Alert archive / Pennsylvania / Mesoscale Discussions in 2017
Mesoscale Discussion 1409
The Storm Prediction Center issued this mesoscale discussion at Jul 23, 2017, 3:44 PM EDT for 5 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 23, 2017, 3:44 PM EDT (19:44 UTC)
- Expired
- Jul 23, 2017, 6:15 PM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 53 counties
Kent County, DE, New Castle County, DE, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Harford County, MD, Kent County, MD, Queen Anne's County, MD, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Allegany County, NY, Chemung County, NY, Livingston County, NY, Ontario County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Tioga County, NY, Tompkins County, NY, Wyoming County, NY, Yates County, NY, Adams County, PA, Berks County, PA, Bradford County, PA, Carbon County, PA, Chester County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Montgomery County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Tioga County, PA, Union County, PA, Wyoming County, PA, York County, PA
The radar
The State College radar (KCCX), 132 km from the middle of the area, began a volume at 19:44 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, 7.7 hours before the alert went out and 215 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.
- Mixed-layer CAPE
- 186 J/kg
- Mixed-layer CIN
- -43 J/kg
- Mixed-layer LCL
- 983 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
- 31 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
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Mesoscale Discussions in Pennsylvania, 2017Mesoscale Discussions in New York, 2017Mesoscale Discussions in Maryland, 2017Every mesoscale discussion in 2017
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.