132
FXUS63 KIWX 262341
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
741 PM EDT Fri Apr 26 2024

.KEY MESSAGES...

- Highs are much warmer over the coming days with 70s being the
  norm. 80 degrees will be possible both weekend days.

- Periodic chances for rain and storms are expected between this
  afternoon and next week with tonight and Monday having the
  greatest chances.

&&

.DISCUSSION...
Issued at 252 PM EDT Fri Apr 26 2024

In a decoupling jet scenario with the Pacific jet taking over, an
upper low deepens and drifts northeast from the Central Plains to
the Northern Plains between this afternoon and Saturday. During this
time, the warm front pushes through the area later this afternoon
and tonight. Saturation appears fairly quick this afternoon and
evening on model time-sections despite Td depressions between 20 and
30F. It is interesting to see much of the omega leaning westward
with much of the large ascent and mid level vorticity staying there
as well. It isn`t until later tonight/early Saturday that the large
ascent shifts eastward likely meaning rainfall will be focused
westward as well. These leans are noticeable on the PWAT
moisture content as well, as to where the maximums lie. Despite
the 1 to 3 SDs above normal, it still appears the lack of
instability and forcing tonight point to lesser QPF output,
which appear to stay less than 0.25 aside from counties west of
IN-31 where closer to 0.5" may be more in reach.

For the weekend, it appears there will be an opportunity to tap into
effective shear during the morning hours, and with instability
available, severe weather is possible. The main threat with that
appears to strong winds and perhaps a stray spin up. Hail appears to
be a lesser threat given the moist low levels during this time.
Another threat for thunderstorms is possible Saturday afternoon, but
the shear appears to be a little bit more sporadic and there`s some
question about how much instability might be left over at that
point. We do actually get 60 degree dew points into the area during
the afternoon and low level temperatures surpass the teens Celsius.
With some mixing, highs will be able to get into the 70s allowing
for a warm day. Sunday has some instability around and a weak area
of vorticity may be able to tap into it to create some thunderstorms
during the morning. But dry air follows allowing for a rain-free
afternoon. 70s and perhaps 80 degree highs will be in play for
Sunday.

A cold front pushes through Sunday night into Monday with some
thunderstorms possible. There is some shear to work with, although
it appears to diminish by Monday morning. The moisture axis appears
to stall out on Monday and may be able to refire in the I-69
corridor on east during the afternoon. Initial model output
indicates some shear and instability will be available for showers
and storms as well.

Some drying out appears likely for Tuesday morning behind the cold
front. The ECMWF shows a dry solution as opposed to GFS/GEM which
hold on to some precipitation. Perhaps they are keying into a warm
front-like feature that rises north during the afternoon to form
showers. Based on its history in these events, will lean towards the
ECMWF at least with messaging. More confidence can be had with
precipitation occurring in the area later Tuesday night as a
shortwave moving through in the flow coincides with a cold
front passage. Thunderstorms are also possible with both
instability and shear present to be tapped into. It then appears
that a break in the unsettled weather can be forecast after a
cold front moves through Thursday night. Temperatures in the 70s
will still continue through this period with Friday having a
good chance to return to cooler temperatures. Once again, NBM
probability of 1 inch in 24 hours is below 20 percent in any one
period through this unsettled time frame indicating its
sporadic nature and that its floor is low as far as QPF is
concerned.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 730 PM EDT Fri Apr 26 2024

The initial impulse of moisture has moved into the region
bringing light showers across the area. A secondary surge with
increased low level jet winds surge in the 05Z-11Z timeframe
will bring increased southerly winds with gusts near 25 kts at
the surface and another bout of light rain showers and even a
few rumbles of thunder will be possible with the weak elevated
instability. Will continue to mention the LLWS chances with the
low level jet placement over the area. Mainly MVFR cigs are
expected through early Saturday morning, with cigs rising to VFR
levels after 14z Saturday for KSBN and 15z for KFWA.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 11 PM this evening to 8 PM EDT
     Saturday for LMZ043-046.

&&

$$

DISCUSSION...Roller
AVIATION...Andersen