Alert archive / Pennsylvania / Mesoscale Discussions in 2013

Mesoscale Discussion 437

April 10, 2013New Castle County, Delaware; 6 counties in Maryland; 11 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Apr 10, 2013, 11:11 PM EDT for New Castle County, Delaware; 6 counties in Maryland; 11 counties in Pennsylvania. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued
Apr 10, 2013, 11:11 PM EDT (03:11 UTC)
Expired
Apr 11, 2013, 12:45 AM EDT
In force
94 min
Issued by
the Storm Prediction Center

Counties New Castle County, DE, Baltimore County, MD, Carroll County, MD, Cecil County, MD, Frederick County, MD, Harford County, MD, Washington County, MD, Adams County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lancaster County, PA, Mifflin County, PA, Perry County, PA, York County, PA

The radar

The Sterling radar (KLWX), 106 km from the middle of the area, began a volume at 03:14 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 00:00Z, 3.2 hours before the alert went out and 107 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 00:00Z on 2013-04-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 420 joules per kilogram.LCLLFCEL10008507005003002001001 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 00:00Z on 2013-04-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 137 square meters per square second.193958Sfc1 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
420 J/kg
Mixed-layer CIN
-60 J/kg
Mixed-layer LCL
2611 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
137 m²/s²
0-3 km storm-relative helicity
203 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 10, 8:28 PM EDTMesoscale DiscussionSPCAdams, Allegheny, Armstrong, Beaver, Bedford, Berks and 30 more2 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2013Mesoscale Discussions in Maryland, 2013Mesoscale Discussions in Delaware, 2013Every mesoscale discussion in 2013

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.