Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2019

Severe Thunderstorm Warning 4, NWS Philadelphia/Mount Holly

March 15, 2019Bucks County, Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Mar 15, 2019, 7:32 PM EDT for Bucks County, Chester County, Montgomery County, Pennsylvania. It was in force for 43 min. 5 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
Mar 15, 2019, 7:32 PM EDT (23:32 UTC)
Expired
Mar 15, 2019, 8:15 PM EDT
In force
43 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
0.88 in
Wind
60.0 mph

Counties Bucks County, PA, Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 89 km from the middle of the area, began a volume at 23:33 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
Mar 15, 7:35 PM EDTTSTM WND DMGMarlborough Twp, PAREPORTS OF SEVERAL TREES AND POWER LINES DOWN.
Mar 15, 7:38 PM EDTTSTM WND DMGPottstown, PASOME TREES DOWN AND LOST POWER. UNKNOWN ESTIMATE OF WINDS.
Mar 15, 7:38 PM EDTHAIL 1Pottstown, PA
Mar 15, 7:40 PM EDTTSTM WND DMGPottstown, PAPHOTO SHOWS SPRUCE TREE OF ROUGHLY 2-3 FEET IN DIAMETER FALLEN ON HOME. NO SIGNIFICANT DAMAGE APPARENT THOUGH. TIME ESTIMATED FROM RADAR.
Mar 15, 7:41 PM EDTHAIL 0.75Pottstown, PA

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

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 11.5 hours before the alert went out and 219 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, Brookhaven, NY at 12:00Z on 2019-03-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Brookhaven, NY at 12:00Z on 2019-03-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 397 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
841 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
397 m²/s²
0-3 km storm-relative helicity
414 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

999 
WUUS51 KPHI 152332
SVRPHI
PAC017-029-091-160015-
/O.NEW.KPHI.SV.W.0004.190315T2332Z-190316T0015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
732 PM EDT FRI MAR 15 2019

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Central Montgomery County in southeastern Pennsylvania...
  Central Bucks County in southeastern Pennsylvania...
  North central Chester County in southeastern Pennsylvania...

* Until 815 PM EDT.

* At 731 PM EDT, a severe thunderstorm was located over Pottstown, or
  16 miles east of Reading, moving east at 45 mph.

  HAZARD...60 mph wind gusts and nickel size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to roofs, siding, trees, and power lines is 
           possible.

* Locations impacted include...
  Pottstown, Lansdale, Perkasie, Doylestown, Hatboro, Souderton,
  Bedminster, Collegeville, Royersford, Chalfont, Trappe, Hatfield,
  Dublin, Langhorne, Schwenksville, Ivyland, Green Lane, Fricks,
  Spring Mount and Richboro.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to hail and damaging winds, frequent cloud to ground 
lightning is occurring with this storm. Move indoors immediately. 
Remember, if you can hear thunder, you are close enough to be struck 
by lightning.

&&

LAT...LON 4025 7569 4034 7561 4045 7507 4042 7506
      4040 7503 4018 7492 4018 7570
TIME...MOT...LOC 2331Z 255DEG 39KT 4025 7563 

HAIL...0.88IN
WIND...60MPH
 
$$

Gorse
1 follow-up statement
033 
WWUS51 KPHI 152354
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
754 PM EDT FRI MAR 15 2019

PAC029-160002-
/O.CAN.KPHI.SV.W.0004.000000T0000Z-190316T0015Z/
Chester PA-
754 PM EDT FRI MAR 15 2019

...THE SEVERE THUNDERSTORM WARNING FOR NORTH CENTRAL CHESTER COUNTY
IS CANCELLED...
    
The severe thunderstorm which prompted the warning has weakened. 
Therefore, the warning has been cancelled.

LAT...LON 4038 7539 4045 7507 4042 7506 4040 7503
      4018 7492 4019 7555 4021 7556 4020 7556
      4020 7557 4021 7558
TIME...MOT...LOC 2352Z 254DEG 47KT 4033 7526 

$$

PAC017-091-160015-
/O.CON.KPHI.SV.W.0004.000000T0000Z-190316T0015Z/
Montgomery PA-Bucks PA-
754 PM EDT FRI MAR 15 2019

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM EDT
FOR CENTRAL MONTGOMERY AND CENTRAL BUCKS COUNTIES...

At 752 PM EDT, a severe thunderstorm was located over Fricks, or 21
miles southeast of Allentown, moving east at 55 mph.

HAZARD...60 mph wind gusts and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Damage to roofs, siding, trees, and power lines is 
         possible.

Around 740 PM, a trained spotter reported quarter size hail and some 
downed trees in Pottstown.

Locations impacted include...
Lansdale, Perkasie, Doylestown, Hatboro, Souderton, Bedminster,
Collegeville, Royersford, Chalfont, Trappe, Hatfield, Dublin,
Langhorne, Schwenksville, Ivyland, Fricks, Spring Mount, Richboro,
Pipersville and Gardenville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In addition to hail and damaging winds, frequent cloud to ground 
lightning is occurring with this storm. Move indoors immediately. 
Remember, if you can hear thunder, you are close enough to be struck 
by lightning.

&&

LAT...LON 4038 7539 4045 7507 4042 7506 4040 7503
      4018 7492 4019 7555 4021 7556 4020 7556
      4020 7557 4021 7558
TIME...MOT...LOC 2352Z 254DEG 47KT 4033 7526 

HAIL...0.88IN
WIND...60MPH
 
$$

Gorse

The office that day

Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 15, 6:02 PM EDTSpecial Weather StatementPHILehigh, Northampton28 min
Mar 15, 6:08 PM EDTSpecial Weather StatementPHIBerks37 min
Mar 15, 6:27 PM EDTSpecial Weather StatementPHINorthampton33 min
Mar 15, 6:33 PM EDTAreal Flood AdvisoryPHIBerks, Lehigh, Northampton117 min
Mar 15, 7:09 PM EDTSevere Thunderstorm WarningPHIBerks, Chester, Montgomery51 min
Mar 15, 7:23 PM EDTSevere Thunderstorm WarningPHIBucks52 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2019Every severe thunderstorm warning in 2019

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.