Alert archive / Pennsylvania / Tornado Watches in 2020

Tornado Watch 119

April 13, 20206 states

The Storm Prediction Center issued this tornado watch at Apr 13, 2020, 11:33 AM EDT for 6 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: Apr 13, 2020, 11:33 AM EDT (15:33 UTC)
Expired: Apr 13, 2020, 4:54 PM EDT
In force: 5 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 99 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Talbot County, MD, Washington County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Adams County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Bucks County, PA, Cambria County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming 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, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Union County, PA, York County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, King George County, VA, Loudoun County, VA, Orange County, VA, Prince William County, VA, Rappahannock County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Jefferson County, WV, Morgan County, WV

The radar

The Philadelphia radar (KDIX), 139 km from the middle of the area, began a volume at 15:33 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 60%
One or more gusts of 65 knots or more: 20%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 10%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

35 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Apr 13, 11:48 AM EDT	Severe Thunderstorm Warning	CTP	Cambria, Clearfield, Somerset	72 min
Apr 13, 11:54 AM EDT	Severe Thunderstorm Warning	LWX	Washington	51 min
Apr 13, 12:07 PM EDT	Tornado Warning	LWX	Baltimore, Howard, City of Baltimore	23 min
Apr 13, 12:14 PM EDT	Tornado Warning	LWX	Prince William, Stafford	31 min
Apr 13, 12:16 PM EDT	Severe Thunderstorm Warning	CTP	Bedford, Franklin, Fulton	44 min
Apr 13, 12:27 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Frederick, Shenandoah, City of Winchester	36 min
Apr 13, 12:32 PM EDT	Severe Thunderstorm Warning	CTP	Franklin, Fulton	58 min
Apr 13, 12:42 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Washington	48 min
Apr 13, 12:45 PM EDT	Severe Thunderstorm Warning	CTP	Blair, Cambria, Centre, Clearfield, Huntingdon	45 min
Apr 13, 12:46 PM EDT	Severe Thunderstorm Warning	LWX	Prince George's	44 min
Apr 13, 12:52 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster, York	38 min
Apr 13, 1:06 PM EDT	Severe Thunderstorm Warning	CTP	Adams	53 min
Apr 13, 1:07 PM EDT	Flash Flood Warning	PHI	Berks, Carbon, Lehigh, Northampton	4 hr
Apr 13, 1:18 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Prince George's	42 min
Apr 13, 1:20 PM EDT	Severe Thunderstorm Warning	LWX	Carroll, Frederick, Howard, Montgomery, Washington	40 min
Apr 13, 1:25 PM EDT	Severe Thunderstorm Warning	CTP	Centre, Clinton, Huntingdon, Mifflin	50 min
Apr 13, 1:27 PM EDT	Severe Thunderstorm Warning	PHI	Chester	33 min
Apr 13, 1:37 PM EDT	Severe Thunderstorm Warning	CTP	Adams, York	68 min
Apr 13, 1:47 PM EDT	Flash Flood Warning	PHI	Chester	3 hr
Apr 13, 1:48 PM EDT	Severe Thunderstorm Warning	LWX	Montgomery	42 min
Apr 13, 2:00 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Carroll, Harford	45 min
Apr 13, 2:01 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Carroll, Howard, Montgomery	44 min
Apr 13, 2:04 PM EDT	Severe Thunderstorm Warning	CTP	Centre, Clinton, Juniata, Lycoming, Mifflin, Perry and 2 more	41 min
Apr 13, 2:13 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster	58 min
Apr 13, 2:18 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Howard, Montgomery, Prince George's	27 min
Apr 13, 2:24 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Baltimore, Howard, Montgomery, Prince George's, City of Baltimore	51 min
Apr 13, 2:27 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Harford	48 min
Apr 13, 2:35 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Montgomery, Prince George's	40 min
Apr 13, 2:41 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	64 min
Apr 13, 2:50 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	55 min
Apr 13, 3:22 PM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	38 min
Apr 13, 3:26 PM EDT	Tornado Warning	PHI	Kent	13 min
Apr 13, 3:40 PM EDT	Severe Thunderstorm Warning	PHI	Kent	65 min
Apr 13, 3:45 PM EDT	Tornado Warning	PHI	Kent	15 min
Apr 13, 4:13 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Cape May, Cumberland	31 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 3.6 hours before the alert went out and 170 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: 712 m above ground
0-6 km bulk shear: 75 kt
0-1 km storm-relative helicity: 487 m²/s²
0-3 km storm-relative helicity: 684 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 13, 10:34 AM EDT	Mesoscale Discussion	SPC	New Castle	86 min
Apr 13, 1:20 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	85 min
Apr 13, 3:03 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle	87 min
Apr 13, 6:46 AM EDT	Mesoscale Discussion	SPC	Somerset	89 min
Apr 13, 2:42 PM EDT	Mesoscale Discussion	SPC	Bergen, Passaic, Sussex	93 min
Apr 13, 4:40 AM EDT	Mesoscale Discussion	SPC	Amelia, Brunswick, Buckingham, Charles City, Charlotte, Chesterfield and 42 more	95 min
Apr 13, 5:01 AM EDT	Tornado Watch	SPC	Amelia, Appomattox, Brunswick, Buckingham, Campbell, Charles City and 36 more	7 hr

Nearby

Tornado Watches in Pennsylvania, 2020 Tornado Watches in Virginia, 2020 Tornado Watches in Maryland, 2020 Every tornado watch in 2020

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.