Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 246, NWS State College, PA

August 18, 2021Dauphin County, Pennsylvania

NWS State College, PA issued this severe thunderstorm warning at Aug 18, 2021, 5:31 PM EDT for Dauphin County, Pennsylvania. It was in force for 74 min. 4 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, 5:31 PM EDT (21:31 UTC)
Expired
Aug 18, 2021, 6:45 PM EDT
In force
74 min
Issued by
NWS State College, PA
Area
Storm-based polygon
Tornado
Possible
Hail
0.75 in
Wind
60.0 mph

County Dauphin County, PA

The radar

The State College radar (KCCX), 108 km from the middle of the area, began a volume at 21:30 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

TimeReportWhereRemark
Aug 18, 5:41 PM EDTTSTM WND DMG1 Ene Duncannon, PATREES DOWN ON WIRES.
Aug 18, 5:48 PM EDTTSTM WND DMG1 Ne Halifax, PATREES DOWN ON WIRES.
Aug 18, 6:30 PM EDTTSTM WND DMG4 E Halifax, PAMULTIPLE TREES DOWN. FUNNEL CLOUD REPORTED.
Aug 18, 6:31 PM EDTTORNADO2 Se Halifax, PA1.5 MILE LONG PATH; 150 YARDS WIDE WITH ESTIMATED MAXIMUM WINDS NEAR 105 MPH.

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.

IssuedProductOfficeLasted
Aug 18, 11:37 AM EDTTornado WatchSPC11 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.5 hours before the alert went out and 177 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2021-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1011 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2021-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 151 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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.

518 
WUUS51 KCTP 182131
SVRCTP
PAC043-182245-
/O.NEW.KCTP.SV.W.0246.210818T2131Z-210818T2245Z/

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

The National Weather Service in State College PA has issued a

* Severe Thunderstorm Warning for...
  Dauphin County in south central Pennsylvania...

* Until 645 PM EDT.

* At 530 PM EDT, a severe thunderstorm was located over Marysville,
  moving northeast at 30 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Locations impacted include...
  Harrisburg, Colonial Park, Progress, Linglestown, Steelton,
  Paxtonia, Rutherford, Skyline View, Lawnton,
  Bressler-Enhaut-Oberlin, Penbrook, Millersburg, Marysville, Lykens,
  Paxtang, Duncannon, Elizabethville, Williamstown, New Buffalo and
  Dehart Dam.

This includes the following Interstates...
 Interstate 81 from mile markers 65 to 80.
 Interstate 83 from mile markers 43 to 50.
 Interstate 283 near mile marker 2.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Remain alert for a possible tornado! Tornadoes can develop quickly
from severe thunderstorms. If you spot a tornado go at once into the
basement or small central room in a sturdy structure.

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.

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

&&

LAT...LON 4026 7690 4035 7693 4037 7702 4042 7702
      4047 7695 4052 7698 4057 7699 4059 7696
      4063 7695 4060 7692 4063 7686 4062 7684
      4065 7680 4066 7671 4056 7654 4048 7668
      4039 7665 4021 7683
TIME...MOT...LOC 2130Z 219DEG 27KT 4034 7696 

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

$$

Colbert

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 18, 9:50 AM EDTSpecial Weather StatementCTPBedford55 min
Aug 18, 10:25 AM EDTAreal Flood AdvisoryCTPBedford3 hr
Aug 18, 10:32 AM EDTSevere Thunderstorm WarningCTPBedford, Blair43 min
Aug 18, 10:53 AM EDTSpecial Weather StatementCTPCambria37 min
Aug 18, 10:57 AM EDTSpecial Weather StatementCTPBedford18 min
Aug 18, 11:15 AM EDTSpecial Weather StatementCTPBlair, Cambria30 min
Aug 18, 11:33 AM EDTAreal Flood AdvisoryCTPBlair, Cambria3 hr
Aug 18, 12:04 PM EDTAreal Flood AdvisoryCTPBedford2 hr
Aug 18, 12:11 PM EDTSpecial Weather StatementCTPBlair34 min
Aug 18, 12:26 PM EDTSpecial Weather StatementCTPSchuylkill34 min
Aug 18, 12:35 PM EDTFlash Flood Warning Considerable damage threatCTPBedford, Blair, Huntingdon3 hr
Aug 18, 12:39 PM EDTSpecial Weather StatementCTPCumberland36 min
Aug 18, 12:54 PM EDTSevere Thunderstorm WarningCTPCumberland, Perry36 min
Aug 18, 1:01 PM EDTSpecial Weather StatementCTPHuntingdon44 min
Aug 18, 1:15 PM EDTSpecial Weather StatementCTPJuniata, Mifflin30 min
Aug 18, 1:31 PM EDTSevere Thunderstorm WarningCTPJuniata, Perry44 min
Aug 18, 1:37 PM EDTFlash Flood Warning Considerable damage threatCTPBlair, Centre, Huntingdon82 min
Aug 18, 2:00 PM EDTSpecial Weather StatementCTPSnyder30 min
Aug 18, 2:02 PM EDTTornado WarningCTPCentre, Huntingdon28 min
Aug 18, 2:12 PM EDTSevere Thunderstorm WarningCTPCentre, Clinton33 min
Aug 18, 2:26 PM EDTSpecial Weather StatementCTPCumberland, Perry34 min
Aug 18, 2:29 PM EDTSpecial Weather StatementCTPCentre31 min
Aug 18, 2:36 PM EDTSevere Thunderstorm WarningCTPCumberland, Perry39 min
Aug 18, 3:03 PM EDTSpecial Weather StatementCTPCumberland42 min
Aug 18, 3:10 PM EDTTornado WarningCTPAdams, York40 min
Aug 18, 3:17 PM EDTAreal Flood WarningCTPBedford, Blair, Huntingdon118 min
Aug 18, 3:36 PM EDTSevere Thunderstorm WarningCTPCumberland, Dauphin, Lancaster, York24 min
Aug 18, 3:56 PM EDTSevere Thunderstorm WarningCTPDauphin, Juniata, Northumberland, Perry, Snyder34 min
Aug 18, 4:03 PM EDTSpecial Weather StatementCTPDauphin42 min
Aug 18, 4:05 PM EDTSevere Thunderstorm WarningCTPFranklin, Fulton40 min
Aug 18, 4:30 PM EDTAreal Flood AdvisoryCTPJuniata, Perry, Snyder4 hr
Aug 18, 4:30 PM EDTSpecial Weather StatementCTPSnyder30 min
Aug 18, 4:39 PM EDTSevere Thunderstorm WarningCTPFranklin36 min
Aug 18, 4:42 PM EDTAreal Flood AdvisoryCTPFulton, Huntingdon2 hr
Aug 18, 4:48 PM EDTAreal Flood AdvisoryCTPCameron, Clinton, Lycoming, Potter, Tioga5 hr
Aug 18, 5:10 PM EDTSevere Thunderstorm WarningCTPAdams, Cumberland, Franklin, Perry, York35 min
Aug 18, 5:18 PM EDTSevere Thunderstorm WarningCTPJuniata, Mifflin45 min
Aug 18, 5:35 PM EDTSpecial Weather StatementCTPLancaster25 min
Aug 18, 5:35 PM EDTSevere Thunderstorm WarningCTPAdams40 min
Aug 18, 5:38 PM EDTSevere Thunderstorm WarningCTPAdams, Cumberland, York37 min
Aug 18, 6:13 PM EDTSevere Thunderstorm WarningCTPAdams, Cumberland, Dauphin, Lancaster, Perry, York47 min
Aug 18, 6:37 PM EDTAreal Flood AdvisoryCTPAdams, Cumberland, Franklin, York2 hr
Aug 18, 6:47 PM EDTSevere Thunderstorm WarningCTPAdams, Dauphin, Lancaster, Lebanon, Schuylkill, York43 min
Aug 18, 6:56 PM EDTSpecial Weather StatementCTPSchuylkill19 min
Aug 18, 7:23 PM EDTAreal Flood AdvisoryCTPColumbia, Sullivan2 hr
Aug 18, 7:30 PM EDTSevere Thunderstorm WarningCTPLancaster, York45 min
Aug 18, 7:37 PM EDTFlash Flood Warning Considerable damage threatCTPSchuylkill2 hr
Aug 18, 7:40 PM EDTFlash Flood WarningCTPDauphin, Lancaster, York3 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2021Every 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.