Area Forecast Discussion
Issued by NWS Omaha/Valley, NE
Issued by NWS Omaha/Valley, NE
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110 FXUS63 KOAX 182217 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 517 PM CDT Fri Sep 18 2026 .KEY MESSAGES... - A couple rounds of showers and storms possible this evening (30-40%) and overnight (40-50%). May see a few isolated strong wind gusts with stronger storms this evening. - Cooler and cloudy on Saturday with potential for showers/storms across southeast Nebraska southwest Iowa (30-50%). - Much cooler starting on Sunday into next week with highs in the 60s and lows in the 50s. Periodic chance for rain Sunday and Monday and again Thursday and Friday. && .DISCUSSION... Issued at 202 PM CDT Fri Sep 18 2026 Partly cloudy skies this afternoon with a warm front lifting northeast across our area. Breezy winds gusting to 20-25 mph behind the front out of the south-southwest helping temperatures to warm into the upper 80s to low 90s this afternoon. Looking at the upper-level pattern, we have broad ridging over the Central US with a trough over the Inter- Mountain West. A subtle shortwave has led to the development of our surface low currently positioned over north-central Nebraska near the SD state line. At the same time, another weak surface low is developing over southeastern Colorado. This evening we`re monitoring the Low over north-central Nebraska, expected to pull the cold front south but hanging up on the developing system to our southwest. This will position a stationary front somewhere southwest to northeast along or just north of I-80 as the upper-level wave moves through. We expect scattered storms to trigger along this boundary around 7PM this evening and track northeast along the front exiting around 11PM-12AM. Model soundings show a fairly strong surface stable layer with an exorbitant amount of MUCAPE aloft (3000-4500 J/kg). Dry air entrainment will likely limit the ability to utilize that amount of energy. While shear is fairly good in the low-levels near the frontal boundary, this is mostly generated by the enhancement of the LLJ with bulk of convection occurring above this layer. This means storms may struggle to organize into anything strong to severe. What we may see, though, if we can get a couple of stronger storms to develop, is potential for localized strong to severe winds. As storms collapse, we may see downbursts attempt to push through the surface stable layer. If they can punch through, this would lead to a couple of isolated bursts of strong to severe wind. That`s probably our main hazard possible with any of these storms this evening. Overnight tonight we see the second weak low pressure center ride up the stationary front into central Nebraska bringing a broader complex of showers with a few rumbles of thunder into our area early Saturday morning. By the time this system arrives, environmental instability will have significantly waned reducing the chance of thunderstorms with this second round. More of what this will do is pick up the stationary front and push it south across far southeast Nebraska into south-central Iowa. Models have been shifting the position of where this frontal boundary will stall on Saturday, shifting the area of potential severe weather Saturday afternoon and evening as another shortwave moves through. Latest trends have been to bring it farther south, keeping the stronger storms south across eastern Kansas into northwest Missouri. For this reason, SPC has shifted our marginal and slight risks for severe storms south, out of our area. We`ll still watch for some potential this shifts back north, but as of now I`d expect Saturday evening to stay quiet across our area. Going into the latter half of the weekend, we see the broad ridge over the Central US shift east with the upper-level trough moving in from the west. This will mean periodic chances for showers and weak storms Sunday through Monday with a cooler air mass in place. Highs on Sunday will only warm into the low-to- mid 60s for most of our area, and Monday many may only peak at 60 degrees. Beyond Monday we see ridging build back up behind the transient upper-level trough with return flow bringing back in drier conditions for Tuesday and Wednesday. We see the belt of moisture advection from the Gulf shift east back over our area for the latter half of the week next week. This will mean more chances for showers and storms Thursday and Friday though temperatures look to remain relatively cool with highs still only in the mid 60s to low 70s. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 512 PM CDT Fri Sep 18 2026 VFR conditions prevail this evening before a line of thunderstorms develops across east-central Nebraska and slowly pushes south. Initial thunderstorms should remain south of KOFK, with a 60% chance of impacts at KOMA and KLNK. Brief gusty winds (up to 40 kts) and patchy MVFR conditions are possible under and stronger storms. A brief period of LLWS will also work into KOMA and KLNK this evening as a 40-45 kt LLJ moves in at FL017. Into the overnight period, a front pushing south across the area will shift winds from southerly to northerly. Additional scattered showers, and perhaps a thunderstorm or two, are possible into the overnight period. The highest chances of impacts are at KOMA and KLNK (50% chance), though exact time frame may need refining. Additionally, a deck of MVFR to IFR ceilings, along with patchy visibility restrictions, will sink south into the area overnight. Confidence is high that KOFK will see a prolonged stretch of MVFR to IFR conditions, with lower chances (30-40%) further south towards KOMA and KLNK. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...McCoy AVIATION...Wood