193 
FXUS63 KIND 281413
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1013 AM EDT Thu May 28 2020

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

&&

.SYNOPSIS...
Issued at 140 AM EDT Thu May 28 2020

An upper level low pressure system over the southern plains is
expected to move toward Indiana today. This will keep warm and
moist flow in place across Indiana today and tonight...resulting
in scattered showers and storms.

As the low pushes toward the Great Lakes on Friday...a cold front
will be pushed across Indiana. This will result in some showers
and thunderstorms in the morning...followed by some drying
conditions in the afternoon.

Canadian High pressure is then expected to build across the 
region on Friday night...providing dry and cooler weather for the 
weekend and the start of the next work week.

&&

.NEAR TERM /Rest of Today/...

Issued at 928 AM EDT Thu May 28 2020

Fine-tuned POPs for the morning update concentrating the highest
POPs across the northern counties for the next several hours to
account for a widespread area of light to moderate rain moving
across the area. After this rain exits, mostly dry conditions
expected with a few scattered showers until later this afternoon
when diurnal heating along with a subtle upper level wave will
bring higher chances for showers and a few thunderstorms. Severe
weather looks unlikely with instability somewhat limited due to 
expected cloud cover for much of the day. Relevant portions of 
previous discussion follows...

After the wave departs late this morning...the very warm...moist
and unstable air mass will remain in place across Indiana ahead of
the approaching upper low. Forecast soundings reveal deep moisture
available with pwats near 1.4 inches...steep lapse rates and CAPE
over 1200 J/KG. Thus given the afternoon heating some scattered
convection will once again be expected...and will continue some
pops in the late afternoon or evening. Although a lull could be
expected mid day as the wave departs and strong enough daytime 
heating has yet to begin.

&&

.SHORT TERM /Tonight through Saturday Night/...
Issued at 140 AM EDT Thu May 28 2020

The model suggest the upper low will push north toward Indiana
overnight before becoming absorbed into a deeper trough. The warm
and humid air mass will still be in place across the area as
forcing associated with the upper low arrives and begins to pass
overnight. Time heights again show a deeply saturated column
arriving by morning with pwats still lingering near 1.4 inches.
Thus will once again trend toward high pops tonight...with best
pops arriving late overnight as forcing with the broader trough
aloft and associated cold front begins to provide lift across
Indiana. Given the expected rain will trend lows at or above the
NBM.

GFS and NAM shows the cold front begin dragged across Central
Indiana on Friday Morning...as subsidence arrives from the
northwest. Saturated columns are present initially in the
day...followed by subsidence in the afternoon. Ample lift will be
in place here along with our very moist air mass. Thus will trend
toward high pops in the morning and dry weather in the afternoon.
Given the ongoing cold air advection but partial afternoon 
sunshine will trend highs on Friday at the NBM. 

Forecast soundings from Friday Night through Saturday night reveal
a dry column in place along with attainable convective temps in
the upper 60s. This should only result in some fair weather CU on
Saturday afternoon. Otherwise the models are in agreement that
strong high pressure will drop out of the northern plains across
the Great Lakes and Ohio Valley. Aloft broad subsidence looks to
be in place from the northern plains to the Ohio Valley as a 
sharp ridge looks to be in place over the Rockies. Thus will trend
toward dry...pleasant weather and temps near the NBM.

&&

.LONG TERM /Sunday through Thursday/...
Issued at 310 AM EDT Thu May 28 2020

Dry and mild weather at the end of the short term will continue
into Monday. Monday night onward, low chances for precipitation
will be necessary at times as guidance hints at convection along
the periphery of the upper ridge centered to our southwest.
Suspect this may be broad brushed and overdone a bit, as is
usually the case with the blend, but in the absence of significant
model signal against it, and given the mesoscale driven nature of
much of this activity, there's little opportunity for significant
refinement on such time scales.

Temps will be mild and pleasant early in the period, climbing back
into the mid 80s by Wednesday and becoming more humid again.

&&

.AVIATION /Discussion for 28/15Z TAF Update/...

Issued at 1011 AM EDT Thu May 28 2020

An area of showers will bring additional rain and reduced vsbys 
to IND over the next couple of hours with generally dry conditions
through the afternoon. Chances for showers and thunderstorms ramp
up again in the evening, but confidence in timing is too low to 
narrow in on specifics. Will reevaluate for 18Z TAFs on a window 
for TSRA or SHRA. Previous discussion follows...


Restrictions likely through at least the mid morning hours at most
sites in scattered showers. Conditions may return to VFR this
afternoon outside of any shower and storm activity, before
dropping to MVFR and then IFR very late in the period as a front
approaches.

Winds through the period will be less than 10KT,
southerly/southeasterly at first, then becoming gradually more
southwesterly and then westerly with time through the period.

Restrictions to visibility will be transient in showers and
storms, with fluctuations likely.


&&

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

$$

SYNOPSIS...JP
NEAR TERM...White
SHORT TERM...JP
LONG TERM...Nield
AVIATION...White/Nield