Alert archive / Colorado / Tornado Warnings in 2011

Tornado Warning 7, NWS Denver/Boulder, CO

May 18, 2011Adams County, Broomfield County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at May 18, 2011, 1:13 PM MDT for Adams County, Broomfield County, Colorado. It was in force for 31 min. 5 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
May 18, 2011, 1:13 PM MDT (19:13 UTC)
Expired
May 18, 2011, 1:44 PM MDT
In force
31 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon

Counties Adams County, CO, Broomfield County, CO

The radar

The Denver radar (KFTG), 41 km from the middle of the area, began a volume at 19:13 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

TimeReportWhereRemark
May 18, 1:15 PM MDTHAIL 1.252 Sse Federal Heights, COHAIL 1 INCH UP TO 1.25 INCHES WITH HEAVY RAIN.
May 18, 1:22 PM MDTHAIL 1.752 S Thornton, CO
May 18, 1:23 PM MDTHAIL 1Northglenn, COONE BROKEN WINDOW IN NEIGHBORHOOD.
May 18, 1:40 PM MDTHAIL 0.25Northglenn, COHAIL TO A DEPTH OF THREE INCHES COVERED THE GROUND IN THE NORTHGLENN THORNTON AREA 104TH ST AND THORNTON PARKWAY
May 18, 1:49 PM MDTHAIL 0.75Thornton, COHAIL COVERED THE GROUND TO A DEPTH OF ONE AND HALF INCHES

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

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 7.2 hours before the alert went out and 149 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-pSkew-T log-p diagram, Denver, CO at 12:00Z on 2011-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 19 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 12:00Z on 2011-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 3 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
19 J/kg
Mixed-layer CIN
-37 J/kg
Mixed-layer LCL
625 m above ground
0-6 km bulk shear
46 kt
0-1 km storm-relative helicity
3 m²/s²
0-3 km storm-relative helicity
99 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.

147 
WFUS55 KBOU 181913
TORBOU
COC001-014-181945-
/O.NEW.KBOU.TO.W.0007.110518T1913Z-110518T1945Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DENVER CO
113 PM MDT WED MAY 18 2011

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHWESTERN ADAMS COUNTY IN NORTHEAST COLORADO
  EASTERN BROOMFIELD COUNTY IN NORTHEAST COLORADO

* UNTIL 145 PM MDT

* AT 113 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO OVER
  NORTHGLENN...OR 11 MILES NORTH OF DENVER. THIS STORM WAS MOVING
  NORTH AT 15 MPH.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO FEDERAL
  HEIGHTS...EASTERN WESTMINSTER...THORNTON...NORTHGLENN...CENTRAL
  COMMERCE CITY AND EASTERN BROOMFIELD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO 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 4000 10496 4000 10485 3980 10491 3980 10504
      4000 10505 4000 10501 4001 10501 4001 10496
TIME...MOT...LOC 1913Z 170DEG 15KT 3989 10499

$$


BAKER
2 follow-up statements
184 
WWUS55 KBOU 181930
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
130 PM MDT WED MAY 18 2011

COC001-014-181945-
/O.CON.KBOU.TO.W.0007.000000T0000Z-110518T1945Z/
ADAMS CO-BROOMFIELD CO-
130 PM MDT WED MAY 18 2011

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 145 PM MDT FOR EASTERN
BROOMFIELD AND NORTHWESTERN ADAMS COUNTIES...

AT 129 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO.  THIS STORM WAS
LOCATED OVER SOUTHERN THORNTON...OR 9 MILES NORTH OF DENVER. THIS
STORM WAS MOVING NORTH AT 10 MPH.

LOCATIONS REMAINING IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
FEDERAL HEIGHTS...EASTERN WESTMINSTER...THORNTON...NORTHGLENN...
CENTRAL COMMERCE CITY AND EASTERN BROOMFIELD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOTORISTS SHOULD NOT TAKE SHELTER UNDER HIGHWAY OVERPASSES. AS A LAST
RESORT...EITHER PARK YOUR VEHICLE AND STAY PUT...OR ABANDON YOUR
VEHICLE AND LIE DOWN IN A LOW LYING AREA.

&&

LAT...LON 4000 10496 4000 10485 3980 10491 3980 10504
      4000 10505 4000 10501 4001 10501 4001 10496
TIME...MOT...LOC 1929Z 182DEG 9KT 3987 10497

$$


BAKER
605 
WWUS55 KBOU 181944
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
144 PM MDT WED MAY 18 2011

COC001-014-181952-
/O.CAN.KBOU.TO.W.0007.000000T0000Z-110518T1945Z/
ADAMS CO-BROOMFIELD CO-
144 PM MDT WED MAY 18 2011

...THE TORNADO WARNING FOR EASTERN BROOMFIELD AND NORTHWESTERN ADAMS 
COUNTIES HAS EXPIRED...

THE SEVERE THUNDERSTORM PRODUCING SEVERAL FUNNEL CLOUDS AND LARGE 
HAIL OVER PORTIONS OF NORTHGLENN AND THORNTON HAS WEAKEN AND WAS NO 
LONGER INDICATING A POSSIBLE TORNADO. 

LAT...LON 4000 10496 4000 10485 3980 10491 3980 10504
      4000 10505 4000 10501 4001 10501 4001 10496
TIME...MOT...LOC 1942Z 170DEG 15KT 4001 10502

$$


BAKER

The office that day

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

IssuedProductOfficeCountiesLasted
May 17, 6:11 PM MDTTornado WarningBOUWashington34 min
May 17, 6:13 PM MDTTornado WarningBOUWashington15 min
May 17, 6:26 PM MDTTornado WarningBOUWashington34 min
May 17, 6:32 PM MDTSevere Thunderstorm WarningBOULogan, Washington43 min
May 17, 6:59 PM MDTTornado WarningBOUWashington31 min
May 18, 4:10 AM MDTFlash Flood WatchBOUBoulder, Larimer16 hr
May 18, 4:43 AM MDTWinter Storm WarningBOUBoulder, Grand, Jackson, Larimer24 hr
May 18, 4:43 AM MDTWinter Weather AdvisoryBOUBoulder, Clear Creek, Douglas, Gilpin, Grand, Jackson and 4 more24 hr
May 18, 2:16 PM MDTAreal Flood AdvisoryBOUAdams, Broomfield119 min
May 18, 2:29 PM MDTTornado WarningBOUAdams14 min
May 18, 2:38 PM MDTSevere Thunderstorm WarningBOUAdams, Broomfield, Weld19 min
May 18, 5:47 PM MDTSevere Thunderstorm WarningBOULincoln58 min

Nearby

Tornado Warnings in Colorado, 2011Every tornado warning in 2011Tornadoes 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.