Alert archive / Pennsylvania / Mesoscale Discussions in 2009

Mesoscale Discussion 121

February 18, 20098 counties in New York; 23 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Feb 18, 2009, 12:38 PM EST for 8 counties in New York; 23 counties in Pennsylvania. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Feb 18, 2009, 12:38 PM EST (17:38 UTC)
Expired: Feb 18, 2009, 3:45 PM EST
In force: 3 hr
Issued by: the Storm Prediction Center

All 31 counties

Allegany County, NY, Broome County, NY, Cattaraugus County, NY, Chemung County, NY, Schuyler County, NY, Steuben County, NY, Tioga County, NY, Tompkins County, NY, Blair County, PA, Bradford County, PA, Cameron County, PA, Centre County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Elk County, PA, Huntingdon County, PA, Juniata County, PA, Lackawanna County, PA, Luzerne County, PA, Lycoming County, PA, McKean County, PA, Mifflin County, PA, Montour County, PA, Potter County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wyoming County, PA

The radar

The State College radar (KCCX), 47 km from the middle of the area, began a volume at 17:41 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 5.6 hours before the alert went out and 225 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1389 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: 151 m²/s²
0-3 km storm-relative helicity: 282 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
Feb 18, 6:28 PM EST	Mesoscale Discussion	SPC	Albany, Columbia, Delaware, Fulton, Greene, Montgomery and 8 more	4 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2009 Mesoscale Discussions in New York, 2009 Every 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.