359
FXUS63 KIND 260507
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
107 AM EDT Sat Apr 26 2025

.KEY MESSAGES...

- Scattered to numerous showers through this evening, with
  some thunderstorms as well. Locally rainfall is possible

- Brief cooldown Saturday before temperatures return to above normal
  levels by early next week

- Active and stormy pattern from Tuesday through Thursday, with the
  potential for severe weather on Tuesday

&&

.MESOSCALE UPDATE...
Issued at 807 PM EDT Fri Apr 25 2025

Scattered thunderstorms will continue along and south of the I-70
corridor over the next 1-2 hours before diminishing in coverage and
intensity.

Radar imagery shows a congealing line of sub-severe thunderstorms
along a line from Rushville to Nashville Indiana associated with the
cold front pushing southeastward. The environment ahead of the front
remains marginally unstable with dew points in the mid 60s. Weak low
and mid level lapse rates and little shear have kept storms
relatively shallow and unable to grow upscale enough to support
strong updrafts or severe weather this evening. These lower centroid
storms have been able to produce quick burst of intense rainfall as
warm rain processes occurred. Despite heavier rain at times, flooding
has not been a threat today as storms have not been training over
the same areas. There have been some reports of cold air funnels
with a few cells, likely due to very localized increased shear and
helicity from a weakening meso-low which pushed through a few hours
ago. These pose no threat to life and property.

For the 8pm - 10pm timeframe, expect sub-severe storms to continue
east-southeast into southeast portions of Indiana with the main
threats being locally heavy rain and isolated lightning strikes.
Observations show that cooler, drier air is lagging behind the front
and still in Northern Illinois and Indiana. Enough lift on the
backside of the front has sparked off a few discrete showers and
thunderstorms along the IN/IL border. This activity will push into
Vigo, Sullivan, Clay, and Greene Counties over the next 1-2 hours
before weakening. No severe weather expected with these either, just
brief periods of heavy rain and an isolated lightning strike.

&&

.SHORT TERM (This evening through Saturday)...
Issued at 301 PM EDT Fri Apr 25 2025

Rest of This Afternoon...

As broad surface low pressure and an upper wave continue to push
east, scattered to numerous showers will continue across central
Indiana.

Clouds and rain have kept temperatures and instability down into
early afternoon, but satellite shows some thinning of the clouds
upstream. This will allow some additional instability to build, so
will keep mention of at least isolated thunder. This will also allow
temperatures to rise some again. Shear is weak, and instability
should remain low enough for any storms to remain subsevere. Given
the moisture content of the atmosphere, locally heavy rain remains a
threat.

Tonight...

A few showers or isolated thunderstorms will remain across the area
ahead of a cold front this evening. Will keep some low PoPs then.
Some clearing will be briefly around, but then as cold air flows in,
lower clouds will return. Skies will be mostly cloudy to cloudy once
again by 12Z Saturday.

Cold advection will bring temperatures back down into the 40s for
lows most places.

Saturday...

Saturday will start out mostly cloudy to cloudy, but as high
pressure builds in, clouds should mix out during the afternoon.

Even with the return of sunshine during the afternoon, highs will
only reach the upper 50s to middle 60s.

&&

.LONG TERM (Saturday night through Friday)...
Issued at 301 PM EDT Fri Apr 25 2025

This Weekend

Surface high pressure arrives following today`s cold front and will
promote generally quiet weather through the weekend. Temperatures
will be near to slightly below average, which is around 66/45 for
the Indy area this time of year. Guidance is showing ideal
radiational cooling potential Saturday night. Some members even have
lows dipping into the upper 30s across our north, which may be cold
enough to allow for some patchy frost. As of right now, it does not
appear that such cold will be widespread enough to warrant a frost
advisory.

A developing warm front may be close enough to the area to bring
some rain on Sunday. There is little support within guidance, but a
few members show it...so it`s at least worth mentioning. The best
chance of any rainfall on Sunday would be across southern portions
of our area.

Next Week

Troughing out west looks to amplify over the weekend while gradually
sliding eastward. The ejecting trough will induce cyclogenesis over
the northern Plains on Monday, with strong warm air advection out
ahead of it. Temperatures across Indiana look to be much warmer both
Monday and Tuesday. The system`s cold front arrives on Tuesday with
a chance of showers and thunderstorms.

Guidance is in good agreement showing sufficient shear (30 to 50
knots) and instability (over 2000 J/Kg MLCAPE) for strong to severe
thunderstorms Tuesday afternoon and evening. Determining the primary
hazard is not yet doable since guidance still varies with parameter
space and the shear profile.

Tuesday`s cold front should clear the area by Wednesday morning,
leaving us with quiet weather once again. Cool temperatures and
northerly winds bring about a day or two of near average temps. The
air mass behind Tuesday`s front does not appear as cool as the one
this weekend, so frost is not as much of a concern. If enough rain
falls, however, there may be some patchy fog if skies clear and
winds go calm.

The front itself may end up stalling just to the south of Indiana,
and the west coast trough looks to remain largely in place over the
western US. A secondary mid-level wave may eject eastward and ride
the front late Wednesday or Thursday. This feature may bring another
round of rain and storms to Indiana, but details are even less clear
at this range.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 106 AM EDT Sat Apr 26 2025

Impacts:

- MVFR/IFR ceilings expected through this morning before improving
  to VFR by early afternoon

- Northerly winds sustained at 10-15 kts through this morning,
  diminishing later in the day

Discussion:

High pressure building in from the north behind the front has
trapped leftover moisture within the boundary layer under a
developing low level inversion. This has led to the development of a
stratus deck with low MVFR to IFR cigs. Expect low clouds to persist
through the morning. Clouds should then lift and clear out towards
midday and early afternoon returning all sites to VFR.

Expect sustained northerly winds around 10-15 kts through the
morning before winds begin to gradually diminish later in the day.
Sporadic gusts of 18-23 kts are possible, mainly through midday.
Gusts should diminish during the afternoon.

&&

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

$$

SHORT TERM...50
LONG TERM...Eckhoff
AVIATION...Melo