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000
FXUS63 KIWX 060722
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
322 AM EDT Thu May 6 2021

.SYNOPSIS...
Issued at 322 AM EDT Thu May 6 2021

Showers are expected today and Friday with highs in the 50s. Lows
will be in the mid to upper 30s tonight and low to mid 30s Friday
night. Areas of frost are expected Friday night. More widespread
rain may be possible on Sunday but confidence is low.

&&

.SHORT TERM...(Today and Tonight)
Issued at 322 AM EDT Thu May 6 2021

Trend in latest guidance and underpinning observational data has
been for a slower frontal passage today and have adjusted PoP`s
accordingly. Still looks like a fairly widespread shower event
this afternoon/evening given healthy midlevel vort max and low
level theta-e ridge peeling off Central Plains. Healthy low level
convergence is noted in a generally moist and marginally unstable
environment during peak diurnal heating. Latest hi-res CAM`s do
suggest that showers may be not quite widespread though with some
moisture quality issues noted in forecast soundings. Will hold
with categorical PoP`s but that may be a tad aggressive. Lapse
rates aloft are largely moist adiabatic but models do indicate a
few hundred J/kg of MUCAPE sneaking into our southern counties and
supporting the potential for a few isolated thunderstorms there.
Any updrafts will remain very weak though and not expected to pose
any threat.

Showers exit our eastern zones by midnight with another round of
weak CAA behind the front. Forecast soundings/RH fields indicate
some cloud cover may linger in our east with additional clouds
moving into the west by early Fri morning. There may be a brief
period of clear skies/light winds but confidence in longevity is low
and leads to some uncertainty in min temp forecast and especially
frost potential. Latest guidance holding in the mid/upper 30s and
made a few minor adjustments for slightly warmer lows especially in
the east. Given uncertainty in cloud trends and overall marginal
setup will hold with just a patchy frost mention and no headlines.

&&

.LONG TERM...(Friday through Wednesday)
Issued at 322 AM EDT Thu May 6 2021

Friday will be similar with two additional height perturbations
rippling through the Great Lakes...one early Fri and another Fri
evening. This will support additional shower chances though much
more widely scattered than today. Track and timing of waves is less
ideal, low levels are much drier than today, and low level front/
convergence signal is much more diffuse. Low to midlevel lapse rates
will be much steeper though and there is a greater risk for graupel
in any showers that manage to develop. Added an afternoon thunder
mention in our east given pockets of up to 500 J/kg of MUCAPE.
Shortwave trough and associated showers will exit by the evening and
this sets the stage for the coldest night of the week. Shortwave
ridging and dry air advection build over the area supporting light
northerly winds and clear skies. Lows still expected to be in the
low/mid 30s and widespread frost is possible (particularly in our
north). Frost/freeze headlines will likely be needed.

A bit more consistency noted in forecast for the weekend but
confidence is still not high. Piece of western CONUS trough expected
to peel eastward and support surface low rippling along tight
baroclinic zone over Ohio Valley. Deterministic runs in better
agreement but still a lot of spread in ensemble guidance with
uncertainty on exact track of surface low and location of primary
precip shield. Our southern counties still have the best chances for
rain during the day Sunday into Sunday evening. Increased confidence
in high pressure and dry conditions Mon-Wed with temps remaining on
the cool side in persistent northerly flow.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 110 AM EDT Thu May 6 2021

VFR met through this morning will give way to showers/MVFR met this
aftn as robust nrn stream disturbance drops through the area.
Brief/transient period of IFR cigs likely this evening within post
frontal cold advection burst but strong drying expected overnight
with a quick return to VFR.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...T


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