Alert archive / Virginia / Frost Advisories in 2012

Frost Advisory 5, NWS Baltimore/Washington

April 27, 20129 counties in Virginia; Baltimore County, Maryland

NWS Baltimore/Washington issued this frost advisory at Apr 27, 2012, 1:55 PM EDT for 9 counties in Virginia; Baltimore County, Maryland. It took effect at Apr 28, 2012, 1:00 AM EDT. It was in force for 7 hr.

The area

The counties it named.

The facts

Issued: Apr 27, 2012, 1:55 PM EDT (17:55 UTC)
In effect from: Apr 28, 2012, 1:00 AM EDT
Expired: Apr 28, 2012, 7:50 AM EDT
In force: 7 hr
Issued by: NWS Baltimore/Washington

Counties Baltimore County, MD, City of Harrisonburg, VA, City of Staunton, VA, City of Waynesboro, VA, Fauquier County, VA, Page County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Warren County, VA

The radar

The Sterling radar (KLWX), 84 km from the middle of the area, began a volume at 17:58 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, 5.9 hours before the alert went out and 189 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 924 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: -7 m²/s²
0-3 km storm-relative helicity: 32 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this frost advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Baltimore/Washington wrote its last area forecast discussion before this frost advisory went out at Apr 27, 10:57 AM EDT, 2 hours 58 minutes earlier.

Area forecast discussion, Apr 27, 10:57 AM EDT, 2 hours 58 minutes before

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Hazardous weather outlook, Apr 27, 1:05 PM EDT, 50 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 26, 10:13 PM EDT	Special Marine Warning	LWX		27 min
Apr 27, 12:09 AM EDT	Gale Warning	LWX		6 hr
Apr 27, 12:09 AM EDT	Small Craft Advisory	LWX		28 hr
Apr 27, 8:06 AM EDT	Gale Warning	LWX		5 hr
Apr 27, 8:06 AM EDT	Small Craft Advisory	LWX		20 hr
Apr 27, 10:03 AM EDT	Freeze Watch	LWX	Clarke, Frederick, City of Winchester	4 hr
Apr 27, 1:55 PM EDT	Freeze Warning	LWX	Clarke, Frederick, Highland, City of Winchester	19 hr
Apr 26, 8:41 PM EDT	Special Weather Statement	LWX	Carroll	34 min

Nearby

Frost Advisories in Virginia, 2012 Frost Advisories in Maryland, 2012 Every frost advisory 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.