IND issues Area Forecast Discussion (AFD) at Jul 12, 1:07 PM EDT591
FXUS63 KIND 121707
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
107 PM EDT Sun Jul 12 2026
.KEY MESSAGES...
- Low chance for a brief shower today across southern Indiana with
minimal thunder potential
- Breezy conditions expected today with wind gusts up to 20-25
mph
- Generally dry weather and a steady warming trend mid to late week
&&
.FORECAST UPDATE...
Issued at 932 AM EDT Sun Jul 12 2026
Forecast is in good shape this morning. Lower clouds were across
much of the southern third or so of the forecast area with some high
clouds farther north. This general setup will continue through the
day so just tweaked sky cover as needed.
With the upper trough just to the south of the area, can't rule out
an isolated shower across mainly the far south. Made some minor
adjustments to PoPs. Thunder cannot be ruled out, but odds are too
low at this time to include a mention.
Forecast high temperatures look good so made no changes.
&&
.DISCUSSION (Today through Saturday)...
Issued at 133 AM EDT Sun Jul 12 2026
Overview.
A weak, passing disturbance will bring a small chance for a light
shower today across southern Indiana, along with breezy conditions.
High pressure will then move into the region, bringing dry weather
for the majority of the upcoming week. Temperatures will steadily
climb each day, with highs in the 90s by mid-week.
Today Through Monday.
A weak mid-level shortwave and an associated surface trough will
track across the southern Great Lakes today. While low-level
moisture remains adequate, deeper saturation is lacking. Forecast
soundings reveal a weak capping inversion above the boundary layer
and poor mid-level lapse rates. Consequently, MLCAPE values are
projected to remain minimal except for southern Indiana, which will
significantly restrict updraft strength and prevent the deep
vertical cloud growth required for sufficient glaciation to create
lightning. Thunder potential is therefore too low to include in the
explicit forecast, with coverage of any light convective showers
remaining isolated to scattered. Breezy conditions will develop by
mid-morning as diurnal heating deepens the boundary layer. Mixing up
to approximately 850mb will tap into a 25 to 30 knot low-level wind
field, translating to sustained surface winds of 12 to 18 mph with
occasional gusts up to 25 mph from the northeast.
By tonight, the upper-level shortwave exits to the east, allowing
surface high pressure and a much drier air mass to advect into
central Indiana from the northwest. Strong large-scale subsidence
and a drying column will rapidly clear out any lingering
stratocumulus. Monday will feature pleasant, albeit warm conditions
with clear skies, light winds, and seasonal high temperatures in the
lower 80s as the core of the surface high settles over the Ohio
Valley.
Tuesday Through Saturday.
Long-term guidance from the GFS and ECMWF, along with their
respective ensemble suites, gives fairly high confidence in the
broader synoptic pattern through mid-week with broad ridging across
the Central Plains and broad troughing across the Eastern states.
Early in the period, the forecast area will sit on the eastern
periphery of a building central Plains ridge. By Wednesday and
Thursday, this expansive upper-level ridge is modeled to expand
eastward, with 500mb heights rising to around 592-594dam over
Indiana. Strong subsidence associated with this feature will
maintain dry conditions and suppress convective potential through at
least Thursday.
A pronounced warming trend will accompany this building ridge as low-
level flow shifts to the southwest, initiating strong warm air
advection. Ensemble means indicate 850mb temperatures climbing from
around 14C on Tuesday to near 21-23C by Friday. At the surface,
this will manifest as a steady climb in afternoon maximum
temperatures, starting in the mid-80s on Tuesday and reaching the
low to mid-90s by Friday and Saturday. As the ridge axis shifts
eastward, a return flow of Gulf moisture will push surface
dewpoints back into the upper 60s to lower 70s. This combination
of heat and humidity will likely produce peak heat index values
approaching 100 at times mid to late week. The next potential
breakdown of the ridge occurs late Friday into Saturday, as a
northern stream shortwave flattens the upper flow and drags a
weak, decaying frontal boundary toward the region, introducing
low-end chances for showers and thunderstorms.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 107 PM EDT Sun Jul 12 2026
Impacts:
- Gusty NE winds from 18-22 kts this afternoon
- Potential for patchy shallow fog at KLAF/KBMG Monday morning
Discussion:
Outside of gusty NE crosswinds at a few of the airports today,
aviation weather conditions will be fairly quiescent through the
period. Winds are expected to diminish quickly with onset of
nocturnal inversion around 00Z this evening.
Winds overnight will lighten to as low as 2-3 kts at KLAF/KBMG. With
clear skies, MIFG is possible at both sites after 08Z through 11Z.
However, confidence is not high enough to include in the TAFs.
Tomorrow will see a continuation of clear skies although a few mid
level clouds are possible during the afternoon. NE Winds will
increase to between 6-8 kts by midday and gusts should remain
under 15 kts.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...50
AVIATION...Crosbie
DISCUSSION...White
Source:
IND issues Area Forecast Discussion (AFD) at Jul 12, 1:07 PM EDT---------------
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