Area Forecast Discussion Issued by NWS Indianapolis, IN
000
FXUS63 KIND 180927
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
527 AM EDT Mon Mar 18 2024
.KEY MESSAGES...
- Few flurries/light snow showers today, hard freeze again tonight
- Gusty winds up to 40 mph tomorrow afternoon along with elevated
fire weather risk
- Hard freeze expected Wednesday night
&&
.SHORT TERM (Today and tonight)...
Issued at 119 AM EDT Mon Mar 18 2024
Today.
Today will be the coldest day of the forecast period with highs only
making it to near 40 across central Indiana with nearly northerly
flow aloft and strong CAA near the surface. The mid level stratus
deck across much of the area will gradually erode during the
daytime hours outside of northeastern Indiana which will see
mostly cloudy skies through the day. Continued CAA will allow the
boundary layer to deepen to around 5000ft even with little
diurnal heating.
A weak shortwave within the broader northwesterly flow may briefly
bring flurries/light snow showers to the area today but think
that this will mostly stay to the north and east of the forecast
area based on the expected flow off Lake Michigan and the dry
layer below the cloud deck.
Tonight.
Focus then shifts to another anomalously cold night tonight with lows
dropping again into the mid to upper 20s. Upper level flow will
gradually become more zonal with a shift to westerly then
southwesterly flow near the surface closer to daybreak Tuesday as
the surface high weakens and shifts to the southeast. To the north,
a surface low will deepen and help to create tighter surface
pressure gradients that will bring a return to gusty winds for
Tuesday.
With the official growing season yet to begin, will be
issuing an SPS to highlight the expected hard freeze considering
recent warm weather has allowed for isolated to scattered plant
growth.
&&
.LONG TERM (Tuesday through Sunday)...
Issued at 119 AM EDT Mon Mar 18 2024
Tuesday Through Thursday.
As mentioned in the short term above, the combination of
strengthening surface pressure gradients will bring gusty winds to
central Indiana during the daytime hours Tuesday with the potential
for wind speeds to approach Wind Advisory criteria. The LLJ at the
top of the boundary layer currently looks to be around 40kts which
would bring surface gusts to around 35kts at times as air mixes
down. Some of the higher resolution models are hinting that there
may be a brief period and axis where the LLJ is stronger which could
lead to occasional gusts up to or above 40kts but those models so
far remain the high outliers. These high winds combined with RH
values around 30 percent will lead to an elevated fire weather
risk. Recent rains will help to limit the overall fire weather
threat.
The southwesterly flow on Tuesday will come to an end Tuesday night
as the LLJ exits and CAA returns which will bring another night of
near freezing temperatures. Quiet weather is expected for Wednesday
with mostly clear skies which will help to then bring another hard
freeze Wednesday night with efficient radiational cooling as winds
drop to near calm along with the mostly clear skies. The pattern
then begins to shift again going into Friday with the potential for
rain.
Friday Through Sunday.
Forecast confidence begins to lessen going into Friday but both the
deterministic and ensemble guidance have begun to coalesce on one
solution vs the spattering of possible outcomes compared to previous
runs. Current thoughts are that the polar jet and associated
shortwave trough will push into the Great Lakes region late Thursday
night into Friday bringing precipitation to the area late Friday
into Friday night as the associated surface cold front pushes
southward. Moisture associated with the subtropical jet looks to
stay south of the forecast area with heavy rain across the
Tennessee Valley before it pushes northward.
This will keep QPF light and lead to the cooler solution for
temperatures but even that will still be near normal for this time
of the year. Snow may mix in, but think that temperatures across
central Indiana will remain warm enough to keep precipitation all
rain but towards the far northern portions of the state, light snow
accumulations look possible. Conditions then will dry Saturday into
Sunday with some lingering precipitation possible depending on the
final timing of the aforementioned system.
A more impactful system then looks probable going into early next
week. At this time heavy rain and thunderstorms looks to be the most
likely threat but will continue to monitor trends for any potential
for strong to severe storms as well.
&&
.AVIATION (12Z TAF Issuance)...
Issued at 522 AM EDT Mon Mar 18 2024
Impacts:
-Southwesterly wind gusts to 35kts after 15Z Tuesday.
Discussion:
VFR conditions expected through the TAF period. A broken to overcast
cloud deck around 050 is expected for much of the daytime hours
today before gradually clearing after sunset. Wind speeds will
increase during the afternoon hours as the boundary layer deepens
but outside of brief periods, gusts are not expected. There could
be stray flurries at IND or LAF this afternoon but potential is
too low for even a VCSH mention. Much stronger winds are expected
for tomorrow afternoon with southwesterly gusts to 35kts.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...White
LONG TERM...White
AVIATION...White