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352
FXUS63 KIWX 281832
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
232 PM EDT Tue May 28 2024

.KEY MESSAGES...

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- Cool conditions with periodic showers and thunderstorms will
  continue through Wednesday.

- Some strong thunderstorms are possible this evening into
  tonight with gusty winds and hail being the main threat.
  Isolated severe storms are possible, mainly west of IN-15.

- Dry weather is expected Thursday and Friday but more rain
  chances increase this weekend into next week.
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&&

.DISCUSSION...
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Issued at 229 PM EDT Tue May 28 2024

A broad trough and collocated cold temperature anomalies over the
Great Lakes shifts eastward between this evening and Thursday
bringing times of showers and storms as various areas of vorticity
pinwheel through the area. After this morning`s vort max shifted
eastward, the break allowed for additional sunshine and surface
heating ahead of a second vort max for this evening between 6pm and
10pm. There is a 25 to 30 kt low level jet that passes by to our
southeast, but that`s fairly weak for shear for storms to tap into.
Given windows of mid level lapse rates between 6 and 7 C/km can see
hail as a possible storm hazard as well as wind with moisture loaded
microbursts. SPC`s marginal appears warranted as despite the weak
shear, perhaps a storm or two could put out outflow boundaries that
could aid downstream storms. These showers and storms are expected
to linger into tonight, but the severity of such storms is expected
to die off. Showers and storms are also expected to continue into
Wednesday as the main vort max shifts slowly eastward around the
base of the trough. Negative theta-e pushes into the area behind an
instability trough during the afternoon Wednesday, but shear is
expected to be lacking. Instability driven thunderstorms will be
capable of gusty winds and locally heavy rain during this time.
Finally, one last vort max slides through east of I-69 on Thursday.
At this point, expect much drier conditions with dew points back in
the 30s and 40s. Surface high pressure is quick to follow allowing
for drier conditions across a good chunk of the forecast area.

Friday comes with the greatest confidence of an all clear call with
surface high pressure overhead and sliding eastward through the day.
With the high pressure center just east of the forecast area later
Friday, expect warm air advection to ensue and bring us back up to
the mid 70s for highs after being in the upper 60s and low 70s in
the days prior.

A couple of days ago, this ridge was much broader, but an area of
low pressure is expected to eject into the Southern Plains Friday
and infringe on its western periphery. A strung out area of
vorticity is located on the western periphery of the mid level ridge
and this is expected to slowly trek towards the area somewhere
between very early Saturday (ECMWF camp) and Saturday afternoon (GFS
camp) bringing a renewed chance for showers and potential
thunderstorms. The ECMWF still has the warm front stalled out
overhead on Saturday and this could still restrict highs on Saturday
to below 80 degrees.
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&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 125 PM EDT Tue May 28 2024

Upper level disturbance dropping through Wisconsin this
afternoon with an area of showers and a few storms. Clearing
skies have allowed steepening low level lapse rates and an
increase in cu both here and upstream ahead of the wave. Models
vary on start of chances for showers/storms, but seem to focus
the greatest coverage (and chances for thunder) maybe as early
as 23Z at KSBN but more likely in the 1-4Z period. KFWA more
questionable with loss of heating and narrow window for thunder
potential. Have made some adjustments with tempo MVFR groups for
cig/vsby as well as thunder in most favored period. Can`t rule
out some locally gusty winds or small hail, mainly at KSBN, but
not covered in TAFs. Showers and MVFR cigs should persist
overnight with the potential for a drop to IFR mainly at KSBN or
during showers. While the showers should move away during Wed
morning, flight conditions may be slow to improve so MVFR
conditions maintained through the end of the period.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
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IN...Beach Hazards Statement from late tonight through Wednesday
     evening for INZ103.
OH...None.
MI...Beach Hazards Statement from late tonight through Wednesday
     evening for MIZ177-277.
MARINE...None.
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&&

$$

DISCUSSION...Roller
AVIATION...Fisher