Alert archive / Pennsylvania / Tornado Watches in 2019
Tornado Watch 686
The Storm Prediction Center issued this tornado watch at Oct 31, 2019, 2:56 PM EDT for 4 states. It was in force for 10 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 31, 2019, 2:56 PM EDT (18:56 UTC)
- Expired
- Nov 1, 2019, 12:45 AM EDT
- In force
- 10 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 65 kt
All 96 counties
Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Garrett County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Washington County, MD, Adams County, PA, Armstrong County, PA, Bedford County, PA, Blair County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Elk County, PA, Fayette County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lycoming County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Union County, PA, Westmoreland County, PA, York County, PA, Albemarle County, VA, Arlington County, VA, Augusta 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, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page 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, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Marion County, WV, Mineral County, WV, Monongalia County, WV, Morgan County, WV, Pendleton County, WV, Preston County, WV, Tucker County, WV
The radar
The Sterling radar (KLWX), 99 km from the middle of the area, began a volume at 18:58 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
- 60%
- One or more EF2 to EF5 tornadoes
- 30%
- Ten or more severe wind reports
- 90%
- One or more gusts of 65 knots or more
- 40%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 95%
Warnings issued inside it
33 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 31, 4:10 PM EDT | Severe Thunderstorm Warning | LWX | Grant, Hampshire, Hardy, Mineral | 50 min |
| Oct 31, 4:27 PM EDT | Severe Thunderstorm Warning | PBZ | Indiana | 48 min |
| Oct 31, 4:41 PM EDT | Severe Thunderstorm Warning | LWX | Highland | 49 min |
| Oct 31, 4:56 PM EDT | Severe Thunderstorm Warning | LWX | Allegany, Washington | 49 min |
| Oct 31, 5:05 PM EDT | Tornado Warning | LWX | Allegany, Washington | 25 min |
| Oct 31, 5:42 PM EDT | Severe Thunderstorm Warning | CTP | Franklin, Fulton | 48 min |
| Oct 31, 5:45 PM EDT | Severe Thunderstorm Warning | LWX | Frederick | 45 min |
| Oct 31, 6:27 PM EDT | Severe Thunderstorm Warning | CTP | Adams, Cumberland, Franklin, Perry | 63 min |
| Oct 31, 6:46 PM EDT | Severe Thunderstorm Warning | LWX | Frederick, Washington | 44 min |
| Oct 31, 7:04 PM EDT | Tornado Warning | LWX | Greene, Madison, Orange | 26 min |
| Oct 31, 7:06 PM EDT | Severe Thunderstorm Warning | CTP | Clinton | 13 min |
| Oct 31, 7:08 PM EDT | Severe Thunderstorm Warning | CTP | Adams, Cumberland, Dauphin, Franklin, Juniata, Lebanon and 4 more | 67 min |
| Oct 31, 7:13 PM EDT | Severe Thunderstorm Warning | CTP | Lycoming | 62 min |
| Oct 31, 7:19 PM EDT | Severe Thunderstorm Warning | LWX | Culpeper, Fauquier, Madison, Rappahannock | 26 min |
| Oct 31, 7:24 PM EDT | Severe Thunderstorm Warning | LWX | Carroll, Frederick, Howard, Montgomery | 51 min |
| Oct 31, 8:05 PM EDT | Severe Thunderstorm Warning | CTP | Adams, Dauphin, Lancaster, Lebanon, Schuylkill, York | 85 min |
| Oct 31, 8:27 PM EDT | Severe Thunderstorm Warning | LWX | Culpeper, Fauquier, Madison, Orange, Stafford | 33 min |
| Oct 31, 8:32 PM EDT | Severe Thunderstorm Warning | LWX | Carroll, Howard, Montgomery | 28 min |
| Oct 31, 8:49 PM EDT | Flash Flood Warning | CTP | Adams, Cumberland, Dauphin, Lebanon, York | 3 hr |
| Oct 31, 9:08 PM EDT | Severe Thunderstorm Warning | LWX | Montgomery | 37 min |
| Oct 31, 9:20 PM EDT | Severe Thunderstorm Warning | LWX | Howard, Montgomery | 25 min |
| Oct 31, 9:24 PM EDT | Severe Thunderstorm Warning | LWX | Prince William, Stafford, City of Fredericksburg | 36 min |
| Oct 31, 9:37 PM EDT | Flash Flood Warning | LWX | Montgomery | 3 hr |
| Oct 31, 10:07 PM EDT | Severe Thunderstorm Warning | LWX | Montgomery, Prince George's | 38 min |
| Oct 31, 10:14 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Harford | 46 min |
| Oct 31, 10:25 PM EDT | Severe Thunderstorm Warning | CTP | Lancaster | 50 min |
| Oct 31, 10:26 PM EDT | Flash Flood Warning | CTP | Lancaster, York | 3 hr |
| Oct 31, 10:40 PM EDT | Flash Flood Warning | LWX | Baltimore, City of Baltimore | 101 min |
| Oct 31, 10:41 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel, Baltimore, Prince George's | 49 min |
| Oct 31, 10:56 PM EDT | Severe Thunderstorm Warning | LWX | Charles | 34 min |
| Oct 31, 11:10 PM EDT | Severe Thunderstorm Warning | LWX | Calvert, Charles, Saint Mary's | 50 min |
| Oct 31, 11:22 PM EDT | Severe Thunderstorm Warning | LWX | Saint Mary's | 38 min |
| Oct 31, 11:23 PM EDT | Severe Thunderstorm Warning | LWX | Calvert | 22 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, 6.9 hours before the alert went out and 107 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
- 489 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 280 m²/s²
- 0-3 km storm-relative helicity
- 246 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
655
WWUS20 KWNS 311854
SEL6
SPC WW 311854
DCZ000-MDZ000-PAZ000-VAZ000-WVZ000-CWZ000-010400-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 686
NWS Storm Prediction Center Norman OK
255 PM EDT Thu Oct 31 2019
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
District Of Columbia
Maryland
Pennsylvania
Northern Virginia
Eastern West Virginia Panhandle
Coastal Waters
* Effective this Thursday afternoon from 255 PM until Midnight
EDT.
* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Widespread damaging winds likely with isolated significant gusts
to 75 mph possible
SUMMARY...Fast-moving squall line over West Virginia should
intensify and elongate as it pushes to the east of the Appalachians.
The risk for damaging winds and embedded tornadoes will increase
through early to mid evening, before waning later tonight.
The tornado watch area is approximately along and 90 statute miles
east and west of a line from 60 miles west southwest of Washington
DC to 30 miles north of State College PA. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU6).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 685...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 0.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 400. Mean
storm motion vector 22045.
...GramsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 31, 11:12 AM EDT | Mesoscale Discussion | SPC | Garrett | 2 hr |
| Oct 31, 1:11 PM EDT | Mesoscale Discussion | SPC | Allegany, Frederick, Montgomery, Washington | 3 hr |
| Oct 31, 4:01 PM EDT | Mesoscale Discussion | SPC | Baltimore, Carroll, Frederick, Howard, Montgomery, Washington and 1 more | 119 min |
| Oct 31, 7:14 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles and 10 more | 2 hr |
| Oct 31, 7:56 PM EDT | Severe Thunderstorm Watch | SPC | Caroline, Cecil, Kent, Queen Anne's, Talbot | 6 hr |
| Oct 31, 4:46 PM EDT | Mesoscale Discussion | SPC | Bradford, Lackawanna, Pike, Susquehanna, Wayne | 119 min |
| Oct 31, 6:16 PM EDT | Severe Thunderstorm Watch | SPC | Bradford, Lackawanna, Luzerne, Pike, Susquehanna, Wayne and 1 more | 8 hr |
| Oct 31, 12:45 PM EDT | Tornado Watch | SPC | Bland, Buchanan, Dickenson, Giles, Grayson, Pulaski and 10 more | 4 hr |
| Oct 31, 3:16 PM EDT | Tornado Watch | SPC | Alleghany, Amelia, Amherst, Appomattox, Bath, Bedford and 56 more | 8 hr |
| Oct 31, 6:36 PM EDT | Mesoscale Discussion | SPC | Amelia, Appomattox, Brunswick, Buckingham, Campbell, Charles City and 32 more | 114 min |
Nearby
Tornado Watches in Pennsylvania, 2019Tornado Watches in Virginia, 2019Tornado Watches in Maryland, 2019Every tornado watch 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.