920
FXUS63 KIND 091629
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1229 PM 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

&&

.FORECAST UPDATE...
Issued at 902 AM EDT Wed Jul 9 2025

Surface analysis late this morning shows a weak frontal boundary
across Central Indiana, stretching from near FWA to IND and HUF.
Radar shows an area of showers and isolated thunderstorms west of
Indiana and another area just west of Vincennes. These echos were
weakening with their eastward progression. Water Vapor showed an
upper trough in place stretching from SE MI to Srn IL and Arkansas.
A subsidence line was building eastward on the backside of the
trough, and was building across NW Indiana early this morning. Winds
remained light and variable across the forecast area due to the weak
and poorly defined pressure gradient across the area. Dew point
temperatures remained quite high in the middle 60s to around 70.

Models suggest the frontal boundary will make slow progression
southeastward through the afternoon. This will keep the southern and
eastern parts of the forecast area within the warm sector, favorable
for convection, through much of the day. Clearings and diminishing
rain chances will also slowly build from the northwest as the
subsidence line pushes southeast and the upper trough exits. HRRR
still keeps a few isolated showers across the area this afternoon,
but best confidence will remain across the previously stated south
and east. Highs will once again reach the middle to upper 80s.
Overall forecast remains in good shape and only minor adjustments
will be made.



T

&&

.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 scattered 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 broader
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 (18Z TAF Issuance)...
Issued at 1229 PM EDT Wed Jul 9 2025

Impacts:

- Showers with isolated thunder exit the area this afternoon
- VFR for much of the period
- IFR/MVFR Fog possible predawn Thursday

Discussion:

An upper level short wave was pushing across the TAF sites early
this afternoon. This was generating a few showers and thunderstorms
across southern and eastern Central Indiana. This may impact the BMG
area for the first few hours of the TAF. HUF/LAF and IND were all
found within the backside of the trough and subsidence was building
across Indiana from the northwest. Thus low VFR cigs are expected to
become very high VFR cigs by late afternoon as the trough departs
and the subsidence arrives.

Dew point depressions are expected to be small overnight. This along
with light to calm winds and residual moisture will result in fog
development During diurnal temperature minimums tonight. Some fog
could potentially be MVFR to IFR.

Any fog will quickly burn off on by mid morning as heating and
mixing resumes.

&&

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

$$

UPDATE...Puma
SHORT TERM...Ryan
LONG TERM...AGM
AVIATION...Puma