Alert archive / Colorado / Tornado Warnings in 2017

Tornado Warning 17, NWS Denver/Boulder, CO

August 10, 2017Adams County, Arapahoe County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Aug 10, 2017, 4:48 PM MDT for Adams County, Arapahoe County, Colorado. It was in force for 27 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 10, 2017, 4:48 PM MDT (22:48 UTC)
Expired: Aug 10, 2017, 5:15 PM MDT
In force: 27 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

The radar

The Denver radar (KFTG), 55 km from the middle of the area, began a volume at 22:49 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
Aug 10, 3:52 PM MDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Denver, CO (KDEN), launched 12:00Z, 10.8 hours before the alert went out and 58 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: 2 J/kg
Mixed-layer CIN: -251 J/kg
Mixed-layer LCL: 866 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 26 m²/s²
0-3 km storm-relative helicity: 76 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

684 
WFUS55 KBOU 102248
TORBOU
COC001-005-102315-
/O.NEW.KBOU.TO.W.0017.170810T2248Z-170810T2315Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Denver CO
448 PM MDT THU AUG 10 2017

The National Weather Service in Denver Colorado has issued a

* Tornado Warning for...
  Northeastern Arapahoe County in northeastern Colorado...
  Eastern Adams County in northeastern Colorado...

* Until 515 PM MDT
    
* At 447 PM MDT, a severe thunderstorm capable of producing a tornado
  was located near Leader, or 28 miles southwest of Fort Morgan,
  moving southeast at 45 mph.

  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...
  Leader.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This Tornado Warning replaces the Severe Thunderstorm Warning issued
for the same area.

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 3978 10371 3972 10371 3964 10390 3996 10423
      4000 10415
TIME...MOT...LOC 2247Z 306DEG 41KT 3993 10410 

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

$$

GIMMESTAD

2 follow-up statements

385 
WWUS55 KBOU 102305
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
505 PM MDT THU AUG 10 2017

COC001-005-102315-
/O.CON.KBOU.TO.W.0017.000000T0000Z-170810T2315Z/
Arapahoe CO-Adams CO-
505 PM MDT THU AUG 10 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 515 PM MDT FOR
NORTHEASTERN ARAPAHOE AND SOUTHEASTERN ADAMS COUNTIES...
    
At 504 PM MDT, a severe thunderstorm capable of producing a tornado
was located 7 miles southwest of Shamrock, or 32 miles south of Fort
Morgan, moving southeast at 45 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. 

Locations impacted include...
Leader.

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 3978 10371 3972 10371 3964 10390 3988 10413
      3994 10402
TIME...MOT...LOC 2304Z 308DEG 40KT 3981 10391 

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

$$

GIMMESTAD

750 
WWUS55 KBOU 102316
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
516 PM MDT THU AUG 10 2017

COC001-005-102325-
/O.EXP.KBOU.TO.W.0017.000000T0000Z-170810T2315Z/
Arapahoe CO-Adams CO-
516 PM MDT THU AUG 10 2017

...THE TORNADO WARNING FOR NORTHEASTERN ARAPAHOE AND SOUTHEASTERN
ADAMS COUNTIES HAS EXPIRED...
                
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 allowed to expire.  However, gusty 
winds, hail, and heavy rain are still likely with this thunderstorm.

A severe thunderstorm watch remains in effect until 1000 PM MDT for
northeastern Colorado.

LAT...LON 3978 10371 3972 10371 3964 10390 3988 10413
      3994 10402
TIME...MOT...LOC 2315Z 306DEG 41KT 3974 10378 

$$

GIMMESTAD

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 2:03 PM MDT	Special Weather Statement	BOU	Larimer	42 min
Aug 10, 2:28 PM MDT	Severe Thunderstorm Warning	BOU	Larimer	36 min
Aug 10, 2:31 PM MDT	Flash Flood Warning	BOU	Larimer	119 min
Aug 10, 3:02 PM MDT	Severe Thunderstorm Warning	BOU	Larimer, Weld	43 min
Aug 10, 3:07 PM MDT	Areal Flood Advisory	BOU	Larimer, Weld	83 min
Aug 10, 3:18 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Denver, Jefferson	42 min
Aug 10, 3:54 PM MDT	Special Weather Statement	BOU	Weld	51 min
Aug 10, 3:54 PM MDT	Severe Thunderstorm Warning	BOU	Elbert, Lincoln	51 min
Aug 10, 4:01 PM MDT	Severe Thunderstorm Warning	BOU	Elbert, Lincoln	17 min
Aug 10, 4:06 PM MDT	Special Weather Statement	BOU	Denver	39 min
Aug 10, 4:13 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Morgan, Weld	47 min
Aug 10, 4:23 PM MDT	Special Weather Statement	BOU	Lincoln	52 min
Aug 10, 4:37 PM MDT	Severe Thunderstorm Warning	BOU	Lincoln, Washington	38 min
Aug 10, 4:40 PM MDT	Areal Flood Advisory	BOU	Weld	65 min
Aug 10, 4:43 PM MDT	Severe Thunderstorm Warning	BOU	Lincoln	32 min
Aug 10, 5:07 PM MDT	Severe Thunderstorm Warning	BOU	Lincoln, Washington	25 min
Aug 10, 5:12 PM MDT	Areal Flood Advisory	BOU	Lincoln	93 min
Aug 10, 5:18 PM MDT	Special Weather Statement	BOU	Washington	27 min
Aug 10, 5:24 PM MDT	Severe Thunderstorm Warning	BOU	Lincoln	16 min

Nearby

Tornado Warnings in Colorado, 2017 Every tornado warning in 2017 Tornadoes in 2017

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.