Alert archive / Maryland / Severe Thunderstorm Watches in 2020
Severe Thunderstorm Watch 511
The Storm Prediction Center issued this severe thunderstorm watch at Nov 15, 2020, 5:35 PM EST for 5 states. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 15, 2020, 5:35 PM EST (22:35 UTC)
- Expired
- Nov 15, 2020, 10:19 PM EST
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Strongest gust expected
- 60 kt
All 71 counties
Kent County, DE, New Castle County, DE, Sussex County, DE, 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, Dorchester County, 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, Somerset County, MD, Talbot County, MD, Wicomico County, MD, Worcester 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, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Schuylkill County, PA, York County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, 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, Northumberland County, VA, Prince William County, VA, Rappahannock County, VA, Stafford County, VA, Westmoreland County, VA
The radar
The Philadelphia radar (KDIX), 89 km from the middle of the area, began a volume at 22:36 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
- 10%
- One or more EF2 to EF5 tornadoes
- 2%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 20%
- 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
- 60%
Warnings issued inside it
19 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 15, 5:37 PM EST | Severe Thunderstorm Warning | LWX | Carroll, Frederick | 68 min |
| Nov 15, 5:44 PM EST | Severe Thunderstorm Warning | LWX | Clarke, Loudoun | 46 min |
| Nov 15, 5:51 PM EST | Severe Thunderstorm Warning | CTP | Dauphin, Lancaster, Lebanon, York | 84 min |
| Nov 15, 5:57 PM EST | Severe Thunderstorm Warning | PHI | Berks, Carbon, Lehigh, Monroe, Northampton | 78 min |
| Nov 15, 6:22 PM EST | Severe Thunderstorm Warning | LWX | Montgomery | 53 min |
| Nov 15, 6:28 PM EST | Severe Thunderstorm Warning | LWX | Anne Arundel, Baltimore, Carroll, Harford, Howard, City of Baltimore | 92 min |
| Nov 15, 6:44 PM EST | Severe Thunderstorm Warning | PHI | Hunterdon, Morris, Sussex, Warren | 76 min |
| Nov 15, 6:53 PM EST | Severe Thunderstorm Warning | PHI | New Castle | 67 min |
| Nov 15, 6:54 PM EST | Severe Thunderstorm Warning | LWX | Cecil | 66 min |
| Nov 15, 7:20 PM EST | Severe Thunderstorm Warning | LWX | Anne Arundel, Prince George's | 40 min |
| Nov 15, 7:28 PM EST | Severe Thunderstorm Warning | LWX | Anne Arundel, Charles, Prince George's | 47 min |
| Nov 15, 7:31 PM EST | Severe Thunderstorm Warning | PHI | Hunterdon, Mercer, Middlesex, Monmouth, Morris, Somerset and 1 more | 74 min |
| Nov 15, 7:40 PM EST | Severe Thunderstorm Warning | PHI | Kent, New Castle, Sussex | 80 min |
| Nov 15, 7:50 PM EST | Severe Thunderstorm Warning | PHI | New Castle | 70 min |
| Nov 15, 8:16 PM EST | Severe Thunderstorm Warning | LWX | Calvert, Charles, Prince George's, Saint Mary's | 59 min |
| Nov 15, 8:42 PM EST | Severe Thunderstorm Warning | AKQ | Dorchester, Wicomico | 63 min |
| Nov 15, 8:43 PM EST | Severe Thunderstorm Warning | PHI | Monmouth | 47 min |
| Nov 15, 8:54 PM EST | Severe Thunderstorm Warning | PHI | Atlantic, Burlington, Cape May, Cumberland, Monmouth, Ocean | 51 min |
| Nov 15, 8:57 PM EST | Severe Thunderstorm Warning | PHI | Kent, Sussex | 63 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, 10.6 hours before the alert went out and 199 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
- 843 m above ground
- 0-6 km bulk shear
- 59 kt
- 0-1 km storm-relative helicity
- 199 m²/s²
- 0-3 km storm-relative helicity
- 356 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
726 WWUS20 KWNS 152232 SEL1 SPC WW 152232 DCZ000-DEZ000-MDZ000-NJZ000-PAZ000-VAZ000-CWZ000-160400- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 511 NWS Storm Prediction Center Norman OK 530 PM EST Sun Nov 15 2020 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of District Of Columbia Delaware Central and eastern Maryland New Jersey Southeastern Pennsylvania Northeastern Virginia Coastal Waters * Effective this Sunday afternoon and evening from 530 PM until 1100 PM EST. THUNDERSTORM WIND GUSTS TO 70 MPH...and DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 25 miles north northeast of Allentown PA to 50 miles southeast of Washington DC. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU1). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for 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. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 510... AVIATION...A few severe thunderstorms with hail surface and aloft to 0 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 200. Mean storm motion vector 26045. ...Thompson
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 15, 3:33 PM EST | Mesoscale Discussion | SPC | Kent, New Castle, Sussex | 2 hr |
| Nov 15, 6:52 PM EST | Mesoscale Discussion | SPC | Kent, New Castle, Sussex | 113 min |
| Nov 15, 11:33 AM EST | Mesoscale Discussion | SPC | Crawford, Erie, Lawrence, Mercer, Venango | 57 min |
| Nov 15, 11:51 AM EST | Severe Thunderstorm Watch | SPC | Beaver, Butler, Crawford, Erie, Lawrence, Mercer and 1 more | 3 hr |
| Nov 15, 1:16 PM EST | Mesoscale Discussion | SPC | Allegheny, Armstrong, Clarion, Elk, Forest, Indiana and 5 more | 89 min |
| Nov 15, 1:57 PM EST | Severe Thunderstorm Watch | SPC | Allegheny, Armstrong, Cameron, Clarion, Clearfield, Elk and 8 more | 4 hr |
Nearby
Severe Thunderstorm Watches in Maryland, 2020Severe Thunderstorm Watches in New Jersey, 2020Severe Thunderstorm Watches in Virginia, 2020Every severe thunderstorm 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.