Alert archive / Pennsylvania / Mesoscale Discussions in 2018

Mesoscale Discussion 68

February 17, 2018Washington County, Maryland; 7 counties in Pennsylvania; Berkeley County, Jefferson County, Morgan County, West Virginia

The Storm Prediction Center issued this mesoscale discussion at Feb 17, 2018, 1:51 PM EST for Washington County, Maryland; 7 counties in Pennsylvania; Berkeley County, Jefferson County, Morgan County, West Virginia. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Feb 17, 2018, 1:51 PM EST (18:51 UTC)
Expired
Feb 17, 2018, 5:45 PM EST
In force
4 hr
Issued by
the Storm Prediction Center

Counties Washington County, MD, Adams County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Fulton County, PA, Juniata County, PA, Perry County, PA, Berkeley County, WV, Jefferson County, WV, Morgan County, WV

The radar

The Sterling radar (KLWX), 108 km from the middle of the area, began a volume at 18:51 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, 6.9 hours before the alert went out and 112 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, Washington/Dulle, VA at 12:00Z on 2018-02-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Washington/Dulle, VA at 12:00Z on 2018-02-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -11 square meters per square second.1939587897117136Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1256 m above ground
0-6 km bulk shear
84 kt
0-1 km storm-relative helicity
-11 m²/s²
0-3 km storm-relative helicity
198 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 17, 6:32 PM ESTMesoscale DiscussionSPCBerks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more4 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2018Mesoscale Discussions in West Virginia, 2018Mesoscale Discussions in Maryland, 2018Every mesoscale discussion in 2018

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.