Alert archive / Washington / Frost Advisories in 2021

Frost Advisory 1, NWS Spokane, WA

August 31, 20216 counties in Idaho; 7 counties in Washington

NWS Spokane, WA issued this frost advisory at Aug 31, 2021, 2:06 PM PDT for 6 counties in Idaho; 7 counties in Washington. It took effect at Sep 1, 2021, 2:00 AM PDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued
Aug 31, 2021, 2:06 PM PDT (21:06 UTC)
In effect from
Sep 1, 2021, 2:00 AM PDT
Expired
Sep 1, 2021, 9:00 AM PDT
In force
7 hr
Issued by
NWS Spokane, WA

Counties Benewah County, ID, Bonner County, ID, Boundary County, ID, Kootenai County, ID, Latah County, ID, Shoshone County, ID, Ferry County, WA, Lincoln County, WA, Okanogan County, WA, Pend Oreille County, WA, Spokane County, WA, Stevens County, WA, Whitman County, WA

The radar

The Spokane radar (KOTX), 28 km from the middle of the area, began a volume at 21:05 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

Spokane, WA (KOTX), launched 12:00Z, 9.1 hours before the alert went out and 74 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, Spokane, WA at 12:00Z on 2021-08-31Temperature 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, Spokane, WA at 12:00Z on 2021-08-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 137 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
1135 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
137 m²/s²
0-3 km storm-relative helicity
121 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

217 
WWUS76 KOTX 312106
NPWOTX

URGENT - WEATHER MESSAGE
National Weather Service Spokane WA
206 PM PDT Tue Aug 31 2021

IDZ001>004-WAZ033-036>038-010515-
/O.NEW.KOTX.FR.Y.0001.210901T0900Z-210901T1600Z/
Northern Panhandle-Coeur d'Alene Area-Idaho Palouse-Central
Panhandle Mountains-Washington Palouse-Spokane Area-Northeast
Mountains-Okanogan Highlands-
Including the cities of Colfax, Chewelah, Wallace, Osburn,
Worley, Cheney, Hayden, Rathdrum, Republic, Eastport, St Maries,
Moscow, Bonners Ferry, Kellogg, Tekoa, Uniontown, Mullan,
Oakesdale, Kettle Falls, Rockford, Rosalia, Spokane, Sandpoint,
Wauconda, Coeur d'Alene, La Crosse, Post Falls, Newport,
Davenport, Priest River, Potlatch, Plummer, Genesee, Deer Park,
Inchelium, Pullman, Colville, and Pinehurst
206 PM PDT Tue Aug 31 2021

...FROST ADVISORY IN EFFECT FROM 2 AM TO 9 AM PDT WEDNESDAY...

* WHAT...Temperatures as low as 37 will result in patchy frost 
  formation.

* WHERE...Colfax, Chewelah, Wallace, Osburn, Worley, Cheney, Hayden, 
  Rathdrum, Republic, Eastport, St Maries, Moscow, Bonners Ferry, 
  Kellogg, Tekoa, Uniontown, Mullan, Oakesdale, Kettle Falls, 
  Rockford, Rosalia, Spokane, Sandpoint, Wauconda, Coeur d'Alene, La 
  Crosse, Post Falls, Newport, Davenport, Priest River, Potlatch, 
  Plummer, Genesee, Deer Park, Inchelium, Pullman, Colville, and 
  Pinehurst.

* WHEN...From 2 AM to 9 AM PDT Wednesday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

* ADDITIONAL DETAILS...Clouds are expected to thin overnight and 
  winds calm down in sheltered valleys after midnight. Coolest 
  temperatures will likely be just before sunrise Wednesday morning.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

TC
2 follow-up statements
575 
WWUS76 KOTX 010322
NPWOTX

URGENT - WEATHER MESSAGE
National Weather Service Spokane WA
822 PM PDT Tue Aug 31 2021

IDZ001>004-WAZ033-036>038-011600-
/O.CON.KOTX.FR.Y.0001.210901T0900Z-210901T1600Z/
Northern Panhandle-Coeur d'Alene Area-Idaho Palouse-Central
Panhandle Mountains-Washington Palouse-Spokane Area-Northeast
Mountains-Okanogan Highlands-
Including the cities of Colfax, Chewelah, Wallace, Osburn,
Worley, Cheney, Hayden, Rathdrum, Republic, Eastport, St Maries,
Moscow, Bonners Ferry, Kellogg, Tekoa, Uniontown, Mullan,
Oakesdale, Kettle Falls, Rockford, Rosalia, Spokane, Sandpoint,
Wauconda, Coeur d'Alene, La Crosse, Post Falls, Newport,
Davenport, Priest River, Potlatch, Plummer, Genesee, Deer Park,
Inchelium, Pullman, Colville, and Pinehurst
822 PM PDT Tue Aug 31 2021

...FROST ADVISORY REMAINS IN EFFECT FROM 2 AM TO 9 AM PDT 
WEDNESDAY...

* WHAT...Temperatures as low as 37 will result in patchy frost 
  formation.

* WHERE...Colfax, Chewelah, Wallace, Osburn, Worley, Cheney, Hayden, 
  Rathdrum, Republic, Eastport, St Maries, Moscow, Bonners Ferry, 
  Kellogg, Tekoa, Uniontown, Mullan, Oakesdale, Kettle Falls, 
  Rockford, Rosalia, Spokane, Sandpoint, Wauconda, Coeur d'Alene, La 
  Crosse, Post Falls, Newport, Davenport, Priest River, Potlatch, 
  Plummer, Genesee, Deer Park, Inchelium, Pullman, Colville, and 
  Pinehurst.

* WHEN...From 2 AM to 9 AM PDT Wednesday.

* IMPACTS...Frost could harm sensitive outdoor vegetation. Sensitive 
  outdoor plants may be killed if left uncovered.

* ADDITIONAL DETAILS...Clouds are expected to thin overnight with 
  winds calming down in sheltered valleys after midnight. The 
  coolest temperatures will likely be just before sunrise Wednesday 
  morning.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

KD
935 
WWUS76 KOTX 011604
NPWOTX

URGENT - WEATHER MESSAGE
National Weather Service Spokane WA
904 AM PDT Wed Sep 1 2021

IDZ001>004-WAZ033-036>038-011715-
/O.EXP.KOTX.FR.Y.0001.000000T0000Z-210901T1600Z/
Northern Panhandle-Coeur d'Alene Area-Idaho Palouse-Central
Panhandle Mountains-Washington Palouse-Spokane Area-Northeast
Mountains-Okanogan Highlands-
Including the cities of Colfax, Chewelah, Wallace, Osburn,
Worley, Cheney, Hayden, Rathdrum, Republic, Eastport, St Maries,
Moscow, Bonners Ferry, Kellogg, Tekoa, Uniontown, Mullan,
Oakesdale, Kettle Falls, Rockford, Rosalia, Spokane, Sandpoint,
Wauconda, Coeur d'Alene, La Crosse, Post Falls, Newport,
Davenport, Priest River, Potlatch, Plummer, Genesee, Deer Park,
Inchelium, Pullman, Colville, and Pinehurst
904 AM PDT Wed Sep 1 2021

...FROST ADVISORY HAS EXPIRED...

The threat has ended.

$$

RP

Nearby

Frost Advisories in Washington, 2021Frost Advisories in Idaho, 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.