Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 082023
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
423 PM EDT Sat Aug 8 2020

.UPDATE...
The AVIATION section has been updated below.

&&

.SYNOPSIS...
Issued at 233 PM EDT Sat Aug 8 2020

An upper air disturbance is expected to move through southern
Indiana during the day Sunday. A cold front is expected to affect
the area around Monday night into Tuesday. This front may linger
over the area for much of next week.

&&

.NEAR TERM /This Afternoon and Tonight/...
Issued at 233 PM EDT Sat Aug 8 2020

A remnant MCV currently over Missouri is progged by short term model
data to drift into southern Illinois tonight. Some of the finer
scale models blow up quite a bit of convection off to the
west/southwest of the local area with this feature later tonight,
with the fringes possibly reaching the southwest zones towards
sunrise Sunday. Convective parameters not very favorable locally for
much to happen tonight, so the better convective threat may remain
off to the southwest. Will bring in some small chance PoPs towards
sunrise Sunday over the far southwest zones to cover this feature,
but keep the majority of the forecast area dry.

Low level thicknesses suggest the GFS MOS guidance lows tonight look
reasonable, so any adjustments will be minor.

&&

.SHORT TERM /Sunday through Tuesday/...
Issued at 233 PM EDT Sat Aug 8 2020

The remnant MCV is expected to drift through southern Indiana on
Sunday. Questions remain as to the amount of convection that may be
associated with this feature locally, as convective parameters
continue to look rather weak. Will keep some chance PoPs over the
southern/southwestern zones on Sunday, due to the presence of the
mid level feature.

Convective potential looks to increase Sunday night and on through
the rest of the short term, as an area of enhanced flow at 850mb
moves into the area Sunday night, and a cold front sags into the
area by Monday night or Tuesday. At this point, operational and
ensemble data suggest the best precipitation potential will be
Monday night into Tuesday, but any preceding outflows may change
that as time goes by.

Air mass may become highly unstable by Monday afternoon, with models
suggesting potential for Lifted Index values below -10 and CAPE
above 4000, which may result in strong organized convection. Deep
layer shear looks rather weak, though.

Lower confidence in high temperature forecast on Sunday, due to
questions revolving around amount of cloud cover tomorrow. Will go
with the GFS MOS highs for now, but highs may be too warm if cloud
cover is more widespread than currently expected. Progged low level
thicknesses suggest the guidance highs look too cool on Monday. Will
raise the highs a category in that period.

&&

.LONG TERM /Tuesday Night through Saturday/...
Issued at 244 PM EDT Sat Aug 8 2020

An active weather pattern will persist throughout the extended
with periodic threats for scattered convection as waves aloft
drift through the quasi-zonal flow and interact with a frontal
boundary oscillating back and forth across the Ohio Valley. While
no day is expected to be a washout...the presence of the boundary
nearby with a steady slate of waves and energy aloft will result
in a daily threat for scattered storms into the weekend with a
moist and unstable airmass over central Indiana. Drier air over
the Great Lakes later in the week will try to advect south into
the area but confidence is not high in that occurring to any great
degree. Have much greater confidence at this point in the more
stagnant pattern discussed above lingering.

Expect warm and humid conditions through the weekend with near
normal temperatures. Highs will be generally in the mid and upper
80s with lows from the mid 60s to the lower 70s.

&&

.AVIATION (Discussion for the 082100Z TAF Update)...
Issued at 423 PM EDT Sat Aug 8 2020

Tweaked wind speed based on latest obs.

Previous discussion follows....

VFR conditions will continue throughout the forecast period.

Mostly sunny skies continue early this afternoon with high
pressure centered just east of the region. Could see a bit of cu
formation through the afternoon...most likely at KBMG and
KIND...but overall subsidence through the column will limit clouds
in general. Any cu will diminish this evening with mainly clear
skies overnight. Clouds will increase Sunday morning as any
convective cloud debris from storms to the west of the area are
likely to drift into central Indiana.

Southerly winds today will become light and variable tonight
before developing again Sunday. Any convection is not likely to
impact the terminals until later on Sunday afternoon at the
earliest.
&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM....Ryan
AVIATION...Ryan/50


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