Alert archive / Pennsylvania / Mesoscale Discussions in 2015

Mesoscale Discussion 1240

June 30, 20156 states

The Storm Prediction Center issued this mesoscale discussion at Jun 30, 2015, 12:31 PM EDT for 6 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jun 30, 2015, 12:31 PM EDT (16:31 UTC)
Expired
Jun 30, 2015, 3:00 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 59 counties

New Castle County, DE, Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Queen Anne's County, MD, Washington County, MD, Hunterdon County, NJ, Morris County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Orange County, NY, Sullivan County, NY, Adams County, PA, Berks County, PA, Bradford County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA, York County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, Fairfax County, VA

The radar

The State College radar (KCCX), 144 km from the middle of the area, began a volume at 16:31 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.

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 4.5 hours before the alert went out and 119 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, Phillips Aaf/Abe, MD at 12:00Z on 2015-06-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 600 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, Phillips Aaf/Abe, MD at 12:00Z on 2015-06-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 128 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
600 J/kg
Mixed-layer CIN
-45 J/kg
Mixed-layer LCL
728 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
128 m²/s²
0-3 km storm-relative helicity
128 m²/s²
Significant tornado parameter
0.3
Supercell composite
2.9

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
Jun 30, 1:21 PM EDTSevere Thunderstorm WatchSPCKent, New Castle7 hr
Jun 30, 4:15 PM EDTMesoscale DiscussionSPCKent, New Castle2 hr
Jun 30, 12:58 PM EDTSevere Thunderstorm WatchSPCGarrett8 hr
Jun 30, 1:38 PM EDTMesoscale DiscussionSPCCharles, Saint Mary's3 hr
Jun 30, 2:22 PM EDTSevere Thunderstorm WatchSPCAllegany, Calvert, Charles, Montgomery, Prince George's, Saint Mary's7 hr
Jun 30, 3:34 PM EDTSevere Thunderstorm WatchSPCDorchester6 hr
Jun 30, 3:48 PM EDTMesoscale DiscussionSPCAllegany, Garrett, Washington117 min
Jun 30, 7:38 PM EDTMesoscale DiscussionSPCAllegany, Garrett67 min
Jun 30, 2:57 PM EDTMesoscale DiscussionSPCWarren63 min
Jun 30, 3:18 PM EDTMesoscale DiscussionSPCAllegany, Cayuga, Chemung, Chenango, Cortland, Livingston and 8 more2 hr
Jun 30, 12:03 PM EDTMesoscale DiscussionSPCAllegheny, Beaver, Greene, Lawrence, Washington2 hr
Jun 30, 12:55 PM EDTMesoscale DiscussionSPCAlbemarle, Alleghany, Amherst, Augusta, Bath, Bedford and 50 more3 hr
Jun 30, 1:37 PM EDTSevere Thunderstorm WatchSPCBuchanan, Dickenson, Lee, Russell, Scott, Washington and 3 more7 hr
Jun 30, 7:08 PM EDTMesoscale DiscussionSPCBland, Buchanan, Dickenson, Grayson, Lee, Russell and 9 more67 min
Jun 30, 7:22 PM EDTMesoscale DiscussionSPCBrunswick, Dinwiddie, Greensville, Southampton, Sussex, City of Emporia and 2 more83 min

Nearby

Mesoscale Discussions in Pennsylvania, 2015Mesoscale Discussions in Maryland, 2015Mesoscale Discussions in New Jersey, 2015Every mesoscale discussion in 2015

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.