IND issues Area Forecast Discussion (AFD) at Aug 17, 1:52 PM EDT831
FXUS63 KIND 171751
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
152 PM EDT Mon Aug 17 2026
.KEY MESSAGES...
- One more round of showers and a few storms early today
- Areas of fog tonight with dense fog possible
- Additional thunderstorms likely mid week
- Turning milder and drier late week into next weekend
&&
.FORECAST UPDATE...
Issued at 847 AM EDT Mon Aug 17 2026
Surface analysis continues to show a trough of low pressure in our
region. The trough was found over Nrn OH and Nrn Indiana, before
diving SW across Indiana to western TN and Arkansas. GOES19 shows a
dying convective cluster in SE Indiana and KY and rain associated
with this system had exited east. Radar shows a few showers ahead of
the trough across Central Indiana stretching from a near MIE-HUF
line. Although the showers were moving along, brief heavy rain
rates, of 2-4 inches per hour will be possible. Water Vapor shows a
significant change today. There are breaks within the ever
persistent tropical plume that has been streaming over Indiana.
Today the plume is only streaming across NM and into KS, while
subsidence was providing drying across IL/MI and drifting toward
Indiana. Dew point temperatures remained quite high across the state
in the lower 70s.
This afternoon, skies will become partly sunny as morning stratus
slowly burns off and high debris clouds from the convective cluster
subside and drift east. As the trough sags southward across Indiana
this morning and early afternoon, a few isolated showers and storm
will still remain possible as we are seeing on radar. With the very
moist air mass in place brief heavy rains will be possible. Time
heights and HRRR continue to keep cloud cover around through the
morning, but show some breaks by afternoon. Thus will continue to
keep skies mostly cloudy/becoming partly sunny this afternoon, with
isolated showers and storms possible. Clouds will help to keep
temperatures from rising. Highs will only reach the lower 80s.
&&
.DISCUSSION (Today through Sunday)...
Issued at 240 AM EDT Mon Aug 17 2026
The persistent upper level ridge to the south that has kept central
Indiana squarely in the bullseye of ring-of-fire convection for the
last week plus will finally begin to retrograde to the west and
amplify this week.
A cold front to the northwest will push through the area today, with
scattered pre-frontal showers and storms early in the day, primarily
across the southern portions of the area. Rain chances will finally
come to an end late today as the tail end of the boundary exits the
area, with dry weather expected tonight into Tuesday as surface high
pressure pushes into the region.
Light to calm winds, clearing skies, and very moist ground will
likely produce areas of fog tonight despite the decreasing
dewpoints. Dense fog will definitely be on the table given how
incredibly waterlogged most of the area is.
The next chance for thunderstorms will come late Tuesday night into
Wednesday night as one or more shortwave disturbances pivoting
around a large upper low over the eastern Canadian provinces drives
another frontal boundary through the area. Heavy rain and strong to
severe storms will again be a threat, as though instability is a bit
more modest owing to more limited moisture (though still 70th-80th
percentile climatologically), deep layer shear should be fairly
robust. Damaging winds would be the primary threat with this
activity, with at least a modest flash flood threat given the
extreme antecedent conditions.
The more amplified pattern looks to persist late week into early
next, with below normal temperatures and mostly quiet weather
appearing likely, though an occasional upper level disturbance in
the cyclonic flow aloft may necessitate a slight chance of a shower.
&&
.AVIATION (18Z TAF Issuance)...
Issued at 148 PM EDT Mon Aug 17 2026
Impacts:
- Patchy to areas of fog overnight/early Tuesday morning.
Discussion:
IVF/MVFR ceilings have been a bit slow to improve to VFR this
afternoon, but all terminals should return to VFR no later than 19z.
A narrow line of showers is currently tracking through the
Bloomington area, but this should be clear of BMG by around or
shortly after 18z this afternoon, with precipitation free conditions
expected through the remainder of the period. Northwesterly winds
around 10 to 12 knots have taken hold behind the front. Winds will
become light and variable to calm after 00Z tonight, with areas of
fog possible as high pressure builds into the region, especially
between 8z and 12z Tuesday morning.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Puma
AVIATION...Williams
DISCUSSION...Nield
Source:
IND issues Area Forecast Discussion (AFD) at Aug 17, 1:52 PM EDT---------------
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