608
FXUS63 KIWX 082336
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
736 PM EDT Mon Jul 8 2024

.KEY MESSAGES...

- Scattered showers and storms expected this evening through
  Tuesday morning.


- Rain chances increasing Tuesday afternoon SW, expanding
  across the rest of the area Tuesday night with moderate to
  locally heavy rain.

- Confidence on heaviest rainfall amounts remain on the lower
  side Wednesday given differences in the track of the surface
  low.

- Hydrologic impacts should be limited by the fast movement of
  the system as well as semi dry conditions and maturing crop
  status.

&&

.DISCUSSION...
Issued at 232 PM EDT Mon Jul 8 2024

While the focus remains on remnants of Beryl, there are still a few
challenges to sort out prior to its arrival as the northern stream
trough edges ever closer and weaker disturbances move across the
region.

The bulk of the showers/isol storms have missed us just to the NW,
hi-res CAMs seem to suggest that the area of showers and storms
moving through central IL may bring the threat for precip a bit
further SE later this afternoon into evening. Coverage should remain
rather limited warranting no more than chc pops that could linger
well into the overnight hours as the overall area of weak lift
remains ahead of the trough but the main disturbance ejects
well north of the area.

Focus then shifts to remnants of Beryl that will be quickly
advancing NE towards the region as it phases with the aformentioned
trough. While everyone should benefit from needed rainfall as very
efficient warm precip processes (14,000 ft or higher) occur and
PWATs approaching or possibly exceeding max levels in the 1.9"
or higher range, challenges remain on where the heaviest precip
will occur given the rather rapid NE progress that is expected
with the greatest rainfall amounts anticipated initially ahead
of the low, and then NW of the track. Even 36 to 48 hours,
models still not in agreement on the track, yielding some large
QPF differences with spectral models more blended and somewhat
SE vs CAMs that that are more bullish on QPF and focus the
highest amounts in NW areas with a more NW low track. Confidence
is increasing that initial impacts from both the trough and
approaching low will overspread the area faster than previously
thought with likely to maybe cat pops needed prior to 6Z Wed and
addition of cat pops for much of the area 6-12Z Wed. Confidence
drops thereafter with pops given the above concerns, leading to
less changes. Will try to capture the latest thinking, but
changes are guaranteed in the coming updates as models hopefully
begin to agree more on the track. The main thing to focus on is
widespread rain amounts of 1 to 2 inches with some areas seeing
potentially more where training of convection occurs and near
the sfc low track. With many areas drying out some in the past
week or so, crop growth well underway and rivers all below flood
stage, overall hydro concerns seem limited for this event at
this point. The track of the sfc low should also limit any
severe weather potential for the area, but a more NW track could
bring in a low end tornado threat to far SE areas Wednesday
given the impressive shear that will still exist.

Once we get past Wednesday night, general upper level trough will
remain in place with a series of disturbances passing through. With
no cold front to scour out the moisture a rather soupy airmass will
likely remain in place with dewpoints in the mid 60s to possibly
lower 70s. As noted above the maturing corn will likely begin to
yield more in the way of evapotranspiration, locally helping raise
dewpoints. This combined with slowly increasing temperatures over
the weekend into next week could yield heat indices well into the
90s and possibly close to 100 at times as well as chances for
showers and storms tied to either diurnally favorable periods or
timed out with one of more of the disturbances. No way to time any
of this out, so extended will have spurious slgt chc pops remain.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 726 PM EDT Mon Jul 8 2024

Showers and thunderstorms continue to percolate near KSBN. This
is in the vicinity of a weak cold front approaching
Chicagoland. KSBN and adjacent areas have seen repeated -TSRA
such that the environment should become less accommodating of
storm development, especially after sunset. However, high
resolution guidance is in fair agreement that storms may
continue to dot the area as late as 06Z. For now, will offer
-TSRA through about 03Z (medium-high confidence on the end
time).

At both sites, mid and high clouds associated with tropical
moisture streaming in ahead of Beryl are generally here to stay.
The chance of rain increases after daybreak Tuesday. There is
some concensus that showers/storms could impact both sites as
early as 15z. Greater confidence on the later arrival as
advertised in the TAFs. PWATS are anomalously high such that
flight conditions can deteriorate quickly within showers and
storms.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Fisher
AVIATION...Brown