EF0 tornado, Alton, Kansas, December 25, 2016

1. EF065 to 85 mphthis tornado

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF0

Date

December 25, 2016

Touchdown

11:45 AM CST (17:45 UTC)

Lifted

11:48 AM CST (17:48 UTC)

On the ground

3 minutes

Path length

1.9 miles (3.0 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Property damage

$5,000

County

Osborne County

Touchdown point

39.503, -99.018

Lift-off point

39.527, -99.003

Record number

1612251145-01

9 damage points were recorded along this path by NWS GID, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 85 mph.

• Small bulding nearby demolished. Some trees snapped and some broken. Some shingle loss. Bulk bin overturned just to west.
• Few smaller Trees uprooted.
• Looking north/northeast down the path. All stocks were up prior to event.
• Ground scour area. Herringbone type convergent pattern.

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

The weather on Christmas 2016 was so unusual that it's probably a safe bet to categorize it as once in a lifetime Christmas weather for this six-county North Central Kansas area. While some past Christmases are remembered for more traditional significant winter weather such as snow, this one will go down in the record books for spring-like severe thunderstorms with damaging winds and even the first December tornado confirmed in this portion of northern Kansas since at least 1950 (when reliable records began). Then, later in the afternoon/evening, the Phillips County area endured an intense damaging wind event featuring sustained values of 30-50 MPH for a few hours and brief peak gusts around 70 MPH. These winds resulted in mainly minor damage to trees and power lines, and also flipped over several irrigation pivots. Because specific storm reports from this area were fairly sparse, the few official reports documented here likely reflect only some of the significant weather observed within North Central Kansas on this day. ||Focusing more detail on the thunderstorms and tornado, the culprit was a narrow, strongly forced squall line that steadily advanced across the entire local area from west-to-east. Timing-wise, this was a fairly early show as convection first entered Rooks/Phillips counties around 11 AM and exited Jewell/Mitchell counties only a few hours later between 1:00-1:30 PM. While most locations experienced sub-severe winds up to around 50 MPH, brief heavy rain and perhaps small hail with the passage of these storms, there were a few transient small-scale bowing segments and circulations embedded within the line, resulting in pockets of damaging winds and one confirmed, short-track tornado. This EF1-rated tornado touched down northwest of Alton around 11:45 AM and tipped over an empty bulk bin and caused very minor damage to a home. ||Even though the day had already featured highly-unusual and locally-damaging Christmas weather, for parts of especially Phillips County the worst was yet to come in the form of early-evening damaging winds. While the vast majority of wind damage associated with this event focused to the north into Nebraska, automated sensors in both Phillipsburg and Logan clocked gusts of 70 MPH from the west-southwest shortly after 5 PM, followed by up to a few hours of sustained speeds to around 40 MPH before easing up. Although gusty evening winds likely brushed into adjacent local counties as well, no known reports breached High Wind Warning criteria. Forecast-wise, while fairly stout winds were anticipated to move in behind the departing low, the ferocity of peak gusts exceeded expectations. ||Closing with an examination of the meteorological setup, it certainly was more reminiscent of March or April in North Central Kansas than late-December. In the mid-upper levels, a powerful, negatively-tilted vorticity maximum deepened over the course of the day as it emerged from the Central Rockies, reaching north central Nebraska by early evening. Just to the southeast of the mid-level low center, a formidable upper jet streak of 120+ knots migrated overhead. At the surface, it was a classic setup for low-topped, severe convection as a deep low pressure system intensified to around 986 millibars in far northeast CO by noon, allowing a warm front to surge north into Nebraska. Despite considerable cloud cover, temperatures rising well into the 50s F and dewpoints climbing into the upper-40s to mid-50s F allowed mixed-layer CAPE to reach a few hundred J/kg. Combined with strong deep-layer wind shear of generally 60-80 knots and exceptional low-level shear of 50-60 knots, even this relatively meager instability proved sufficient for damaging winds and brief tornadoes. By early evening, the intense surface low pressure center reached north central Nebraska, placing the local area behind an occluded Pacific cold front and within a zone of deep atmospheric subsidence. In tandem with other factors such as steadily-rising pressures and increased vertical mixing, this allowed very strong west-southwest winds within a few thousand feet of the surface to mix downward, driving the evening damaging winds in the Phillips County area.

This tornado briefly touched down northwest of Alton. Along its short path, it damaged trees, tipped over an empty bulk bin and caused very minor damage to a home. The maximum wind speed was estimated to be 85 MPH.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

The county was under a severe thunderstorm watch, issued at 16:48 UTC and running to 20:26 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 16:24 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The Grand Island radar (KUEX), 102 km away, was scanning. The volume nearest the touchdown began at 17:47 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2016 tornado in KansasEvery tornado in Kansas since 1950Warnings in force in Kansas nowThe forecast where you are

10 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.