Alert archive / Colorado / Tornado Warnings in 2011

Tornado Warning 33, NWS Denver/Boulder, CO

July 12, 2011Weld County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Jul 12, 2011, 9:10 PM MDT for Weld County, Colorado. It was in force for 34 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: Jul 12, 2011, 9:10 PM MDT (03:10 UTC)
Expired: Jul 12, 2011, 9:44 PM MDT
In force: 34 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon

County Weld County, CO

The radar

The Cheyenne radar (KCYS), 72 km from the middle of the area, began a volume at 03:12 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 (KDNR), launched 00:00Z, 3.2 hours before the alert went out and 123 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: 596 J/kg
Mixed-layer CIN: -61 J/kg
Mixed-layer LCL: 1449 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -12 m²/s²
0-3 km storm-relative helicity: 256 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

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

402 
WFUS55 KBOU 130310
TORBOU
COC123-130400-
/O.NEW.KBOU.TO.W.0033.110713T0310Z-110713T0400Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
910 PM MDT TUE JUL 12 2011

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* TORNADO WARNING FOR...
  CENTRAL WELD COUNTY IN NORTHEAST COLORADO

* UNTIL 1000 PM MDT

* AT 910 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 7 MILES WEST OF
  KEOTA...OR 33 MILES NORTHEAST OF GREELEY. THIS STORM WAS MOVING
  EAST AT 20 MPH.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO KEOTA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

WHEN A TORNADO WARNING IS ISSUED BASED ON DOPPLER RADAR...IT MEANS
THAT STRONG ROTATION HAS BEEN DETECTED IN THE STORM. A TORNADO MAY
ALREADY BE ON THE GROUND...OR MAY DEVELOP SHORTLY.

&&

LAT...LON 4085 10407 4062 10400 4061 10429 4072 10432
TIME...MOT...LOC 0310Z 251DEG 17KT 4069 10420

$$


BAKER

1 follow-up statement

623 
WWUS55 KBOU 130344
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
944 PM MDT TUE JUL 12 2011

COC123-130352-
/O.CAN.KBOU.TO.W.0033.000000T0000Z-110713T0400Z/
WELD CO-
944 PM MDT TUE JUL 12 2011

...THE TORNADO WARNING FOR CENTRAL WELD COUNTY IS CANCELLED...

THE THUNDERSTORM THAT PROMPTED THE WARNING HAS WEAKENED AND IS NO
LONGER EXPECTED TO PRODUCE SEVERE WEATHER.

HOWEVER THIS STORM IS STILL LIKELY TO PRODUCE STRONG WINDS...HEAVY 
RAIN...AND FREQUENT CLOUD-TO-GROUND LIGHTNING AS IT CONTINUES TO 
TRACK EAST ACROSS NORTHEAST WELD COUNTY.   

LAT...LON 4085 10407 4062 10400 4061 10429 4072 10432
TIME...MOT...LOC 0342Z 251DEG 17KT 4074 10401

$$


BAKER

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 12, 6:34 PM MDT	Flash Flood Warning	BOU	Arapahoe, Elbert	2 hr
Jul 12, 6:39 PM MDT	Severe Thunderstorm Warning	BOU	Arapahoe, Elbert	51 min
Jul 12, 7:03 PM MDT	Tornado Warning	BOU	Elbert	42 min
Jul 12, 7:19 PM MDT	Flash Flood Warning	BOU	Arapahoe, Elbert	91 min
Jul 12, 7:23 PM MDT	Severe Thunderstorm Warning	BOU	Weld	52 min
Jul 12, 7:27 PM MDT	Tornado Warning	BOU	Elbert	48 min
Jul 12, 7:34 PM MDT	Tornado Warning	BOU	Weld	41 min
Jul 12, 7:45 PM MDT	Tornado Warning	BOU	Elbert	45 min
Jul 12, 7:48 PM MDT	Areal Flood Advisory	BOU	Weld	87 min
Jul 12, 8:05 PM MDT	Severe Thunderstorm Warning	BOU	Weld	40 min
Jul 12, 8:17 PM MDT	Tornado Warning	BOU	Elbert	43 min
Jul 12, 8:21 PM MDT	Severe Thunderstorm Warning	BOU	Weld	54 min
Jul 12, 8:33 PM MDT	Flash Flood Warning	BOU	Arapahoe, Elbert	3 hr
Jul 12, 8:44 PM MDT	Flash Flood Warning	BOU	Weld	2 hr
Jul 12, 9:00 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	60 min
Jul 12, 9:04 PM MDT	Severe Thunderstorm Warning	BOU	Weld	56 min
Jul 12, 9:15 PM MDT	Areal Flood Advisory	BOU	Adams, Arapahoe, Denver, Jefferson	90 min
Jul 12, 9:30 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Denver	44 min
Jul 12, 9:40 PM MDT	Areal Flood Advisory	BOU	Boulder	95 min
Jul 12, 9:59 PM MDT	Severe Thunderstorm Warning	BOU	Weld	61 min
Jul 12, 10:35 PM MDT	Areal Flood Advisory	BOU	Larimer, Weld	115 min
Jul 12, 10:48 PM MDT	Flash Flood Warning	BOU	Weld	3 hr
Jul 12, 10:54 PM MDT	Flash Flood Warning	BOU	Larimer	2 hr
Jul 12, 11:19 PM MDT	Areal Flood Warning	BOU	Arapahoe, Elbert	6 hr
Jul 13, 12:04 AM MDT	River Flood Advisory	BOU	Adams	10 hr
Jul 13, 12:16 AM MDT	Flash Flood Warning	BOU	Weld	3 hr
Jul 13, 12:32 AM MDT	River Flood Advisory	BOU	Weld	47 hr
Jul 13, 12:37 AM MDT	Areal Flood Advisory	BOU	Weld	83 min
Jul 13, 1:11 AM MDT	Areal Flood Advisory	BOU	Logan	94 min
Jul 13, 2:01 PM MDT	Special Weather Statement	BOU	Elbert	29 min
Jul 13, 2:22 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	38 min
Jul 13, 2:42 PM MDT	Areal Flood Advisory	BOU	Elbert	93 min
Jul 13, 2:58 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	38 min
Jul 13, 3:52 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	38 min
Jul 13, 4:22 PM MDT	Severe Thunderstorm Warning	BOU	Elbert	16 min
Jul 13, 5:08 PM MDT	Special Weather Statement	BOU	Jefferson	52 min
Jul 13, 5:53 PM MDT	Areal Flood Advisory	BOU	Boulder	82 min
Jul 13, 5:56 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe, Denver, Douglas, Jefferson	49 min

Nearby

Tornado Warnings in Colorado, 2011 Every tornado warning in 2011 Tornadoes in 2011

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.