602
FXUS63 KIND 081351
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
951 AM EDT Fri Aug 8 2025

.KEY MESSAGES...

- Dry, warm and humid conditions continue through the weekend

- Shower and thunderstorm chances return for much of next week with
  muggy conditions persisting

&&

.FORECAST UPDATE...
Issued at 951 AM EDT Fri Aug 8 2025

Forecast is in good shape this morning. Fog has mixed out. Some
cirrus was moving through parts of the area, but skies were sunny to
mostly sunny.

Made some minor adjustments to hourly forecasts based on trends seen
in surface observations and satellite, but no significant changes
were made to the forecast. Will have to keep an eye on the upstream
cirrus from convection well to the northwest to see if it holds
together for potentially more sky cover this afternoon.

Increasing mid-level temperatures will help prevent convection
today, but still cannot rule out an isolated shower or storm. Odds
continue to be too low to mention in the forecast though.

&&

.SHORT TERM (Today and Tonight)...
Issued at 244 AM EDT Fri Aug 8 2025

Skies were mainly clear early this morning as ridging aloft to the
west continues to expand towards the Ohio Valley. Have already seen
localized fog in a few spots and expect that to increase in coverage
a bit through daybreak. 06Z temperatures were ranged from the upper
60s to the mid 70s.

A sharp upper level low tracking across western Canada just north of
the US border will aid in enabling the persistent upper ridge over
the southern Rockies to expand east through tonight with heights
aloft rising through the course of the day. This will promote a
greater level of subsidence across the region which should further
limit overall convective development focused during the afternoon
and early evening.

As mentioned above...skies will remain mostly clear through daybreak
and with stagnant flow within the boundary layer anticipate a
gradual expansion to ongoing patchy fog...especially across the
southern and western portions of the forecast area. Any locations
that received rainfall on Thursday will also be increasingly
susceptible for fog through daybreak. Fog will diminish quickly
after sunrise setting the table for a warm and humid day for central
Indiana.

There remains a non-zero threat for a stray shower or thunderstorm
during peak heating...but model soundings show a strengthening mid
level cap which combined with the warmer air aloft will largely
place a lid on any convection. Coverage will only be 5% to 10% at
best and will maintain a dry forecast for the entire area. Quiet but
muggy conditions are then again expected for tonight.

Temps...low level thermals support highs similar to Thursday in the
upper 80s and lower 90s. The presence of subsidence in the mid
levels may enable slightly drier air to be brought to the surface
during the afternoon. Peak heat indices should remain in the low to
mid 90s. Lows tonight will drop into the upper 60s and lower 70s.

&&

.LONG TERM (Saturday through Thursday)...
Issued at 244 AM EDT Fri Aug 8 2025

The upper low tracking across the Canadian prairies will be blocked
from making it much further east than the northern Plains by strong
ridging over the eastern part of the country. The ridging will move
little into early next week maintaining a very warm and humid
airmass across the Ohio Valley with little to no threat for
convection. As the week progresses though...the upper level flow
will transition to more of a quasi-zonal regime which will enable
weak waves aloft to drop further south into the region and introduce
a better chance for scattered convection beginning Tuesday and
continuing for much of the rest of next week.

Saturday through Monday Night

Ridging aloft and at the surface will remain the primary features
influencing the weather across the Ohio Valley through the
weekend...and keeping the upper low and subsequent trough locked in
place across the northern and central Plains. This will leave a
typical humid midsummer airmass across central Indiana with daily
highs/lows within a few degrees either side of 90 and 70 degrees
respectively. The heating will breed moderate instability levels
each day through Monday despite the lingering mid level cap. Similar
to today...there will be a nonzero convective threat but it will be
difficult to see much more than a few stray showers or storms
considering the mitigating factors mentioned above. Will continue
with a dry forecast Saturday and Sunday but as the cap weakens
slightly by Monday...low chance pops for isolated storms will be
introduced.

One item to keep an eye on though will be the potential development
of a convective cluster over the upper Midwest on Saturday that
could drop into northern Illinois by the evening. The bulk of the
convection would likely migrate south or even southwest into
Saturday night following the deeper instability and riding along the
nose of the low level jet. While this would not directly impact the
forecast area...there could be a remnant outflow from the complex
that makes it this far southeast on Sunday to give a bit of an
assist to any isolated convective development for the afternoon.

Tuesday through Thursday

The flattening of the upper level flow will enable the perturbations
aloft to make a further south track into the region and bring a
daily threat for isolated to scattered convection each day. The main
convective risks through the period will again be on heavy rainfall
and localized flooding as a lack of substantial shear will ensure
slow movement to storms that will pulse up and down in intensity.
There is always the potential for a cell to strengthen enough
briefly to produce localized downbursts as the cores collapse but
that is likely to remain a secondary concern through late next week.

The airmass will remain warm...muggy and stagnant through much of
next week with highs in the mid and upper 80s and dewpoints likely
creeping up a bit into the lower 70s. There are growing signals that
this may continue right through next weekend and potentially even
beyond with cooler and drier air being held well north of the region.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 539 AM EDT Fri Aug 8 2025

Impacts:

- Fog early this morning and again predawn Saturday, mainly at KBMG
  and KHUF

Discussion:

Calm winds and mainly clear skies combined with deeper moisture in
the near surface layer has led to shallow ground fog with
oscillating visibilities to under 1SM at both KBMG and KHUF for most
of the overnight. Reduced visibilities will linger for a short time
after daybreak before fog diminishes.

Diurnal cu will develop this afternoon but should not be as
extensive as Thursday with greater capping in the mid levels. Light
S/SE winds are expected into the early evening before again becoming
light and variable tonight. Patchy fog is likely to redevelop again
at KBMG and KHUF during the predawn hours Saturday.


&&

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

$$

UPDATE...50
SHORT TERM...Ryan
LONG TERM...Ryan
AVIATION...Ryan