552
fxus63 kiwx 151752
afdiwx
area forecast discussion
national weather service northern indiana
152 pm edt fri may 15 2026
.key messages...
- very warm this weekend with highs in the low 80s.
- showers and thunderstorms at time this weekend and into monday
pose a risk for heavy rainfall and instances of damaging wind
gusts.
- wet and stormy conditions linger into the middle of next
week.
&&
.discussion...
issued at 152 pm edt fri may 15 2026
an active forecast lies ahead but is one muddied by elements of
uncertainty. low pressure over the manitoba/quebec line has a
cold front spreading through the central plains this afternoon.
this cold front is the focus for showers and thunderstorms later
today well to our west. this activity tracks east overnight
arriving to southern lake michigan just before daybreak
saturday. high resolution guidance varies notably with how this
progresses. i have some preference to members that offer a
weakening trend as the line reaches southern michigan. this
occurs as the primary 500-mb jet (75 kts) is focused well north
across the up during the early- morning hours. rising heights
are noted at 500mb as well. in contrast, there is a blossoming
40-knot 850mb jet over northern il. a narrow corridor of 1,000
j/kg mucape paired with 30 knots of bulk shear yields a non-zero
chance for early morning isolated severe storms, but the lack
of upper-level support may be the greatest limiting factor.
as this area of showers and storms tracks east after daybreak
saturday, or perhaps bypasses north, the aformentioned cold front is
now stalled east-west across the forecast area and will be the
focus for scattered afternoon thunderstorms. boundary- parallel
flow increases the risk of training (backbuilding) thunderstorms
which can result in instances of flooding. our airmass will be
plenty warm and humid, with dew points in the 60s and pwats in
excess of 1.6"; high confidence in rain rates of 1" per hour
saturday afternoon. because of lingering cloud cover, it will
take time for instability to rebuild, struggling to reach 1,000
j/kg paired with about 30 knots of shear. overall, a marginal
risk of isolated damaging wind gusts saturday afternoon, with
heavy rainfall the greater concern.
this front is kicked poleward saturday night as the warm sector
amplifies in response to a trough digging in over the four corner
region. increasing confidence in a mainly-dry sunday as showers and
storms become focused elsewhere in the midwest and upper great
lakes, but will hold on to nbm populated 20-30% pops. monday
still appears to be the "best" day overall for severe
thunderstorms, but timing remains uncertain. a prefrontal
shortwave could be the focus for afternoon storms, well ahead of
the cold front that moves through overnight. in the afternoon,
steep low-level lapse rates present a damaging wind gust concern
from thunderstorms while a unidirectional wind profile, along
with elevated cloud bases, limits the overall tornado concern.
boundary-parallel flow will continue to pose a risk for heavy
rainfall in this warm, humid environment.
the cold front slowly moves through tuesday and wednesday, its
eastward progress slowed by strong subtropical high pressure. thus,
a rainy and stormy start to the week that lingers into at least
wednesday before high pressure pushes in for the late-week
period.
&&
.aviation /18z tafs through 18z saturday/...
issued at 112 pm edt fri may 15 2026
at the onset, relatively dry air was over the forecast area at
the surface with dew points in the 40s. mid clouds were associated
with strong warm air advection in the mid levels. embedded short
waves in the upper flow will continue to track east and bring
showers accompanied by the chance for thunder. added timing of
showers and thunderstorms late in the period to coincide with
the arrival of the next wave. these times include 09-12z at sbn
and 11-18z at fwa. one significant challenge was the development
of mvfr clouds as the moisture advection increases. for now,
considering the latest guidance, went with mvfr ceilings at fwa
with storms (12z) and then with the predominant lower clouds by
the end of the taf period.
&&
.iwx watches/warnings/advisories...
in...none.
oh...none.
mi...none.
marine...none.
&&
$$
discussion...brown
aviation...skipper