Alert archive / Virginia / Frost Advisories in 2013

Frost Advisory 2, NWS Baltimore/Washington

May 12, 201310 counties in Virginia; Allegany County, Washington County, Maryland; 7 counties in West Virginia

NWS Baltimore/Washington issued this frost advisory at May 12, 2013, 4:35 PM EDT for 10 counties in Virginia; Allegany County, Washington County, Maryland; 7 counties in West Virginia. It took effect at May 13, 2013, 2:00 AM EDT. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued
May 12, 2013, 4:35 PM EDT (20:35 UTC)
In effect from
May 13, 2013, 2:00 AM EDT
Expired
May 13, 2013, 8:00 AM EDT
In force
6 hr
Issued by
NWS Baltimore/Washington

Counties Allegany County, MD, Washington County, MD, City of Harrisonburg, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Frederick County, VA, Page County, VA, Rockingham County, VA, Shenandoah County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV

The radar

The Sterling radar (KLWX), 88 km from the middle of the area, began a volume at 20:32 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

Pittsburgh, PA (KPIT), launched 12:00Z, 8.6 hours before the alert went out and 206 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, Pittsburgh, PA at 12:00Z on 2013-05-12Temperature 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, Pittsburgh, PA at 12:00Z on 2013-05-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -29 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
1047 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
-29 m²/s²
0-3 km storm-relative helicity
-2 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
May 11, 9:24 PM EDTSpecial Marine WarningLWX96 min
May 11, 10:53 PM EDTSpecial Marine WarningLWX82 min
May 11, 11:44 PM EDTSpecial Marine WarningLWX91 min
May 12, 1:53 PM EDTFreeze WatchLWXClarke, Frederick, Highland, Page, Rockingham, Shenandoah and 5 more25 hr
May 12, 1:53 PM EDTFreeze WarningLWXHighland18 hr
May 12, 2:37 PM EDTSmall Craft AdvisoryLWX35 hr
May 12, 5:16 PM EDTSmall Craft AdvisoryLWX32 hr
May 11, 9:17 PM EDTSpecial Weather StatementLWXCalvert43 min

Nearby

Frost Advisories in Virginia, 2013Frost Advisories in West Virginia, 2013Frost Advisories in Maryland, 2013Every frost advisory in 2013

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.