599
FXUS63 KIND 090645
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
245 AM EDT Wed Jul 9 2025

.KEY MESSAGES...

- Scattered storms today with best chances across the southeast
  half of central Indiana

- Generally very warm/humid through this weekend...greatest rain/
  storm chances on Saturday...not as humid Sunday

&&

.SHORT TERM (Today and Tonight)...
Issued at 245 AM EDT Wed Jul 9 2025

Remnant pockets of showers continue to drift across the northern
Wabash Valley southwest into eastern Illinois in tandem with an
upper level wave and a weak surface front. The airmass remained dry
below 10kft over much of the region with mid level clouds
increasing. 06Z temperatures ranged from the upper 60s to the mid
70s.

The aforementioned upper wave and surface boundary will track across
the region today and provide at least the opportunity for scattered
convective development with a moist and unstable airmass across
central Indiana. As this shifts off to the east this evening... weak
high pressure will expand into the area with slightly drier air.

Cannot rule out isolated showers continuing to develop across the
northwest half of the forecast area through much of the morning but
the current ACARS sounding at KIND highlights the problems in the
lower levels of the atmosphere that will likely limit if not
completely mitigate convective development over the next several
hours. Mainly...the air remains dry up into the 600-500mb layer with
negligent instability. Much of the better forcing aloft is displaced
to the north across lower Michigan as well. Will maintain low pops
through late morning but most locations will remain dry due to the
extenuating factors above.

Low level moisture will improve this afternoon along and ahead of
the front as it moves into the forecast area and this will aid in
MLCAPES peaking at near 2000 j/kg. But the forcing aloft will remain
weak with little to near shear as well. This will likely keep
convection in a scattered and disorganized state focused especially
across the southeast half of the forecast area ahead of the
boundary. Once again as has been the case for the last several
days...primary threats from convection this afternoon will be brief
and localized heavy rainfall and cloud to ground lightning.

Convection will linger into the evening across eastern counties
before departing to the east as weak high pressure expands south
from the western Great Lakes. Despite dry air advecting in
overnight...potential for patchy fog will exist in the predawn hours
Thursday as winds lighten to near calm levels and skies clear.

Temps...low level thermals support mid 80s across the forecast area
today. With the arrival of a slightly drier airmass tonight...lows
will fall into the mid and upper 60s.

&&

.LONG TERM (Thursday through Tuesday)...
Issued at 245 AM EDT Wed Jul 9 2025

Overall typical midsummer weather is expected through the long term
as generally very warm and humid conditions with scattered diurnally-
driven convection...surround a couple rather brief less humid and
mainly rain-free periods.  Synoptically, North America will be more
trough dominant, although only along the Canadian border and
north...while any attempts of the southern subtropical ridge to
regain momentum is suppressed to the southwestern CONUS through at
least this weekend. In between these features, weak zonal flow will
carry embedded small weaknesses into the Midwest through Saturday...
before light southwest flow tries to quietly build the ridge towards
Indiana, bringing a marginally-hot set-up around next Monday and
onward.

This will all translate to more early mornings usually starting in
the upper 60s/lower 70s, with higher humidity capping diurnal
spreads up to around 85-90F.  Maximum afternoon heat indices usually
in the upper 80s to mid-90s...may approach 100F on Saturday, and
again at the end of the long term.  Widely scattered afternoon/
evening showers and thunderstorms will be the rule most days...while
occasional modest wind shear may promote a few stronger storms. Best
opportunity for greater coverage of rain/storms will be around the
Saturday period when a more amplified northern wave should drag a
weak cold front across the region. Milder and less humid conditions
will hopefully accompany subtle drops in heights/H850 temperatures/
precipitable water both at the start of the long term and then
through the latter half of the weekend, when several northern zones
may observe a tandem of overnights dropping into the mid-60s.
Indianapolis` normal max/min will maintain the year`s peak values
through July 22...85/67.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1244 AM EDT Wed Jul 9 2025

Impacts:

- Brief MVFR visibilities near daybreak possible in fog
- Scattered thunderstorms possible this afternoon, but too low
  probability for mention at this time

Discussion:

Showers continue to diminish over the northern Wabash Valley early
this morning with much drier air across the region. Other than a
stray light shower...expect largely dry conditions through daybreak.
Patchy fog remains a possibility at the outlying terminals in the
predawn hours...but the expansion of mid level clouds into the
region should mitigate this threat to some degree despite ample
moisture lingering near the surface.

An upper wave and weak surface boundary will cross central Indiana
later today and will likely spark scattered convection potentially
as early as later this morning continuing into the afternoon.
Overall coverage is expected to remain too low to even include
PROB30s at this time. Diurnal cu will again develop into the
afternoon before diminishing this evening as slightly drier air
arrives in the wake of the weak frontal passage.

Winds will be light through the forecast period...gradually
transitioning to W/NW this evening.

&&

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

&&

$$

SHORT TERM...Ryan
LONG TERM...AGM
AVIATION...Ryan