Alert archive / Maryland / Tornado Warnings in 2021

Tornado Warning 25, NWS Baltimore/Washington

August 18, 2021Frederick County, Washington County, Maryland

NWS Baltimore/Washington issued this tornado warning at Aug 18, 2021, 5:26 PM EDT for Frederick County, Washington County, Maryland. It was in force for 17 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 18, 2021, 5:26 PM EDT (21:26 UTC)
Expired: Aug 18, 2021, 5:43 PM EDT
In force: 17 min
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Frederick County, MD, Washington County, MD

The radar

The Sterling radar (KLWX), 78 km from the middle of the area, began a volume at 21:29 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 18, 11:37 AM EDT	Tornado Watch	SPC	11 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.4 hours before the alert went out and 81 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1011 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 592 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 151 m²/s²
0-3 km storm-relative helicity: 175 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 4.6

Open this sounding in Storm Lab

The text

As transmitted.

392 
WFUS51 KLWX 182126
TORLWX
MDC021-043-182200-
/O.NEW.KLWX.TO.W.0025.210818T2126Z-210818T2200Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Baltimore MD/Washington DC
526 PM EDT Wed Aug 18 2021

The National Weather Service in Sterling Virginia has issued a

* Tornado Warning for...
  Northeastern Washington County in north central Maryland...
  Northwestern Frederick County in north central Maryland...

* Until 600 PM EDT.
    
* At 526 PM EDT, a severe thunderstorm capable of producing a tornado
  was located near Rouzerville, or near Thurmont, moving east at 35
  mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...For those in the direct path of a tornado touchdown, 
           flying debris will be dangerous to those caught without 
           shelter. Damage to roofs, siding, and windows may occur. 
           Mobile homes may be damaged or destroyed. Tree damage is 
           likely.

* This dangerous storm will be near...
  Emmitsburg around 540 PM EDT.

Other locations impacted by this tornadic thunderstorm include
Sabillasville, Cascade and Fort Ritchie.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 3966 7728 3962 7756 3969 7757 3972 7747
      3972 7724
TIME...MOT...LOC 2126Z 253DEG 29KT 3968 7749 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

KLW

2 follow-up statements

890 
WWUS51 KLWX 182137
SVSLWX

Severe Weather Statement
National Weather Service Baltimore MD/Washington DC
537 PM EDT Wed Aug 18 2021

MDC043-182146-
/O.CAN.KLWX.TO.W.0025.000000T0000Z-210818T2200Z/
Washington MD-
537 PM EDT Wed Aug 18 2021

...THE TORNADO WARNING FOR NORTHEASTERN WASHINGTON COUNTY IS
CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 800 PM EDT for north central
Maryland.

LAT...LON 3967 7727 3966 7743 3972 7745 3972 7724
TIME...MOT...LOC 2136Z 255DEG 24KT 3969 7741 

$$

MDC021-182200-
/O.CON.KLWX.TO.W.0025.000000T0000Z-210818T2200Z/
Frederick MD-
537 PM EDT Wed Aug 18 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 600 PM EDT FOR NORTH
CENTRAL FREDERICK COUNTY IN NORTH CENTRAL MARYLAND...
    
At 536 PM EDT, a severe thunderstorm capable of producing a tornado
was located near Carroll Valley, or near Thurmont, moving east at 30
mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

IMPACT...For those in the direct path of a tornado touchdown, flying 
         debris will be dangerous to those caught without shelter. 
         Damage to roofs, siding, and windows may occur. Mobile 
         homes may be damaged or destroyed. Tree damage is likely.

This dangerous storm will be near...
  Emmitsburg around 545 PM EDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 3967 7727 3966 7743 3972 7745 3972 7724
TIME...MOT...LOC 2136Z 255DEG 24KT 3969 7741 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

SMZ

710 
WWUS51 KLWX 182143
SVSLWX

Severe Weather Statement
National Weather Service Baltimore MD/Washington DC
543 PM EDT Wed Aug 18 2021

MDC021-182151-
/O.CAN.KLWX.TO.W.0025.000000T0000Z-210818T2200Z/
Frederick MD-
543 PM EDT Wed Aug 18 2021

...THE TORNADO WARNING FOR NORTH CENTRAL FREDERICK COUNTY IN NORTH
CENTRAL MARYLAND IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 800 PM EDT for north central
Maryland.

Remember, a Severe Thunderstorm Warning still remains in effect for 
portions of Washington, Frederick and Carroll Counties in north 
central Maryland.

LAT...LON 3967 7727 3966 7743 3972 7745 3972 7724
TIME...MOT...LOC 2141Z 253DEG 29KT 3970 7736 

$$

SMZ

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 18, 3:12 PM EDT	Tornado Warning	LWX	Allegany, Washington	16 min
Aug 18, 4:29 PM EDT	Severe Thunderstorm Warning	LWX	Saint Mary's	14 min
Aug 18, 5:13 PM EDT	Severe Thunderstorm Warning	LWX	Carroll, Frederick, Washington	47 min
Aug 18, 6:31 PM EDT	Tornado Warning	LWX	Cecil	29 min
Aug 18, 7:01 PM EDT	Coastal Flood Advisory	LWX	Anne Arundel, Baltimore, Harford, City of Baltimore	14 hr

Nearby

Tornado Warnings in Maryland, 2021 Every tornado warning in 2021 Tornadoes in 2021

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.