Alert archive / Wyoming / Frost Advisories in 2021

Frost Advisory 1, NWS Cheyenne, WY

September 20, 2021Albany County, Laramie County, Platte County, Wyoming

NWS Cheyenne, WY issued this frost advisory at Sep 20, 2021, 1:26 PM MDT for Albany County, Laramie County, Platte County, Wyoming. It took effect at Sep 21, 2021, 1:00 AM MDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Sep 20, 2021, 1:26 PM MDT (19:26 UTC)
In effect from
Sep 21, 2021, 1:00 AM MDT
Expired
Sep 21, 2021, 8:00 AM MDT
In force
7 hr
Issued by
NWS Cheyenne, WY

Counties Albany County, WY, Laramie County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 66 km from the middle of the area, began a volume at 19:29 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 12:00Z, 7.4 hours before the alert went out and 259 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 2021-09-20Temperature 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 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 12:00Z on 2021-09-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 87 square meters per square second.1939587897117Sfc1 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
1498 m above ground
0-6 km bulk shear
66 kt
0-1 km storm-relative helicity
87 m²/s²
0-3 km storm-relative helicity
180 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

038 
WWUS75 KCYS 201926
NPWCYS

URGENT - WEATHER MESSAGE
National Weather Service Cheyenne WY
126 PM MDT Mon Sep 20 2021

WYZ103>105-109>111-113-115-116-211400-
/O.UPG.KCYS.FZ.A.0001.210921T0700Z-210921T1400Z/
/O.NEW.KCYS.FZ.W.0002.210921T0700Z-210921T1400Z/
North Laramie Range-Ferris/Seminoe/Shirley Mountains-
Shirley Basin-Central Carbon County-North Snowy Range Foothills-
Southwest Carbon County-Upper North Platte River Basin-
Laramie Valley-South Laramie Range-
Including the cities of Garrett, Esterbrook, Seminoe Dam, 
Medicine Bow, Shirley Basin, Rawlins, Arlington, Elk Mountain, 
Baggs, Saratoga, Encampment, Laramie, Bosler, Buford, 
Pumpkin Vine, and Vedauwoo
126 PM MDT Mon Sep 20 2021

...FREEZE WARNING IN EFFECT FROM 1 AM TO 8 AM MDT TUESDAY...

* WHAT...Sub-freezing temperatures as low as 29 expected.

* WHERE...North Laramie Range, Ferris/Seminoe/Shirley Mountains, 
  Shirley Basin, Central Carbon County, North Snowy Range 
  Foothills, Southwest Carbon County, Upper North Platte River 
  Basin, Laramie Valley and South Laramie Range.

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

* IMPACTS...Frost and freeze conditions will kill crops, other
  sensitive vegetation and possibly damage unprotected outdoor
  plumbing. If recreating outdoors, be sure to have warm enough
  clothing for freezing temperatures.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. To prevent
freezing and possible bursting of outdoor water pipes they should
be wrapped, drained, or allowed to drip slowly. Those that have
in-ground sprinkler systems should drain them and cover above-
ground pipes to protect them from freezing.

&&

$$

WYZ106-117>119-211400-
/O.NEW.KCYS.FR.Y.0001.210921T0700Z-210921T1400Z/
Central Laramie Range and Southwest Platte County-
South Laramie Range Foothills-Central Laramie County-
East Laramie County-
Including the cities of Bordeaux, Whitaker, Federal, Horse Creek,
Cheyenne, and Pine Bluffs
126 PM MDT Mon Sep 20 2021

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

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

* WHERE...Central Laramie Range and Southwest Platte County, 
  South Laramie Range Foothills, Central Laramie County and East 
  Laramie County.

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

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 20, 1:26 PM MDTFreeze WarningCYSAlbany, Carbon, Converse, Laramie, Platte19 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.