IND issues Area Forecast Discussion (AFD) at Sep 19, 9:50 AM EDT
022
FXUS63 KIND 191350
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
950 AM EDT Fri Sep 19 2025
.KEY MESSAGES...
- Very warm to hot conditions will persist into Saturday
- Heat and low RH values each afternoon into Saturday may lead to a
marginally elevated fire threat, but light winds should limit
overall concerns
- Milder afternoons next week to oversee increased humidity and
daily chances of showers/t-storms during mainly Sunday-Wednesday
&&
.FORECAST UPDATE...
Issued at 950 AM EDT Fri Sep 19 2025
Going forecast is in good shape this morning. While a modest cluster
of thunderstorms is ongoing well to our southwest associated with
the slowly approaching upper low that has been held to the west by
the eroding Omega block all week, this cluster will gradually
dissipate and remain well to our southwest, and no precipitation is
anticipated across central Indiana through today as the overall
column is quite dry.
Thicknesses suggest high temperatures at or a bit above persistence
today, and have made minor tweaks to high temperatures based on
this, though changes are fairly minimal. Most areas should at least
get within shouting distance of the 90 degree mark, with several
breaching it into the low 90s. Low surface RH values this afternoon
will keep apparent temperatures at or even below the actual air
temperature.
These RH values will be near critical fire weather values, but weak
winds will mitigate these concerns to a significant degree.
&&
.SHORT TERM (Today and tonight)...
Issued at 303 AM EDT Fri Sep 19 2025
Early This Morning...
Some cirrus may sneak into the western forecast area. Otherwise,
clear skies and light winds will allow some localized fog, mainly
near rivers. Coverage will likely not be high enough to mention.
Today...
The persistent upper ridge will slowly move east as some upper
troughing gradually approaches the area. This will result in
high clouds moving in from the west. Mid clouds may also
accompany the higher clouds in the west later in the day.
Some weak forcing may actually make it to the far western forecast
area by the end of the today period, but there won't be much
moisture for it to work with. Will continue with a dry forecast.
With no change in airmass today, and mainly high clouds moving in,
would expect similar temperatures to Thursday.
Tonight...
The upper trough will continue it slow march east and keep the flow
of mid and high clouds into the area. Some isentropic lift will move
into the western forecast area, but forecast soundings continue to
show very dry low levels.
Blended guidance looks a bit aggressive with its chance PoPs in the
far west given the expected moisture profile. Will keep a slight
chance mention late tonight in the far west, but anything may not
amount to more than sprinkles.
Blended guidance still looks too warm with low temperatures,
especially east where clouds will be thinner. Will trim them some.
&&
.LONG TERM (Saturday through Thursday)...
Issued at 303 AM EDT Fri Sep 19 2025
Saturday through Tuesday...
Next wave will slowly spin while lifting slightly from the Upper
Mississippi Valley into Ontario through Monday. Low-level flow will
veer to SSW by Sunday...along with a long-awaited return of moderate
gusts that will help boost precipitable water values to around 1.50
inches, albeit with a noticeable north-south gradient. Initial lack
of forcing per the wave hanging back to our northwest...will provide
mainly stray showers through dawn Sunday, focused near the Wabash
Valley.
Appears 1-2 periods within the Sunday Night-Monday Night timeframe
will carry the peak opportunity for numerous showers and at least a
few TRWs as the trough's subtle axis crosses Indiana. Severe weather
so far does not appear likely as downward trend in high temperatures
to the upper 70s by Monday will provide only near-zero instability.
Although occasional patches of better wind shear may promote a few
strong cells. Perhaps the most noteworthy feature...despite rain
chances in September over several consecutive days!...will be the
advection and maintenance of dewpoints into the mid to upper 60s
that will hold overnight temperatures closer to August levels.
Lower POPs are expected to follow into the mid-week...when the
lingering surface trough axis under weaker/less-organized forcing
should bring, at times scattered showers and isolated thunder.
Wednesday and Thursday...
Guidance is indicating that the pattern may attempt to arrange into
another omega-style stacked, blocking ridge...this time over the
Great Lakes and into southeastern Canada. Such a feature would help
to lock a more disturbed pattern over the Ohio Valley, if not also
much of the Midwest...although ensembles note better chances of the
ridge and its drier column nudging southward into the region by the
end of the long term. Therefore expect greatest chances of a north-
south gradient of POPs, with lower confidence in actual distribution
of showers during any given period...especially north of I-70.
Expect slightly above normal, yet reasonable readings for late
September...with highs in the 70s and lows slowly trending downward
to around 60F for most locations.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 625 AM EDT Fri Sep 19 2025
Impacts:
- Brief MVFR fog possible early mainly at KBMG
Discussion:
Outside of the fog chance early, VFR conditions are expected
through the period.
Patchy fog has formed at KBMG and may continue until valid time, but
for now feel odds of it lasting significantly past 12Z to be low
enough not to include in the TAF.
Otherwise, cirrus will increase today from the west. Some few to
perhaps scattered cumulus will pop up during the day. Mid cloud may
move in this evening into the overnight.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
UPDATE...Nield
SHORT TERM...50
LONG TERM...AGM
AVIATION...50
Source: IND issues Area Forecast Discussion (AFD) at Sep 19, 9:50 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202509191350-KIND-FXUS63-AFDIND)
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