Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 110344

Area Forecast Discussion
National Weather Service Indianapolis IN
1144 PM EDT Mon May 10 2021

...Updated Aviation Discussion...

.Forecast Update...
Issued at 910 PM EDT Mon May 10 2021

Radar indicates fairly widespread light rain currently over
the northern zones, which appears to be tied to some decent forcing
at the 850mb level. Short term model data suggests this area of
forcing will gradually sag south during the course of the night, and
weaken a bit with time.

Given it appears the forcing will continue most of the night over
the north, will keep some PoPs going in those areas for the rest of
the night.


.Short Term...(This evening through Tuesday night)
Issued at 300 PM EDT Mon May 10 2021

Current synoptic setup consists of a broad upper low situated over
eastern Ontario/Great Lakes Region with a large area of ridging
following it.  This pattern will result in a relatively quiet short
term period for central Indiana.  However, focus will be on a weak
wave in the upper cyclonic flow this evening and early tonight.

This Evening/Tonight...after plenty of sunshine this morning, mid
clouds are slowly starting to fill in ahead of the aforementioned
upper wave. This wave will be the focus for the next 12 hours as
it tracks through northern Indiana. Despite limited moisture,
there should be enough to support isolated rain showers late this
afternoon/evening over the northern half of the forecast area when
upper level divergence is strongest with the 130 kt upper level
jet. The forcing, however, will be short lived and any chances
will quickly taper off after midnight. Any lingering cloud cover
though will help to mitigate radiational cooling tonight, thus
limiting the frost threat. As a result, will not carry any frost
headlines tonight as temperatures generally stay in the upper
30s/low 40s over most of the forecast area.

Tuesday/Tuesday the ridge of high pressure strengthens
over the northern Plains, so will the subsidence over central
Indiana.  Time cross sections are showing a dry column for much of
the day Tuesday and Tuesday night.  Despite the ample sunshine
though, temperatures will have a tough time climbing much above the
upper 50s/low 60s as surface winds remain northerly.  And,
radiational cooling will resume on Tuesday night, so additional
frost headlines may have to be revisited tomorrow with lows expected
to dip back into the mid to upper 30s.


.Long Term...(Wednesday through Monday)
Issued at 300 PM EDT Mon May 10 2021

...Temperatures Climbing back to Near Normal Late this Weekend...

Good confidence in well below normal temperatures and mostly dry
weather through late week as cool Canadian surface high pressure
builds in. Although a broad upper trough will pass across the Great
Lakes and Ohio Valley Thursday, model rh sections too dry for PoPs.
The southern system is also now well south of where it was with
earlier runs, so that should not keep it from being dry through the
early weekend. Temperatures over northern sections may finally
return to the 60s Wednesday under near full sunshine.

As the surface high moves off to the east this weekend, increasing
southerly flow off the Gulf supports a return to near normal
temperatures in the lower and middle 70s by Sunday.  The increasing
moisture and temperatures combined with a warm front potentially
setting up near the Ohio River could trigger some weekend
convection. Once more precise location of this front is more in
focus, confidence in PoPs will grow. For now, low PoPs look good by
Late Saturday.


.Aviation...(110600Z TAF Issuance)
Issued at 1144 PM EDT Mon May 10 2021

- Surface winds 010-040 degrees at 7-11 kts overnight, increasing to
10-15 kts by late morning Tuesday.
- Scattered light showers in the KLAF/KIND vicinity through about

DISCUSSION: An area of forcing around the 850mb level will keep the
threat for shower activity in the vicinity of the KLAF/KIND
terminals into the daylight hours of Tuesday, as short term model
data suggest this forcing will weaken by then. Most of the shower
activity should be light enough that the threat for any associated
prolonged visibility restrictions will be low.

Otherwise, low convective temperatures due to thermal troughing
aloft will lead to instability cloud development towards midday
Tuesday, with bases around 040-050. A tightening pressure gradient
and daytime mixing may lead to some wind speeds near 15 kts at times
by late morning Tuesday.




Short Term...TDUD
Long Term...Koch
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