MESSAGES...
- Scattered thunderstorms possible today with the potential for
strong to severe storms, primarily across far SE portions of
central Indiana
- Damaging wind gusts are the primary threat, but large hail,
localized flooding, and an isolated tornado threat are also possible
- Noticeably cooler and less humid for the second half of the week
&&
.FORECAST UPDATE...
Issued at 916 AM EDT Tue Jul 21 2026
Surface analysis late this morning shows low pressure over northern
Ontario with a cold front that extended SW to NW Indiana and Central
IL. Water vapor imagery shows an associated deep upper trough over
Ontario, with a trough axis moving through the Great Lakes. Water
vapor shows some storm development beginning over northern Indiana on
the leading edge of some subsidence. Radar shows some scattered
precipitation ahead of the front over NW Central Indiana and across
northern Indiana. Mainly SW flow was in place across central Indiana
with high dew point values in the lower 70s.
The cold front is expected to progress southeast across Central
Indiana late this morning and this afternoon. The air mass ahead of
the front remains warm and humid, favorable for convective
development. Forecast soundings early this afternoon show favorable
CAPE ahead of the front along with high pwats over 1.9 inches. HRRR
continues to suggest convective development through the late morning
and early afternoon hours, particularly across eastern parts of
Central Indiana within the warm sector ahead of the front. Given
recent radar trends and the ingredients in place, thunderstorm
development is expected. Will focus high pops mainly across the east
and southeast parts of the forecast area. HIgh temperatures this
afternoon should be reached early, and precipitation and a change in
air mass should allow temperatures to fall back to the lower 80s in
the afternoon.
&&
.DISCUSSION (Today through Monday)...
Issued at 304 AM EDT Tue Jul 21 2026
Today through tonight...
Current KIND Radar imagery depicts quiet weather conditions across
central Indiana as weak surface ridging remains in place. Upstream
convection is ongoing across portions of MO/IL with an approaching
system. Look for the disturbance along with an associated cold front
to move in later today promoting scattered thunderstorm development,
primarily from mid-morning into the afternoon hours. Moderate to
strong destabilization ahead of the cold front and strengthening
deep-layer wind shear supports the potential for severe
thunderstorms.
Organized convection and supercells are expected with
effective shear values around 35-50 kt, mainly over southeast
portions of central Indiana as the cold front will likely move
through the northwest half of the forecast area before sufficient
destabilization occurs. Damaging wind gusts are the primary hazard,
but large hail, localized flooding, and an isolated tornado threat
also appear possible. Forecast soundings depict gradually veering
low-level hodographs during the afternoon hours while a LLJ pushes
through supporting the isolated tornado threat.
Look for the cold front and associated convection to quickly move
out by the early evening hours. Cold air advection from surface high
pressure building in behind the departing front will then promote
quiet weather conditions. Expect cooler temperatures in the low to
mid 60s overnight.
Wednesday through Friday night...
Another embedded shortwave and associated cold front will advect
even cooler-drier air into the area late Tuesday night into
Wednesday. Stronger surface high pressure building in favors quiet
weather conditions during the period. Expect an upper wave
approaching from the west on Friday to result in increasing mid-high
clouds. Most guidance suggest subsidence induced dry air from the
surface high should inhibit any precipitation chances from the
weakening disturbance so will keep the forecast dry. Look for
temperatures to remain cooler than normal with highs generally in
the 70s to near 80F.
Saturday through early next week...
Long range guidance depicts weak surface high pressure remaining the
dominant weather feature for much of the weekend providing mostly
quiet weather conditions. Aloft, northwesterly flow should allow for
a few shortwaves to pass through the region. These disturbances
along with deeper moisture advecting into central Indiana will
return low rain chances to the forecast at times late Sunday into
early next week.
Diverging model solutions leads to lower confidence in exact details
towards the end of the period. Widespread severe weather is not
expected at this time, but ensemble guidance suggest at least
moderate destabilization both Sunday and Monday afternoon. This
along with enhancement of mid-upper level flow from the passing
shortwaves could support a threat for severe weather. Uncertainty
will remain high until models become better aligned.
Warm air advection ahead of the aforementioned disturbances should
warm temperatures well into the 80s to possibly near 90F in some
spots Sunday and Monday.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 644 AM EDT Tue Jul 21 2026
Impacts:
- Chance for TSRA at KIND/KBMG within 14Z-19Z, where brief
MVFR/brief IFR will be possible
- Brief MVFR ceilings cannot be ruled out 12Z-18Z outside of
convection
- Winds gradually veering through the period, gusting 17-21 kt today
Discussion:
Mainly VFR to prevail over central Indiana terminals through most of
the TAF period with brief periods of MVFR possible within 12Z-18Z
from both lower ceilings and at times scattered convection near
KIND/KBMG, as slowly passing cold front -SHRA/isolated TSRA and
associated lower decks progress from NW to SE.
Winds will slowly increase through the day with sustained flow of 8-
14KT and gusts to 17-21 kt possible during the day. Winds then
diminish to 3-8KT by late this evening. Wind direction will veer
through the period.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Puma
AVIATION...Melo
DISCUSSION...Melo
Source:
IND issues Area Forecast Discussion (AFD) at Jul 21, 9:16 AM EDT---------------
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