621
FXUS63 KIWX 131734
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
134 PM EDT Thu Jun 13 2024

.KEY MESSAGES...

- Hot today with chances for severe storms late today through
  early tonight. Damaging winds and large hail are the greatest
  threats.

- Dry, cooler and less humid Friday and Saturday.

- Hot & humid Sunday through Thursday; highs around 90 to 95
  with afternoon heat indices 95 to possibly as high as 105.
  Storms possible each day, mainly late afternoons & evenings.

&&

.DISCUSSION...
Issued at 313 AM EDT Thu Jun 13 2024

The third day of return flow was underway; however, deeper moisture
had not yet made it into the forecast area. But despite the lack
of deeper moisture, an EML intrusion was just off to the west.
Steep mid level lapse rates will favor severe storms, especially
west of Highway 31 where the bulk of a slight risk for severe
storms is indicated by SPC. It looks like the best window for
storms is from 20Z to 04Z (4pm to midnight EDT). Some weak
capping at the base of the EML is likely to help storms to be
initially more focused along the south moving front over Lower
Michigan. The latest/06Z run of the HRRR appears on track in
this regard with convection initiating near the Michigan border
by 6pm and then spreading rapidly south during the evening.
Given BUFKIT profiles, it appears damaging winds are the
greatest threat from storms late today and this evening. Large
hail, locally heavy rainfall and an isolated tornado are all
possible.


After tonight, cooler and less humid air will be over the area
Friday and Saturday. By Sunday, the heat will return followed by
the humidity arriving Sunday night and Monday. Precipitable
water values will be substantial with values at times above 2.0
inches from Monday through Thursday. In this environment and
during this time of year, believe storms will be highly diurnal
in the 19Z to 02Z window (3pm - 10pm EDT). Large CAPES topping
over 3000 J/Kg at times and relatively weak shear should limit
severe potential to locally heavy rainfall. Concurrently, the
tropical plume of moisture is expected to arrive early next
week with the hot conditions. These combined factors are
expected to cause afternoon heat indices to reach near 100F to
105F. Will continue to message this heat hazard.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 128 PM EDT Thu Jun 13 2024

An active TAF period is anticipated amid the risk for severe
thunderstorms, especially at KSBN. Cumulus clouds are developing
over Illinois and southern Michigan ahead of a cold front
located near the WI-IA-IL lines. Severe thunderstorms are
expected to develop near the Michigan state line and drop south.
Strong wind gusts, hail, and heavy rain are the primary
concerns.

Synoptic wind gusts abate behind these thunderstorms, through
wind gradually veers through the night behind the cold front.
There is a non-zero chance of MVFR ceilings tonight amid post-
frontal stratus. Probabilities are generally near 30% or so, per
the in-house blend. Therefore, retained the mention at KSBN but
avoided the introduction of such ceilings at KFWA for the time
being. Satellite trends will be monitored.

&&

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

&&

$$

DISCUSSION...Skipper
AVIATION...Brown