Alert archive / Colorado / Tornado Warnings in 2015

Tornado Warning 52, NWS Denver/Boulder, CO

August 11, 2015Arapahoe County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Aug 11, 2015, 3:55 PM MDT for Arapahoe County, Colorado. It was in force for 35 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 11, 2015, 3:55 PM MDT (21:55 UTC)
Expired: Aug 11, 2015, 4:30 PM MDT
In force: 35 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Tornado: Observed
Hail: 1.0 in

County Arapahoe County, CO

The radar

The Denver radar (KFTG), 27 km from the middle of the area, began a volume at 21:58 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.

The nearest sounding before it

Denver, CO (KDEN), launched 12:00Z, 9.9 hours before the alert went out and 139 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: 7 J/kg
Mixed-layer CIN: -292 J/kg
Mixed-layer LCL: 2089 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 18 m²/s²
0-3 km storm-relative helicity: 62 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

542 
WFUS55 KBOU 112155
TORBOU
COC005-112230-
/O.NEW.KBOU.TO.W.0052.150811T2155Z-150811T2230Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
355 PM MDT TUE AUG 11 2015

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHWESTERN ARAPAHOE COUNTY IN NORTHEASTERN COLORADO...

* UNTIL 430 PM MDT

* AT 355 PM MDT...A CONFIRMED TORNADO WAS LOCATED OVER WESTERN
  AURORA...OR 9 MILES EAST OF DENVER...THE STORM WAS NEARLY STATIONARY.  

  HAZARD...TORNADO AND QUARTER SIZE HAIL. 

  SOURCE...PUBLIC CONFIRMED TORNADO. 

  IMPACT...EXPECT DAMAGE TO MOBILE HOMES...ROOFS AND VEHICLES. 

* LOCATIONS IMPACTED INCLUDE...
  WESTERN AURORA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3968 10487 3974 10484 3974 10477 3967 10481
      3967 10487
TIME...MOT...LOC 2155Z 290DEG 49KT 3971 10479 

TORNADO...OBSERVED
HAIL...1.00IN

$$

COOPER

1 follow-up statement

063 
WWUS55 KBOU 112228
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
428 PM MDT TUE AUG 11 2015

COC005-112237-
/O.EXP.KBOU.TO.W.0052.000000T0000Z-150811T2230Z/
ARAPAHOE CO-
428 PM MDT TUE AUG 11 2015

...THE TORNADO WARNING FOR NORTHWESTERN ARAPAHOE COUNTY WILL EXPIRE
AT 430 PM MDT...
    
THE TORNADIC THUNDERSTORM WHICH PROMPTED THE WARNING HAS WEAKENED. THEREFORE
THE WARNING WILL BE ALLOWED TO EXPIRE.

LAT...LON 3968 10487 3974 10484 3974 10477 3967 10481
      3967 10487
TIME...MOT...LOC 2226Z 290DEG 49KT 3971 10479 

$$

COOPER

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 11, 2:16 PM MDT	Areal Flood Advisory	BOU	Larimer	3 hr
Aug 11, 3:14 PM MDT	Special Weather Statement	BOU	Douglas	46 min
Aug 11, 3:39 PM MDT	Special Weather Statement	BOU	Denver	51 min
Aug 11, 4:04 PM MDT	Tornado Warning	BOU	Adams, Denver	26 min
Aug 11, 4:26 PM MDT	Severe Thunderstorm Warning	BOU	Arapahoe, Douglas	10 min
Aug 11, 4:40 PM MDT	Areal Flood Advisory	BOU	Arapahoe, Denver, Douglas	95 min

Nearby

Tornado Warnings in Colorado, 2015 Every tornado warning in 2015 Tornadoes in 2015

Sources

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