Area Forecast Discussion

KEY MESSAGES

- Extreme to very high fire danger is forecast for northeast Nebraska on Wednesday afternoon.

- Shower and storm chances Wednesday night into Thursday (50-80%). Some storms on Thursday afternoon and evening may be severe (15% chance for any given storm.)

- Cooler temperatures going into next weekend with more chances for showers Saturday (30%) into Sunday (70%).

DISCUSSION

Issued at 1229 PM CDT Tue Apr 21 2026

Skies are primarily clear across Nebraska, Iowa, and the High Plains as H5 ridging suggests subsidence. A boundary draped across the area's mid-section is more of a dryline than a cold front.

As of the lunch hour, temps are primarily in the mid- to upper-70s with a few 80s popping up in northeast Nebraska where the drier air is easier to heat. Dewpoints currently range from the mid-50s south of the boundary draped across the area to some mid- to lower-30s north of it.

The boundary is progged to slip south by only 50 miles or so through the afternoon hours before southerly winds drive it north over the course of the evening and overnight. By midnight a nocturnal LLJ develops over western/central Nebraska and helps with moisture return over this forecast area.

WEDNESDAY

A deep upper low approaches from the west while a sfc low develops in lee of the Rockies. Breezy southerly winds develop ahead of the system. A dryline will push through east and approach northeast Nebraska. Stronger gusts of 25-35 knots in this part of the state will help mix some drier air to the surface where dewpoints may find their way back into the 30s again. This would allow RH values to slip below 20%. There is lots of uncertainty as to how far east the boundary will push and how low the dewpoints will get. This forecast is undoubtedly aggressively dry and closer to the 25th percentile of model solutions. However, fire weather days do tend to lean this way. Have flipped the FIRE WEATHER WATCH to a RED FLAG WARNING and expanded considerably. Recent contact with local fire officials increases confidence in fuel readiness in northern counties.

Were the dryline to remain in central Nebraska, fire concerns would be tamped down.

Showers and some thunder look possible late Wednesday night thanks to the LLJ and a little elevated instability.

THURSDAY

A powerful 985 hPa low will track just north of the US/Canadian border on Thursday and drag a cold front/dryline through the area on Thursday afternoon and evening. There's still plenty of uncertainty in its timing, but it's worth noting that the EC and the RAP both slowed the front with 12Z runs today and therefore produce a better chance of severe weather for Thursday as our area should spend the afternoon in the warm sector. Ahead of the front, plenty of instability and straight hodographs mean thunderstorms are likely. Although they may start as supercells, the straight hodos suggest interference between storms as upscale growth continues. Expect an eventual line of storms to form as they push east. This will reduce the threat of tornado development (early supercells would be capable of producing funnels/tornados). Heavy rain looks possible, too, with PWAT values above the 97th percentile.

FRIDAY AND THE WEEKEND

Behind the departing system, cooler weather builds in with highs anticipated to peak only in the (seasonally normal) sixties. Two different rounds of precipitation are possible over the weekend with lesser chances on Saturday (40%) and best chances on Sunday (70-80%) with an upper low and attendant surface system developing across SD/Nebraska vicinity. Moisture return and PWAT values are noteworthy once again on Sunday. It's early, but NBM ensemble probabilities suggest a 50-60% chance of 0.50" or more precip falling this weekend. That holds true for the entire CWA.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1159 AM CDT Tue Apr 21 2026

VFR conditions will persist. Two air masses are across the area with southwesterly winds south of the boundary and northeasterly winds north of it. Regardless, these winds are relatively slow at 5-10 knots.

Expect southerly winds to dominate by midnight tonight with stronger winds developing on Wednesday morning, still out of the south.

OAX WATCHES / WARNINGS / ADVISORIES

NE...Red Flag Warning from noon to 8 PM CDT Wednesday for NEZ011- 012-015>018-030>033-042. IA...None.