Alert archive / Virginia / Severe Thunderstorm Watches in 2018
Severe Thunderstorm Watch 314
The Storm Prediction Center issued this severe thunderstorm watch at Jul 27, 2018, 1:52 PM EDT for 18 counties in Maryland; 47 counties in Virginia; 8 counties in West Virginia. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 27, 2018, 1:52 PM EDT (17:52 UTC)
- Expired
- Jul 27, 2018, 8:58 PM EDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 55 kt
All 73 counties
Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Somerset County, MD, Washington County, MD, Wicomico County, MD, Worcester County, MD, Accomack County, VA, Albemarle County, VA, Arlington County, VA, Augusta County, VA, Caroline 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, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Highland County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Nelson County, VA, Northumberland County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Pendleton County, WV
The radar
The Sterling radar (KLWX), 23 km from the middle of the area, began a volume at 17:52 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
- 5%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 40%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
18 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 27, 2:23 PM EDT | Severe Thunderstorm Warning | LWX | Fauquier, Prince William, City of Manassas, City of Manassas Park | 29 min |
| Jul 27, 2:42 PM EDT | Severe Thunderstorm Warning | LWX | Charles | 23 min |
| Jul 27, 2:44 PM EDT | Flash Flood Warning | LWX | Saint Mary's | 4 hr |
| Jul 27, 2:49 PM EDT | Severe Thunderstorm Warning | LWX | Grant, Hampshire, Hardy, Mineral | 19 min |
| Jul 27, 3:09 PM EDT | Severe Thunderstorm Warning | LWX | Charles, Saint Mary's | 31 min |
| Jul 27, 3:45 PM EDT | Severe Thunderstorm Warning | LWX | Saint Mary's | 30 min |
| Jul 27, 4:15 PM EDT | Severe Thunderstorm Warning | AKQ | Dorchester, Somerset, Wicomico | 45 min |
| Jul 27, 4:31 PM EDT | Severe Thunderstorm Warning | LWX | Frederick, Washington | 59 min |
| Jul 27, 4:52 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Carroll | 38 min |
| Jul 27, 5:01 PM EDT | Severe Thunderstorm Warning | LWX | Carroll, Frederick, Howard, Montgomery | 44 min |
| Jul 27, 5:02 PM EDT | Severe Thunderstorm Warning | LWX | Fairfax, Fauquier, Loudoun, Prince William, City of Manassas, City of Manassas Park | 23 min |
| Jul 27, 5:17 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel, Baltimore, Howard, City of Baltimore | 28 min |
| Jul 27, 5:25 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Carroll | 20 min |
| Jul 27, 5:38 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Harford, City of Baltimore | 47 min |
| Jul 27, 5:42 PM EDT | Flash Flood Warning | LWX | Baltimore, City of Baltimore | 3 hr |
| Jul 27, 5:46 PM EDT | Flash Flood Warning | LWX | Baltimore, Harford | 4 hr |
| Jul 27, 6:36 PM EDT | Severe Thunderstorm Warning | LWX | Culpeper, Madison, Orange | 39 min |
| Jul 27, 7:05 PM EDT | Severe Thunderstorm Warning | LWX | Orange, Spotsylvania | 40 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, 5.9 hours before the alert went out and 16 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
- 958 J/kg
- Mixed-layer CIN
- -54 J/kg
- Mixed-layer LCL
- 1053 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 7 m²/s²
- 0-3 km storm-relative helicity
- 34 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 27, 1:17 PM EDT | Severe Thunderstorm Watch | SPC | Caroline, Cecil, Kent, Queen Anne's, Talbot | 9 hr |
| Jul 27, 1:28 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Charles, Frederick, Howard, Montgomery, Prince George's | 62 min |
| Jul 27, 4:50 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 13 more | 55 min |
| Jul 27, 7:06 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Caroline, Cecil, Charles and 13 more | 54 min |
Nearby
Severe Thunderstorm Watches in Virginia, 2018Severe Thunderstorm Watches in Maryland, 2018Severe Thunderstorm Watches in West Virginia, 2018Every severe thunderstorm watch 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.