Alert archive / California / Frost Advisories in 2017

Frost Advisory 14, NWS Eureka, CA

September 20, 2017Humboldt County, Mendocino County, Trinity County, California

NWS Eureka, CA issued this frost advisory at Sep 20, 2017, 3:12 AM PDT for Humboldt County, Mendocino County, Trinity County, California. It took effect at Sep 21, 2017, 3:00 AM PDT. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued
Sep 20, 2017, 3:12 AM PDT (10:12 UTC)
In effect from
Sep 21, 2017, 3:00 AM PDT
Expired
Sep 21, 2017, 8:00 AM PDT
In force
5 hr
Issued by
NWS Eureka, CA

Counties Humboldt County, CA, Mendocino County, CA, Trinity County, CA

The radar

The Eureka (Bunker Hill) radar (KBHX), 73 km from the middle of the area, began a volume at 10:11 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

Medford/Jackson, OR (KMFR), launched 00:00Z, 10.2 hours before the alert went out and 241 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, Medford/Jackson, OR at 00:00Z on 2017-09-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 16 joules per kilogram.LCLLFCEL10008507005003002001001 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, Medford/Jackson, OR at 00:00Z on 2017-09-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 201 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
16 J/kg
Mixed-layer CIN
-16 J/kg
Mixed-layer LCL
1080 m above ground
0-6 km bulk shear
78 kt
0-1 km storm-relative helicity
201 m²/s²
0-3 km storm-relative helicity
257 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

440 
WWUS76 KEKA 201012
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
312 AM PDT Wed Sep 20 2017

CAZ107-108-110-111-202315-
/O.NEW.KEKA.FR.Y.0014.170921T1000Z-170921T1500Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
312 AM PDT Wed Sep 20 2017

...FROST ADVISORY IN EFFECT FROM 3 AM TO 8 AM PDT THURSDAY...

The National Weather Service in Eureka has issued a Frost
Advisory...which is in effect from 3 AM to 8 AM PDT Thursday. 

* TEMPERATURES...33 TO 36F early Thurday morning. 

* LOCATIONS INCLUDE...Weaverville...Trinity Center...
  Hayfork...Ruth...Laytonville...Willits and Covelo.

* FOR A DETAILED VIEW OF THE HAZARD AREA...visit 
  http://www.wrh.noaa.gov/map

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Frost Advisory means that frost is possible. Sensitive outdoor
plants may be killed if left uncovered.

&&

$$
4 follow-up statements
299 
WWUS76 KEKA 201859 CCA
NPWEKA

URGENT - WEATHER MESSAGE...CORRECTED
National Weather Service Eureka CA
1159 AM PDT Wed Sep 20 2017

CAZ107-108-110-111-202315-
/O.COR.KEKA.FR.Y.0014.170921T1000Z-170921T1500Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
1159 AM PDT Wed Sep 20 2017

...FROST ADVISORY IN EFFECT FROM 3 AM TO 8 AM PDT THURSDAY...

The National Weather Service in Eureka has issued a Frost
Advisory...which is in effect from 3 AM to 8 AM PDT Thursday. 

* TEMPERATURES...33 TO 36F early Thursday morning. 

* LOCATIONS INCLUDE...Weaverville...Trinity Center...
  Hayfork...Ruth...Laytonville...Willits and Covelo.

* FOR A DETAILED VIEW OF THE HAZARD AREA...visit 
  http://www.wrh.noaa.gov/map

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Frost Advisory means that frost is possible. Sensitive outdoor
plants may be killed if left uncovered.

&&

$$
964 
WWUS76 KEKA 202210
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
310 PM PDT Wed Sep 20 2017

CAZ105-211115-
/O.EXA.KEKA.FR.Y.0014.170921T1000Z-170921T1500Z/
Northern Humboldt Interior-
310 PM PDT Wed Sep 20 2017

...FROST ADVISORY IN EFFECT FROM 3 AM TO 8 AM PDT THURSDAY...

The National Weather Service in Eureka has issued a Frost
Advisory...which is in effect from 3 AM to 8 AM PDT Thursday. 

* TEMPERATURES...33 TO 36F early Thursday morning. 

* LOCATIONS INCLUDE...Orleans...Willow Creek...Hoopa.

* FOR A DETAILED VIEW OF THE HAZARD AREA...visit 
  http://www.wrh.noaa.gov/map

$$

CAZ107-108-110-111-211115-
/O.CON.KEKA.FR.Y.0014.170921T1000Z-170921T1500Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
310 PM PDT Wed Sep 20 2017

...FROST ADVISORY REMAINS IN EFFECT FROM 3 AM TO 8 AM PDT
THURSDAY...

* TEMPERATURES...33 TO 36F early Thursday morning. Isolated
  locations may drop slightly below freezing for a brief period.  

* LOCATIONS INCLUDE...Weaverville...Trinity Center...
  Hayfork...Ruth...Laytonville...Willits and Covelo.

* FOR A DETAILED VIEW OF THE HAZARD AREA...visit 
  http://www.wrh.noaa.gov/map

$$
965 
WWUS76 KEKA 211103
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
403 AM PDT Thu Sep 21 2017

CAZ105-211215-
/O.CAN.KEKA.FR.Y.0014.000000T0000Z-170921T1500Z/
Northern Humboldt Interior-
403 AM PDT Thu Sep 21 2017

...FROST ADVISORY IS CANCELLED...

The National Weather Service in Eureka has cancelled the Frost
Advisory. 

Temperatures are too warm for frost. 

$$

CAZ107-108-110-111-211500-
/O.CON.KEKA.FR.Y.0014.000000T0000Z-170921T1500Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
403 AM PDT Thu Sep 21 2017

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

* TEMPERATURES...mid 30s.

* LOCATIONS INCLUDE...Hayfork...Ruth...Laytonville...
  Willits...Covelo...Weaverville and Trinity Center.

* FOR A DETAILED VIEW OF THE HAZARD AREA...visit 
  http://www.wrh.noaa.gov/map

$$
179 
WWUS76 KEKA 211446
NPWEKA

URGENT - WEATHER MESSAGE
National Weather Service Eureka CA
746 AM PDT Thu Sep 21 2017

CAZ107-108-110-111-211600-
/O.EXP.KEKA.FR.Y.0014.000000T0000Z-170921T1500Z/
Northern Trinity-Southern Trinity-Northwestern Mendocino Interior-
Northeastern Mendocino Interior-
746 AM PDT Thu Sep 21 2017

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

Temperatures have warmed and the current Frost Advisory has been
allowed to expire. However, additional pockets of frost will be 
possible overnight tonight and tomorrow morning.


$$

Nearby

Frost Advisories in California, 2017Every frost advisory in 2017

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.