Alert archive / Colorado / Tornado Warnings in 2014

Tornado Warning 18, NWS Denver/Boulder, CO

May 21, 2014Adams County, Arapahoe County, Denver County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at May 21, 2014, 2:23 PM MDT for Adams County, Arapahoe County, Denver County, Colorado. It was in force for 22 min. 5 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 21, 2014, 2:23 PM MDT (20:23 UTC)
Expired: May 21, 2014, 2:45 PM MDT
In force: 22 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.75 in

Counties Adams County, CO, Arapahoe County, CO, Denver County, CO

The radar

The Denver radar (KFTG), 19 km from the middle of the area, began a volume at 20:23 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
May 21, 2:25 PM MDT	HAIL 0.75	Aurora, CO	MINOR STREET FLOODING
May 21, 2:30 PM MDT	HAIL 0.5	Aurora, CO	COVERED THE GROUND TO A DEPTH OF 6 INCHES
May 21, 2:30 PM MDT	TORNADO	4 Ne Aurora, CO
May 21, 2:30 PM MDT	TORNADO	E Denver, CO
May 21, 2:45 PM MDT	TORNADO	Watkins, CO

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 21, 12:34 PM MDT	Tornado Watch	SPC	8 hr

The nearest sounding before it

Denver, CO (KDEN), launched 12:00Z, 8.4 hours before the alert went out and 132 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

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.

Mixed-layer CAPE: 268 J/kg
Mixed-layer CIN: -75 J/kg
Mixed-layer LCL: 786 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 86 m²/s²
0-3 km storm-relative helicity: 158 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 2.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

638 
WFUS55 KBOU 212023
TORBOU
COC001-005-031-212045-
/O.NEW.KBOU.TO.W.0018.140521T2023Z-140521T2045Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
223 PM MDT WED MAY 21 2014

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* TORNADO WARNING FOR...
  WESTERN ARAPAHOE COUNTY IN NORTHEAST COLORADO...
  CENTRAL DENVER COUNTY IN NORTHEAST COLORADO...
  SOUTHWESTERN ADAMS COUNTY IN NORTHEAST COLORADO...

* UNTIL 245 PM MDT

* AT 220 PM MDT...SEVERE THUNDERSTORMS CAPABLE OF PRODUCING BOTH
  TORNADOES AND EXTENSIVE STRAIGHT LINE WIND DAMAGE WERE LOCATED OVER
  NORTHWESTERN AURORA...OR 12 MILES EAST OF DENVER...MOVING EAST AT 
  15 MPH. THE BEST CIRCULATION WITH THIS THUNDERSTORM APPEARS THAT 
  IT WILL MOVE SOUTH OF DENVER INTERNATIONAL AIRPORT.  HEAVY RAIN IS 
  OCCURRING WITH THIS THUNDERSTORM WHICH WILL LIKELY OBSCURE ANY 
  TORNADOES THAT ARE PRODUCED.  

  HAZARD...TORNADO AND GOLF BALL SIZE HAIL. 

  SOURCE...RADAR INDICATED ROTATION. 

  IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT 
           SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. 
           DAMAGE TO ROOFS...WINDOWS AND VEHICLES WILL OCCUR.  TREE 
           DAMAGE IS LIKELY. 

* LOCATIONS IMPACTED INCLUDE...
  DENVER...AURORA...NORTHEASTERN CENTENNIAL...SOUTHWESTERN COMMERCE
  CITY...GREENWOOD VILLAGE...SOUTHWESTERN DENVER INTERNATIONAL
  AIRPORT...ARAPAHOE PARK...WATKINS AND BUCKLEY AFB.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE LOWEST
FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A
VEHICLE OR OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND
PROTECT YOURSELF FROM FLYING DEBRIS.

MOTORISTS SHOULD NOT TAKE SHELTER UNDER HIGHWAY OVERPASSES. IF YOU
CANNOT SAFELY DRIVE AWAY FROM THE TORNADO...AS A LAST RESORT...EITHER
PARK YOUR VEHICLE AND STAY PUT...OR ABANDON YOUR VEHICLE AND LIE DOWN
IN A LOW LYING AREA AND PROTECT YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 3981 10454 3959 10460 3958 10493 3978 10497
      3981 10499
TIME...MOT...LOC 2020Z 269DEG 12KT 3975 10472 

TORNADO...RADAR INDICATED
HAIL...1.75IN

$$

DANKERS

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 6:19 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Elbert, Lincoln, Washington	41 min
May 20, 10:51 PM MDT	Special Weather Statement	BOU	Weld	39 min
May 20, 11:43 PM MDT	Special Weather Statement	BOU	Weld	62 min
May 20, 11:51 PM MDT	Areal Flood Advisory	BOU	Morgan, Weld	114 min
May 21, 6:47 AM MDT	Areal Flood Advisory	BOU	Morgan	3 hr
May 21, 1:00 PM MDT	Severe Thunderstorm Warning	BOU	Jefferson	45 min
May 21, 1:36 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Denver	39 min
May 21, 1:56 PM MDT	Tornado Warning	BOU	Adams, Arapahoe, Denver	34 min
May 21, 2:21 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Denver	39 min
May 21, 2:42 PM MDT	Tornado Warning	BOU	Adams, Arapahoe	33 min
May 21, 3:18 PM MDT	Tornado Warning Tornado observed	BOU	Adams, Arapahoe, Denver	27 min
May 21, 3:47 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe	28 min
May 21, 3:57 PM MDT	Severe Thunderstorm Warning	BOU	Douglas, Elbert	48 min
May 21, 4:18 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe	42 min
May 21, 4:57 PM MDT	Tornado Warning	BOU	Adams	48 min
May 21, 5:34 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Morgan, Washington	41 min

Nearby

Tornado Warnings in Colorado, 2014 Every tornado warning in 2014 Tornadoes in 2014

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.