Alert archive / Wyoming / Severe Thunderstorm Warnings in 2010

Severe Thunderstorm Warning 176, NWS Cheyenne, WY

August 16, 2010Platte County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at Aug 16, 2010, 4:22 PM MDT for Platte County, Wyoming. It was in force for 53 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
Aug 16, 2010, 4:22 PM MDT (22:22 UTC)
Expired
Aug 16, 2010, 5:15 PM MDT
In force
53 min
Issued by
NWS Cheyenne, WY
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Platte County, WY

The radar

The Cheyenne radar (KCYS), 110 km from the middle of the area, began a volume at 22:26 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 16, 2:34 PM MDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 10.4 hours before the alert went out and 291 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 2010-08-16Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 874 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, Denver, CO at 12:00Z on 2010-08-16The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 78 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
874 J/kg
Mixed-layer CIN
-179 J/kg
Mixed-layer LCL
828 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
78 m²/s²
0-3 km storm-relative helicity
75 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

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 Aug 16, 2:49 PM MDT, 1 hour 33 minutes earlier.

Area forecast discussion, Aug 16, 2:49 PM MDT, 1 hour 33 minutes before
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHEYENNE WY
249 PM MDT MON AUG 16 2010

UPDATED HAZARDOUS WEATHER OUTLOOK AND ZONE FORECAST PRODUCTS FOR
SEVERE THUNDERSTORM WATCH #622 VALID UNTIL 10 PM MDT.

&&

.PREV DISCUSSION... /ISSUED 115 PM MDT MON AUG 16 2010/

SHORT TERM...THIS AFTERNOON THROUGH WEDNESDAY...
A CHALLENGING FORECAST FOR THIS AFTERNOON/EARLY EVENING WITH
SEVERAL QUESTION MARKS EXISTING. AN EXTENSIVE AREA OF UPSLOPE
DRIVEN LOW STRATUS/FOG THIS MORNING HAS BEEN SLOW TO BURN
OFF...WHICH HAS LIMITED THE AMOUNT OF SURFACE INSOLATION THAT
HAS TAKEN PLACE THUS FAR. THAT SAID...VISIBLE SATELLITE IMAGERY
EARLY THIS AFTERNOON DEPICTS PRETTY SIGNIFICANT BREAKS UPSTREAM
OVR SWEETWATER AND CARBON COUNTIES. SO...ANTICIPATE CONVECTIVE
INITIATION OVR THE SNOWY RANGE AND/OR THE LARAMIE RANGE DURING THE
EARLY AFTERNOON HOURS. THE QUESTION COMES INTO JUST HOW MUCH AREAS
EAST OF THE MOUNTAINS ARE ABLE TO DESTABILIZE THIS AFTERNOON...
WHICH WILL DEPEND ON IF/WHEN LOW CLOUDS ERODE. A 500 MB SHORTWAVE
TROUGH AXIS EVIDENT OVR NRN UTAH/SRN IDAHO WILL REACH SWRN WY BY
LATE THIS AFTERNOON. AN ABUNDANT AMOUNT OF SURFACE MOISTURE IS
AVAILABLE WITH DEW POINTS IN THE UPPER 50S/LOW 60S EAST OF THE
MOUNTAINS...ONCE CONVECTIVE TEMPERATURES ARE REALIZED. IN ADDITION
TO THE HIGHER TERRAIN...CONVECTION WILL LIKELY BE INITIATED ALONG
LOW-LEVEL CONVERGENCE BOUNDARIES. MLCAPES OF 600 TO 1200 J/KG CAN
BE EXPECTED ALONG WITH INCREASING LOW/MID-LEVEL THETA-E RIDGING.
SO...EXPECT THE POSSIBILITY OF A FEW SEVERE THUNDERSTORMS LATE
THIS AFTERNOON/EVENING CONTAINING LARGE HAIL AND DAMAGING WINDS.
EVEN THOUGH THE PRESENCE OF A 80KT 300 MB JET COUPLET SUGGESTS
DECENT STORM MOVEMENT...PRECIPITABLE WATER VALUES IN EXCESS OF ONE
INCH WILL KEEP HEAVY RAIN A CONCERN. THUNDERSTORMS WILL MERGE INTO A
COMPLEX DURING THE EVENING HOURS...IMPACTING THE WRN NE PANHANDLE.
CONVECTION WILL GRADUALLY DISSIPATE FROM WEST TO EAST BY AROUND
MIDNIGHT...WITH PERHAPS JUST SOME SHOWERS REMAINING AS MID-LEVEL
COLD POOL PASSES OVERHEAD.

DRIER ANTICYCLONIC NORTHWEST FLOW WILL WORK IN ON TUESDAY WITH
INCREASING UPPER HEIGHTS AS THE UPSTREAM RIDGE AMPLIFIES. HAVE
KEPT TUESDAY DRY AND WARMER...AS MID-LEVEL TEMPERATURES INCREASE.
BY WEDNESDAY...UPPER RIDGE AXIS WILL SHIFT EAST ALLOWING SOUTHWEST
FLOW TO ENSUE IN ADVANCE OF THE NEXT SHORTWAVE TROUGH. MID AND
UPPER-LEVEL MOISTURE EMBEDDED WITHIN THE FLOW WILL DEVELOP BY
AFTERNOON...SO KEPT AFTERNOON THUNDERSTORM CHANCES FOR CARBON AND
ALBANY COUNTIES. WEDNESDAY WILL BE THE WARMEST DAY OF THE SHORT-TERM
AS 700 MB TEMPERATURES PEAK AROUND 15-18C.

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY...
ONLY MINOR DIFFERENCES WERE OBSERVED BETWEEN THE 12Z GFS AND ECMWF
WITH THE TIMING AND STRENGTH OF THE NEXT UPPER LEVEL SHORTWAVE
TROUGH  EARLY IN THE PERIOD. THE GFS IS SLIGHTLY FASTER/MORE
AMPLIFIED THAN THE ECMWF. IN EITHER CASE...THIS FEATURE WILL
INCREASE SHWR/TSTM CHANCES OVER THE CWA WEDNESDAY NIGHT AND
THURSDAY...HIGHEST WEST OF THE LARAMIE RANGE. THE ASSOCIATED
PACIFIC COLD FRONT WILL PASS THROUGH THE AREA LATE WEDNESDAY NIGHT
THROUGH THURSDAY AFTERNOON. THE TROUGH WILL EXIT EAST OF THE CWA
THURSDAY NIGHT AND BE LOCATED OVER THE UPPER MIDWEST ON FRIDAY. IN
ITS PLACE...UPSTREAM RIDGING ALOFT BEGINS TO BUILD OVER THE ROCKIES
AND HIGH PLAINS ON FRIDAY. AS THE RIDGE AXIS SHIFTS EAST INTO THE
PLAINS AND UPPER TROUGH DIGS SOUTHEASTWARD ALONG THE PACIFIC
COAST...THE SOUTHWESTERLY FLOW ALOFT WILL DEEPEN...WITH MID AND
UPPER LEVEL MOISTURE INCREASING. THE GFS AND ECMWF DEPICT LIGHT
QPF...MAINLY OVER THE MOUNTAINS ON SATURDAY AFTERNOON AND
EVENING...AND MOST AREAS SUNDAY AFTERNOON AND EVENING. AT THIS
TIME...POPS WILL BE CAPPED AT 20 PERCENT. DAILY TEMPS WILL AVERAGE
5-10 DEGREES ABOVE NORMAL...WITH THE WARMEST DAY EXPECTED TO BE
SATURDAY WITH 700 MB TEMPS RANGING BETWEEN 15 AND 18C. FIRE WEATHER
CONCERNS MAY INCREASE THIS WEEKEND DUE TO THE COMBINATION OF VERY
WARM DAYTIME TEMPS...LOW RELATIVE HUMIDITIES AND BREEZY WEST TO
SOUTHWEST SURFACE WINDS.

&&

AVIATION...18Z TAF ISSUANCE
LINGERING MVFR CIGS FROM XTRM SERN WY THRU SRN NEB PNHDL WILL ERODE
EARLY THIS AFTN...WITH VFR ELSEWHERE. SCT SHWRS/TSTMS WILL DEVELOP
AND MOVE FROM W TO E...POSSIBLY IMPACTING ALL AERODROMES.
THEREFORE...HAVE INCLUDED SCT-BKN030-040CB AND VCTS FROM 19Z THRU
03Z THIS EVENING. SOME OF THE TSTMS MAY PRODUCE GUSTY
WINDS...MODERATE TURBULENCE...AND BRIEF MVFR CONDITIONS DUE TO
LOWERED VSBYS. AFTER CONVECTION ENDS LATE THIS EVENING...EXPECT
PERIODS OF VFR CIGS IN AC/CI. BOTH NAM/GFS MOS CIG/VSBY PROGS
IMPLYING POSSIBLE MVFR CONDITIONS AFTER 08Z TUE AT CYS...AIA...SNY
AND BFF. HAVE TRENDED THIS DIRECTION WITH 6SM VSBY IN BR AND KEPT
CIGS VFR...BUT LATER SHIFTS MAY LOWER FURTHER.

&&

FIRE WEATHER...
AN UPPER LEVEL DISTURBANCE WILL BRING SCATTERED SHOWERS AND
THUNDERSTORMS TO THE DISTRICT THROUGH THE EVENING HOURS. A DRIER
AND WARMER PATTERN WILL BEGIN TO WORK IN FOR TUESDAY AND WEDNESDAY.
MINIMUM RELATIVE HUMIDITIES WILL DROP INTO THE TEENS IN THE WEST
ON TUESDAY...AND ACROSS OF WYOMING FOR WEDNESDAY. THE NEXT CHANCE
OF PRECIPITATION WILL ARRIVE LATE WEDNESDAY THROUGH THURSDAY.

&&

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

&&

SHORT TERM/FIRE WEATHER...HAHN
LONG TERM/AVIATION...JAMSKI
Hazardous weather outlook, Aug 16, 2:47 PM MDT, 1 hour 35 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
247 PM MDT MON AUG 16 2010

NEZ002-003-019>021-054-055-095-096-WYZ101>103-106>108-115>119-
171115-
DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE-
NORTH SIOUX-SOUTH SIOUX-CONVERSE COUNTY LOWER ELEVATIONS-
NIOBRARA COUNTY-NORTH LARAMIE RANGE-
CENTRAL LARAMIE RANGE AND SOUTHWEST PLATTE COUNTY-
EAST PLATTE COUNTY-GOSHEN COUNTY-LARAMIE VALLEY-
SOUTH LARAMIE RANGE-SOUTH LARAMIE RANGE FOOTHILLS-
CENTRAL LARAMIE COUNTY-EAST LARAMIE COUNTY-
247 PM MDT MON AUG 16 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA
PANHANDLE...SOUTHEAST WYOMING.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A SEVERE THUNDERSTORM WATCH IS IN EFFECT UNTIL 10 PM THIS EVENING.
SCATTERED TO NUMEROUS THUNDERSTORMS WILL DEVELOP AND MOVE EAST
ACROSS THE AREA. SOME OF THE STORMS MAY PRODUCE VERY HEAVY
RAIN...DAMAGING WINDS...AND HAIL IN EXCESS OF ONE INCH IN
DIAMETER. THE STORMS WILL WEAKEN AND END LATER THIS EVENING.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A CHANCE OF SHOWERS AND THUNDERSTORMS WILL BE OVER SOUTHEAST
WYOMING AND THE WESTERN NEBRASKA PANHANDLE WEDNESDAY NIGHT THROUGH
THURSDAY AND POSSIBLY AGAIN SUNDAY AFTERNOON. NO SEVERE WEATHER
IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

&&

THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND
CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT...
HTTP://WEATHER.GOV/CHEYENNE

WYZ104-105-109>114-171115-
FERRIS/SEMINOE/SHIRLEY MOUNTAINS-SHIRLEY BASIN-
CENTRAL CARBON COUNTY-NORTH SNOWY RANGE FOOTHILLS-
SOUTHWEST CARBON COUNTY-SIERRA MADRE RANGE-
UPPER NORTH PLATTE RIVER BASIN-SNOWY RANGE-
247 PM MDT MON AUG 16 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTH CENTRAL WYOMING.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED SHOWERS AND THUNDERSTORMS WILL AFFECT THIS AREA THIS
AFTERNOON AND EVENING. SOME OF THE STORMS WILL PRODUCE GUSTY
WINDS AND SMALL HAIL.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A CHANCE OF SHOWERS AND THUNDERSTORMS WILL BE OVER SOUTH CENTRAL
WYOMING WEDNESDAY NIGHT THROUGH THURSDAY AND POSSIBLY AGAIN
SUNDAY AFTERNOON. NO SEVERE WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED THIS AFTERNOON AND TONIGHT.

&&

THIS PRODUCT...ALONG WITH OTHER WEATHER...HYDROLOGIC...AND
CLIMATE INFORMATION IS AVAILABLE ON THE WEB AT...
HTTP://WEATHER.GOV/CHEYENNE

JAMSKI

In the hours before

Special weather statement, Aug 16, 2:11 PM MDT, 2 hours 11 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
211 PM MDT MON AUG 16 2010

WYZ116>118-162115-
CENTRAL LARAMIE COUNTY WY-SOUTH LARAMIE RANGE WY-SOUTH LARAMIE RANGE
FOOTHILLS WY-
211 PM MDT MON AUG 16 2010

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN LARAMIE AND
SOUTHEASTERN ALBANY COUNTIES UNTIL 315 PM MDT...

AT 207 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 5 MILES NORTHEAST OF VIRGINIA DALE...OR 26 MILES
SOUTHEAST OF LARAMIE...MOVING NORTHEAST AT 25 MPH.

HAIL UP TO THE SIZE OF NICKELS AND WIND GUSTS UP TO 50 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  CHEYENNE...
  BUFORD...
  GRANITE SPRINGS RESERVOIR...
  CRYSTAL LAKE RESERVOIR...
  FEDERAL...
  WARREN AF BASE...
  NORTH CHEYENNE...
  SOUTH GREELEY HIGHWAY...
  FOX FARM-COLLEGE...

THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS... FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.

CLAYCOMB
Special weather statement, Aug 16, 2:16 PM MDT, 2 hours 6 minutes before
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Special weather statement, Aug 16, 3:19 PM MDT, 1 hour 3 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
319 PM MDT MON AUG 16 2010

NEZ054-WYZ118-119-162145-
CENTRAL LARAMIE COUNTY WY-EAST LARAMIE COUNTY WY-KIMBALL NE-
319 PM MDT MON AUG 16 2010

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LARAMIE AND
SOUTHWESTERN KIMBALL COUNTIES UNTIL 345 PM MDT...

AT 312 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR CARPENTER...OR 26 MILES EAST OF CHEYENNE...
MOVING SOUTHEAST AT 25 MPH.

SMALL HAIL AND BRIEF GUSTY WINDS ARE POSSIBLE WITH THIS STORM.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
MAINLY RURAL AREAS OF EXTREME SOUTHEASTERN LARAMIE AND SOUTHWESTERN
KIMBALL COUNTIES.

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.
Special weather statement, Aug 16, 3:23 PM MDT, 59 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
323 PM MDT MON AUG 16 2010

NEZ003-096-162215-
BOX BUTTE NE-SOUTH SIOUX NE-
323 PM MDT MON AUG 16 2010

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN SIOUX AND WESTERN
BOX BUTTE COUNTIES UNTIL 415 PM MDT...

AT 322 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 13 MILES NORTHWEST OF KILPATRICK LAKE...OR 26
MILES NORTH OF SCOTTSBLUFF...MOVING EAST AT 15 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THIS STORM...
ALONG WITH HEAVY RAIN.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  KILPATRICK LAKE...

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.
Special weather statement, Aug 16, 4:09 PM MDT, 13 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Aug 16, 6:44 AM MDTDense Fog AdvisoryCYSAlbany, Laramie2 hr

Nearby

Severe Thunderstorm Warnings in Wyoming, 2010Every severe thunderstorm warning in 2010

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.