textproduct: Sioux Falls

KEY MESSAGES

- Light rain/snow will continue to drift through the MO River valley into the afternoon. No accumulation expected.

- Narrow snow band expected near or more likely south of Highway 20 after dark. Any travel south of Sioux City towards Omaha or Des Moines may be impacted.

- A gradual warmup through the second half of the week with temperatures returning above normal, and exceeding normal next weekend.

- A few showers move through the area Wednesday and again Thursday night, with slightly higher shower and thunderstorm chances this weekend. A few stronger storms could be possible by Sunday.

DISCUSSION

Issued at 1239 PM CDT Mon Apr 6 2026

THIS AFTERNOON: A very light rain/snow mix driven by 650:700 mb frontogenesis may continue along the MO River valley this afternoon, though in most areas, a dry subcloud layer focused around 850 mb will limit any accumulation. Elsewhere, variable cloud cover continues as temperatures remain 10+ degrees below normal.

TONIGHT: CAMs really picking up on a great NW to SE oriented mesoscale banded feature developing after dark, mostly impacting areas along or south of Highway 20. Given instability within the band, any travelers heading south of Sioux City towards Omaha will need to be prepared for travel impacts through daybreak. There remains some variability in the location of the frontogenesis associated with this precipitation, with HRRR focused too far north most of this morning. Have favored the NAM/RAP for updates overnight, but we'll need to watch this closely. Further north, an easterly wind and scattered cloud layer will allow temperatures to drop into the 20s, some 10 degree below normal.

TUESDAY: Weak mid-lvl flow will keep vorticity streaming through the Central Plains on Tuesday. Eventually, 925:850 mb winds will turn southerly, allowing warm advection to spread back northward. Eventually a deeper low lvl moisture field will track north, and with persistent low-lvl warm advection, can't rule out very light snow, drizzle, or freezing drizzle in the afternoon. Have went with a higher PoP but low QPF forecast. The abundance of clouds should again hold temperatures back below normal, with most areas struggling to reach 40 degrees.

WEDNESDAY: By Wednesday, we'll begin to see a stronger upper trough track eastward through the Canadian Rockies, allowing a frontal boundary to form across the western Dakotas. A few lingering spits may continue into Wednesday morning ahead of this boundary, but the greater story will be the advection of much warmer low-lvl air northward. Latest guidance has timed the arrival of this front slightly faster than previous solutions, meaning low-lvl moisture will be scoured east quickly in the day. In the wake of this front, a warm westerly downslope wind will both lower RH values into the 25 to 35 percent range, but allow promote highs in the lower 60s and gusty 30 mph winds at times. This combination, along with drying out fine fuels may lead to elevated fire danger in the afternoon.

THURSDAY-FRIDAY: The aforementioned upper wave tracks into the Great Lakes by the end of the week, pushing cooler Canadian air southward into the Plains. High temperatures only retreat slightly into the middle 50s, near climatological normals. Medium range models begin to diverge a bit at the end of the week, suggesting an increasing risk of showers and isolated thunderstorms Thursday night into Friday over the southeastern 1/3 of the CWA. The latest NBM would suggest around a 50% probability of >0.10" of QPF along and southeast of a line from Yankton to Jackson into Friday morning. The remainder Friday should be dry, as high pressure once again pushes drier air southeastward.

NEXT WEEKEND: We're continuing to see increased potential for a pattern shift by next weekend and into the following week. Mid-lvl heights are projected to rise over the southeastern US, allowing more persistent troughing to develop along and west of the Rockies. This shift in mid-lvl flow should result in above normal temperatures as well as increased shower and thunderstorm potential across the Plains into next week. That said, there remains quite a bit of spread in temperature guidance for Saturday and Sunday, with the deterministic NBM pushed towards the 75th percentile. However on Sunday, the NBM is suggesting a 10-15 degree spread in high temperatures, with the deterministic near the 25th percentile in the mid-70s. Should deep southwesterly flow develop, then much warmer temperatures into the 80s are possible.

As far as precipitation is concerned, we're at least beginning to see signs of more instability tracking northeast over the weekend given the more meridional low-lvl flow trajectories. While a great deal of spread continues in ensemble guidance, several machine learning convective outlook models are indicating rising potential for severe storms moving northward into the Plains and Upper Midwest by the end of the weekend.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1140 AM CDT Mon Apr 6 2026

In most areas VFR conditions continue at mid-day as a light to occasionally breezy north wind begins to turn to the northeast. Very light rain/snow may linger along the MO river valley towards SUX, but in most areas this precipitation is not reaching the ground, but instead is visible as virga.

We'll see ceilings remain at VFR levels in the overnight hours as the main focus for precipitation shifts south of the Missouri River and Highway 20. Models show a very narrow snow band developing after dark near or likely south of Highway 20. Aviation interests near SUX will need to monitor this band, as it would have impacts if it drifts northward. ATTM, will only include a Prob30 given better focus to the south.

FSD WATCHES/WARNINGS/ADVISORIES

SD...None. MN...None. IA...None. NE...None.