Alert archive / Wyoming / Frost Advisories in 2021

Frost Advisory 2, NWS Cheyenne, WY

September 30, 20215 counties in Wyoming

NWS Cheyenne, WY issued this frost advisory at Sep 30, 2021, 2:24 PM MDT for 5 counties in Wyoming. It took effect at Oct 1, 2021, 1:00 AM MDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Sep 30, 2021, 2:24 PM MDT (20:24 UTC)
In effect from
Oct 1, 2021, 1:00 AM MDT
Expired
Oct 1, 2021, 8:00 AM MDT
In force
7 hr
Issued by
NWS Cheyenne, WY

Counties Converse County, WY, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 129 km from the middle of the area, began a volume at 20:28 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 12:00Z, 8.4 hours before the alert went out and 250 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 2021-09-30Temperature 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°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Rapid City, SD at 12:00Z on 2021-09-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 46 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
1788 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
46 m²/s²
0-3 km storm-relative helicity
150 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

997 
WWUS75 KCYS 302024
NPWCYS

URGENT - WEATHER MESSAGE
National Weather Service Cheyenne WY
224 PM MDT Thu Sep 30 2021

WYZ101-102-107-108-118-119-011200-
/O.NEW.KCYS.FR.Y.0002.211001T0700Z-211001T1400Z/
Converse County Lower Elevations-Niobrara County-
East Platte County-Goshen County-Central Laramie County-
East Laramie County-
Including the cities of Douglas, Glenrock, Bill, Deer Creek, 
Lusk, Redbird, Wheatland, Guernsey, Torrington, Cheyenne, 
and Pine Bluffs
224 PM MDT Thu Sep 30 2021

...FROST ADVISORY IN EFFECT FROM 1 AM TO 8 AM MDT FRIDAY...

* WHAT...Temperatures as low as 33 will result in frost 
  formation.

* WHERE...Converse County Lower Elevations, Niobrara County, 
  East Platte County, Goshen County, Central Laramie County and 
  East Laramie County.

* WHEN...From 1 AM to 8 AM MDT Friday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

Brothers
2 follow-up statements
459 
WWUS75 KCYS 010957
NPWCYS

URGENT - WEATHER MESSAGE
National Weather Service Cheyenne WY
357 AM MDT Fri Oct 1 2021

WYZ101-102-107-108-118-119-011400-
/O.CON.KCYS.FR.Y.0002.000000T0000Z-211001T1400Z/
Converse County Lower Elevations-Niobrara County-
East Platte County-Goshen County-Central Laramie County-
East Laramie County-
Including the cities of Douglas, Glenrock, Bill, Deer Creek, 
Lusk, Redbird, Wheatland, Guernsey, Torrington, Cheyenne, 
and Pine Bluffs
357 AM MDT Fri Oct 1 2021

...FROST ADVISORY REMAINS IN EFFECT UNTIL 8 AM MDT THIS MORNING...

* WHAT...Temperatures as low as 33 will result in frost 
  formation.

* WHERE...Converse County Lower Elevations, Niobrara County, 
  East Platte County, Goshen County, Central Laramie County and 
  East Laramie County.

* WHEN...Until 8 AM MDT Friday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

Gimmestad
644 
WWUS75 KCYS 011343
NPWCYS

URGENT - WEATHER MESSAGE
National Weather Service Cheyenne WY
743 AM MDT Fri Oct 1 2021

WYZ101-102-107-108-118-119-011445-
/O.EXP.KCYS.FR.Y.0002.000000T0000Z-211001T1400Z/
Converse County Lower Elevations-Niobrara County-
East Platte County-Goshen County-Central Laramie County-
East Laramie County-
Including the cities of Douglas, Glenrock, Bill, Deer Creek, 
Lusk, Redbird, Wheatland, Guernsey, Torrington, Cheyenne, 
and Pine Bluffs
743 AM MDT Fri Oct 1 2021

...FROST ADVISORY WILL EXPIRE AT 8 AM MDT THIS MORNING...

Temperatures are expected to increase this morning into the upper
30s. Therefore, the frost advisory will be allowed to expire on
time.

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 30, 7:00 AM MDTDense Fog AdvisoryCYSAlbany, Laramie3 hr

Nearby

Frost Advisories in Wyoming, 2021Every frost advisory in 2021

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.