Alert archive / Wyoming / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 149, NWS Cheyenne, WY

July 18, 2009Goshen County, Laramie County, Wyoming

NWS Cheyenne, WY issued this severe thunderstorm warning at Jul 18, 2009, 1:35 AM MDT for Goshen County, Laramie County, Wyoming. It was in force for 42 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 18, 2009, 1:35 AM MDT (07:35 UTC)
Expired
Jul 18, 2009, 2:17 AM MDT
In force
42 min
Issued by
NWS Cheyenne, WY
Area
Storm-based polygon

Counties Goshen County, WY, Laramie County, WY

The radar

The Cheyenne radar (KCYS), 65 km from the middle of the area, began a volume at 07:38 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 00:00Z, 7.6 hours before the alert went out and 230 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 00:00Z on 2009-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 00:00Z on 2009-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 25 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3559 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
25 m²/s²
0-3 km storm-relative helicity
179 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 Cheyenne, WY wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 17, 1:39 PM MDT, 11 hours 56 minutes earlier.

Area forecast discussion, Jul 17, 1:39 PM MDT, 11 hours 56 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHEYENNE WY
139 PM MDT FRI JUL 17 2009

.SHORT TERM...NW FLOW WILL OCCUR ALOFT THIS AFTERNOON AND EVENING
AS AN UPPER RIDGE BUILDS OVER THE WEST. DEW POINTS IN THE NEBRASKA
PANHANDLE THIS AFTERNOON ARE IN THE 50S. LIS INDICATE VERY
UNSTABLE AIRMASS OVER THE AREA EAST OF THE LAR RANGE AND CAPE
VALUES ARE IN THE 1000 TO 2000 J/KG RANGE. TORNADO WATCH HAS BEEN
ISSUED FOR PARTS OF SE WY AND THE NEB PANHANDLE DUE TO DEEP LAYER
SHEER. A JET MAX AT 200 MB WILL ALSO AID IN THUNDERSTORM
DEVELOPMENT THIS AFTERNOON AND EVENING. THE UPPER RIDGE AXIS WILL
MOVE EAST OVER THE NORTHERN ROCKIES ON SAT . MID LEVEL MOISTURE
AND UNSTABLE CONDITIONS WILL OCCUR ONCE AGAIN SAT AFTERNOON. WILL
KEEP ISOLATED THUNDERSTORMS...ESPECIALLY EAST OF THE LARAMIE RANGE
FOR SAT AFT AND EVENING. ON SUN...NW FLOW WILL CONT ALOFT AND THE
UPPER RIDGE AXIS WILL EXTEND FROM THE NORTHERN PLAINS TO THE
DESERT SW. WILL KEEP DRY CONDITIONS IN THE FORECAST...BUT CANNOT
RULE OUT A FEW THUNDERSTORMS EAST OF THE LARAMIE RANGE. HIGH
TEMPERATURES WILL BE AROUND NORMAL SATURDAY...THEN AS THERMAL
RIDGE MOVES OVER THE CWA ON SUNDAY...EXPECT TEMPERATURES TO BE
SEVERAL DEGREES ABOVE NORMAL.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY.
UPPER SHORT WAVE MOVING NORTH OF AREA WILL ALLOW FOR A COLD FRONT
TO PUSH SOUTH SUNDAY NIGHT INTO MONDAY...WITH CHANCES OF SHOWERS
OR THUNDERSTORMS PERSISTING INTO TUESDAY. FOR WEDNESDAY THROUGH
FRIDAY IT LOOKS LIKE DIURANALLY DRIVE CONVECTION WITH WARMER
TEMPERATURES. ON FRIDAY...A BACKDOOR COLD FRONT IS EXPECTED WITH A
CONTINUATION OF SHOWERS OR THUNDERSTORMS AND SOMEWHAT COOLER
TEMPERATURES.

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL OVER THE AREA THROUGH
SUNDAY WITH THE EXCEPTION OF AREAS IN AND NEAR LATE DAY THUNDERSTORMS
WHERE LOW CIGS AND VSBYS WILL RESULT IN MVFR OR BRIEF IFR
CONDITIONS.

&&

.FIRE WEATHER...FUELS CONTINUE TO DRY ACROSS THE
DISTRICT...HOWEVER WIND SPEEDS SHOULD REMAIN BELOW RED FLAG
CRITERIA. LOW RHS WILL OCCUR ESPECIALLY WEST OF THE LARAMIE RANGE
THROUGH THE WEEKEND.

&&

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

&&

SHORT TERM/AVIATION...KMD
LONG TERM...EISE
Hazardous weather outlook, Jul 17, 7:04 PM MDT, 6 hours 31 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
704 PM MDT FRI JUL 17 2009

WYZ059>066-181945-
CONVERSE-NIOBRARA-SOUTHWEST CARBON-NORTH CARBON-SNOWY RANGE-
NORTH LARAMIE RANGE-LARAMIE VALLEY-LARAMIE RANGE-
704 PM MDT FRI JUL 17 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST WYOMING.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.

&&

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

NEZ001-003-019>021-054-055-WYZ067>070-181945-
SIOUX-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE-
PLATTE-GOSHEN-CHEYENNE FOOTHILLS-PINE BLUFFS-
704 PM MDT FRI JUL 17 2009

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

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.

&&

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

NEZ002-181945-
DAWES-
704 PM MDT FRI JUL 17 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE WESTERN NEBRASKA
PANHANDLE.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT.

&&

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

WEILAND

In the hours before

Special weather statement, Jul 18, 12:47 AM MDT, 48 minutes before
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Local storm report, Jul 18, 12:53 AM MDT, 42 minutes before
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Local storm report, Jul 18, 12:55 AM MDT, 40 minutes before
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Special weather statement, Jul 18, 1:17 AM MDT, 18 minutes before
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        The site you requested is temporarily down for maintenance or an unexpected outage.
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Local storm report, Jul 18, 1:34 AM MDT, 1 minute before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 18, 2:06 AM MDTSevere Thunderstorm WarningCYSKimball39 min

Nearby

Severe Thunderstorm Warnings in Wyoming, 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.