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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KIND 211009
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
609 AM EDT Sun Apr 21 2024

.KEY MESSAGES...

- Mostly cloudy this morning with gradual clearing

- Frost late tonight through Monday morning

- Increasing rain chances Tuesday with low chance for
  thunderstorms

- Temperatures near or below normal the next week

&&

.SHORT TERM (Today and tonight)...
Issued at 304 AM EDT Sun Apr 21 2024

An upstream positively tilted upper trough will cross through
Indiana by early afternoon. Sensible weather impacts will be clouds.
Stratus has been more persistent than expected early this morning
due to residual low-level moisture and increasing ascent from the
trough. Trends suggest this may linger through at least early-mid
morning with more midlevel clouds and cirrus also preceding the
trough`s passage. We expect to remain dry today with ascent not
being enough to overcome pronounced subsidence inversion and dry
layer.

Clearing and MSLP pattern supporting light winds raises concern for
at least patchy frost across central Indiana tonight through early
Monday morning. Greater frost coverage may favor southern portions
of the area closer to MSLP high center where a longer period of very
light or calm winds may occur. Urban areas including Indianapolis
are the least likely to experience frost. Will cover this potential
with a Frost Advisory.

&&

.LONG TERM (Monday through Saturday)...
-- Changed Discussion --
Issued at 304 AM EDT Sun Apr 21 2024

.Monday...

A cooler and drier pattern continues this weekend and into early
next week for Central Indiana. Currently focusing on the potential
for patchy frost Monday morning for wind sheltered and low lying
areas. Surface high pressure becomes centered over Arkansas Monday
with a weak low level pressure gradient extending into the Ohio
Valley. Winds Monday morning fall to 5 kts or less, with South
Central and Eastern Indiana having the best chance for calm winds
and better radiational cooling. Confidence is increasing for frost
potential for this time period, so will go ahead and issue a frost
advisory through around 10 AM Monday. Not too concerned for frost
within urban areas, especially within Marion County, however still
take precautions as temps in the low to mid 30s can still damage
sensitive vegetation.

Other that potnetial for frost, no other hazards expected through
Monday.

.Tuesday through Next Weekend...

Brief ridging builds in Tuesday ahead of another upper trough diving
into the Great Lakes region from the northwest. Warm air advection
ahead of the associated surface low tracking through Michigan should
lead to temperatures near average in the mid 60s, but with the
threat for rain. Sufficient moisture return combined with increasing
dynamics supports likely POPs on Tuesday. Guidance is coming into
better agreement for timing of precipitation, with the mid to late
afternoon timeframe having the highest PoPs. Model CAPE and
instability values for Tuesday are still fairly low, so not
concerned with severe weather at this moment, but a few
thunderstorms may be possible.

Cold air advection and surface high pressure building in behind the
departing low will allow for quiet weather conditions to return
briefly Wednesday and Thursday. Another chance for frost returns
Thursday morning as high pressure becomes centered over the Great
Lakes. Watching North Central Indiana for the best chance for frost.

.Friday into Next Weekend...

Another pattern shift is expected to take place late in the week
with a much warmer and wetter weather pattern setting up for Late
April into early May. Mid to long range guidance has been consistent
in showing an active storm track setting up in the Plains beginning
Friday. Ridging builds over the Midwest with a southwest flow
pattern over the Plains. Numerous strong lows and associated fronts
are expected to push northeast from the Plains and into the Great
Lakes region during this timeframe resulting in multiple chances for
shower and thunderstorms. Warm front pushes northward through
Indiana on Friday bringing the first chance for showers and storms.
Model disagreement increases into the weekend. While confidence is
lower on exact details of timing of storms, exact track of lows and
fronts, confidence is high in a wetter and warmer pattern continuing
through the weekend and into the next week.

One thing to note, Indianapolis is already in the top 13 for wettest
April`s on record. Numerous chances for rainfall Tuesday, and then
again the weekend of April 27-28th will likely push Indianapolis at
least into the top 10 for wettest April`s on record.
-- End Changed Discussion --

&&

.AVIATION (12Z TAF Issuance)...
-- Changed Discussion --
Issued at 609 AM EDT Sun Apr 21 2024

Impacts:

- None

Discussion:

Stratocumulus is diminishing but heating/mixing and residual
moisture should lead to some cumulus at least through the afternoon.
Mid clouds and cirrus will be present as well, but VFR conditions
will prevail. Wind direction and speed will change little.
-- End Changed Discussion --

&&

.IND WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
Frost Advisory from 1 AM to 10 AM EDT Monday for INZ021-028>031-
035>049-051>057-060>065-067>072.
-- End Changed Discussion --

&&

$$

SHORT TERM...BRB
LONG TERM...CM
AVIATION...BRB