Alert archive / Virginia / Freeze Warnings in 2020

Freeze Warning 13, NWS Baltimore/Washington

October 29, 202013 counties in Virginia; 5 counties in Maryland; Jefferson County, West Virginia

NWS Baltimore/Washington issued this freeze warning at Oct 29, 2020, 4:14 PM EDT for 13 counties in Virginia; 5 counties in Maryland; Jefferson County, West Virginia. It took effect at Oct 31, 2020, 3:00 AM EDT. It was in force for 6 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
Oct 29, 2020, 4:14 PM EDT (20:14 UTC)
In effect from
Oct 31, 2020, 3:00 AM EDT
Expired
Oct 31, 2020, 9:00 AM EDT
In force
6 hr
Issued by
NWS Baltimore/Washington

Counties Baltimore County, MD, Carroll County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, City of Harrisonburg, VA, City of Staunton, VA, City of Waynesboro, VA, Clarke County, VA, Culpeper County, VA, Fauquier County, VA, Greene County, VA, Loudoun County, VA, Madison County, VA, Page County, VA, Rappahannock County, VA, Rockingham County, VA, Warren County, VA, Jefferson County, WV

The radar

The Sterling radar (KLWX), 41 km from the middle of the area, began a volume at 20:16 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, 8.2 hours before the alert went out and 229 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 2020-10-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 171 joules per kilogram.LCLLFCEL10008507005003002001001 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 2020-10-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 280 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
171 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
507 m above ground
0-6 km bulk shear
75 kt
0-1 km storm-relative helicity
280 m²/s²
0-3 km storm-relative helicity
452 m²/s²
Significant tornado parameter
0.3
Supercell composite
1.1

Open this sounding in Storm Lab

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 29, 1:12 AM EDTSmall Craft AdvisoryLWX29 hr
Oct 29, 3:24 AM EDTFreeze WatchLWXLoudoun13 hr
Oct 29, 9:41 AM EDTAreal Flood WarningLWXFairfax, City of Fairfax11 hr
Oct 29, 11:30 AM EDTAreal Flood WarningLWXArlington, Fairfax, City of Alexandria, City of Falls Church6 hr
Oct 29, 1:00 PM EDTAreal Flood WarningLWXCulpeper, Fairfax, Fauquier, Madison, Orange, Prince William and 3 more8 hr
Oct 29, 3:22 PM EDTAreal Flood WarningLWXAlbemarle, Greene, Madison, Orange, City of Charlottesville6 hr
Oct 29, 6:46 PM EDTGale WarningLWX18 hr
Oct 29, 6:46 PM EDTSmall Craft AdvisoryLWX41 hr
Oct 29, 8:50 AM EDTWind AdvisoryLWXCalvert, Saint Mary's11 hr
Oct 29, 3:16 PM EDTAreal Flood WarningLWXSaint Mary's12 hr
Oct 29, 4:37 PM EDTAreal Flood WarningLWXPrince George's27 hr
Oct 29, 7:03 PM EDTAreal Flood WarningLWXCharles, Prince George's31 hr

Nearby

Freeze Warnings in Virginia, 2020Freeze Warnings in Maryland, 2020Freeze Warnings in West Virginia, 2020Every freeze warning in 2020

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.