KIMBALL – A forecast winter storm developed into a near-blizzard last Friday (April 13) across the southern Nebraska Panhandle and some adjacent areas in the tri-state region.

The weather system arrived late Thursday evening (April 12) with rainfall, cooling air temperatures, and increasing northwesterly winds. Snow was beginning to fall by 9 a.m. on Friday and continued throughout the day and into early Saturday morning. Air temperatures fell from 40 degrees to about 25 degrees and stiff winds (30 mph sustained, gusting to more than 50 mph) caused reduced visibility, occasional whiteout conditions, and drifting. I-80 was closed in both directions, as were Nebraska Highways 71 and 385. Although the snow ended early on Saturday and winds abated in the face of warming air temperatures, roads were not reopened until after noon.

Air temperatures warmed following the storm but daytime highs remained 5-10 degrees cooler than normal. As the snow melted, brisk northwesterly winds developed and daytime winds persisted through Tuesday and were forecast to continue until a follow-on weather system arrives in the region Friday (today).

Regional Forecast and Conditions

As of Tuesday morning (April 17), the temperature at sunrise was 32 degrees. The morning was fair and mild with a southeast wind at 8 mph. The barometer was falling at 29.60 inches of mercury (in/Hg). The day was expected to remain sunny but quite windy with 40 mph sustained winds gusting to 60 mph. Air temperatures were expected to peak at near 60 degrees before falling to an overnight low of 28 degrees. There was a 20 percent chance of snow overnight. Similar conditions, including continued brisk northwest winds, were expected to persist through early Friday (today), when forecasters anticipate the arrival of a weather system bringing cooling air temperatures and a 60 percent chance of widespread rain and rain/snow mix late in the day and throughout most of tomorrow.

Today’s weather is expected to become overcast and cool after noon with a high of 39 degrees. As evening approaches forecasters expect widespread rainfall to begin, followed by a rain/snow mix as temperatures cool after sunset. The temperature is expected to fall to about 31 degrees overnight with a continued rain/snow mix continuing into Saturday. As air temperatures warm toward a high of 48 Saturday, snowfall will become rain, and the rainfall is expected to taper off toward evening as air temperatures fall toward a low of 30 overnight. Sunday should be mostly sunny as the weather front passes, with a high of 58 degrees and an overnight low of 31.

Monday through Wednesday next week are expected to be sunny and warming, with daytime air temperatures ranging in the 60’s and overnight lows in the 30’s. As of April 17, there was no precipitation forecast for the Monday-Wednesday period.

Despite the winter storm, daytime air temperatures warmed across the region last week. At Kimball the April 10-16 daytime high averaged 57.57 degrees, about 6 degrees warmer than the previous week. The weekly high temperature was 76 degrees on April 11. Overnight lows warmed as well, averaging 29.14, or about 5.5 degrees warmer than the previous week. The weekly low temperature was 20 degrees on April 14. The weekly mean temperature was 43.35 degrees, about 5.71 degrees warmer than the previous week, and not quite 2 degrees cooler than the April average of 45.2 degrees. The long-term average high and low temperatures at Kimball for April are 59.6 and 30.9, respectively.

Rain followed by snow visited much of the Panhandle last week. Over the April 10-16 period 9 of 13 Panhandle stations reported snow with quantities ranging from 1.5 inches at Scottsbluff to 12.2 inches at Harrison. Agate, Alliance, Gordon, and Hemingford reported zero snowfall. Eleven of 13 stations reported precipitation, with liquid equivalent moisture ranging from 0.10 at Dalton to 1.1 inches at Kimball. Agate, Gordon, and Hemingford reported zero precipitation. Across the Panhandle snowfall averaged 3.5 inches and liquid equivalent precipitation averaged 0.40 inches. Last week’s averages were 1.8 inches and 0.18 inches respectively.

Soil temperatures also warmed across the Panhandle over the April 10-16 period: (this week/last week/change): Alliance 42.6/38.9 (+3.7) degrees; Gordon 41.8/39.1 (+2.7) degrees; Mitchell 44.3/40.5 (+3.2) degrees; Scottsbluff 45.0/40.9 (+4.1); and Sidney 43.5/41.1 (+2.4) degrees.

Winds near Kimball averaged southerly and occasionally quite breezy over the April 10-16 period. Gusts for the week averaged 36.57 mph. High gust for the week was 58 mph on April 13.

Weather Almanac

Here’s an overview of April 20 temperature and precipitation highs, lows, and averages over the preceding 125 years at Kimball. Data is taken from the High Plains Regional Climate Center (www.hprcc.unl.edu), where you can easily find and track data for your own particular location.

Last year: Daily high temperature 67 degrees, overnight low 29 degrees, average temperature 48.0 degrees. Precipitation zero inches, snowfall zero inches, snow depth zero inches.

The warmest April 20 on record was 85 degrees in 1962. The coolest high temperature was 33 degrees in 1959. The coldest overnight low was 3 degrees in 1966. The warmest overnight low was 46 degrees in 1965. Over the years since 1893 the high temperature has averaged 59 degrees, the overnight low 32 degrees, the daily average 45.4 degrees, precipitation has averaged 0.06 inches, snowfall 0.1 inches, snow depth zero inches.

The greatest precipitation total was 2.50 inches liquid equivalent (6.0 inches snow) in 1988. The greatest snowfall was 6.0 inches in 1988. Greatest snow depth was 6.0 inches in 19, followed by 2.0 inches in 1966.

Snow has fallen on April 20 at Kimball 18 times over the last 125 years, with quantities ranging from a trace to 6.0 inches.

U.S. Drought Monitor

National Summary: A series of storms systems with varying amounts of precipitation swept across most of the lower 48 States this week, including the Far West which was mostly dry last week.

After a very dry February, normally one of the wettest months of the year in California, repeated storms have brought welcome precipitation to most of the state, gradually increasing WYTD precipitation and Sierra snows closer to normal. Decent precipitation (2-6 inches, locally to 10 inches) also fell on western Oregon and Washington and in the Cascades.

In the Southwest, however, storms have generally bypassed this region this winter (and this week), and after a disappointing 2017 summer monsoon, drought conditions expanded and worsened.

To the east, light to moderate precipitation fell on the northern and central Rockies, north-central Plains, the western Corn Belt, and most locations in the eastern third of the Nation. The greatest amounts (1.5-4 inches) fell on the lower Mississippi and eastern Ohio Valleys, eastern Carolinas, and north-central Florida.

Subnormal temperatures prevailed across much of the contiguous U.S. east of the Rockies (except Florida), and averaged above-normal in the Southwest. Showery weather continued across Hawaii and Puerto Rico (where no drought existed) while drier weather occurred across Alaska.

High Plains: Another week of light precipitation (snow) and subnormal temperatures enveloped the northern Plains, with some heavier amounts (0.5-1 inch) falling on northern and eastern South Dakota and the Black Hills. In east-central South Dakota, 4-8 inches of snow fell from Aberdeen southeastward past Watertown, and with this moisture, a slight D0 removal was made where indices out to 6-months were wet, and since this D0 was short-term, it was easier to justify its removal; however, the D0 was kept where frost depths were deeper (down to 2-4 feet) in the northeast.

After several weeks of gradual improvements in eastern Montana and the western Dakotas, no changes were made this week as precipitation was lighter.

In northern Colorado, some decent precipitation fell on the central Rockies, finally allowing for some small 1-category improvements in northwestern and north-central sections of the state as WYTD indicators climbed above various D0-D2 percentile thresholds.

Farther south, similar to other south-central Plain states, Kansas saw little or no precipitation (less than 0.25 inches) as not only short-term indices (6-months or less) but also longer-term tools (9- and 12-months) indicated drier conditions than depicted. Accordingly, the D4, D3, D2, and D1 borders were slightly extended northward to reflect the severe conditions and growing deficits (8-14 inches at 12-months in central Kansas). The April 8 NASS/USDA winter wheat rating for Kansas stood at 44% in poor or very poor condition, with Kansas the top state for winter wheat production. No changes were made between the border of Nebraska and Kansas as a few extra snow events this year across this area have contributed enough moisture to prevent deterioration, at least for now.

West: D2 was increased in east-central Colorado with 6-month SPIs between -1 and -2.5. D3 now covered southeastern Utah, southwest Colorado, and central New Mexico as another dry and warm week dropped WYTD basin average precipitation to 50, 43, and 19-27 percent of normal, respectively, while the mountain snows have completely melted in eastern Arizona and most of New Mexico (0 percent SWE).

After experiencing rather tranquil weather last week, stormy weather returned to the Far West as has thankfully been the case since early March - after a near-record dry February. With the continued train of spring storms providing badly-needed moisture to California, additional improvements were made to areas with the greatest weekly totals (3-8 inches) that have also neared their normal WYTD precipitation. With most major reservoirs above their April 10 historic average and stream flows nearing 7-day record highs due to the combination of heavy rains and some snow melt, D0 was removed from northern and central coastal and Sierra Nevada locations, while D1 was improved to D0 near and south of Fresno to near Bakersfield. Although WYTD deficits remained, this latest storm caused flooding, and coupled with last winter’s surplus precipitation, conditions have improved with the spring storms. April 10 snow water equivalents (SWE), however, remained below normal, with northern (36 percent), central (51 percent), and southern (39 percent) Sierras seeing some snow melt from lower elevation rains. Statewide, the SWE summary stood at 11.7 inches, or 43 percent of normal for April 10. Likewise, additional precipitation over northeastern Nevada (D0 to nothing hole) and along the Nevada-Oregon border (D1 to D0) warranted a 1-category improvement.

In contrast, another week of disappointing dry and warm weather in the Southwest led to additional deterioration. In southern California, after reassessing reservoir conditions at Lakes Cachuma, Casitas, and Piru in Santa Barbara and Ventura counties, the earlier March rains did little to increase their levels, thus D2 was returned to those counties. While higher terrains in California’s Owen Valley and eastward into Nevada did fairly well with March storms, the lower elevations did not, and when combined with a poor fall and winter, D1 conditions were expanded into southern Nevada.

In southeastern Utah and northeastern Arizona, D4 areas were added to reflect both the poor winter conditions and the weak and early ending summer monsoon of last year (12-month indices at D4). In northeastern New Mexico, D4 was extended into Union and Colfax counties as near- or record dry 6-month precipitation, above-normal temperatures, low humidity, and strong winds combined to produce very poor irrigated winter wheat, along with bare, dead, or very poor pasture and range conditions according to field observations.

Water supply forecast for the Western U.S.

La Niña’s strength began to wane in early spring, although lingering impacts may have included ongoing drought in the nation’s southwestern quadrant and generally wet conditions from the Pacific Northwest to the northern Rockies. Late-season storminess in California may have been due to other factors, such as atmospheric blocking, which helped to shift the Pacific storm track southward at times. Cool weather accompanied many of the late-season storms in California, helping to boost high-elevation snowpack closer to normal. Many other areas of the West, excluding the Four Corners region, also benefited due to the cool, showery conditions. The northern tier of the West remained in great shape in terms of both snowpack and water supply. 

Snowpack and Precipitation

As of April 10, river basins in Oregon and across the southern half of the West had subpar snowpack. The situation was especially dire in Arizona and New Mexico – mostly less than 25 percent of average. Since late winter, storms and cool conditions have generally boosted snowpack across the middle one-third of the West. Consequently, many basins within that area have a snowpack that has improved to at least 50 to 75 percent of average. Meanwhile, near- to above-normal snowpack covered most of Idaho, Montana, Washington, and Wyoming.

Season-to-date precipitation (Oct. 1 – April 10) was slightly more impressive than snowpack, in part due to early- and mid-winter warmth limiting accumulation of high-elevation snowpack. Still, precipitation was less than 50 percent of normal in most Southwestern basins, and less than 90 percent of normal in all of the West except Idaho, Montana, Washington, Wyoming, and northern Oregon, as well as the Sierra Nevada. 

Spring and Summer Streamflow Forecasts

As of April 1, for spring and summer streamflow projections indicated the likelihood of near- or above-normal runoff in the Pacific Northwest and the northern Rockies. In other parts of the Northwest, including much of Oregon, a lack of snow has reduced runoff potential, despite an active weather pattern. Meanwhile, the Southwest has only sporadically received winter precipitation, leading to forecasts of poor spring and summer runoff—less than 25 percent of the normal volume in several river basins.

Reservoir Storage

As of April 1, reservoir storage as a percent of average for the date was substantially below average in Arizona and New Mexico. Cumulative storage for this time of year was near or above average in all other Western States. In several states, including Utah, reservoir storage continues to reflect bounteous runoff in the spring and summer of 2017. 

U.S. Conditions and Weather Report

(April 17) Several minor weather systems affected the country until late in the week, when a powerful spring storm emerged from the West and brought extreme conditions to several regions. For example, historic, late-season snow blanketed portions of the northern Plains and upper Midwest, snarling traffic and severely stressing livestock.

Cold air remained entrenched from Montana to New England, with weekly temperatures averaging more than 10 degrees below normal across parts of the northern Plains and upper Midwest.

Meanwhile, hot, dry, windy weather contributed to blowing dust and a wildfire outbreak across the drought-ravaged southern High Plains. In western Oklahoma, the three largest wildfires scorched more than 300,000 acres of grass and brush and destroyed at least four dozen structures.

By the end of the week, heavy showers and locally severe thunderstorms erupted across the mid-South and began to spread eastward.

Through April 14, rainfall totals of 1 to 2 inches or more were reported across the lower Mississippi Valley and neighboring areas. 

In contrast, warm, dry, breezy weather dominated areas from southern California to western Texas, leading to further drought intensification. Weekly temperatures averaged as much as 10 degrees above normal in Arizona and New Mexico.

Elsewhere, unsettled, showery weather affected the Northwest, maintaining favorable winter grain and water-supply forecasts. Precipitation extended as far south as northern California and the central Rockies.