Alert archive / Pennsylvania / Mesoscale Discussions in 2009
Mesoscale Discussion 1841
The Storm Prediction Center issued this mesoscale discussion at Aug 9, 2009, 2:45 PM EDT for 5 states. It was in force for 60 min.
The area
The outline as issued.
The facts
- Issued
- Aug 9, 2009, 2:45 PM EDT (18:45 UTC)
- Expired
- Aug 9, 2009, 3:45 PM EDT
- In force
- 60 min
- Issued by
- the Storm Prediction Center
All 87 counties
New Castle County, DE, Carroll County, MD, Cecil County, MD, Harford County, MD, Burlington County, NJ, Camden County, NJ, Essex County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Allegany County, NY, Broome County, NY, Cattaraugus County, NY, Cayuga County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Livingston County, NY, Madison County, NY, Oneida County, NY, Onondaga County, NY, Ontario County, NY, Oswego County, NY, Richmond County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Sullivan County, NY, Tioga County, NY, Tompkins County, NY, Wayne County, NY, Yates County, NY, Adams County, PA, Berks County, PA, Blair County, PA, Bradford County, PA, Bucks County, PA, Cameron 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, Delaware County, PA, Elk County, PA, Forest County, PA, Franklin County, PA, Huntingdon County, PA, Jefferson County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, McKean County, PA, Mifflin 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, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Warren County, PA, Wayne County, PA, Wyoming County, PA, York County, PA
The radar
The State College radar (KCCX), 99 km from the middle of the area, began a volume at 18:45 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, 6.8 hours before the alert went out and 234 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
- 255 J/kg
- Mixed-layer CIN
- -88 J/kg
- Mixed-layer LCL
- 1087 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 243 m²/s²
- 0-3 km storm-relative helicity
- 282 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 6.6
The text
As transmitted, in the capitals the NWS used until 2016.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 9, 3:18 PM EDT | Severe Thunderstorm Watch | SPC | New Castle | 5 hr |
| Aug 9, 5:33 PM EDT | Severe Thunderstorm Watch | SPC | Kent, Sussex | 4 hr |
| Aug 9, 7:11 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle, Sussex | 2 hr |
| Aug 9, 11:36 AM EDT | Mesoscale Discussion | SPC | Allegany, Cattaraugus, Chautauqua, Chemung, Erie, Genesee and 10 more | 24 min |
| Aug 9, 11:57 AM EDT | Severe Thunderstorm Watch | SPC | Allegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 21 more | 6 hr |
Nearby
Mesoscale Discussions in Pennsylvania, 2009Mesoscale Discussions in New York, 2009Mesoscale Discussions in New Jersey, 2009Every mesoscale discussion in 2009
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.