143
FXUS63 KIWX 081834
AFDIWX

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

.KEY MESSAGES...

- Isolated to maybe scattered showers and storms expected this
  afternoon into 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 troughm 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
efficent 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 intially 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 /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 119 PM EDT Mon Jul 8 2024

Beryl was still down in TX and was weakening as it was moving
farther inland. Well ahead of this tropical system over northern
Indiana, the atmosphere was destabilizing with surface based
CAPEs over 1500 J/Kg per SPC meso. Included SBN with a VCTS
mention in this more unstable air; otherwise, the showers and
storms from Beryl should hold off until after the end of the
TAF period.

&&

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

&&

$$

DISCUSSION...Fisher
AVIATION...Skipper