Alert archive / Colorado / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 12, NWS Denver/Boulder, CO

May 18, 2013Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at May 18, 2013, 2:59 PM MDT for Weld County, Colorado. It was in force for 46 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 18, 2013, 2:59 PM MDT (20:59 UTC)
Expired: May 18, 2013, 3:45 PM MDT
In force: 46 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

County Weld County, CO

The radar

The Cheyenne radar (KCYS), 75 km from the middle of the area, began a volume at 21:00 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, 9.0 hours before the alert went out and 125 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: 4413 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: -48 m²/s²
0-3 km storm-relative helicity: 9 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Denver/Boulder, CO wrote its last area forecast discussion before this severe thunderstorm warning went out at May 18, 11:19 AM MDT, 3 hours 40 minutes earlier.

Area forecast discussion, May 18, 11:19 AM MDT, 3 hours 40 minutes before

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Hazardous weather outlook, May 18, 11:35 AM MDT, 3 hours 24 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1135 AM MDT SAT MAY 18 2013

COZ030>051-191745-
JACKSON COUNTY BELOW 9000 FEET-
WEST JACKSON AND WEST GRAND COUNTIES ABOVE 9000 FEET-
GRAND AND SUMMIT COUNTIES BELOW 9000 FEET-
SOUTH AND EAST JACKSON/LARIMER/NORTH AND NORTHEAST GRAND/
NORTHWEST BOULDER COUNTIES ABOVE 9000 FEET-
SOUTH AND SOUTHEAST GRAND/WEST CENTRAL AND SOUTHWEST BOULDER/
GILPIN/CLEAR CREEK/SUMMIT/NORTH AND WEST PARK COUNTIES ABOVE
9000 FEET-LARIMER AND BOULDER COUNTIES BETWEEN 6000 AND 9000 FEET-
JEFFERSON AND WEST DOUGLAS COUNTIES ABOVE 6000 FEET/GILPIN/CLEAR
CREEK/NORTHEAST PARK COUNTIES BELOW 9000 FEET-
CENTRAL AND SOUTHEAST PARK COUNTY-
LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY-
BOULDER AND JEFFERSON COUNTIES BELOW 6000 FEET/WEST BROOMFIELD
COUNTY-
NORTH DOUGLAS COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND
ARAPAHOE COUNTIES/EAST BROOMFIELD COUNTY-
ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET-
NORTHEAST WELD COUNTY-CENTRAL AND SOUTH WELD COUNTY-MORGAN COUNTY-
CENTRAL AND EAST ADAMS AND ARAPAHOE COUNTIES-
NORTH AND NORTHEAST ELBERT COUNTY BELOW 6000 FEET/NORTH LINCOLN
COUNTY-
SOUTHEAST ELBERT COUNTY BELOW 6000 FEET/SOUTH LINCOLN COUNTY-
LOGAN COUNTY-WASHINGTON COUNTY-SEDGWICK COUNTY-PHILLIPS COUNTY-
1135 AM MDT SAT MAY 18 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL
COLORADO.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THERE IS A GOOD CHANCE OF THUNDERSTORMS...SOME POSSIBLY SEVERE...
THIS AFTERNOON AND EVENING IN THE NORTHEAST CORNER OF COLORADO.
THE GREATEST THREAT FOR SEVERE STORMS IS IN LOGAN...NORTHERN
WASHINGTON...SEDGWICK AND PHILLIPS COUNTIES. THE PRIMARY THREAT IS
VERY LARGE HAIL AND DAMAGING STRAIGHTLINE WINDS. HOWEVER A
TORNADO OR TWO FORMING ON THUNDERSTORM OUTFLOW BOUNDARIES OR ALONG
THE DRY LINE MEANDERING ACROSS THESE COUNTIES SHOULD NOT BE RULED
OUT.

THE REMAINDER OF THE OUTLOOK AREA INCLUDING THE MOUNTAINS AND HIGH
VALLEYS WILL ALSO SEE ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND EVENING. THESE STORMS ARE NOT
EXPECTED TO BECOME SEVERE...BUT A FEW MAY STILL PRODUCE SMALL
HAIL AND WIND GUSTS TO AROUND 45 MPH.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THERE WILL BE A CHANCE OF SHOWERS AND THUNDERSTORMS FOR MUCH OF
THE FORECAST AREA SUNDAY THROUGH MONDAY NIGHT. FROM TUESDAY
THROUGH NEXT FRIDAY...THERE WILL ONLY BE A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS...MAINLY IN THE MOUNTAINS. TEMPERATURES
WILL BE BELOW SEASONAL NORMALS SUNDAY THROUGH TUESDAY...THEN WARM
UP SOMEWHAT FOR WEDNESDAY THROUGH FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED IN NORTHEASTERN COLORADO THIS
AFTERNOON.

BAKER/RJK/MEIER

In the hours before

Special weather statement, May 18, 2:44 PM MDT, 15 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DENVER CO
244 PM MDT SAT MAY 18 2013

COZ042-182115-
NORTHEAST WELD COUNTY-
244 PM MDT SAT MAY 18 2013

THE NATIONAL WEATHER SERVICE HAS ISSUED A SIGNIFICANT WEATHER
ADVISORY FOR NORTHEASTERN WELD COUNTY UNTIL 315 PM MDT.

AT 243 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 4 MILES NORTH OF NEW RAYMER...OR 28 MILES NORTH
OF FORT MORGAN...MOVING NORTH AT 25 MPH.

HAIL UP TO THE SIZE OF DIMES WILL BE POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE BUT ARE NOT LIMITED TO...
NEW RAYMER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM.
LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.

&&

LAT...LON 4059 10376 4059 10396 4094 10393 4095 10375
TIME...MOT...LOC 2043Z 178DEG 23KT 4067 10385

The office that day

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

Issued	Product	Office	Counties	Lasted
May 18, 3:14 PM MDT	Severe Thunderstorm Warning	BOU	Washington	46 min
May 18, 3:59 PM MDT	Severe Thunderstorm Warning	BOU	Washington	46 min
May 18, 4:07 PM MDT	Severe Thunderstorm Warning	BOU	Logan	38 min
May 18, 4:24 PM MDT	Severe Thunderstorm Warning	BOU	Washington	51 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2013 Every severe thunderstorm warning in 2013

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.