Alert archive / Colorado / Tornado Warnings in 2015

Tornado Warning 1, NWS Denver/Boulder, CO

April 17, 2015Washington County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Apr 17, 2015, 4:27 PM MDT for Washington County, Colorado. It was in force for 18 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: Apr 17, 2015, 4:27 PM MDT (22:27 UTC)
Expired: Apr 17, 2015, 4:45 PM MDT
In force: 18 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

County Washington County, CO

The radar

The Denver radar (KFTG), 107 km from the middle of the area, began a volume at 22:30 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, 10.5 hours before the alert went out and 27 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 603 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 205 m²/s²
0-3 km storm-relative helicity: 227 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.

534 
WFUS55 KBOU 172227
TORBOU
COC121-172245-
/O.NEW.KBOU.TO.W.0001.150417T2227Z-150417T2245Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
427 PM MDT FRI APR 17 2015

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* TORNADO WARNING FOR...
  CENTRAL WASHINGTON COUNTY IN NORTHEASTERN COLORADO...

* UNTIL 445 PM MDT
    
* AT 426 PM MDT...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A
  TORNADO WAS LOCATED 8 MILES SOUTH OF MIDWAY...OR 10 MILES SOUTHWEST
  OF AKRON...MOVING NORTHWEST AT 15 MPH.

  HAZARD...TORNADO. 

  SOURCE...RADAR INDICATED ROTATION. 

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

* THIS TORNADIC THUNDERSTORM WILL REMAIN OVER MAINLY RURAL AREAS OF
  CENTRAL WASHINGTON COUNTY.

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 YOU ARE IN A MOBILE
HOME...A VEHICLE OR OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL
SHELTER AND PROTECT YOURSELF FROM FLYING DEBRIS.

&&

LAT...LON 4002 10328 4002 10347 4020 10347 4020 10329
TIME...MOT...LOC 2226Z 153DEG 12KT 4010 10338 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

RPK

2 follow-up statements

457 
WWUS55 KBOU 172234
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
434 PM MDT FRI APR 17 2015

COC121-172245-
/O.CON.KBOU.TO.W.0001.000000T0000Z-150417T2245Z/
WASHINGTON CO-
434 PM MDT FRI APR 17 2015

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 445 PM MDT FOR CENTRAL
WASHINGTON COUNTY...
    
AT 434 PM MDT...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO
WAS LOCATED 7 MILES SOUTH OF MIDWAY...OR 10 MILES WEST OF AKRON...
MOVING NORTHWEST AT 15 MPH.

HAZARD...TORNADO. 

SOURCE...RADAR INDICATED ROTATION. 

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

THIS TORNADIC THUNDERSTORM WILL REMAIN OVER MAINLY RURAL AREAS OF
CENTRAL WASHINGTON COUNTY.

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.

&&

LAT...LON 4002 10328 4002 10347 4020 10347 4020 10329
TIME...MOT...LOC 2234Z 153DEG 12KT 4013 10340 

TORNADO...RADAR INDICATED
HAIL...<.75IN

$$

RPK

417 
WWUS55 KBOU 172243
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
443 PM MDT FRI APR 17 2015

COC121-172253-
/O.EXP.KBOU.TO.W.0001.000000T0000Z-150417T2245Z/
WASHINGTON CO-
443 PM MDT FRI APR 17 2015

...THE TORNADO WARNING FOR CENTRAL WASHINGTON COUNTY WILL EXPIRE AT
445 PM MDT...
                
THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER APPEARS CAPABLE OF PRODUCING A TORNADO.
THEREFORE THE WARNING WILL BE ALLOWED TO EXPIRE.  HOWEVER SMALL HAIL
AND GUSTY WINDS ARE STILL POSSIBLE WITH THIS THUNDERSTORM.

A TORNADO WATCH REMAINS IN EFFECT UNTIL MIDNIGHT MDT FOR NORTHEASTERN
COLORADO.

LAT...LON 4002 10328 4002 10347 4020 10347 4020 10329
TIME...MOT...LOC 2240Z 153DEG 12KT 4013 10340 

$$

RPK

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 17, 4:52 PM MDT	Special Weather Statement	BOU	Morgan	23 min
Apr 17, 5:31 PM MDT	Special Weather Statement	BOU	Morgan	29 min
Apr 17, 5:57 PM MDT	Tornado Warning	BOU	Logan	18 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.