Alert archive / Virginia / Freeze Warnings in 2012

Freeze Warning 20, NWS Baltimore/Washington

November 4, 201211 counties in Virginia; Baltimore County, Carroll County, Frederick County, Maryland

NWS Baltimore/Washington issued this freeze warning at Nov 4, 2012, 2:43 PM EST for 11 counties in Virginia; Baltimore County, Carroll County, Frederick County, Maryland. It took effect at Nov 5, 2012, 4:00 AM EST. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Nov 4, 2012, 2:43 PM EST (19:43 UTC)
In effect from
Nov 5, 2012, 4:00 AM EST
Expired
Nov 5, 2012, 8:00 AM EST
In force
4 hr
Issued by
NWS Baltimore/Washington

Counties Baltimore County, MD, Carroll County, MD, Frederick County, MD, City of Harrisonburg, VA, City of Staunton, VA, City of Waynesboro, VA, Culpeper County, VA, Fauquier County, VA, Greene County, VA, Madison County, VA, Page County, VA, Rappahannock County, VA, Rockingham County, VA, Warren County, VA

The radar

The Sterling radar (KLWX), 65 km from the middle of the area, began a volume at 19:45 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

Roanoke, VA (KRNK), launched 12:00Z, 7.7 hours before the alert went out and 205 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, Roanoke, VA at 12:00Z on 2012-11-04Temperature 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°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Roanoke, VA at 12:00Z on 2012-11-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 161 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
660 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
161 m²/s²
0-3 km storm-relative helicity
232 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Nov 4, 3:30 AM ESTFreeze WatchLWXCulpeper, Fairfax, Fauquier, Greene, Madison, Nelson and 13 more11 hr

Nearby

Freeze Warnings in Virginia, 2012Freeze Warnings in Maryland, 2012Every freeze warning in 2012

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.