Alert archive / Wyoming / Flash Flood Watches in 2018

Flash Flood Watch 4, NWS Cheyenne, WY

June 18, 20184 counties in Wyoming; 4 counties in Nebraska

NWS Cheyenne, WY issued this flash flood watch at Jun 18, 2018, 1:05 PM MDT for 4 counties in Wyoming; 4 counties in Nebraska. It took effect at Jun 19, 2018, 6:00 AM MDT. It was in force for 19 hr.

The area

The counties it named.

The facts

Issued
Jun 18, 2018, 1:05 PM MDT (19:05 UTC)
In effect from
Jun 19, 2018, 6:00 AM MDT
Expired
Jun 20, 2018, 12:48 AM MDT
In force
19 hr
Issued by
NWS Cheyenne, WY
Flood severity
None

Counties Box Butte County, NE, Dawes County, NE, Scotts Bluff County, NE, Sioux County, NE, Converse County, WY, Goshen County, WY, Niobrara County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 154 km from the middle of the area, began a volume at 19:08 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 (KRAP), launched 12:00Z, 7.1 hours before the alert went out and 207 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 12:00Z on 2018-06-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCLEL10008507005003002001001 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 12:00Z on 2018-06-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 55 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
513 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
55 m²/s²
0-3 km storm-relative helicity
208 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 flash flood watch 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 flash flood watch went out at Jun 18, 11:53 AM MDT, 1 hour 12 minutes earlier.

Area forecast discussion, Jun 18, 11:53 AM MDT, 1 hour 12 minutes before
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Hazardous weather outlook, Jun 18, 5:33 AM MDT, 7 hours 32 minutes before
Hazardous Weather Outlook
National Weather Service Cheyenne WY
533 AM MDT Mon Jun 18 2018

NEZ002-003-019>021-054-055-095-096-WYZ101>103-106>108-116>119-
191145-
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-South Laramie Range-
South Laramie Range Foothills-Central Laramie County-
East Laramie County-
533 AM MDT Mon Jun 18 2018

This hazardous weather outlook is for portions of western
Nebraska...east central Wyoming and southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

A few thunderstorms are possible late this afternoon and early
evening across the high plains of southeast Wyoming and the
western Nebraska Panhandle. Some storms could become strong to
severe, with large hail and damaging winds. A tornado or two is
also possible.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A few strong to severe thunderstorms are possible again on
Tuesday.

.Spotter information statement...

Spotter activation is possible between 3 PM and 10 PM MDT today.

WYZ104-105-109>115-191145-
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-Laramie Valley-
533 AM MDT Mon Jun 18 2018

This hazardous weather outlook is for portions of south central
Wyoming and southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

The probability for widespread hazardous weather is low.

.Spotter information statement...

Spotter activation will not be needed.

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 18, 4:09 PM MDTSpecial Weather StatementCYSPlatte51 min
Jun 18, 5:14 PM MDTSpecial Weather StatementCYSGoshen46 min
Jun 18, 5:20 PM MDTSevere Thunderstorm WarningCYSGoshen, Platte40 min
Jun 18, 5:53 PM MDTSevere Thunderstorm WarningCYSGoshen24 min

Nearby

Flash Flood Watches in Wyoming, 2018Flash Flood Watches in Nebraska, 2018Every flash flood watch in 2018

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.