Alert archive / Colorado / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 172, NWS Denver/Boulder, CO

July 31, 2013Arapahoe County, Elbert County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 31, 2013, 8:42 PM MDT for Arapahoe County, Elbert 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 counties it named.

The facts

Issued: Jul 31, 2013, 8:42 PM MDT (02:42 UTC)
Expired: Jul 31, 2013, 9:15 PM MDT
In force: 33 min
Issued by: NWS Denver/Boulder, CO
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 70.0 mph

Counties Arapahoe County, CO, Elbert County, CO

The radar

The Denver radar (KFTG), 44 km from the middle of the area, began a volume at 02:43 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 2.7 hours before the alert went out and 360 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: 1537 J/kg
Mixed-layer CIN: -15 J/kg
Mixed-layer LCL: 1192 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: -10 m²/s²
0-3 km storm-relative helicity: 112 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 3.3

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 Jul 31, 8:29 PM MDT, 13 minutes earlier.

Area forecast discussion, Jul 31, 8:29 PM MDT, 13 minutes before

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Hazardous weather outlook, Jul 31, 10:31 AM MDT, 10 hours 11 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DENVER/BOULDER CO
1031 AM MDT WED JUL 31 2013

COZ030>051-010445-
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-
1031 AM MDT WED JUL 31 2013

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

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED THUNDERSTORMS ARE EXPECTED TO FORM OVER THE
HIGHER TERRAIN LATE THIS MORNING THEN SPREAD EAST-SOUTHEAST THIS
AFTERNOON AND EVENING OVER THE PLAINS. MOST OF THEM WILL ONLY
PRODUCE LIGHT RAIN...THOUGH ONE OR TWO COULD PRODUCE BRIEF HEAVY
RAIN AND WIND GUSTS TO 40 MPH. THERE IS A SLIGHT CHANCE OF A FEW
STORMS OVER THE FAR NORTHEAST PLAINS PAST MIDNIGHT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THERE WILL BE A CHANCE OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD...MAINLY ACROSS THE MOUNTAINS.
HEAVY RAINFALL WILL BE POSSIBLE WITH SOME OF THE STORMS FRIDAY AND
SATURDAY. TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT.

KRIEDERMAN/D-L

In the hours before

Local storm report, Jul 31, 7:34 PM MDT, 1 hour 8 minutes before

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Local storm report, Jul 31, 8:04 PM MDT, 38 minutes before

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Local storm report, Jul 31, 8:11 PM MDT, 31 minutes before

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Local storm report, Jul 31, 8:17 PM MDT, 25 minutes before

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Local storm report, Jul 31, 8:27 PM MDT, 15 minutes before

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Local storm report, Jul 31, 8:36 PM MDT, 6 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 31, 7:00 PM MDT	Special Weather Statement	BOU	Adams	30 min
Jul 31, 7:11 PM MDT	Severe Thunderstorm Warning	BOU	Adams	34 min
Jul 31, 7:42 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe	33 min
Jul 31, 8:07 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Arapahoe	23 min
Jul 31, 8:18 PM MDT	Tornado Warning	BOU	Arapahoe, Elbert	27 min
Jul 31, 9:32 PM MDT	Special Weather Statement	BOU	Lincoln	28 min
Jul 31, 9:34 PM MDT	Special Weather Statement	BOU	Washington	26 min
Jul 31, 9:44 PM MDT	Severe Thunderstorm Warning	BOU	Washington	31 min
Aug 1, 3:40 PM MDT	Severe Thunderstorm Warning	BOU	Adams, Weld	50 min
Aug 1, 3:45 PM MDT	Severe Thunderstorm Warning	BOU	Lincoln	30 min
Aug 1, 4:02 PM MDT	Areal Flood Advisory	BOU	Elbert	118 min
Aug 1, 4:11 PM MDT	Areal Flood Advisory	BOU	Lincoln	2 hr
Aug 1, 5:23 PM MDT	Severe Thunderstorm Warning	BOU	Logan, Weld	52 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.