Corunna, Indiana Weather Forecast Discussion

189
FXUS63 KIWX 130434
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1234 AM EDT Sat Sep 13 2025
.KEY MESSAGES...
- 20-40% chances for rain and storms Saturday afternoon through
  early Sunday. Isolated severe weather is possible.
- A persistent dry and warm pattern sets up starting on Sunday
  and lasting through next week. Expect highs in the upper 80s
  to low 90s each day.
- Minimum relative humidities as low as 30% to 40% next week may
  be conducive for elevated fire danger.
&&
.DISCUSSION...
Issued at 236 PM EDT Fri Sep 12 2025
The only chances for rain in the next 7 days will be Saturday
afternoon/evening into early Sunday morning. An upper level ridge
continues to amplify over the central CONUS; With the forecast area
on the eastern edge of this building ridge, there are 20-40% chances
for rain and storms on Saturday. Clusters of convection currently
over northern Minnesota will dive southeast overnight into the day
tomorrow. Rain and storms chances increase in our northwest near
Lake Michigan around midday Saturday and propagate
south/southeast during the afternoon and evening along the
periphery of the ridge. A warm front lifts northward tonight,
with southerly winds allowing for WAA and decent moisture
transport behind it into the day tomorrow. SPC has introduced a
Marginal Risk for severe weather on Saturday and WPC has
introduced a Marginal Risk for localized flash flooding.
Forecast soundings show a mainly capped environment but I
wouldn`t be surprised if a few storms develop. Should storms
develop, they will be capable of heavy rain and gusty winds.
Isolated severe weather is possible. Best chances for rain
tomorrow into early Sunday morning will likely be along and east
of the I-69 corridor. Have lowered PoPs in northwest Ohio due
to waning a waning instability gradient and given a stronger
model consensus on the location of precipitation.
For Sunday and into early next week, an Omega Block pattern sets up.
The aforementioned ridge axis will move over the Midwest and
Great Lakes regions, allowing for warmer temperatures and
persistent dry conditions. Highs will be in the upper 80s to low
90s each day from Sunday through the middle of next week. The
humidity will be noticeable with dewpoints in the mid 60s.
While not uncommon this late in the summer, the heat will also
allow for large diurnal temperature swings as dry conditions
persist through next week. In fact, given that we have been
lacking significant rainfall since mid August, drought is likely
to persist and/or develop in the coming weeks.
One additional concern for next week given the above normal
temperatures and dry conditions is fire danger. Sunny skies and
persistent warmth should allow for minimum afternoon relative
humidity values to drop between 30 to 40 percent. However,
should any grass or brush fires develop, winds should be light
enough that it likely won`t spread quickly. Avoid outdoor
burning!
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1230 AM EDT Sat Sep 13 2025
Inherited TAFs were in good shape when compared to the latest
high resolution guidance. All eyes are on a upper-level
disturbance over WI tracking southeast. Guidance is in good
agreement that there will be increasing coverage of showers and
storms across southern WI and into northern IL this morning. The
instability gradient is located along the IL-IN line through the
morning such that, when factoring in the dry sub-cloud layer,
the PROB30 continues at KSBN. Redevelopment in the afternoon
there appears unlikely given little to no instability and the
best synoptic forcing elsewhere.
I`ve maintained the dry TAF at KFWA. We`ll continue to monitor
the risk of afternoon -TSRA. However, concerns at KSBN are
identical to KFWA in that regard.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Johnson
AVIATION...Brown

NWS IWX Office Area Forecast Discussion