Alert archive / Pennsylvania / Mesoscale Discussions in 2020

Mesoscale Discussion 382

April 13, 20206 states

The Storm Prediction Center issued this mesoscale discussion at Apr 13, 2020, 1:20 PM EDT for 6 states. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued
Apr 13, 2020, 1:20 PM EDT (17:20 UTC)
Expired
Apr 13, 2020, 2:45 PM EDT
In force
85 min
Issued by
the Storm Prediction Center
All 78 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Talbot County, MD, Washington County, MD, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Morris County, NJ, Salem County, NJ, Somerset County, NJ, Warren County, NJ, Adams County, PA, Berks County, PA, Blair County, PA, Bucks County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Mifflin County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Schuylkill County, PA, Snyder County, PA, Union County, PA, York 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, Clarke County, VA, Fairfax County, VA, Fauquier County, VA, King George County, VA, Loudoun County, VA, Prince William County, VA, Stafford County, VA, Berkeley County, WV, Jefferson County, WV

The radar

The Sterling radar (KLWX), 123 km from the middle of the area, began a volume at 17:20 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.3 hours before the alert went out and 121 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, Washington/Dulle, VA at 12:00Z on 2020-04-13Temperature 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, Washington/Dulle, VA at 12:00Z on 2020-04-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 487 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
712 m above ground
0-6 km bulk shear
75 kt
0-1 km storm-relative helicity
487 m²/s²
0-3 km storm-relative helicity
684 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.

IssuedProductOfficeCountiesLasted
Apr 13, 10:34 AM EDTMesoscale DiscussionSPCNew Castle86 min
Apr 13, 11:33 AM EDTTornado WatchSPCKent, New Castle, Sussex5 hr
Apr 13, 3:03 PM EDTMesoscale DiscussionSPCKent, New Castle87 min
Apr 13, 6:46 AM EDTMesoscale DiscussionSPCSomerset89 min
Apr 13, 2:42 PM EDTMesoscale DiscussionSPCBergen, Passaic, Sussex93 min
Apr 13, 4:40 AM EDTMesoscale DiscussionSPCAmelia, Brunswick, Buckingham, Charles City, Charlotte, Chesterfield and 42 more95 min
Apr 13, 5:01 AM EDTTornado WatchSPCAmelia, Appomattox, Brunswick, Buckingham, Campbell, Charles City and 36 more7 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2020Mesoscale Discussions in Maryland, 2020Mesoscale Discussions in Virginia, 2020Every mesoscale discussion 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.