Alert archive / Maryland / Mesoscale Discussions in 2018

Mesoscale Discussion 396

May 12, 20184 states

The Storm Prediction Center issued this mesoscale discussion at May 12, 2018, 7:16 PM EDT for 4 states. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: May 12, 2018, 7:16 PM EDT (23:16 UTC)
Expired: May 12, 2018, 8:15 PM EDT
In force: 59 min
Issued by: the Storm Prediction Center

All 33 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Queen Anne's County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Mercer County, NJ, Ocean County, NJ, Salem County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Montgomery County, PA, Philadelphia County, PA, York County, PA

The radar

The Philadelphia radar (KDIX), 121 km from the middle of the area, began a volume at 23:19 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, 11.3 hours before the alert went out and 170 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: 1390 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 178 m²/s²
0-3 km storm-relative helicity: 201 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 12, 3:59 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle	3 hr
May 12, 4:58 PM EDT	Tornado Watch	SPC	Kent, New Castle, Sussex	5 hr
May 12, 1:51 PM EDT	Mesoscale Discussion	SPC	Allegany, Garrett	2 hr
May 12, 2:47 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Calvert, Charles, Frederick, Garrett, Montgomery and 3 more	8 hr
May 12, 5:05 PM EDT	Mesoscale Discussion	SPC	Allegany, Frederick, Garrett, Washington	115 min

Nearby

Mesoscale Discussions in Maryland, 2018 Mesoscale Discussions in Pennsylvania, 2018 Mesoscale Discussions in New Jersey, 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.