202
FXUS63 KIWX 082310
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
710 PM EDT Mon Jun 8 2026

.KEY MESSAGES...

- Heat and humidity is on the increase through Thursday, with
  highs in the mid-upper 80s and 90s and lows in the 60s to mid
  70s. Heat indices on Wednesday and Thursday will be around 100
  degrees. A greater than 50 percent chance for 90 degree high
  temps exists on Wednesday for a large part of the forecast
  area.

- Daily chances (generally 40-80 percent) for showers and storms
  this week. SPC has portions of our area in a marginal risk for
  severe weather for Wednesday evening into Wednesday night,
  with damaging winds the main threat. Severe weather is also
  possible on Thursday. Confidence in severe weather occurring
  is low to medium.

- Lower chances (20-50 percent) for showers and storms continue
  through the weekend, with temps cooling into the low to mid
  80s by Sunday and decreasing humidity.

&&

.DISCUSSION...
Issued at 1159 AM EDT Mon Jun 8 2026

Between today and Wednesday, a slowly southeastward moving high
pressure system takes over in the Bermuda high area and sets up a
relatively weak southeastern CONUS ridge. This puts the area in a
warm advection pattern that continues into late week when a cold
front pushes through Thursday night or Friday morning. Meanwhile, a
moderately vigorous shortwave that`s slowly weakening moves
northeastward through the Great Lakes into into Canada by Wednesday.
As a result, unsettled weather in the form of showers and
thunderstorms will be common as 70 degree dew points creep into the
area and MUCAPE reaches to between 1000 to 2000 J/kg at times during
this period. The Wednesday and Thursday period seems to have the
greatest instability as it passes 2000 J/kg of MUCAPE.

For this afternoon into tonight, a more moist airmass pushes into
the area and the HRRR seems to show cells pushing into areas west of
I-69 before dissipating. With the 70 degree dew points pushing in at
the surface and 850 mb dew points running from 10 to 15C, this will
create an environment for locally heavy rain.

For Tuesday, both the NAM and the GFS have the greatest effective
shear (30 to 40 kts) in what appears to be the time where
suppression behind the vort max moves in and weak height rises
appear to ensue. So that while we have moisture, instability, shear,
and an EML advecting in, the limiting factor for Tuesday`s chance
for thunderstorms to go severe will be lift. There are periods of
large scale ascent advecting through in the progressive flow so
maybe that could be enough to set something off? This may mean
Tuesday`s severe weather chance will rely on advecting in already
strong storms if it`s going to produce severe weather.

For Wednesday, a few relatively weak shortwaves move through in the
flow and as mentioned earlier, strong instability is across the area
with plenty of moisture. We`ve also got a lingering EML. Perhaps
this environment is enough to get some severe weather because, while
it appears the better shear may stay to our west, we may be able to
advect stronger storms into the area and have the better mid level
lapse rates maintain severity of the storms. The better large scale
ascent does appear to stay in MI though. Damaging wind and some hail
will be the most likely possibility with helicity lacking in the
hodograph, but flooding cannot be ruled out from the repeated storm
chances and moist atmospheric column.

For Thursday, a strong shortwave moves from the Central Rockies late
Wednesday night up into the Northwest Great Lakes late Thursday.
This pushes a relatively strong surface low pressure system into the
area Thursday. Again, strong instability and moisture will be around
the area, but the low`s track may keep it just far enough west to
restrict forcing to northwest of the area until Thursday night/
Friday with the cold front. By this time, we`ve lost the EML and we
still only have 20 kts of effective shear at most. So, again severe
weather could be possible, but we`d have to rely on cell collisions
or advecting in something elsewhere to produce something
substantial.

Another aspect of this period is that as the Bermuda high pressure
system sets up, warmth and moisture moves towards the area. At the
same time that we have the 70 degree dew points, we`ve also got 850
mb temperatures that surpass 18C, which with good mixing would make
90 degree surface temperatures also possible creating a heat
advisory situation. Of course, the fly in this ointment is the
thunderstorm chances. The closer we get to Wednesday and Thursday,
the better chance we`d have an idea about if thunderstorms or cloud
cover would around to affect our warming for these days. On
Wednesday, the greatest chance to see 90 degree temps is highest (50
to 100%) west of IN-15 and along US-24. Elsewhere has more like 30
to 50% chance, mainly north of US-24 and east of IN-15. Thursday`s
chance is more marginal with areas east of I-69 having the best
chance (greater than 50% chance). Additionally, Wednesday night has
Min apparent temperatures bottoming out around the low 70s which
indicates the difficulty to see any recovery (cooling) period at
night. The cold front pushes through Friday and allows highs to fall
back into the 80s and 70s into the following Monday.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 710 PM EDT Mon Jun 8 2026

Cluster of storms associated with slowly advancing warm front
will impact KSBN during the next 1-2 hours. Behind that,
additional storms could develop later tonight given very moist
environment but confidence is not high and will hold with a
PROB30. Of greater confidence is the expectation for IFR
ceilings given nocturnal cooling in a very moist airmass. At
KFWA, isolated storms can`t be entirely ruled out through the
overnight into the morning but confidence is too low for even a
PROB30 mention here. Will hold with just TEMPO showers and IFR
ceilings. Better chances for storms at KFWA will be Tuesday
afternoon as diurnal instability rebuilds.

&&

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

&&

$$

DISCUSSION...Roller
AVIATION...AGD