Alert archive / Nebraska / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 59, NWS Cheyenne, WY

June 17, 2009Box Butte County, Nebraska

NWS Cheyenne, WY issued this severe thunderstorm warning at Jun 17, 2009, 8:50 PM MDT for Box Butte County, Nebraska. It was in force for 55 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
Jun 17, 2009, 8:50 PM MDT (02:50 UTC)
Expired
Jun 17, 2009, 9:45 PM MDT
In force
55 min
Issued by
NWS Cheyenne, WY
Area
Storm-based polygon

County Box Butte County, NE

The radar

The Cheyenne radar (KCYS), 186 km from the middle of the area, began a volume at 02:50 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

Rapid City, SD (KUNR), launched 00:00Z, 2.8 hours before the alert went out and 206 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, Rapid City, SD at 00:00Z on 2009-06-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1229 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Rapid City, SD at 00:00Z on 2009-06-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 199 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
1229 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
1320 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
199 m²/s²
0-3 km storm-relative helicity
299 m²/s²
Significant tornado parameter
0.8
Supercell composite
7.3

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 Cheyenne, WY wrote its last area forecast discussion before this severe thunderstorm warning went out at Jun 17, 12:48 PM MDT, 8 hours 2 minutes earlier.

Area forecast discussion, Jun 17, 12:48 PM MDT, 8 hours 2 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
1248 PM MDT WED JUN 17 2009

.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT...
SHOWERS AND THUNDERSTORMS HAVE DEVELOPED QUICKLY SINCE 1730Z TO
THE WEST OF THE LARAMIE RANGE.  STILL LOOKS LIKE THE STORMS WILL
INTENSIFY EAST OF THE LARAMIE RANGE IN THE CURRENT MOIST AND
INSTABLE ENVIRONMENT.  THE ACTIVITY IS BEING TRIGGERED BY THE
LEADING EDGE OF AN APPROACHING SHORTWAVE TROUGH AND A SHORTWAVE
TROUGH CURRENTLY NEAR THE LARAMIE RANGE.  LARGE HAIL...STRONG
OUTFLOW WIND GUSTS AND HEAVY RAIN WILL LIKELY BE ASSOCIATED WITH
THE STORMS IN THE EAST PART OF THE CWA.  THE 0-6KM BULK SHEAR
VALUES WOULD ALSO SUPPORT SOME TORNADIC SUPERCELLS...MAINLY IN THE
PANHANDLE.  SHOWERS AND A FEW THUNDERSTORMS WILL LINGER AFTER LATE
EVENING IN THE NORTH AND EAST PARTS OF THE CWA.  A SURFACE COLD
FRONT WILL MOVE ACROSS THE CWA ON THURSDAY AND WILL PROVIDE SURFACE
FORCING FOR AT LEAST A SCATTERED COVERAGE OF WEAKER STORMS IN THE
AFTERNOON AND EVENING HOURS.  SURFACE HIGH PRESSURE BUILDS OVER THE
CWA BY 12Z FRIDAY AND WILL PRODUCE CLEARING SKIES AND COOLER
TEMPERATURES.

.LONG TERM...FRIDAY THROUGH TUESDAY
SPLIT FLOW PATTERN INITIALLY ACROSS THE WESTERN CONUS AS THE UPPER
CUT-OFF WAITS TO PHASE WITH THE NORTHERN STREAM...WHICH OCCURS
FRIDAY NIGHT. A DRY AND WARMER DAY IN STORE FOR FRIDAY BENEATH
PREVAILING LARGE SCALE SUBSIDENCE WITHIN UPPER SHORTWAVE RIDGING.
FLOW SWIFTLY BACKS FOR SATURDAY...AS THE NEXT SHORTWAVE TROUGH
ROTATES INTO THE NORTHERN ROCKIES. THE SFC REFLECTION OUT AHEAD OF
THIS ENERGY WILL RESULT IN PRESSURE FALLS IN THE LEE...AND THUS
CONVERGENCE ALONG TERRAIN...SPECIFICALLY THE LARAMIE RANGE. SO
AFTERNOON/EVENING THUNDERSTORMS A GOOD BET FOR SATURDAY...WITH BEST
COVERAGE IN MOUNTAINS AND OUT ON ADJACENT PLAINS. WOULD NOT BE
SURPRISED FOR A FEW SEVERE STORMS ON SATURDAY AS WELL...WITH
500-1000 J/KG OF PROGD CAPE AND FAVORABLE SHEAR PROFILES. SOUTHWEST
FLOW CONTINUES WITH THUNDERSTORMS AGAIN POSSIBLE ON SUNDAY AS THE
LONGWAVE TROUGH AXIS REMAINS ACROSS THE WESTERN CONUS. THIS ENERGY
WILL WOBBLE A BIT FURTHER EAST INTO THE CANADIAN ROCKIES ON
MONDAY...WHICH WILL YIELD STILL MORE CHANCES FOR AFTERNOON/EVENING
CONVECTION ACROSS SE WY/WRN NE. THE PATTERN BEGINS TO BECOME MORE
SUMMER-LIKE FOR TUE/WED AS THE UPPER HIGH BUILDS ACROSS THE CENTRAL
CONUS. MEDIUM RANGE PROGS DIFFER SOME ON THE STRENGTH OF THIS
FEATURE...WHICH OF COURSE WILL INFLUENCE UPSTREAM/DOWNSTREAM WAVE
DAMPENING. AT ANY RATE...THE PRESENCE OF THIS UPPER HIGH SHOULD
SUPPRESS MUCH OF THE CONVECTIVE POTENTIAL FOR TUE/WED...SO HAVE LEFT
THESE TWO DAYS DRY AT THIS TIME. TEMPERATURES WILL WARM ABOVE
SEASONAL NORMALS FOR THE LATTER HALF OF THE WEEKEND AND INTO THE
FIRST OF NEXT WEEK.

&&

.AVIATION...VFR CONDITIONS WILL BE OVER THE CWA THROUGH THURSDAY
NIGHT.  MVFR CEILINGS AND VISIBILITIES WILL BE ASSOCIATED WITH THE
THUNDERSTORMS OVER THE CWA THIS EVENING AND AGAIN THURSDAY AFTERNOON
AND EVENING.  SOME OF THE STORMS WILL PRODUCE HAIL AND STRONG WIND
GUSTS OVER THE EAST PART OF THE CWA THIS EVENING.

&&

.FIRE WEATHER...THE FUELS ARE STILL GREEN AT THIS TIME AND SHOULD NOT
SUPPORT LARGE FIRE GROWTH FOR THE NEAR FUTURE.  THUNDERSTORMS
THROUGH THIS EVENING SHOULD PRODUCE WETTING RAINFALL ALONG WITH
LIGHTNING AND ERRATIC WINDS.  A COLD FRONT WILL MOVE ACROSS THE CWA
ON THURSDAY AND IN MOST PLACES WILL PRODUCE A SHIFT IN THE WIND
DIRECTION TO MORE NORTHWEST.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...NONE.
NE...NONE.

&&

WEILAND
Hazardous weather outlook, Jun 17, 5:57 PM MDT, 2 hours 53 minutes before
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In the hours before

Local storm report, Jun 17, 4:02 PM MDT, 4 hours 48 minutes before
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Local storm report, Jun 17, 4:34 PM MDT, 4 hours 16 minutes before
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Special weather statement, Jun 17, 7:28 PM MDT, 1 hour 22 minutes before
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Special weather statement, Jun 17, 8:08 PM MDT, 42 minutes before
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Local storm report, Jun 17, 8:26 PM MDT, 24 minutes before
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Local storm report, Jun 17, 8:34 PM MDT, 16 minutes before
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The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 17, 8:27 PM MDTSevere Thunderstorm WarningCYSBox Butte, Scotts Bluff, Sioux48 min
Jun 17, 9:13 PM MDTSevere Thunderstorm WarningCYSBox Butte, Dawes47 min
Jun 17, 9:47 PM MDTSevere Thunderstorm WarningCYSBox Butte, Morrill58 min
Jun 17, 10:08 PM MDTAreal Flood AdvisoryCYSBox Butte, Morrill4 hr
Jun 17, 11:19 PM MDTSevere Thunderstorm WarningCYSScotts Bluff30 min
Jun 18, 5:35 PM MDTSevere Thunderstorm WarningCYSDawes, Sioux40 min

Nearby

Severe Thunderstorm Warnings in Nebraska, 2009Every severe thunderstorm warning in 2009

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.