Alert archive / Colorado / Tornado Warnings in 2018

Tornado Warning 20, NWS Denver/Boulder, CO

June 17, 2018Washington County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Jun 17, 2018, 5:29 PM MDT for Washington County, Colorado. It was in force for 20 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: Jun 17, 2018, 5:29 PM MDT (23:29 UTC)
Expired: Jun 17, 2018, 5:49 PM MDT
In force: 20 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.25 in

County Washington County, CO

The radar

The Goodland radar (KGLD), 122 km from the middle of the area, began a volume at 23:29 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 watch it was issued in

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

Issued	Product	Office	Lasted
Jun 17, 1:35 PM MDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Denver, CO (KDEN), launched 12:00Z, 11.5 hours before the alert went out and 33 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: 1003 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: -69 m²/s²
0-3 km storm-relative helicity: 36 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

378 
WFUS55 KBOU 172329
TORBOU
COC121-180000-
/O.NEW.KBOU.TO.W.0020.180617T2329Z-180618T0000Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Denver CO
529 PM MDT SUN JUN 17 2018

The National Weather Service in Denver Colorado has issued a

* Tornado Warning for...
  East central Washington County in northeastern Colorado...

* Until 600 PM MDT.
    
* At 526 PM MDT, a severe thunderstorm capable of producing a tornado
  was located 10 miles east of Elba, or 17 miles southwest of Yuma,
  moving east at 25 mph.

  HAZARD...Tornado and half dollar 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.

* This tornadic thunderstorm will remain over mainly rural areas of
  east 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 outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4000 10279 4000 10280 3985 10280 3984 10305
      4011 10310 4013 10279
TIME...MOT...LOC 2326Z 255DEG 21KT 3996 10298 

TORNADO...RADAR INDICATED
HAIL...1.25IN

$$

RPK

1 follow-up statement

896 
WWUS55 KBOU 172349
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
549 PM MDT SUN JUN 17 2018

COC121-172358-
/O.CAN.KBOU.TO.W.0020.000000T0000Z-180618T0000Z/
Washington CO-
549 PM MDT SUN JUN 17 2018

...THE TORNADO WARNING FOR EAST CENTRAL WASHINGTON COUNTY IS
CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 900 PM MDT for northeastern
Colorado.

LAT...LON 4000 10279 4000 10280 3985 10280 3984 10305
      4011 10310 4013 10279
TIME...MOT...LOC 2348Z 255DEG 21KT 3999 10281 

$$

RPK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 17, 1:40 PM MDT	Special Weather Statement	BOU	Sedgwick	35 min
Jun 17, 1:44 PM MDT	Severe Thunderstorm Warning	BOU	Sedgwick	31 min
Jun 17, 1:51 PM MDT	Tornado Warning	BOU	Sedgwick	24 min
Jun 17, 2:13 PM MDT	Tornado Warning	BOU	Sedgwick	17 min
Jun 17, 2:36 PM MDT	Areal Flood Advisory	BOU	Douglas	114 min
Jun 17, 3:52 PM MDT	Severe Thunderstorm Warning	BOU	Arapahoe	38 min
Jun 17, 4:20 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe	25 min
Jun 17, 4:32 PM MDT	Severe Thunderstorm Warning	BOU	Washington	43 min
Jun 17, 4:58 PM MDT	Severe Thunderstorm Warning	BOU	Washington	47 min
Jun 17, 5:05 PM MDT	Tornado Warning	BOU	Washington	25 min

Nearby

Tornado Warnings in Colorado, 2018 Every tornado warning in 2018 Tornadoes in 2018

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.