Alert archive / Pennsylvania / Tornado Warnings in 2021
Tornado Warning 31, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this tornado warning at Aug 19, 2021, 12:47 AM EDT for 4 counties in Pennsylvania. It was in force for 28 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 19, 2021, 12:47 AM EDT (04:47 UTC)
- Expired
- Aug 19, 2021, 1:15 AM EDT
- In force
- 28 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Tornado
- Radar indicated
- Hail
- 0.75 in
Counties Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 84 km from the middle of the area, began a volume at 04:48 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 nearest sounding before it
Washington/Dulle, VA (KIAD), launched 00:00Z, 4.8 hours before the alert went out and 215 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
- 1288 J/kg
- Mixed-layer CIN
- -8 J/kg
- Mixed-layer LCL
- 1100 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 126 m²/s²
- 0-3 km storm-relative helicity
- 171 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 5.9
The text
As transmitted.
392
WFUS51 KPHI 190447
TORPHI
PAC029-045-091-101-190515-
/O.NEW.KPHI.TO.W.0031.210819T0447Z-210819T0515Z/
BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Mount Holly NJ
1247 AM EDT Thu Aug 19 2021
The National Weather Service in Mount Holly NJ has issued a
* Tornado Warning for...
South central Montgomery County in southeastern Pennsylvania...
East central Chester County in southeastern Pennsylvania...
Northwestern Philadelphia County in southeastern Pennsylvania...
Northern Delaware County in southeastern Pennsylvania...
* Until 115 AM EDT.
* At 1247 AM EDT, a severe thunderstorm capable of producing a
tornado was located over King Of Prussia, or 12 miles northeast of
West Chester, moving northeast at 10 mph.
HAZARD...Tornado.
SOURCE...Radar indicated rotation.
IMPACT...Flying debris will be dangerous to those caught without
shelter. Mobile homes will be damaged or destroyed.
Damage to roofs, windows, and vehicles will occur. Tree
damage is likely.
* Locations impacted include...
Philadelphia, Norristown, West Norriton, East Norriton,
Conshohocken, Plymouth Meeting, King Of Prussia, Valley Forge,
Radnor Township, Bridgeport, West Conshohocken, Audubon, Blue Bell,
Chesterbrook, Flourtown, Devon-Berwyn, Trooper and Wyndmoor.
This includes the following highways...
Pennsylvania Turnpike between mile markers 323 and 336.
Northeast Extension between mile markers 21 and 27.
Interstate 76 in Pennsylvania between mile markers 327 and 334.
Interstate 476 in Pennsylvania between mile markers 15 and 19.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!
Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!
&&
LAT...LON 4003 7544 4008 7549 4022 7532 4008 7518
TIME...MOT...LOC 0447Z 239DEG 9KT 4007 7542
TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
$$
SFJ2 follow-up statements
330
WWUS51 KPHI 190458
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
1258 AM EDT Thu Aug 19 2021
PAC029-045-190508-
/O.CAN.KPHI.TO.W.0031.000000T0000Z-210819T0515Z/
Chester PA-Delaware PA-
1258 AM EDT Thu Aug 19 2021
...THE TORNADO WARNING FOR EAST CENTRAL CHESTER AND NORTHERN DELAWARE
COUNTIES IS CANCELLED...
The tornadic thunderstorm which prompted the warning has moved out
of the warned area. Therefore, the warning has been cancelled.
LAT...LON 4022 7532 4008 7518 4006 7535 4007 7536
4006 7538 4007 7540 4010 7542
TIME...MOT...LOC 0458Z 239DEG 11KT 4009 7537
$$
PAC091-101-190515-
/O.CON.KPHI.TO.W.0031.000000T0000Z-210819T0515Z/
Montgomery PA-Philadelphia PA-
1258 AM EDT Thu Aug 19 2021
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 115 AM EDT FOR SOUTH
CENTRAL MONTGOMERY AND NORTHWESTERN PHILADELPHIA COUNTIES...
At 1258 AM EDT, a severe thunderstorm capable of producing a tornado
was located over King Of Prussia, or 13 miles northwest of
Philadelphia, moving northeast at 15 mph.
HAZARD...Tornado.
SOURCE...Radar indicated rotation.
IMPACT...Flying debris will be dangerous to those caught without
shelter. Mobile homes will be damaged or destroyed. Damage
to roofs, windows, and vehicles will occur. Tree damage is
likely.
Locations impacted include...
Philadelphia, Norristown, West Norriton, East Norriton, Conshohocken,
King Of Prussia, Plymouth Meeting, Bridgeport, West Conshohocken,
Blue Bell, Flourtown and Wyndmoor.
This includes the following highways...
Pennsylvania Turnpike between mile markers 327 and 336.
Northeast Extension between mile markers 21 and 27.
Interstate 76 in Pennsylvania between mile markers 327 and 333.
Interstate 476 in Pennsylvania between mile markers 16 and 19.
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.
Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!
Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!
&&
LAT...LON 4022 7532 4008 7518 4006 7535 4007 7536
4006 7538 4007 7540 4010 7542
TIME...MOT...LOC 0458Z 239DEG 11KT 4009 7537
TORNADO...RADAR INDICATED
MAX HAIL SIZE...0.00 IN
$$
SFJ007
WWUS51 KPHI 190515
SVSPHI
Severe Weather Statement
National Weather Service Mount Holly NJ
115 AM EDT Thu Aug 19 2021
PAC091-101-190525-
/O.EXP.KPHI.TO.W.0031.000000T0000Z-210819T0515Z/
Montgomery PA-Philadelphia PA-
115 AM EDT Thu Aug 19 2021
...THE TORNADO WARNING FOR SOUTH CENTRAL MONTGOMERY AND NORTHWESTERN
PHILADELPHIA COUNTIES HAS EXPIRED...
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning has
been allowed to expire.
LAT...LON 4022 7532 4008 7518 4006 7535 4007 7536
4006 7538 4007 7540 4010 7542
TIME...MOT...LOC 0515Z 239DEG 9KT 4011 7532
$$
MeolaThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 8:53 PM EDT | Areal Flood Advisory | PHI | Berks | 3 hr |
| Aug 18, 9:10 PM EDT | Areal Flood Advisory | PHI | Lehigh, Monroe, Northampton | 3 hr |
| Aug 18, 9:30 PM EDT | Flash Flood Warning | PHI | Berks | 2 hr |
| Aug 18, 9:35 PM EDT | Areal Flood Advisory | PHI | Berks, Lehigh | 3 hr |
| Aug 18, 9:45 PM EDT | Areal Flood Advisory | PHI | Berks | 3 hr |
| Aug 18, 9:47 PM EDT | Special Weather Statement | PHI | Berks | 58 min |
| Aug 18, 10:16 PM EDT | Flash Flood Warning | PHI | Berks, Lehigh | 3 hr |
| Aug 18, 10:44 PM EDT | Flash Flood Warning | PHI | Lehigh, Monroe, Northampton | 4 hr |
| Aug 18, 10:50 PM EDT | Flash Flood Warning | PHI | Bucks, Chester, Montgomery | 4 hr |
| Aug 18, 11:19 PM EDT | Areal Flood Advisory | PHI | Bucks, Lehigh, Northampton | 3 hr |
| Aug 18, 11:19 PM EDT | Special Weather Statement | PHI | Bucks, Chester, Montgomery | 41 min |
| Aug 18, 11:47 PM EDT | Flash Flood Warning | PHI | Chester | 2 hr |
| Aug 19, 12:04 AM EDT | Special Weather Statement | PHI | Bucks, Delaware, Montgomery | 71 min |
| Aug 19, 12:26 AM EDT | Tornado Warning | PHI | Bucks, Montgomery | 34 min |
| Aug 19, 12:31 AM EDT | Flash Flood Warning | PHI | Bucks, Chester, Delaware, Montgomery | 4 hr |
| Aug 19, 12:44 AM EDT | River Flood Warning | PHI | Chester | 5 hr |
| Aug 19, 12:48 AM EDT | Tornado Warning | PHI | Bucks | 27 min |
| Aug 19, 1:14 AM EDT | Special Weather Statement | PHI | Bucks, Delaware, Philadelphia | 91 min |
| Aug 19, 1:30 AM EDT | Flash Flood Warning | PHI | Bucks, Delaware, Montgomery, Philadelphia | 4 hr |
| Aug 19, 2:05 AM EDT | Areal Flood Advisory | PHI | Bucks | 3 hr |
| Aug 19, 2:13 AM EDT | Flash Flood Warning | PHI | Bucks, Philadelphia | 4 hr |
| Aug 19, 4:33 AM EDT | Areal Flood Warning | PHI | Chester, Delaware | 4 hr |
| Aug 19, 6:09 AM EDT | Areal Flood Warning | PHI | Bucks, Philadelphia | 3 hr |
| Aug 19, 8:50 AM EDT | Areal Flood Warning | PHI | Montgomery, Philadelphia | 3 hr |
| Aug 19, 10:40 AM EDT | Areal Flood Warning | PHI | Delaware | 3 hr |
Nearby
Tornado Warnings in Pennsylvania, 2021Every tornado warning in 2021Tornadoes 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.