Alert archive / Virginia / Frost Advisories in 2021

Frost Advisory 2, NWS Blacksburg, VA

October 17, 2021Alleghany County, Ashe County, Watauga County, North Carolina; 5 counties in Virginia

NWS Blacksburg, VA issued this frost advisory at Oct 17, 2021, 2:15 PM EDT for Alleghany County, Ashe County, Watauga County, North Carolina; 5 counties in Virginia. It took effect at Oct 18, 2021, 4:00 AM EDT. It was in force for 11 min.

The area

The counties it named.

The facts

Issued
Oct 17, 2021, 2:15 PM EDT (18:15 UTC)
In effect from
Oct 18, 2021, 4:00 AM EDT
Expired
Oct 18, 2021, 4:11 AM EDT
In force
11 min
Issued by
NWS Blacksburg, VA

Counties Alleghany County, NC, Ashe County, NC, Watauga County, NC, Bland County, VA, Grayson County, VA, Smyth County, VA, Tazewell County, VA, Wythe County, VA

The radar

The Roanoke radar (KFCX), 102 km from the middle of the area, began a volume at 18:19 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 6.3 hours before the alert went out and 149 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, Greensboro/Hi Pt, NC at 12:00Z on 2021-10-17Temperature 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, Greensboro/Hi Pt, NC at 12:00Z on 2021-10-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -76 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
1474 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
-76 m²/s²
0-3 km storm-relative helicity
9 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

437 
WWUS71 KRNK 171815
NPWRNK

URGENT - WEATHER MESSAGE
National Weather Service Blacksburg VA
215 PM EDT Sun Oct 17 2021

NCZ001-002-018-VAZ007-009-010-012-015-180215-
/O.NEW.KRNK.FR.Y.0002.211018T0800Z-211018T1300Z/
Ashe-Alleghany NC-Watauga-Tazewell-Smyth-Bland-Wythe-Grayson-
Including the cities of West Jefferson, Sparta, Boone, Tazewell, 
Marion, Bland, Wytheville, Independence, Whitetop, Troutdale, 
and Volney
215 PM EDT Sun Oct 17 2021

...FROST ADVISORY IN EFFECT FROM 4 AM TO 9 AM EDT MONDAY...

* WHAT...Temperatures falling into the low to mid 30s will result
  in frost formation.

* WHERE...In Virginia, Tazewell, Smyth, Bland, Wythe and Grayson 
  Counties. In North Carolina, Ashe, Alleghany NC and Watauga 
  Counties.

* WHEN...From 4 AM to 9 AM EDT Monday.

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

* ADDITIONAL DETAILS...Isolated spots, particularly in sheltered
  valleys, may briefly fall to freezing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$
2 follow-up statements
429 
WWUS71 KRNK 180104
NPWRNK

URGENT - WEATHER MESSAGE
National Weather Service Blacksburg VA
904 PM EDT Sun Oct 17 2021

NCZ001-002-018-VAZ007-009-010-012-015-180915-
/O.CON.KRNK.FR.Y.0002.211018T0800Z-211018T1300Z/
Ashe-Alleghany NC-Watauga-Tazewell-Smyth-Bland-Wythe-Grayson-
Including the cities of West Jefferson, Sparta, Boone, Tazewell, 
Marion, Bland, Wytheville, Independence, Whitetop, Troutdale, 
and Volney
904 PM EDT Sun Oct 17 2021

...FROST ADVISORY REMAINS IN EFFECT FROM 4 AM TO 9 AM EDT
MONDAY...

* WHAT...Temperatures falling into the low to mid 30s will 
  result in frost formation.

* WHERE...In Virginia, Tazewell, Smyth, Bland, Wythe and Grayson 
  Counties. In North Carolina, Ashe, Alleghany NC and Watauga 
  Counties.

* WHEN...From 4 AM to 9 AM EDT Monday.

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

* ADDITIONAL DETAILS...Isolated spots, particularly in sheltered 
  valleys, may briefly fall to freezing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$
193 
WWUS71 KRNK 180811
NPWRNK

URGENT - WEATHER MESSAGE
National Weather Service Blacksburg VA
411 AM EDT Mon Oct 18 2021

NCZ001-002-018-VAZ007-009-010-012-015-180915-
/O.CAN.KRNK.FR.Y.0002.000000T0000Z-211018T1300Z/
Ashe-Alleghany NC-Watauga-Tazewell-Smyth-Bland-Wythe-Grayson-
Including the cities of West Jefferson, Sparta, Boone, Tazewell, 
Marion, Bland, Wytheville, Independence, Whitetop, Troutdale, 
and Volney
411 AM EDT Mon Oct 18 2021

...FROST ADVISORY IS CANCELLED...

Widespread frost has failed to develop across the region this
morning thanks to a persistent westerly breeze. This has allowed
temperatures to remain well into the 40s in most areas that were
within the Frost Advisory. There still may be some isolated
locations that drop low enough into the 30s to support patches of
frost for a few hours early this morning. Nonetheless, at this
point in time, a widespread killing frost is no longer expected.
Thus, the Frost Advisory has been cancelled.

$$

RAB

Nearby

Frost Advisories in Virginia, 2021Frost Advisories in North Carolina, 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.