Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 241, NWS State College, PA

August 18, 20215 counties in Pennsylvania

NWS State College, PA issued this severe thunderstorm warning at Aug 18, 2021, 3:56 PM EDT for 5 counties in Pennsylvania. It was in force for 34 min. 2 reports 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, 3:56 PM EDT (19:56 UTC)
Expired: Aug 18, 2021, 4:30 PM EDT
In force: 34 min
Issued by: NWS State College, PA
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Dauphin County, PA, Juniata County, PA, Northumberland County, PA, Perry County, PA, Snyder County, PA

The radar

The State College radar (KCCX), 93 km from the middle of the area, began a volume at 19:55 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, 4:35 PM EDT	TORNADO	3 Ene Middleburg, PA	0.5MI/15YD PATH LENGTH/WIDTH WITH ESTIMATED MAX WIND 65-70MPH.
Aug 18, 4:40 PM EDT	TSTM WND DMG	4 Wsw Kratzerville, PA	ROOF PARTIALLY REMOVED ON A HOME AND A GARAGE IN MIDDLECREEK TWP. TREE LIMBS SNAPPED.

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 12:00Z, 7.9 hours before the alert went out and 200 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.

260 
WUUS51 KCTP 181956
SVRCTP
PAC043-067-097-099-109-182030-
/O.NEW.KCTP.SV.W.0241.210818T1956Z-210818T2030Z/

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

The National Weather Service in State College PA has issued a

* Severe Thunderstorm Warning for...
  Southwestern Northumberland County in central Pennsylvania...
  Northwestern Dauphin County in south central Pennsylvania...
  Northeastern Juniata County in central Pennsylvania...
  Eastern Snyder County in central Pennsylvania...
  Northeastern Perry County in south central Pennsylvania...

* Until 430 PM EDT.

* At 355 PM EDT, a severe thunderstorm was located near Millersburg,
  moving north at 35 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* This severe thunderstorm will be near...
  Meiserville, Port Trevorton and Mount Pleasant Mills around 410 PM 
  EDT.
  Kreamer, Fremont and Middleburg around 420 PM EDT.
  Selinsgrove, Sunbury, Hummels Wharf, Shamokin Dam, Kratzerville 
  and Winfield around 430 PM EDT.

Other locations impacted by this severe thunderstorm include Seven
Points, Liverpool, New Berlin, Freeburg, Dalmatia, Herndon, Halifax,
Pillow and Selinsgrove Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 800 PM EDT for south central
and central Pennsylvania.

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

Very heavy rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4042 7694 4049 7716 4086 7702 4088 7699
      4089 7694 4089 7682 4084 7666
TIME...MOT...LOC 1955Z 201DEG 35KT 4053 7701 

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, 9:50 AM EDT	Special Weather Statement	CTP	Bedford	55 min
Aug 18, 10:25 AM EDT	Areal Flood Advisory	CTP	Bedford	3 hr
Aug 18, 10:32 AM EDT	Severe Thunderstorm Warning	CTP	Bedford, Blair	43 min
Aug 18, 10:53 AM EDT	Special Weather Statement	CTP	Cambria	37 min
Aug 18, 10:57 AM EDT	Special Weather Statement	CTP	Bedford	18 min
Aug 18, 11:15 AM EDT	Special Weather Statement	CTP	Blair, Cambria	30 min
Aug 18, 11:33 AM EDT	Areal Flood Advisory	CTP	Blair, Cambria	3 hr
Aug 18, 12:04 PM EDT	Areal Flood Advisory	CTP	Bedford	2 hr
Aug 18, 12:11 PM EDT	Special Weather Statement	CTP	Blair	34 min
Aug 18, 12:26 PM EDT	Special Weather Statement	CTP	Schuylkill	34 min
Aug 18, 12:35 PM EDT	Flash Flood Warning Considerable damage threat	CTP	Bedford, Blair, Huntingdon	3 hr
Aug 18, 12:39 PM EDT	Special Weather Statement	CTP	Cumberland	36 min
Aug 18, 12:54 PM EDT	Severe Thunderstorm Warning	CTP	Cumberland, Perry	36 min
Aug 18, 1:01 PM EDT	Special Weather Statement	CTP	Huntingdon	44 min
Aug 18, 1:15 PM EDT	Special Weather Statement	CTP	Juniata, Mifflin	30 min
Aug 18, 1:31 PM EDT	Severe Thunderstorm Warning	CTP	Juniata, Perry	44 min
Aug 18, 1:37 PM EDT	Flash Flood Warning Considerable damage threat	CTP	Blair, Centre, Huntingdon	82 min
Aug 18, 2:00 PM EDT	Special Weather Statement	CTP	Snyder	30 min
Aug 18, 2:02 PM EDT	Tornado Warning	CTP	Centre, Huntingdon	28 min
Aug 18, 2:12 PM EDT	Severe Thunderstorm Warning	CTP	Centre, Clinton	33 min
Aug 18, 2:26 PM EDT	Special Weather Statement	CTP	Cumberland, Perry	34 min
Aug 18, 2:29 PM EDT	Special Weather Statement	CTP	Centre	31 min
Aug 18, 2:36 PM EDT	Severe Thunderstorm Warning	CTP	Cumberland, Perry	39 min
Aug 18, 3:03 PM EDT	Special Weather Statement	CTP	Cumberland	42 min
Aug 18, 3:10 PM EDT	Tornado Warning	CTP	Adams, York	40 min
Aug 18, 3:17 PM EDT	Areal Flood Warning	CTP	Bedford, Blair, Huntingdon	118 min
Aug 18, 3:36 PM EDT	Severe Thunderstorm Warning	CTP	Cumberland, Dauphin, Lancaster, York	24 min
Aug 18, 4:03 PM EDT	Special Weather Statement	CTP	Dauphin	42 min
Aug 18, 4:05 PM EDT	Severe Thunderstorm Warning	CTP	Franklin, Fulton	40 min
Aug 18, 4:30 PM EDT	Areal Flood Advisory	CTP	Juniata, Perry, Snyder	4 hr
Aug 18, 4:30 PM EDT	Special Weather Statement	CTP	Snyder	30 min
Aug 18, 4:39 PM EDT	Severe Thunderstorm Warning	CTP	Franklin	36 min
Aug 18, 4:42 PM EDT	Areal Flood Advisory	CTP	Fulton, Huntingdon	2 hr
Aug 18, 4:48 PM EDT	Areal Flood Advisory	CTP	Cameron, Clinton, Lycoming, Potter, Tioga	5 hr
Aug 18, 5:10 PM EDT	Severe Thunderstorm Warning	CTP	Adams, Cumberland, Franklin, Perry, York	35 min
Aug 18, 5:18 PM EDT	Severe Thunderstorm Warning	CTP	Juniata, Mifflin	45 min
Aug 18, 5:31 PM EDT	Severe Thunderstorm Warning	CTP	Dauphin	74 min
Aug 18, 5:35 PM EDT	Special Weather Statement	CTP	Lancaster	25 min
Aug 18, 5:35 PM EDT	Severe Thunderstorm Warning	CTP	Adams	40 min
Aug 18, 5:38 PM EDT	Severe Thunderstorm Warning	CTP	Adams, Cumberland, York	37 min
Aug 18, 6:13 PM EDT	Severe Thunderstorm Warning	CTP	Adams, Cumberland, Dauphin, Lancaster, Perry, York	47 min
Aug 18, 6:37 PM EDT	Areal Flood Advisory	CTP	Adams, Cumberland, Franklin, York	2 hr
Aug 18, 6:47 PM EDT	Severe Thunderstorm Warning	CTP	Adams, Dauphin, Lancaster, Lebanon, Schuylkill, York	43 min
Aug 18, 6:56 PM EDT	Special Weather Statement	CTP	Schuylkill	19 min
Aug 18, 7:23 PM EDT	Areal Flood Advisory	CTP	Columbia, Sullivan	2 hr
Aug 18, 7:30 PM EDT	Severe Thunderstorm Warning	CTP	Lancaster, York	45 min
Aug 18, 7:37 PM EDT	Flash Flood Warning Considerable damage threat	CTP	Schuylkill	2 hr
Aug 18, 7:40 PM EDT	Flash Flood Warning	CTP	Dauphin, Lancaster, York	3 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.