Alert archive / Virginia / Severe Thunderstorm Watches in 2017
Severe Thunderstorm Watch 133
The Storm Prediction Center issued this severe thunderstorm watch at Apr 6, 2017, 12:45 PM EDT for 5 states. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 6, 2017, 12:45 PM EDT (16:45 UTC)
- Expired
- Apr 6, 2017, 5:00 PM EDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 60 kt
All 46 counties
Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, 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, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia 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, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, King George County, VA, Loudoun County, VA, Orange County, VA, Prince William County, VA, Spotsylvania County, VA, Stafford County, VA
The radar
The Sterling radar (KLWX), 74 km from the middle of the area, began a volume at 16:46 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
- 20%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 6, 1:08 PM EDT | Severe Thunderstorm Warning | PHI | Kent, New Castle, Sussex | 40 min |
| Apr 6, 1:12 PM EDT | Severe Thunderstorm Warning | LWX | Montgomery, Prince George's | 48 min |
| Apr 6, 1:26 PM EDT | Tornado Warning | LWX | Montgomery | 19 min |
| Apr 6, 1:57 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Carroll, Howard, Montgomery | 48 min |
| Apr 6, 2:01 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel, Baltimore, Calvert, Howard, Montgomery, Prince George's and 1 more | 44 min |
| Apr 6, 2:48 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Harford | 27 min |
| Apr 6, 4:18 PM EDT | Severe Thunderstorm Warning | LWX | Calvert, Charles, Prince George's, Saint Mary's | 27 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, 4.8 hours before the alert went out and 68 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 550 m above ground
- 0-6 km bulk shear
- 75 kt
- 0-1 km storm-relative helicity
- 243 m²/s²
- 0-3 km storm-relative helicity
- 459 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 6, 12:18 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle, Sussex | 57 min |
| Apr 6, 3:12 PM EDT | Mesoscale Discussion | SPC | Kent, New Castle | 63 min |
| Apr 6, 5:59 AM EDT | Mesoscale Discussion | SPC | Calvert, Charles, Dorchester, Saint Mary's | 91 min |
| Apr 6, 7:06 AM EDT | Tornado Watch | SPC | Dorchester, Somerset, Wicomico, Worcester | 8 hr |
| Apr 6, 12:51 AM EDT | Mesoscale Discussion | SPC | Appomattox, Bedford, Campbell, Charlotte, Floyd, Franklin and 8 more | 114 min |
| Apr 6, 10:38 AM EDT | Mesoscale Discussion | SPC | Amelia, Brunswick, Caroline, Charles City, Chesterfield, Dinwiddie and 37 more | 67 min |
Nearby
Severe Thunderstorm Watches in Virginia, 2017Severe Thunderstorm Watches in Maryland, 2017Severe Thunderstorm Watches in New Jersey, 2017Every severe thunderstorm watch in 2017
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.