Sims, IN Weather

Key messages

- 20% to 40% chance of isolated showers this afternoon as a cold front moves through. Remaining very warm ahead of the front.

- Not quite as warm this weekend but still above-normal to end October.

- 20 to 40% chance of showers on Halloween, mainly west of I- 69.

Update

Issued at 906 AM EDT Thu Oct 29 2026

Cold front extends from central WI to eastern IA this morning and is expected to make slow progress through the day. 12Z KILX sounding shows some improvement in moisture compared to 24 hours ago, but still a decent amount of dry air in the low levels. This has resulted in any showers being limited to some sprinkles. Conditions improve somewhat this afternoon, with pops on track at this point as isolated to maybe scattered showers (storm?) develop.

Discussion

Issued at 212 AM EDT Thu Oct 29 2026

High pressure continues to flex its muscle over the eastern CONUS early this morning. Water vapor shows fleeting Pacific moisture return to a cold front working its way through the Midwest, but battling the aformentioned high. Satellite and radar show a broken line of showers from central WI (whose population is basking in a World Series championship) through eastern Iowa, while a better organized area of rain occurs north-northeast of there. Back at home, preexisting dry air keeps a majority of the day dry. However, there is growing concensus that modest saturation below 16,000 ft and adequate upper-level forcing from the right entrance region of a departing 500-mb jet will be enough for at least isoalted showers along the cold front from west to east after 12pm EDT. Cannot completely rule out an isoalted thunderstorm as a thin ribbon of instability accompanies the front, per high resolution ensembles. Skies quickly clear out behind the front and lows will tumble to near 40 by Friday morning.

The rest of the forecast period is characterized by cooler, but still above-normal temperatures, and increasing chances for rain. We continue to monitor the 20-40% chance of showers Saturday west of I- 69 as a weak shortwave lifts in from the Southern Plains. Preceding high pressure, will be fighting to keep Halloween dry, yet the rain chance must continue at this time. The better surge of moisture arrives in the Sunday-Monday time frame as high pressure centers over the Appalachians steering Gulf moisture poleward. This area of rain would be followed by a mid-latitude cyclone in the Tuesday- Wednesday period, bringing mild and breezy conditions ahead of it, rain, and then a dose of cooler air. The magnitude of these details remain murky owing to the uncertain degree of phasing between a subtropical jet moving over the Baja, and a Great Basin trough poised to move onshore this weekend.

Aviation

Issued at 607 AM EDT Thu Oct 29 2026

Existing TAFs remain on track at this time. A narrow area of MVFR ceilings upstream warrants the continued MVFR mention at KSBN. Otherwise, opted to improve visiblilty associated with -SHRA given the shallow moisture source. Isoalted afternoon showers give way to veering surface wind, becoming calm near daybreak with decreasing clouds behind the front.

Watches, warnings and advisories

IN: None. OH: None. MI: None. MARINE: None.