Omaha/Valley, Nebraska

• 15-20% chance for some light rain showers Sunday afternoon. Highs warm to the mid 60s under cloudy skies.
• Good chance (90-100%) for showers and storms late Sunday into Monday morning. Storms Monday afternoon and evening could become strong to severe for areas southeast of a line from Albion to Norfolk to Onawa.
• Rain clears out by Wednesday while more rain chances arrive late this week. Temperatures remain in the 50s and 60s from Tuesday through Saturday.

04z RAP objective analysis reveals an H5 shortwave trof lifting northeast over the forecast area. Remnant forcing tied to the vort max has helped spark some more scattered rain showers in southeast Nebraska into southwest Iowa.

This activity will pivot to the north northeast as the wave moves through. While we see some subtle height rises behind the departing wave today, H8 warm advection driven by the southerly flow should result in more scattered rain showers, or even some periods of drizzle this afternoon. Have kept light PoPs of 15 to 20% this afternoon. Highs only warm to the mid 60s under cloudy skies.

Late tonight into early Monday morning, an H5 longwave trof currently off the Pacific Coast will deepen and eject toward the Plains. Forcing tied to the deepening mid level wave and increasing moisture transport provided by a 50 kt low level jet will result in widespread rain showers and a few storms across most of OAX. PoPs of 90 to 100% are forecast for essentially all of the area during that timeframe. Winds will also increase in speed as a tight pressure gradient sets up over the area: expect southerly wind gusts of 40 to 45 mph at times on Monday.

The arcing band of precip lifts northeast as the sfc low moves into South Dakota. At this point, we`ll be within the warm sector of the low where a plume of 500-1,000 J/kg of CAPE creeps into our southwest areas. 40 to 50 kts of 0-6 km bulk shear overlapping in that general vicinity could result in some storms becoming severe. However, there are still quite a few uncertainties that make this a tricky forecast. Cloudy skies and any lingering rain showers could limit the amount of destabilization we see and thus impact the severe threat. Forecast soundings reveal a pretty significant amount of low level SRH, ranging from 200-300 J/kg, while hodographs show good low level curvature. Given the expected low LCLs, the threat for a tornado can`t be ruled out, in addition to seeing strong wind gusts or some small hail (H7-H5 lapse rates appear rather poor at around 6 deg C/km).

Latest 00z suite of CAMs suggest some showers lingering in that general vicinity during the afternoon, while convection develops just ahead of the approaching sfc cold front, then merging into a line and lifting northeast into areas along and south of the Platte River. At this time, the SPC maintains a level 1 of 5 risk of severe weather for areas southeast of a line from Albion to Norfolk to Onawa. Storms will exit the area late Monday night.

Tuesday will see the deformation zone of the sfc low wrap back around into the area, resulting in more rain showers and storms. Strong cold advection and subsidence behind the low should drive some of the strong H8 winds downward resulting in gusty 40 to 45 mph sfc winds. The windy conditions taper off late Tuesday evening from west to east.

The mid-level wave and any lingering precip across our far north finally departs Wednesday afternoon, although model guidance does show some differences in how fast the wave ejects east. Models hint at another compact, weakening H5 shortwave that ejects from the Rockies area toward the Central Plains Thursday. The track of the wave will largely play a role on if we`ll see additional rain chances that day: NBM is currently dry for the area. More rain chances arrive by the weekend, but significant model discrepancies regarding placement of features are seen at this point.

Temperatures largely remain in the 50s and 60s Tuesday through Saturday with the coolest conditions expected across our far northern areas.

Low cigs have spread across much of eastern Nebraska with cigs around 800ft at KOFK and KLNK. Low cigs have been slow to arrive at KOMA, with FEW016 reported, while cigs at KAHQ has cigs around 1100ft. Seems like a 50/50 chance these cigs actually make it to KOMA at this point, more likely bouncing in and out of the terminal for a period before lifting at 17Z. Expect cigs around 2000-2500ft at the terminals through the afternoon, becoming broken, possibly scattering out to VFR (40% chance). At 00Z we see cigs lower back to around 1500ft, with borderline low MVFR/IFR cigs moving in as rain arrives around 03-06Z Monday. Winds remain out of the southeast through the TAF period, generally around 08-10kt today (gusting to 20kt at KOFK). These winds will increase toward the end of the TAF period between 06-12Z. There is some uncertainty if there will be a window for LLWS between 06-12Z as winds aloft increase more rapidly than surface winds. Will leave LLWS out of the TAFs for now, but may need to be added later.

NE

None.

IA

None.