Alert archive / Pennsylvania / Mesoscale Discussions in 2018

Mesoscale Discussion 408

May 14, 20185 states

The Storm Prediction Center issued this mesoscale discussion at May 14, 2018, 11:56 AM EDT for 5 states. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: May 14, 2018, 11:56 AM EDT (15:56 UTC)
Expired: May 14, 2018, 1:00 PM EDT
In force: 64 min
Issued by: the Storm Prediction Center
Chance of a watch: 95%

All 69 counties

Allegany County, MD, Carroll County, MD, Frederick County, MD, Garrett County, MD, Howard County, MD, Montgomery County, MD, Washington County, MD, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Harrison County, OH, Jefferson County, OH, Monroe County, OH, Adams County, PA, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Bedford County, PA, Blair County, PA, Butler County, PA, Cambria County, PA, Cumberland County, PA, Fayette County, PA, Franklin County, PA, Fulton County, PA, Greene County, PA, Huntingdon County, PA, Indiana County, PA, Lawrence County, PA, Somerset County, PA, Washington County, PA, Westmoreland County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Loudoun County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Shenandoah County, VA, Warren County, VA, Barbour County, WV, Berkeley County, WV, Brooke County, WV, Grant County, WV, Hampshire County, WV, Hancock County, WV, Hardy County, WV, Harrison County, WV, Jefferson County, WV, Marion County, WV, Marshall County, WV, Mineral County, WV, Monongalia County, WV, Morgan County, WV, Ohio County, WV, Preston County, WV, Taylor County, WV, Tucker County, WV, Wetzel County, WV

The radar

The Pittsburgh radar (KPBZ), 121 km from the middle of the area, began a volume at 15:56 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 88May 14, 12:30 PM EDT

The nearest sounding before it

Pittsburgh, PA (KAGC), launched 12:00Z, 3.9 hours before the alert went out and 104 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: 39 J/kg
Mixed-layer CIN: -196 J/kg
Mixed-layer LCL: 822 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 82 m²/s²
0-3 km storm-relative helicity: 103 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 14, 12:29 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Charles and 9 more	9 hr
May 14, 3:26 PM EDT	Mesoscale Discussion	SPC	Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Charles and 10 more	2 hr
May 14, 5:37 PM EDT	Mesoscale Discussion	SPC	Somerset	53 min
May 14, 6:11 PM EDT	Severe Thunderstorm Watch	SPC	Dorchester, Somerset, Wicomico, Worcester	4 hr
May 14, 7:22 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Charles, Howard, Prince George's, Saint Mary's and 1 more	53 min

Nearby

Mesoscale Discussions in Pennsylvania, 2018 Mesoscale Discussions in West Virginia, 2018 Mesoscale Discussions in Virginia, 2018 Every mesoscale discussion in 2018

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.