458
FXUS63 KIWX 051738
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
138 PM EDT Wed Jun 5 2024

.KEY MESSAGES...

- There is a marginal risk of severe thunderstorms from midday
  through this evening.

- Damaging wind gusts, heavy rain, and hail are the primary
  hazards.

- Warm and humid conditions today give way to cooler than-normal
 temperatures for much of the next seven days.

&&

.UPDATE...
Issued at 1248 PM EDT Wed Jun 5 2024

Ongoing thunderstorms across the forecast area have not been
severe, but some gusts 40 to 50 mph have been observed. This
convection is expected to continue tracking northeastward
through the afternoon and into the early evening. A second line
of storms associated with the cold front is still being shown by
CAMS to develop between 2 PM and 3 PM and cross from the west.
However, there is low confidence that this will amount to much
after this first round finishes working over the atmosphere and
exhausts much of the instability.

&&

.DISCUSSION...
Issued at 232 AM EDT Wed Jun 5 2024

A cold front approaching the Mississippi River this morning will
bring a marginal risk of severe thunderstorms in the afternoon and
evening along and east of I-69 (generally speaking). Damaging wind
gusts are the primary concern, followed by heavy rainfall and hail.
The timing of these storms remains about 2pm to 8pm EDT.

Showers and thunderstorms are ongoing over northwest Indiana early
this morning, associated with a MCV lifting in from Illinois, aided
further by a strengthening 850-mb jet. Heavy rainfall and perhaps
strong wind gusts near 40 mph are possible (as reported over
northeast IL). Elsewhere in the forecast area will be untouched by
the time the cold front arrives in the afternoon. Temperatures
rising in the 80s with dew points near 70 degrees will permit
impressive CAPE ahead of the cold front while shear and lapse rates
are lacking (25 knots 0-6km and 6C/KM mid-level, respectively).
Coverage of storms along the cold front varies among model guidance,
likely due to the marginal environment, but guidance favors discrete
cells in our area perhaps congealing into a line across central Ohio.

Drying out for a time early in the night behind the cold front but a
a few showers may arrive later on associated with a screaming, 85-
knot jet at 500mb. Moisture transport from the Pacific is somewhat
poor, navigating significantly poleward atop a towering ridge over
the Four Corners before spilling over the Great Lakes. However, RH
remains elevated in the column through Friday, warranting at least
slight chance POPs at times as various embedded vorticity maximums
rotated around the closed low aloft. Temperature-wise, Friday looks
to be the coolest of the next seven with highs right near 70
following two distinct waves of CAA.

This upper-level low lingers over the (eastern) Great Lakes into at
least the start of next week, if not longer. This complicates the
forecast as models do not handle cut-off lows very well. Overall,
showers at times are probable paired with cooler-than-normal
temperatures for June.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 138 PM EDT Wed Jun 5 2024

Initial line of thunderstorms is currently exiting the area and
has stabilized the environment for now. While the main cold
front is still well to the west additional storms are not
expected at KSBN and the chances are low at KFWA. A period of
low MVFR ceilings along the front is likely though based on
upstream obs. A secondary cold front will then cross the area
overnight but conditions will remain VFR and no thunder is
expected. Gusty winds expected on Thursday as low pressure
settles into the Great Lakes.

&&

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

&&

$$

UPDATE...Cobb
DISCUSSION...Brown
AVIATION...AGD