043
fxus63 kiwx 030717
afdiwx
area forecast discussion
national weather service northern indiana
317 am edt thu sep 3 2026
.key messages...
- heat and humidity continue through with peak heat indices
around 100 degrees.
- 20-30% chance of thunderstorms starting late this afternoon.
the chance of storms peaks overnight when damaging wind gusts
and hail are possible hazards. confidence in severe storms
occurring is medium.
- remaining unsettled with opportunities for thunderstorms friday
and saturday.
&&
.discussion...
issued at 317 am edt thu sep 3 2026
an upper-level ridge and stalled out frontal boundary remain the
primary items of focus for this forecast period. hot and humid air
prevails once again this afternoon as heat indicies are forecast to
be around 100. the heat advisory was expanded to the entire forecast
area. an overall absence of convection across wi and mi have limited
the anticipated cloud cover, thus, a hotter afternoon than
originally forecast. we`ll run into a similar situation for friday,
which, as it stands right now, is heat-advisory free, but may need
to be reevaluated based on convective trends.
turning now to those pesky thunderstorm chances; initial 00z cam
runs revealed dreadful initialization with over-convection noted in
ia and wi at the time, while struggling to handle convection
elsewhere in the plains. this weakens already battered forecast
confidence in this pattern. however, sifting past the over-
convection, ensembles and hourly runs appear to be converging on
storms developing over southern wi this evening in the vicinity of a
strengthening 500-mb jet and stalled front below. timing is murky,
but "after dark" appears to be a reasonable bet locally. the overall
severe weather environment is favorable, but nothing truly alarming,
with ample mucape, bulk shear near 30 knots and mid-level lapse
rates near 7 c/km. damaging wind gusts and hail appear to be the
most likely outcome from storm clusters that emerge from southern
wisconsin. this activity may persist beyond daybreak friday
depending on the upstream start time.
with the upper-level ridge still folding over our area friday and
saturday, thunderstorm chances persist but details are sparse owing
to the anticipated feedback loop day-to-day. perhaps some relief
sunday and the start of monday as canadian high pressure seeping
over the eastern great lakes works to suppress the upper-level ridge
westward for a time. guidance is split on how the coming week
evolves, but the overall upper air pattern to me favors a upper-
level ridge becoming centered over the mid-mississippi valley as a
trough arrives to the pacific northwest. this would promote
continued heat and storm chances.
&&
.aviation /06z tafs through 06z friday/...
issued at 1244 am edt thu sep 3 2026
pitiful model initialization of upstream convection across the
dakotas, along with suspicious over convection of activity
across ia and far northwest il muddies the forecast confidence.
will carry on with the inherited taf at this time.
satellite trends over the il-ia line indicate activity is
struggling due to an absence of deep layer shear. the next best
upper- level disturbance spills overhead in the 21z to 06z
window. models that have over-convected this morning favor tsra
as early as 21z. based on current observations, have thrown
these out. instead, am favoring late arrival of any tsra as we
await upper- level support to spark any organized thunderstorms.
will monitor trends and perhaps add -tsra to ksbn in the
vicinity of 06z friday for the next taf period.
&&
.iwx watches/warnings/advisories...
in...heat advisory until 8 pm edt /7 pm cdt/ this evening 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 this evening for ohz001-002-004-
005-015-016-024-025.
mi...heat advisory until 8 pm edt this evening for miz078>081-177-
277.
marine...none.
&&
$$
discussion...brown
aviation...brown