Alert archive / Colorado / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 95, NWS Denver/Boulder, CO

September 26, 2012Larimer County, Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Sep 26, 2012, 4:33 PM MDT for Larimer County, Weld County, Colorado. It was in force for 33 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
Sep 26, 2012, 4:33 PM MDT (22:33 UTC)
Expired
Sep 26, 2012, 5:06 PM MDT
In force
33 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon

Counties Larimer County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 70 km from the middle of the area, began a volume at 22:35 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 12:00Z, 10.6 hours before the alert went out and 155 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 2012-09-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 26 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 12:00Z on 2012-09-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 17 square meters per square second.1939Sfc1 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
26 J/kg
Mixed-layer CIN
-27 J/kg
Mixed-layer LCL
687 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
17 m²/s²
0-3 km storm-relative helicity
39 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.

556 
WUUS55 KBOU 262233
SVRBOU
COC069-123-262315-
/O.NEW.KBOU.SV.W.0095.120926T2233Z-120926T2315Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DENVER CO
433 PM MDT WED SEP 26 2012

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EXTREME SOUTHEASTERN LARIMER COUNTY IN NORTH CENTRAL COLORADO...
  EXTREME WEST CENTRAL WELD COUNTY IN NORTHEAST COLORADO...

* UNTIL 515 PM MDT

* AT 426 PM MDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
  CAPABLE OF PRODUCING QUARTER SIZE HAIL. THIS STORM WAS LOCATED
  NEAR BERTHOUD...OR 16 MILES SOUTHWEST OF GREELEY...AND MOVING
  NORTH AT 10 MPH.

* LOCATIONS IMPACTED INCLUDE...
  JOHNSTOWN...KELIM AND WELTY. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS IN EXCESS OF 60 MPH...
DESTRUCTIVE HAIL...DEADLY LIGHTNING AND VERY HEAVY RAIN. FOR YOUR
PROTECTION...MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 4025 10490 4027 10507 4046 10503 4046 10484
TIME...MOT...LOC 2226Z 199DEG 7KT 4030 10500 

$$

BARJENBRUCH
2 follow-up statements
873 
WWUS55 KBOU 262253
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
453 PM MDT WED SEP 26 2012

COC069-123-262315-
/O.CON.KBOU.SV.W.0095.000000T0000Z-120926T2315Z/
LARIMER CO-WELD CO-
453 PM MDT WED SEP 26 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM
MDT FOR EXTREME SOUTHEASTERN LARIMER AND EXTREME WEST 
CENTRAL WELD COUNTIES...

AT 449 PM MDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING QUARTER SIZE HAIL AND DAMAGING WINDS IN
EXCESS OF 60 MPH. 

THE PUBLIC ALSO REPORTED A FUNNEL CLOUD ASSOCIATED WITH THIS STORM 
NEAR JOHNSTOWN.
 
THIS STORM WAS LOCATED NEAR JOHNSTOWN...OR 13 MILES SOUTHWEST OF 
GREELEY...MOVING NORTH AT 10 MPH.

LOCATIONS IMPACTED INCLUDE...
JOHNSTOWN...KELIM AND WELTY. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS IN EXCESS OF 60 MILES
PER HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING AND VERY HEAVY
RAIN. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST
FLOOR OF YOUR HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO
DO NOT DRIVE INTO AREAS WHERE WATER COVERS THE ROAD.

IF A TORNADO IS SPOTTED...MOVE IMMEDIATELY INDOORS AND TAKE SHELTER 
IN AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS.

&&

LAT...LON 4025 10490 4027 10507 4046 10503 4046 10484
TIME...MOT...LOC 2249Z 199DEG 7KT 4034 10498 

$$

BARJENBRUCH
713 
WWUS55 KBOU 262306
SVSBOU

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
506 PM MDT WED SEP 26 2012

COC069-123-262314-
/O.CAN.KBOU.SV.W.0095.000000T0000Z-120926T2315Z/
LARIMER CO-WELD CO-
506 PM MDT WED SEP 26 2012

...THE SEVERE THUNDERSTORM WARNING FOR EXTREME SOUTHEASTERN
LARIMER AND EXTREME WEST CENTRAL WELD COUNTIES IS CANCELLED...

THE SEVERE THUNDERSTORM WHICH PROMPTED THE WARNING HAS WEAKENED. 
THEREFORE THE WARNING HAS BEEN CANCELLED.

THE STORMS WILL STILL PRODUCE HEAVY RAIN AND POSSIBLY SMALL HAIL AS 
IT MOVES NORTHWARD THROUGH THE FORT COLLINS AND WINDSOR AREAS. MINOR 
STREET FLOODING CAN BE EXPECTED IN LOW LYING AREAS.  

LAT...LON 4025 10490 4027 10507 4046 10503 4046 10484
TIME...MOT...LOC 2304Z 199DEG 7KT 4034 10498 

$$

BARJENBRUCH

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 26, 5:46 PM MDTFlash Flood WarningBOUWeld2 hr
Sep 26, 5:57 PM MDTAreal Flood AdvisoryBOUWeld93 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2012Every severe thunderstorm warning in 2012

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.