Blizzard — Polk, Nebraska

2023-12-25 · Polk, Nebraska

Event narrative

Snowfall amounts of mainly 3 to 6 inches blanketed the county. A few reported totals included: 5.0 inches, from the NWS Cooperative Observer in Polk; 4.7 inches, from the NWS Cooperative Observer three miles northeast of Shelby; 4.3 inches from the NWS Cooperative Observer in Osceola.

Wider weather episode

Although not as historic/impactful as its infamous predecessor exactly 14 years prior (the Christmas Blizzard of 2009), Christmas 2023 nonetheless gifted South Central Nebraska the most impactful snow event to strike on the holiday since then. This one took the form of a moderately-strong winter storm featuring at least brief/sporadic blizzard conditions, prompting various travel-related issues/accidents...including at least a brief closure of Interstate 80 mainly between York and Aurora. Across the state as a whole, the Nebraska State Patrol reported that it responded to around 150 weather-related incidents. The wintry Christmas Day weather was actually the main act of a slow-moving low pressure system that dropped various rounds of precipitation within South Central Nebraska between the 23rd-26th. Precipitation started out as rain in most areas on the 23rd-24th, before changing to snow on the 25th-26th, and with even a touch of light freezing drizzle mixing in before the system departed. However, by far the majority of accumulating snow and resultant travel impacts occurred during the Christmas calendar day. The majority of the 24-county area picked up between 2-6 inches of snow, with the overall-highest concentration of 6-8 totals clustered in northern counties such as Valley, Greeley and Howard. Admittedly, snow amounts fell at least a few inches short of forecast expectations in most places. However, the combination of several hours of light-to-moderate (and briefly heavy) snow, in tandem with moderately-strong north-northwest winds (commonly sustained 20-30 MPH/gusting 25-40 MPH), reduced visibility to under 1 mile for several hours in most locations and induced at least sporadic blizzard/white-out conditions...particularly within counties along/north of Interstate 80. As for snow totals, per dozens of NWS and NeRAIN/CoCoRaHS observers, some of the very-highest tallies featured: 8.0 in Bradshaw, 7.5 eight miles north-northeast of Scotia and also nine miles northwest of Ord, 7.0 near St. Paul and Elba, and 6.5 in Ord. In the Tri Cities, official totals ranged from 2.5 to 3.7, but there were unofficial reports of as much as 4-5 in Grand Island. Temperatures/wind chills were not overly-cold by late-December standards, with temperatures during the day mainly 25-30 F, and wind chills commonly 5-15 F. Wind gusts above 40 MPH were the exception, but official airport ASOS sensors at Ord and Grand Island clocked peak gusts of 49 and 43 MPH, respectively.

Delving deeper into the meteorological background and timing of this event, the Christmas Day winter storm/blizzard was again the main act of a multi-day precipitation event that brought much-needed total precipitation (including rain and melted snow) of 0.30-1.00 to most of South Central Nebraska (and localized higher amounts closer to 1.50, particularly in/near Valley County). In the mid-upper levels, some of the above-average forecast uncertainty regarding snow amounts stemmed from the fact that the powerful, closed low pressure system that eventually blossomed over the heart of the Central Plains on the 25th-26th evolved from a complex merger of two, initially-separate shortwave troughs approaching from the western United States...a northern stream disturbance tracking from the Pacific Northwest across the Northern Rockies, and a southern stream wave swinging northeastward out of the Desert Southwest. During the morning of the 25th, these disturbances completed their phasing/merger, as a vigorous, closed mid-upper low quickly developed over western Nebraska/Kansas. While parts of the area received some light snow on the evening of the 24th, things really ramped up on Christmas morning, as several snow bands blossomed and started rotating from east-to-west across South Central Nebraska. Although some locations already had at least 1-2 of snow on the ground by sunrise, the bulk of snow accumulation played out during the daytime and early evening hours. As a mid-level dry slot wrapped into the area from the east, most counties along/east of Highway 281 saw snow gradually end from east-to-west between 2-6 p.m., while particularly those counties west of Highway 281 and south of Interstate 80 held onto snow well into the evening as additional snow bands wrapped southward around the back side of the slow-moving upper low, but even this activity mostly-ended/departed the area by midnight. At the surface, the moderately-strong north-northwest winds that prevailed across South Central Nebraska for the majority of the 25th were driven by a fairly tight pressure gradient sandwiched between high pressure (around 1035 millibars) centered over the Northern Rockies, and a roughly 1004 millibar low pressure center that embarked on a circuitous trek...well-displaced from the parent upper low. On the morning of the 25th, the heart of this low tracked due-north from southwest Missouri to western Iowa. Then, during the afternoon-evening hours, the low actually retrograded a bit to the northwest (to near Sioux Falls), before sinking southwestward into north central Nebraska by midnight. As the heart of this surface low crawled ever-closer to South Central Nebraska during the evening, winds actually eased up considerably between sunset and midnight within the weakening pressure gradient...ending any lingering blizzard conditions.

Source: NOAA Storm Events Database, event_id 1146729. Narrative written by the NWS forecast office that issued the report.