Alert archive / Colorado / Tornado Warnings in 2015

Tornado Warning 4, NWS Denver/Boulder, CO

April 18, 2015Washington County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Apr 18, 2015, 1:38 PM MDT for Washington County, Colorado. It was in force for 22 min. 2 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: Apr 18, 2015, 1:38 PM MDT (19:38 UTC)
Expired: Apr 18, 2015, 2:00 PM MDT
In force: 22 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Tornado: Observed
Hail: 0.75 in

County Washington County, CO

The radar

The Goodland radar (KGLD), 128 km from the middle of the area, began a volume at 19:41 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
Apr 18, 1:40 PM MDT	TORNADO	6 Se Otis, CO	TORNADO REPORTED ON GROUND BY SPOTTER
Apr 18, 1:40 PM MDT	TORNADO	8 Sw Yuma, CO	TORNADO ON THE GROUND REPORTED BY W-Y COMMS FROM LAW ENFORCEMENT THROUGH NAWAS

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

The nearest sounding before it

Denver, CO (KDEN), launched 12:00Z, 7.6 hours before the alert went out and 29 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: 33 J/kg
Mixed-layer CIN: -26 J/kg
Mixed-layer LCL: 692 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 44 m²/s²
0-3 km storm-relative helicity: 75 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.

408 
WFUS55 KBOU 181938
TORBOU
COC121-182000-
/O.NEW.KBOU.TO.W.0004.150418T1938Z-150418T2000Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
138 PM MDT SAT APR 18 2015

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

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

* UNTIL 200 PM MDT

* AT 137 PM MDT...A CONFIRMED TORNADO WAS LOCATED 11 MILES SOUTHWEST
  OF YUMA...MOVING NORTH AT 25 MPH.

  HAZARD...TORNADO. 

  SOURCE...PUBLIC CONFIRMED TORNADO. 

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

* LOCATIONS IMPACTED INCLUDE...
  OTIS AND PLATNER. 

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 3985 10300 4024 10309 4025 10280 3986 10280
TIME...MOT...LOC 1937Z 206DEG 22KT 3998 10283 

TORNADO...OBSERVED
HAIL...<.75IN

$$

MEIER

2 follow-up statements

363 
WWUS55 KBOU 181946
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
146 PM MDT SAT APR 18 2015

COC121-182000-
/O.CON.KBOU.TO.W.0004.000000T0000Z-150418T2000Z/
WASHINGTON CO-
146 PM MDT SAT APR 18 2015

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 200 PM MDT FOR EAST
CENTRAL WASHINGTON COUNTY...
    
AT 146 PM MDT...THERE CONTINUES TO BE REPORTS OF A TORNADO ON THE 
GROUND LOCATED 11 MILES SOUTHWEST OF YUMA...MOVING NORTH AT 20 MPH.

HAZARD...TORNADO. 

SOURCE...PUBLIC CONFIRMED TORNADO. 

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

LOCATIONS IMPACTED INCLUDE...
OTIS.

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

&&

LAT...LON 3994 10299 4024 10307 4025 10280 3993 10280
TIME...MOT...LOC 1946Z 171DEG 16KT 3999 10286 

TORNADO...OBSERVED
HAIL...<.75IN

$$

MEIER

487 
WWUS55 KBOU 181958
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
158 PM MDT SAT APR 18 2015

COC121-182006-
/O.EXP.KBOU.TO.W.0004.000000T0000Z-150418T2000Z/
WASHINGTON CO-
158 PM MDT SAT APR 18 2015

...THE TORNADO WARNING FOR EAST CENTRAL WASHINGTON COUNTY WILL EXPIRE
AT 200 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.

LAT...LON 3994 10299 4024 10307 4025 10280 3993 10280
TIME...MOT...LOC 1954Z 206DEG 22KT 3999 10286 

$$

MEIER

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 17, 6:11 PM MDT	Tornado Warning	BOU	Washington	19 min
Apr 17, 7:08 PM MDT	Special Weather Statement	BOU	Logan	37 min
Apr 17, 8:14 PM MDT	Special Weather Statement	BOU	Logan	31 min
Apr 17, 8:42 PM MDT	Special Weather Statement	BOU	Logan	33 min
Apr 18, 2:49 PM MDT	Special Weather Statement	BOU	Logan	41 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.