Alert archive / Virginia / Mesoscale Discussions in 2019

Mesoscale Discussion 401

April 19, 2019Howard County, Montgomery County, City of Baltimore, Maryland; 39 counties in Virginia; Berkeley County, Jefferson County, West Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2019, 12:08 PM EDT for Howard County, Montgomery County, City of Baltimore, Maryland; 39 counties in Virginia; Berkeley County, Jefferson County, West Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 19, 2019, 12:08 PM EDT (16:08 UTC)
Expired
Apr 19, 2019, 2:15 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
80%
All 44 counties

City of Baltimore, MD, Howard County, MD, Montgomery County, MD, Albemarle County, VA, Amelia County, VA, Arlington County, VA, Augusta County, VA, Buckingham County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince William County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Jefferson County, WV

The radar

The Sterling radar (KLWX), 93 km from the middle of the area, began a volume at 16:07 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, 4.1 hours before the alert went out and 97 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 2019-04-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 7 joules per kilogram.LCLLFCEL10008507005003002001001 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 2019-04-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 209 square meters per square second.19395878Sfc1 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
7 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
781 m above ground
0-6 km bulk shear
43 kt
0-1 km storm-relative helicity
209 m²/s²
0-3 km storm-relative helicity
191 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
Apr 19, 12:48 PM EDTTornado WatchSPCAnne Arundel, Baltimore, Calvert, Carroll, Charles, Frederick and 7 more9 hr
Apr 19, 1:17 PM EDTTornado WatchSPCDorchester, Somerset, Wicomico, Worcester11 hr
Apr 19, 3:18 PM EDTMesoscale DiscussionSPCSomerset87 min
Apr 19, 4:32 PM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Charles, Frederick, Howard, Kent and 3 more58 min
Apr 19, 6:21 PM EDTMesoscale DiscussionSPCCharles, Frederick, Montgomery, Prince George's84 min
Apr 19, 10:06 AM EDTMesoscale DiscussionSPCFloyd, Franklin, Henry, Patrick, Pittsylvania, City of Danville and 2 more84 min
Apr 19, 10:31 AM EDTTornado WatchSPCAlleghany, Amherst, Appomattox, Bath, Bedford, Bland and 29 more9 hr
Apr 19, 12:29 PM EDTMesoscale DiscussionSPCBrunswick, Caroline, Charles City, Chesterfield, Dinwiddie, Greensville and 19 more2 hr
Apr 19, 1:40 PM EDTMesoscale DiscussionSPCAmherst, Appomattox, Bedford, Botetourt, Buckingham, Campbell and 18 more2 hr
Apr 19, 4:35 PM EDTMesoscale DiscussionSPCAppomattox, Brunswick, Campbell, Charlotte, Dinwiddie, Greensville and 9 more55 min

Nearby

Mesoscale Discussions in Virginia, 2019Mesoscale Discussions in Maryland, 2019Mesoscale Discussions in West Virginia, 2019Every mesoscale discussion in 2019

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.