Tornadoes · United States · Arizona · 2015

EF0 tornado, Sunrise Spgs to Cornfield, Arizona, October 20, 2015

Name: EF0 tornado, Sunrise Spgs to Cornfield, Arizona, October 20, 2015
Start: 2015-10-20T20:00:00.000Z
End: 2015-10-20T20:05:00.000Z
Location: Sunrise Spgs to Cornfield, Arizona

From Sunrise Spgs to Cornfield, this EF0 tornado ran 6.9 miles across Apache County on October 20, 2015, touching down at 1:00 PM MST and reaching 10 yards wide. It killed nobody.

The rating scale

Tracks are drawn in the color of the rating. The Enhanced Fujita scale rates the damage rather than measuring the wind: the speeds are what that damage is taken to imply.

EF065 to 85 mphthis tornado
Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.
EF186 to 110 mph
Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.
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.
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.
EF4166 to 200 mph
Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.
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.
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.

The record

Rating: EF0
Date: October 20, 2015
Touchdown: 1:00 PM MST (20:00 UTC)
Lifted: 1:05 PM MST (20:05 UTC)
On the ground: 5 minutes
Path length: 6.9 miles (11.2 km)
Path width: 10 yards (9 m)
Deaths: 0
Injuries: 0
County: Apache County
Touchdown point: 35.650, -109.770
Lift-off point: 35.735, -109.705
Record number: 1510201400-01

What the Weather Service recorded

A trough of low pressure off the West Coast moved across northern Arizona with weak large scale lift, cooling aloft, and strong deep-layer shear. This lead to numerous strong to severe storms across northern Arizona with a tornado, large hail, and localized flash flooding.

Law enforcement confirmed the tornado with several pictures. No property damage or injuries were reported.

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

What forecasters said that day

The local office's own words before the tornado touched down, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Flagstaff, AZ wrote its last area forecast discussion before the tornado touched down at Oct 20, 10:55 AM MST, 2 hours 5 minutes earlier.

Area forecast discussion, Oct 20, 10:55 AM MST, 2 hours 5 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1055 AM MST TUE OCT 20 2015

.SYNOPSIS...A PERSISTENT LOW PRESSURE SYSTEM WILL BRING WIDESPREAD
SHOWERS AND THUNDERSTORMS TO NORTHERN ARIZONA THROUGH WEDNESDAY.
THURSDAY SHOULD SEE THE START OF A SLOW DRYING TREND WITH SLIGHT
CHANCES OF PRECIPITATION THROUGH FRIDAY. DRY WEATHER WITH NEAR
NORMAL HIGH AND LOW TEMPERATURES ARE FORECAST FOR THIS WEEKEND.

&&

UPDATE TO ADD SEVERE THUNERSTORM WATCH FOR ALL OF NAVAJO...APACHE
AND NORTHERN GILA COUNTIES NOW THROUGH 7 PM MST TONIGHT.

.DISCUSSION... ONE TROUGH OF LOW PRESSURE WILL SETTLE OVER ARIZONA
FROM TODAY THROUGH THURSDAY...WITH SEVERAL SHORTWAVES TO ROTATE
THROUGH THE LOW. THE FIRST WAVE IS MOVING ACROSS ARIZONA THIS
MORNING...AND BROUGHT A FEW HAIL REPORTS AT .75 INCH IN DIAMETER
AROUND FLAGSTAFF. WIDESPREAD PRECIP ACCUMULATIONS START AT .20" AND
APPROACHING AN INCH IN THE VERDE VALLEY. THERE IS A THREAT OF SEVERE
THUNDERSTORMS TODAY...PRETTY MUCH ACROSS THE NORTHLAND THIS MORNING
AND THEN EAST OF A WINDOW ROCK THROUGH PHOENIX LINE THIS AFTERNOON
AND EVENING.

MADE A FEW SHORT TERM FORECAST ADJUSTMENTS TO INCREASE PRECIP
CHANCES TODAY FOR MUCH OF NORTHERN AZ PER CURRENT AND EXPECTED
CONDITIONS. A LARGE AREA OF STRATIFORM RAIN WITH EMBEDDED
THUNDERSTORMS TO AFFECT AREAS NORTH OF A LINE FROM VALLE TO WINDOW
ROCK THROUGH THIS MORNING. RAINFALL ACCUMULATIONS HAVE INCREASED AS
WELL WITH WIDESPREAD .15 TO .35 INCH EXPECTED THROUGH 5 PM TODAY.
HEAVIER AMOUNTS CERTAINLY POSSIBLE IF STORMS TRAIN OVER THE SAME
AREA. STORM MOTION TODAY FROM SOUTH TO NORTH.

ON WEDNESDAY THE UPPER LOW SITS OVER ARIZONA AND NUMEROUS SHOWERS
AND THUNDERSTORMS ARE FORECAST ACROSS NORTHERN AZ. THE SEVERE
THUNDERSTORM THREAT WEDNESDAY IS LOW AS WIND SHEAR IS WEAK.

THURSDAY THE UPPER LOW MOVES INTO NEW MEXICO. UNSETTLED AND SHOWERY
WEATHER TO CONTINUE ACROSS CENTRAL AND EASTERN AZ...THE
SOUTHWESTERN PORTION OF THE STATE TO GET INTO A DRIER AND MORE
STABLE NORTHWEST FLOW.

FRIDAY ANOTHER WEAK TROUGH TO MOVE QUICKLY MOVING OVER NORTHERN
ARIZONA AND BRING A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS. HIGH
TEMPERATURES WILL BE BELOW NORMAL THROUGH FRIDAY.

SATURDAY-MONDAY...WESTERLY FLOW ALOFT TO BRING DRY WEATHER WITH NEAR
NORMAL HIGH AND LOW TEMPS.

&&

.AVIATION... FOR THE 18Z PACKAGE...SCATTERED TO NUMEROUS SHRA/TSRA
THROUGH 01Z ACROSS MOST OF NORTHERN ARIZONA...ACTIVITY DECREASING TO
SCATTERED COVERAGE OVERNIGHT AND INTO WEDNESDAY MORNING. A FEW OF
THE STORMS COULD BECOME SEVERE WITH LARGE HAIL AND STRONG WIND
GUSTS. MVFR/IFR CONDITIONS IN THE STRONGER STORMS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&

PUBLIC...DL
AVIATION...JJ

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT
WEATHER.GOV/FLAGSTAFF

Hazardous weather outlook, Oct 20, 10:48 AM MST, 2 hours 12 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1048 AM MST TUE OCT 20 2015

AZZ004>018-037>040-210245-
KAIBAB PLATEAU-MARBLE AND GLEN CANYONS-GRAND CANYON COUNTRY-
COCONINO PLATEAU-YAVAPAI COUNTY MOUNTAINS-
NORTHEAST PLATEAUS AND MESAS HWY 264 NORTHWARD-CHINLE VALLEY-
CHUSKA MOUNTAINS AND DEFIANCE PLATEAU-
LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY-
LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY-
LITTLE COLORADO RIVER VALLEY IN APACHE COUNTY-
WESTERN MOGOLLON RIM-EASTERN MOGOLLON RIM-WHITE MOUNTAINS-
NORTHERN GILA COUNTY-YAVAPAI COUNTY VALLEYS AND BASINS-
OAK CREEK AND SYCAMORE CANYONS-BLACK MESA AREA-
NORTHEAST PLATEAUS AND MESAS SOUTH OF HWY 264-
1048 AM MST TUE OCT 20 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR APACHE...COCONINO...
NORTHERN GILA...NAVAJO...AND YAVAPAI COUNTIES IN NORTHERN
ARIZONA.

.DAY ONE...TODAY AND TONIGHT

A SEVERE THUNDERSTORMS WATCH IS IN EFFECT FOR ALL OF
NAVAJO...APACHE AND GILA COUNTIES THROUGH 7 PM MST. LARGE HAIL IS
THE PRIMARY THREAT. STRONG WIND GUSTS AND AN ISOLATED TORNADO ARE
ALSO POSSIBLE.

MINOR FLOODING TO CONTINUE ACROSS SOUTHWESTERN YAVAPAI COUNTY
THROUGH AT LEAST EARLY THIS AFTERNOON.

THESE WEATHER CONDITIONS ARE DUE TO WIND SHEAR AHEAD OF A LOW
PRESSURE TROUGH THAT WILL MOVE INTO ARIZONA TODAY.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

WEDNESDAY THROUGH THURSDAY...SHOWERS AND THUNDERSTORM CHANCES
WILL CONTINUE WEDNESDAY THEN DECREASE ON THURSDAY AS THE UPPER
LOW MOVES AWAY FROM THE AREA. THUNDERSTORMS THAT DEVELOP BOTH DAYS
SHOULD REMAIN BELOW SEVERE LEVELS.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THE NATIONAL WEATHER SERVICE FLAGSTAFF OFFICE AT
1-888-745-1637.

In the hours before

Local storm report, Oct 20, 10:21 AM MST, 2 hours 39 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1021 AM MST TUE OCT 20 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0950 AM     HAIL             KAYENTA                 36.72N 110.25W
10/20/2015  E0.50 INCH       NAVAJO             AZ   PUBLIC

&&

EVENT NUMBER FGZ1500163

DGV

Special weather statement, Oct 20, 10:29 AM MST, 2 hours 31 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1029 AM MST TUE OCT 20 2015

AZZ012-013-040-201800-
NORTHEAST PLATEAUS AND MESAS SOUTH OF HWY 264-
LITTLE COLORADO RIVER VALLEY IN COCONINO COUNTY-
LITTLE COLORADO RIVER VALLEY IN NAVAJO COUNTY-
1029 AM MST TUE OCT 20 2015

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN COCONINO AND WEST
CENTRAL NAVAJO COUNTIES UNTIL 1100 AM MST...

AT 1028 AM MST...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM 10
MILES SOUTHEAST OF TOLANI LAKE...OR 20 MILES NORTH OF WINSLOW...
MOVING NORTHEAST AT 25 MPH.

DIME SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

THIS STORM WILL REMAIN OVER MAINLY RURAL AREAS OF SOUTHEASTERN
COCONINO AND WEST CENTRAL NAVAJO COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM MST FOR
NORTH CENTRAL ARIZONA.

LAT...LON 3523 11070 3530 11086 3556 11074 3544 11048
TIME...MOT...LOC 1728Z 202DEG 22KT 3532 11072

MOTTICE

Special weather statement, Oct 20, 11:40 AM MST, 1 hour 20 minutes before

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Special weather statement, Oct 20, 11:48 AM MST, 1 hour 12 minutes before

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Local storm report, Oct 20, 12:07 PM MST, 53 minutes before

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Special weather statement, Oct 20, 12:53 PM MST, 7 minutes before

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The air that afternoon

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.

Flgstf/Belemont, AZ (KFGZ), 12:00Z

8.0 hours before the tornado, 194 km from the path. October 20, 2015.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed. The warm shading is its CAPE, the cool shading the inhibition it has to break through.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km. RM and LM are the right and left moving storms Bunkers' method gives; the shaded area is the 0 to 1 km storm-relative helicity.

Mixed-layer CAPE: 329 J/kg
Mixed-layer CIN: -8 J/kg
Surface CAPE: 58 J/kg
Mixed-layer LCL: 761 m above ground
0-6 km bulk shear: 42 kt
0-1 km bulk shear: 17 kt
0-1 km storm-relative helicity: 114 m²/s²
0-3 km storm-relative helicity: 212 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.0
0-3 km lapse rate: 6.1 K/km

Open this sounding in Storm Lab

The surface observations

Window Rock (Was P34) (RQE), 61 km from the path, in the two hours either side.

Time (UTC)	Temp (°F)	Dew point (°F)	Wind	Gust (kt)	Pressure (mb)	Weather
00:00 UTC

From the Iowa Environmental Mesonet's archive of airport observations.

The radar

The Flagstaff radar (KFSX), 182 km away, was scanning. The volume nearest the touchdown began at 19:59 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.

This ground now

The live radar over the track Every 2015 tornado in Arizona Every tornado in Arizona since 1950 Warnings in force in Arizona now The forecast where you are

What this means

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.

Sources

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