Sims, Indiana Weather Forecast Discussion

321
FXUS63 KIWX 040647
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
247 AM EDT Sat Oct 4 2025
.KEY MESSAGES...
- Warm and dry conditions persist this weekend with highs near 90.
- The combination of dry conditions and gusty winds could lead
  to an elevated risk for field fires this weekend,
  particularly on Sunday.
- Rain is expected on Tuesday, with much cooler conditions for
  the middle and end of next week.
&&
.DISCUSSION...
Issued at 247 AM EDT Sat Oct 4 2025
No major changes to the forecast for this weekend. Mid/upper ridge
still slated to rebuild over the Great Lakes as minor shortwave
continues to shear out and much more formidable upper low settles
into the Desert Southwest. Net result will be a steady increase in
S/SW flow through the weekend. Dry airmass and ample sun will
support deep mixing each day with highs near 90F which is record
territory for Oct 4-5. Surface dewpoints also likely crash into the
low 50s. Lack of any appreciable rain over the previous 10 days and
typical loss of vegetation moisture during fall raises an increasing
concern for field fires with harvest activities now well underway.
Sunday will be the biggest concern for fires to get out of control
with increasing wind gusts near 25 mph (sustained near 15 mph) and
afternoon RH values near 25 percent. Wind and 10-hour fuel moisture
criteria likely fall short of a red flag warning but this is about
as close as we get and we often see numerous field fires while
harvesting in these conditions.
Monday will still be very warm and likely dry given the cold front
will still be well upstream. We do get some moisture pooling ahead
of the front though with more cloud cover and higher dewpoints/RH
values anticipated. A stray shower can`t be ruled out during the
late afternoon, particularly in our NW, but I think a dry forecast
will win out given lack of forcing and still overall dry/stable
conditions prior to 00Z. Surface cold front settles into our NW on
Mon night with some notable fgen forcing in the right entrance
region of a 100+ kt upper jet over the northern Lakes/Canada. The
problem is the best fgen may set up just north of our CWA and very
poor diurnal timing will limit convection potential. Instability
does rebuild slightly by late Tue morning and the arrival of a
secondary shortwave late Tue will further enhance fgen forcing.
However, by then the front has cleared most of our CWA and the
potential for our area to be split by these two rounds of forcing
remains. Still think there will be some showers around late Mon
night into Tue and worth a likely PoP but not expecting a
widespread, substantial rain. Thunderstorms are possible but lack of
appreciable SBCAPE will limit the severe threat.
A return to dry conditions with much more seasonable temps is
expected mid-late week. Highs drop into the 60s Wed-Thu with lows
touching mid/upper 30s Wed night. Moderating temps expected by the
end of the week. Another upper low may drop into the region by
Fri/Sat but models are in wide disagreement on strength and
track.
&&
.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 247 AM EDT Sat Oct 4 2025
Strong ridge of high pressure will ensure VFR conditions with
light S/SW winds through the period. A few diurnal cu possible
along with some passing high clouds but no aviation impact
anticipated.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...AGD
AVIATION...AGD

NWS IWX Office Area Forecast Discussion