153
fxus63 kiwx 011654
afdiwx
area forecast discussion
national weather service northern indiana
1254 pm edt tue sep 1 2026
.key messages...
- heat and humidity continue through at least midweek with peak heat
indices around 100 degrees.
- low chances for showers and storms (15-20%) north of i-80/i-90 tonight
and wednesday. if an isolated storm or two develops, it could
produce gusty to damaging winds. low confidence at this time.
- 30-50% chances for showers and storms area-wide later in the
week on thursday and friday.
&&
.discussion...
issued at 1250 pm edt tue sep 1 2026
happy september 1st and start to meteorological fall! summer shows
no signs of slowing down as we start september, with an expansive
upper level ridge overhead expected to bring hot and humid
conditions through much of this week. a heat advisory remains in
effect for the entire forecast area through 8 pm edt wednesday. our
late summer/early fall heatwave brings high temperatures in the
upper 80s to low 90s through at least midweek. with return flow off
of the gulf due to surface high pressure centered over the southeast
conus, high humidity is expected to persist through at least
midweek. despite the unexpected showers and storms this morning,
clearing is already ongoing this afternoon per visible
satellite imagery, which will allow for temperatures to climb
into at least the mid to upper 80s for highs today slightly
warmer wednesday with highs in the low 90s with the peak of the
ridge overhead. heat indices are expected to be at or slightly
above 100 degrees, especially this afternoon and again wednesday
afternoon. there will be minimal relief overnight with near
record lows in the mid 70s. heat indices around 100 degrees may
persist along and south of us 30 into thursday, so the heat
advisory may need extended in a future forecast update.
considerable uncertainty remains in regards to rain and storms
chances this week. all models have struggled with this pattern
over the past few days; a majority of recent runs of hi-res
guidance have been misleading, keeping the upper level ridge
well to our north whereas in reality, our area (especially the
northern half) has been on that periphery as well. we had
scattered showers and storms in the vicinity of the us 30
corridor this morning and none of the models showed anything
occuring. models have been taking the rain/storm chances north
out of our area, which has created challenges and considerable
uncertainty in regards to what to do with pops over the next few
days. the nbm wants to hold off on any rain for our lower
michigan counties until early thursday at the earliest. however,
i cannot rule out at least isolated shower/storm development in
our forecast area (especially north of i-80/i-90) tonight and
wednesday, where i have added broad 15-20% pops. should any
storms develop, heat and humidity should fuel mlcape values of
up to 3000-4000 j/kg and steeping low level lapse rates. spc
does have at least the northern/northeast half of our area in a
marginal risk each day through thursday with the main risk being
gusty to damaging winds. confidence is low given the
aforementioned uncertainty with models. better chances (30-50%)
for rain/storms area- wide are in the forecast for later
thursday into friday as the upper level ridge gradually
flattens, although uncertainty still remains in the forecast
several days out given the recent unreliable model guidance. our
far southwest counties have the best chances for remaining
completely dry this week with heat and humidity continuing
through late in the week. by the weekend, temperatures trend
closer towards normal with highs in the low 80s.
&&
.aviation /12z tafs through 12z wednesday/...
issued at 645 am edt tue sep 1 2026
a west-east band of showers is ongoing this morning from
northeast illinois to just south of the ksbn vicinity. these
showers appear to be developing at the crest of a mid level
thermal ridge where a very subtle mid trough is approaching
southern lake michigan. persistent isentropic ascent along this
west-east corridor (albeit weaker than last evening) should
sustain these showers eastward across northeast indiana,
possibly taking a slight southeast turn mid morning. isolated
showers should affect ksbn vicinity early this morning and may
clip kfwa during the mid morning hours. it does appear by midday
that this isentropic ascent should largely weaken and attention
will turn to any isolated shower/storm development this
afternoon and early evening across far northern indiana.
confidence remains low in this redevelopment this afternoon and
will keep tafs dry after 18z at this time. better chances of
storms tonight should focus back across northern iowa/southern
minnesota at the nose of a low level jet. this may keep focus of
showers and storms focus northwest of the local area tonight
into early wednesday morning.
&&
.iwx watches/warnings/advisories...
in...heat advisory until 8 pm edt /7 pm cdt/ wednesday for
inz005>009-012>015-017-018-020-022>027-032>034-103-104-
116-203-204-216.
oh...heat advisory until 8 pm edt wednesday for ohz001-002-004-005-
015-016-024-025.
mi...heat advisory until 8 pm edt wednesday for miz078>081-177-277.
marine...none.
&&
$$
discussion...johnson
aviation...marsili