Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 252, NWS State College, PA

August 18, 2021Lancaster County, Lebanon County, Pennsylvania

NWS State College, PA issued this severe thunderstorm warning at Aug 18, 2021, 8:08 PM EDT for Lancaster County, Lebanon County, Pennsylvania. It was in force for 37 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 18, 2021, 8:08 PM EDT (00:08 UTC)
Expired: Aug 18, 2021, 8:45 PM EDT
In force: 37 min
Issued by: NWS State College, PA
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Lancaster County, PA, Lebanon County, PA

The radar

The Philadelphia radar (KDIX), 156 km from the middle of the area, began a volume at 00:12 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 was reported inside it

Time	Report	Where	Remark
Aug 18, 8:20 PM EDT	TSTM WND DMG	1 Sw Lititz, PA	TREES DOWN ON WIRES SOUTH OF LITITZ.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

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 00:00Z, 0.1 hours before the alert went out and 172 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: 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

Open this sounding in Storm Lab

The text

As transmitted.

981 
WUUS51 KCTP 190008
SVRCTP
PAC071-075-190045-
/O.NEW.KCTP.SV.W.0252.210819T0008Z-210819T0045Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service State College PA
808 PM EDT Wed Aug 18 2021

The National Weather Service in State College PA has issued a

* Severe Thunderstorm Warning for...
  Northeastern Lancaster County in south central Pennsylvania...
  Southeastern Lebanon County in south central Pennsylvania...

* Until 845 PM EDT.

* At 807 PM EDT, a severe thunderstorm was located over Rothsville,
  moving east at 30 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* This severe thunderstorm will be near...
  Akron, Ephrata, Leola and Kleinfeltersville around 810 PM EDT.
  Adamstown, Reamstown, Denver and Terre Hill around 820 PM EDT.

Other locations impacted by this severe thunderstorm include
Goodville, Schoeneck, Bowmansville, Penryn, Fivepointville, Blue
Ball, Farmersville, Reinholds and Lancaster Airport.

This includes The Pennsylvania Turnpike from mile markers 268 to 295.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1100 PM EDT for south central
Pennsylvania.

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4005 7631 4027 7645 4036 7621 4031 7614
      4015 7588
TIME...MOT...LOC 0007Z 250DEG 43KT 4018 7626 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Jurewicz

The office that day

Everything else NWS State College, PA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 18, 8:27 PM EDT	Areal Flood Advisory	CTP	Lancaster, Lebanon	3 hr
Aug 18, 8:45 PM EDT	Special Weather Statement	CTP	Lancaster	45 min
Aug 18, 8:48 PM EDT	Areal Flood Advisory	CTP	Tioga	76 min
Aug 18, 9:11 PM EDT	Flash Flood Warning Considerable damage threat	CTP	Lancaster	108 min
Aug 18, 9:12 PM EDT	Severe Thunderstorm Warning	CTP	York	33 min
Aug 18, 9:21 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster	39 min
Aug 18, 10:28 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster	47 min
Aug 18, 10:34 PM EDT	Areal Flood Warning	CTP	Lancaster, York	11 min
Aug 18, 10:48 PM EDT	Areal Flood Warning	CTP	Lancaster, York	2 hr
Aug 18, 10:53 PM EDT	Areal Flood Advisory	CTP	Lancaster, York	3 hr
Aug 18, 10:59 PM EDT	Areal Flood Warning	CTP	Lancaster	2 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2021 Every severe thunderstorm warning 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.