Hello NSCO community! Apologies for the late posting. This past week, Nebraska ran unseasonably warm this late December, with highs commonly in the 40s and 50s, and even 50s to low 60s at times, especially for central and northeast Nebraska with our reduced daylight hours, and reduced snow cover helped temps jump. Humidity stayed fairly low for most of the time, but near-surface moisture increased briefly as any remaining snow eroded, which raised the fog potential, most notably toward eastern Nebraska river valleys and into west-central Iowa. The only meaningful precipitation window showed up late Wednesday into early Thursday, when a quick-moving system brought light rain before shifting into colder and windier weather.
A ridging pattern early in the week supported the warmer temperatures, with warm air advection and 850 mb temperatures specifically, which is plenty to drive temperatures into 50s/60s at the surface, which in mid-December, is rare. Midweek, a stronger shortwave/clipper-type system created a deeper 500 mb trough as it crossed the Northern Plains, tightening the gradients and setting the stage for the big winds. After that system exited toward the latter half of the week into Friday. Winds shifted right back toward a zonal, straight-line flow, which is why temperatures rebounded quickly, and this trend will continue heading toward Christmas this week.
The main event this past week was a cold front which occurred Wednesday evening, pushing west-to-east across Nebraska. Ahead of this front were those strong winds (especially north/central), temperature dips, and increased clouds. With frontal passage, there was a swath of light rain showers, for that central region of the state, and behind the front, rapid cold advection, and sharper wind shifts to the northwest. Travel impacts concerned the high wind speeds, and any falling snow which briefly reduced visibility.
Precipitation overall was light with many places seeing a few hundredths up to around a couple of tenths in that general central area of the state. The mid-week cold front event was more of a soaking rain, with less snow accumulation for this time of the year. The exception risk was northeast Nebraska, where a narrow window of snow showers/short-lived squalls combined with strong northwest winds that briefly drove visibility down, but without much accumulation. Here are some pointers of the main events of this past week:
- Warmest highs: typically, southwest/central Nebraska on the mildest days (downslope + mixing), occasionally pushing into the upper 50s to 60s.
- Coolest highs: north/northeast Nebraska during/after frontal passage Thursday when cold advection is strongest (highs nearer the upper 20s/30s in the colder pocket).
- Warmest lows: often southeast/east ahead of the front with stronger mixing and southerly flow.
- Coolest lows: sheltered spots under clearing skies and lighter winds (especially after the system exits), with 10-20 degrees Fahrenheit common.
- Highest precip: localized where the band sets up Wednesday night/Thursday.
Overall, the state experienced a quick midweek system with a windy blast Thursday, and dry and warm conditions heading into Christmas, with record warm temperatures possible late this week where the ridge peaks. The outlook stays mostly dry, and temps trend back into the 50s and even 60s in many spots under persistent ridging in eastern and central Nebraska. So, if you’re traveling or have holiday plans, the bigger issues are likely going to be high winds into Thursday. Otherwise, I hope everyone has a happy holiday season!
