Alert archive / Pennsylvania / Mesoscale Discussions in 2015

Mesoscale Discussion 1339

July 9, 20154 states

The Storm Prediction Center issued this mesoscale discussion at Jul 9, 2015, 12:59 PM EDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 9, 2015, 12:59 PM EDT (16:59 UTC)
Expired: Jul 9, 2015, 3:00 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 95%

All 61 counties

Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Garrett County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Washington County, MD, Adams County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Cambria County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Fayette County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Monroe County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Union County, PA, Westmoreland County, PA, Wyoming County, PA, York County, PA, City of Winchester, VA, Clarke County, VA, Frederick County, VA, Loudoun County, VA, Berkeley County, WV, Hampshire County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV

The radar

The State College radar (KCCX), 97 km from the middle of the area, began a volume at 17:03 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.0 hours before the alert went out and 184 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: 1 J/kg
Mixed-layer CIN: -194 J/kg
Mixed-layer LCL: 1091 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: -19 m²/s²
0-3 km storm-relative helicity: -2 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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.

Issued	Product	Office	Counties	Lasted
Jul 9, 11:27 AM EDT	Mesoscale Discussion	SPC	Garrett	2 hr
Jul 9, 1:27 PM EDT	Tornado Watch	SPC	Allegany, Baltimore, Carroll, Frederick, Garrett, Harford and 2 more	6 hr
Jul 9, 3:09 PM EDT	Mesoscale Discussion	SPC	Allegany, Anne Arundel, Baltimore, Caroline, Carroll, Cecil and 10 more	96 min
Jul 9, 4:55 PM EDT	Mesoscale Discussion	SPC	Allegany, Baltimore, Carroll, Cecil, Frederick, Garrett and 5 more	95 min
Jul 9, 4:57 PM EDT	Severe Thunderstorm Watch	SPC	Caroline, Cecil, Kent, Queen Anne's, Talbot	5 hr
Jul 9, 6:25 PM EDT	Mesoscale Discussion	SPC	Cecil, Harford	95 min
Jul 9, 7:04 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Caroline, Charles, Dorchester, Prince George's and 6 more	86 min
Jul 9, 12:15 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson, Lee, Wise, City of Norton	3 hr
Jul 9, 5:58 PM EDT	Mesoscale Discussion	SPC	Bland, Buchanan, Dickenson, Russell, Smyth, Tazewell and 2 more	2 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2015 Mesoscale Discussions in Maryland, 2015 Mesoscale Discussions in West Virginia, 2015 Every 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.