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000
FXUS63 KIND 181917
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
317 PM EDT Thu Apr 18 2024

.KEY MESSAGES...

- Severe storms and locally heavy rain are possible from after 8pm
  through around sunrise.

- Cooler but dry Friday through Monday. Some frost potential mainly
  north Sunday morning, more widespread frost possible Monday
  morning.

- Increasing rain chances next Tuesday, low chance for thunderstorms

&&

.SHORT TERM (This evening through Friday)...
Issued at 317 PM EDT Thu Apr 18 2024

It`s another day of above normal temperatures and a conditional
threat for severe weather. Satellite shows high clouds currently
over central Indiana while surface observations show temperatures
warming into the 70s and dew points creeping higher over the SW
counties.

Thunderstorms will move in this evening, likely entering the state
between 8 and 10 pm and tracking eastward through the overnight
hours. The storms in question are currently over Missouri as of this
afternoon. As they approach, winds will start to increase to
around 10-15 mph with non-thunderstorm gusts possible through the
night. Withe the severe threat, confidence remains low given the
conditional nature. The latest CAMs show that variables may not
line up quite right, but if they do damaging winds will be the
main threat while an isolated tornado and isolated hail can`t be
ruled out. Isolated flooding may also be a concern as up to an
inch of rain will be possible as the line of storms moves through
a region that already has a pretty saturated ground.

The best threat for severe weather will be over the SW counties
where the best instability and moisture content will be. As the
storms reach the area, CAPE of 500 to 1000 J/kg are expected,
especially over those SW counties, but looks to drop to less than
500 J/kg over the following few hours. However, latest CAMs are
showing less than impressive shear and helicity over the area and
the surface low driving this system looks to lift as it reaches
central Indiana. Lapse rates of 7 C/km may still be around when the
line arrives but confidence is low and it seems more likely that
those will have dropped off beforehand.

The line of storms and the cold front causing them are expected to
move out of the forecast area by sunrise or shortly after. Highs
tomorrow will be lower and closer to normal, reaching only the mid
50s to low 60s. Otherwise, nice weather is expected for the day
tomorrow with only partly cloudy skies remaining.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 317 PM EDT Thu Apr 18 2024

Friday night through Monday...

Quiet weather conditions are expected for several days as surface
high pressure remains dominant over the region. Aloft, guidance
shows a few upper level impulses traversing the region which could
help to keep clouds around at times over the weekend. A weak LLJ
associated with an upper disturbance moving through Saturday will
likely help promote breezy conditions. Gusts up to 25 mph are
possible during the day.

Expect temperatures to trend cooler heading into the weekend due to
cold air advection. Lows dropping into the 30s both Saturday/Sunday
night combined with relatively light winds could support the
potential for frost. There is higher confidence in frost Sunday
night into Monday morning at this time since guidance shows much
less cloud cover. Greater cloud cover from an upper level impulse
Saturday night leads to higher uncertainty. Highs are generally
going to range from the low 50s to near 60F over the weekend before
warming up early next week.

Monday night onward...

Rain chances return late Monday night into Tuesday as a shortwave
trough and associated low pressure system move across the Great
Lakes Region. Return flow ahead of the approaching system should
allow for temperatures to continue moderating. Sufficient moisture
return combined with increasing dynamics supports likely POPs on
Tuesday. The system is likely going to move out Tuesday night. Cold
air advection and surface high pressure building in behind the
departing low will allow for quiet weather conditions to return
briefly before another system approaches late next week.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 240 PM EDT Thu Apr 18 2024

Impacts:

- Thunderstorms moving in 01-02Z and lasting through 06-09Z

- MVFR ceilings to move in after 03z and IFR possible from 05-10Z,
visibilities may drop within storms

- Winds sustained at 10 kts or higher from 00z and on with gusts up
to 25 kts possible at times with storms

Discussion:

VFR conditions expected through early evening.

Light and variable winds will start off the TAF period but are
expected to increase this evening with the approach of a low
pressure system. Winds will be southerly to southwesterly ahead of
the system but will shift northwesterly during the late overnight
hours and through tomorrow.

High-level clouds will continue to increase through the day as the
front approaches. By about 01-02z, showers and thunderstorms will
begin working their way in from the west. Expect MVFR conditions
from around 03 to 13Z with several hours of IFR ceilings possible
with the passage of the storms and cold front. Visibilities may drop
as well with the storms.

The front should be through Indiana by 10z at the latest, and
conditions will improve to VFR by the morning.


&&

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

$$

SHORT TERM...KF
LONG TERM...Melo
AVIATION...KF