F0 tornado, Merino, Colorado, August 24, 2002

1. F040 to 72 mphthis tornado

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

2. F173 to 112 mph

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

3. F2113 to 157 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. F3158 to 206 mph

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

5. F4207 to 260 mph

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

6. F5261 to 318 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

F0

Date

August 24, 2002

Touchdown

5:27 PM MDT (23:27 UTC)

Path length

0.1 miles (0.2 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

County

Logan County

Touchdown point

40.550, -103.450

Lift-off point

40.550, -103.450

Record number

261

A small tornado touched down but did no damage.

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

23 minutes of warning. NWS BOU issued a tornado warning for this county at 23:04 UTC, 23 minutes before the tornado touched down, in force until 23:45 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 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:36 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.

NWS Denver/Boulder, CO wrote its last area forecast discussion before the tornado touched down at Aug 24, 3:15 PM MDT, 2 hours 12 minutes earlier.

NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DENVER COLORADO
315 PM MDT SAT AUG 24 2002

STRONG CONVECTION JUST ABT READY TO MOVE OVER THE NE CORNER OF THE
STATE.  LOW LVL MSTR...STEEP LAPSE RATES AND DRIER AIR ALOFT ARE
COMBINING WITH OUTFLOW BOUNDARIES FM EARLIER NEB PANHANDLE
CONVECTION TO PRODUCE ISOLATED SEVERE STORMS WITH LARGE HAIL AND
PSBLY SOME TORNADOS.  TORNADO WATCH REMAINS IN EFFECT FOR THIS AREA
UNTIL 8 PM MDT.  THE CHANCE OF SCT THUNDERSTORMS EXTENDS ACRS THE
REST OF NE CO THRU THIS EVENING.  MOD SELY SFC WNDS ACRS NE CO HAVE
BROUGHT SFC DEWPTS INTO THE MID 50S WITH TEMPS INTO THE LOW 80S.
SFC BASED CAPES FM LAPS ARE AS HIGH AS 2200 J/KG.  OUTFLOW
BOUNDARIES CONTINUING TO MOVE SWWD WL PROBABLY BE THE FOCUSING
MECHANISM FOR ADDITIONAL THUNDERSTORM DEVELOPMENT WELL INTO THE
EVENING.  ALOFT...A 100+ KT JET IS ARCING ACROSS THE NRN BORDER OF
THE STATE AND WILL BE IN PLACE THRU 06Z.  OVR THE MTNS...A MUCH
DRIER AIRMASS IS IN PLACE AND ONLY A MINIMUM AMNT OF SHOWERS IS
EXPECTED THROUGH TONIGHT.

ON SUNDAY...SOME OF THE DRIER AIR WILL WORK ONTO THE PLAINS BUT THE
LATEST MESO-ETA STILL HANGS ONTO LOW LEVEL MSTR FM WASHINGTON COUNTY
NWD AND EWD.  THE WEAK UPR RDG OVR THE SWRN U.S. IS GOING TO BE SET
IN PLACE OVR THE NEXT FEW DAYS...SO THE GENERAL PATTERN OF AFTN
SHOWER ACTIVITY ON THE PLAINS WILL CONTINUE.  THE MTNS WL CONT TO BE
TOO DRY FOR SHOWER ACTIVITY...BUT THE WLY FLOW IS NOT GOING TO BE
STRONG ENOUGH TO FLUSH THE LOW LVL MSTR OUT OF OUR FCST AREA.  TEMPS
ARND THE DENVER AREA WILL CLIMB A FEW DEGREES WARMER...BUT FARTHER
EAST ON THE PLAINS WL BE PERSISTENT IN THEIR AFTN HIGHS.

THIS PATTERN SHOULD CONTINUE MUCH OF THE WEEK...ALTHOUGH AFTER
MONDAY IT IS HARD TO PINPOINT ANY PART OF THE PLAINS THAT HAVE A
HIGHER CHANCE OF SHOWERS THAN ANYWHERE ELSE.  INDICATIONS ARE THAT A
FRONT MOVE INTO THE AREA TUESDAY WHICH MAY BRING MSTR AND
INSTABILITY ALL THE WAY BACK TO THE FOOTHILLS.  LATER IN THE
WEEK...TEMPS MAY BE A FEW DEGS WARMER THAN TUES AND WED...WHICH WL
BE THE COOLEST DAYS OF THE WEEK.               KDRBY

.DEN...NONE.

In the hours before

LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DENVER CO
425 PM MDT SAT AUG 24 2002

...PRELIMINARY STORM REPORT FOR AUGUST 24 2002...

TIME(MDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0205 AM    8 SW DENVER               CO   0.88 INCH HAIL
08/24/02   DENVER                         QUINCY/WADSWORTH

0310 PM    1 E JULESBURG             CO   1.25 INCH HAIL
08/24/02   SEDGWICK

0320 PM    2 SE JULESBURG            CO   0.88 INCH HAIL
08/24/02   SEDGWICK

0345 PM    12 SE JULESBURG           CO   1.00 INCH HAIL
08/24/02   SEDGWICK

CLB

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 Denver radar (KFTG), 126 km away, was scanning. The volume nearest the touchdown began at 23:24 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.

The live radar over the trackEvery 2002 tornado in ColoradoEvery tornado in Colorado since 1950Warnings in force in Colorado nowThe forecast where you are

7 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.