Mexico, Indiana Weather Forecast Discussion

517
FXUS63 KIWX 190534
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
134 AM EDT Fri Sep 19 2025
.KEY MESSAGES...
- Remaining warm through the weekend with above normal high
  temperatures in the 80s.
- Chances of rain return for the weekend, especially later Sunday
  into Sunday night (50-60%).
&&
.DISCUSSION...
Issued at 207 PM EDT Thu Sep 18 2025
More of the same into tonight and Friday as upper level ridging
lingers between a low pressure center over the North-central US and
an upper trough over southeast Canada. A backdoor cool front
associated with the southeast Canada trough drops into northern
zones tonight into Friday morning with the only potential impact
being patchy fog early Friday in its wake thanks to some marine
influence from Lake Huron/Erie.
Weak height falls overspread the region Friday night into this
weekend as the Plains low/upper trough evolves east toward the MS
River Valley and western Great Lakes. This will bring initial low
(20-30%) chances for a few showers into mainly western IN and
southwest MI Friday night into Saturday as a weak shortwave and
elevated warm front lift through. Most of the area will remain dry
however with more clouds around and temps still above normal for
late Sept.
Late Sunday into Sunday night still appears to be the best
opportunity (50-60%) for greater rain shower coverage and perhaps a
few embedded storms as a more pronounced shortwave and surge of
deeper moisture track east-northeast through the western/lower Great
Lakes. Predictability then falls off into next week as the broad
upstream trough eventually cuts off under building south-central
Canada heights. Opted to hold with NBM daily broadbrush PoPs as a
result (mainly 20-50%) through at least the mid-week periods given
expectations for moist low levels with a front and this meandering
upper low nearby. High temperatures will be a bit cooler in this
regime (near normal), though humidity levels will be more
elevated.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 133 AM EDT Fri Sep 19 2025
A weak sfc trough will continue to sag south and should stall
out across extreme northern Indiana. Sfc dew points have risen a
few degrees into the lower 60s in the wake of this front with
some eastern Great Lakes marine influence. Hires guidance does
indicate some increased fog potential in the vicinity of, and
just in wake of this sfc trough, but this potential should
remain north and east of KSBN/KFWA. Some patchy shallow fog is
possible, but this appears to be more favorable in outlying
rural areas and will continue to omit from 06Z TAFs. Otherwise,
mid/upper level ridge will maintain its location today,
eventually starting to shift eastward by this evening. Some weak
sfc based instability is possible at KSBN later this afternoon,
but better instability and forcing should remain across
Illinois. VFR conditions are expected to hold through this
period.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Steinwedel
AVIATION...Marsili

NWS IWX Office Area Forecast Discussion