IND issues Area Forecast Discussion (AFD) at Aug 6, 4:00 AM EDT990
FXUS63 KIND 060800
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
400 AM EDT Thu Aug 6 2026
.KEY MESSAGES...
- Occasion showers/t-storms today into next week, with greatest
chances today through Friday night
- Localized ponding/flooding of low-lying areas will be possible
where repeated rounds of downpours occur
- A few strong/severe storms are possible this weekend into early
next week...with low confidence on exact details
&&
.DISCUSSION (Today through Wednesday)...
Issued at 400 AM EDT Thu Aug 6 2026
Today through Friday night...
Synoptic pattern through the next three 12-hour periods will feature
a rather stagnant set-up between two broad and well-maintained upper
level features...a trough over central/south-central Canada and a
subtropical ridge across mainly the southern two-thirds of the
CONUS, except through the OH/TN Valleys where heights will be more
neutral courtesy of the southern end of the Canadian trough's axis.
This will place central Indiana in a sort of saddle point...south of
any sub-seasonal air, but north of any consistent above normal
readings.
Quasi-steady flow of small weaknesses curling around this axis,
casually extending to the southeast of the Canadian trough will keep
an overall disturbed pattern over the local region, amid
precipitable water values of 1.70 inches or so per southerly flow
around a Bermuda high ridging west into the Carolinas.
However, overall weak forcing will keep any scattered to briefly
numerous showers occasional in nature. Generally isolated thunder
will be sub-severe with greatest potential impact ponding of low-
lying areas due to weak storm motion. Timing of higher chances/
coverage of convection will focus around early this morning from
upper forcing...and then perhaps also mid/late afternoon if clouds
can partially clear enough to facilitate better daytime heating...
with both of these periods favored more west of Interstate 69.
The diurnal uptick in clouds/showers Friday will most likely be for
eastern/southeastern counties ahead of a more southern-tracking mini-
vort coming up the Ohio Valley. A spatially larger-scale shift east
of the quasi-stacked trough, across Indiana, could potentially bring
several hours of scattered rain coverage around Friday night's early
overnight...ahead of quieter weather to start the weekend.
Higher humidity will be the rule through the end of the workweek,
with dewpoints nearing 75F Friday on southwest breezes gusting up to
15 mph. Cloudier skies to promote smaller diurnal temperature
ranges from 66-72F in early mornings to a damp 81-86F during
afternoons.
Saturday Through Sunday...
Synoptically, Saturday morning shows a quasi-stationary surface
front across northern Indiana, situated along the southern edge of
an elongated 500mb trough stretching across the Upper Great Lakes.
Boundary layer moisture transport remains elevated ahead of the
boundary, with ensemble means from the GEFS and EPS maintaining PWAT
values near 1.8 to 2.0 inches, representing the 90th percentile for
early August climatology. HREF probability-matched mean guidance
indicates convective initiation by mid-to-late Saturday morning as
low-level thermal advection and weak PVA associated with an embedded
vorticity maximum traverse the region. Model soundings across
central Indiana depict MLCAPE values rising to 1500-2500 J/kg during
peak afternoon heating. Weak kinematic forcing, characterized by 0-
6km bulk shear of 15-20 kts, will preclude well-organized mesoscale
convective systems, but slow cell motion along the quasi-stationary
front presents a localized threat for training convection and flash
flooding. Forecast soundings show a deep CAPE profile with freezing
levels above 14,000 feet.
By Sunday, the surface boundary will continue to lift to the north
further into the Great Lakes and have less overall impact on central
Indiana weather. Aloft an upper-level ridge centered over the
Central Plains will slowly strengthen with minor height rises across
the area. 700-500mb temperatures will also warm a degree or two
helping to build a mid-level cap with will help to suppress
thunderstorm development. Mesoscale models including the HREF
members suggest isolated High temperatures both days will range from
the mid to upper 80s, with heat indices approaching the low to mid
90s.
Monday Through Wednesday...
The broad synoptic regime during the extended period will feature an
amplified mid-level ridge across the South-Central Plains and an
anchored longwave trough over the northeastern CONUS, establishing
active west-northwesterly flow aloft over the Ohio Valley.
Deterministic GFS and ECMWF runs, alongside GEFS and EPS cluster
analyses, remain in general agreement regarding this large-scale
pattern, though variance exists regarding the exact timing and
magnitude of embedded shortwave troughs propagating around the
northern periphery of the ridge.
There has been a slight trend for the jet stream to be further north
into the Great Lakes which has led to lower rain chances across the
Ohio Valley. That being said, the thermodynamic setup will maintain
strong thermal instability, with diurnal CAPE values frequently
exceeding 2000 J/kg. Lifting associated with shortwave disturbances
traversing the broader trough, coupled with nocturnal LLJ
strengthening (25-35 kts at 850mb), will foster potential for
upstream MCS development over the Upper Midwest that could track
southeastward into the CWA. Given the synoptic uncertainty inherent
in timing northwest flow impulses at days 5 through 7, POPs will
remain capped in the chance category (20-40%) throughout the week.
Outside of convective active periods, subsidence beneath the ridge
interface will promote warm and humid surface conditions, with high
temperatures consistently reaching the upper 80s to low 90s and
maximum afternoon heat indices nearing 100 degrees.
&&
.AVIATION (06Z TAF Issuance)...
Issued at 113 AM EDT Thu Aug 6 2026
Impacts:
- Patchy fog 08Z to 12Z
- Occasional MVFR vsbys due to rain after 14Z
- Potential for thunder after 18Z
Discussion:
VFR conditions expected through the early portions of the TAF period
before patchy MVFR to potentially IFR fog forms from 08Z to 12Z. Fog
chances will be greatest at HUF and BMG, but may also occur at LAF.
Any fog will dissipate quickly after sunrise with increasing mid
level clouds after 12Z. Chances for showers increase after 14Z with
rain initially impacting LAF and HUF. There could be a few rumbles
of thunder at times, but expectations are that the lightning will be
low in coverage through the day. Confidence on timing for any
showers and storms is low at this time with best chances towards
LAF. Winds will generally remain light and variable through 12Z
before becoming southerly to southwesterly at 5-10kts through the
day.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
AVIATION...White
DISCUSSION..AGM/White
Source:
IND issues Area Forecast Discussion (AFD) at Aug 6, 4:00 AM EDT---------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
