Alert archive / Pennsylvania / Mesoscale Discussions in 2020

Mesoscale Discussion 760

May 29, 20204 states

The Storm Prediction Center issued this mesoscale discussion at May 29, 2020, 3:03 PM EDT for 4 states. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: May 29, 2020, 3:03 PM EDT (19:03 UTC)
Expired: May 29, 2020, 4:30 PM EDT
In force: 87 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 234

Counties Baltimore County, MD, Carroll County, MD, Howard County, MD, Montgomery County, MD, Sussex County, NJ, Warren County, NJ, Sullivan County, NY, Berks County, PA, Carbon County, PA, Lancaster County, PA, Lehigh County, PA, Monroe County, PA, Northampton County, PA, Pike County, PA, York County, PA

The radar

The Philadelphia radar (KDIX), 141 km from the middle of the area, began a volume at 19:04 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, 7.1 hours before the alert went out and 203 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: 648 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 701 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 99 m²/s²
0-3 km storm-relative helicity: 108 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 1.9

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 29, 12:27 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Carroll, Cecil, Charles, Frederick and 7 more	63 min
May 29, 2:25 PM EDT	Severe Thunderstorm Watch	SPC	Baltimore, Carroll, Cecil, Frederick, Harford, Howard and 3 more	7 hr
May 29, 10:47 AM EDT	Mesoscale Discussion	SPC	Allegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 20 more	118 min
May 29, 3:01 PM EDT	Severe Thunderstorm Watch	SPC	Clinton, Essex	6 hr
May 29, 4:54 PM EDT	Mesoscale Discussion	SPC	Allegany, Schuyler, Steuben	2 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2020 Mesoscale Discussions in Maryland, 2020 Mesoscale Discussions in New Jersey, 2020 Every 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.