Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 88, NWS Philadelphia/Mount Holly

July 13, 2017Bucks County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 13, 2017, 5:44 PM EDT for Bucks County, Montgomery County, Pennsylvania. It was in force for 46 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
Jul 13, 2017, 5:44 PM EDT (21:44 UTC)
Expired
Jul 13, 2017, 6:30 PM EDT
In force
46 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Tornado
Possible
Hail
0.75 in
Wind
60.0 mph

Counties Bucks County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 86 km from the middle of the area, began a volume at 21:48 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Jul 13, 2:57 PM EDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 9.7 hours before the alert went out and 221 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 2017-07-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 572 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, Brookhaven, NY at 12:00Z on 2017-07-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 103 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
572 J/kg
Mixed-layer CIN
-82 J/kg
Mixed-layer LCL
1449 m above ground
0-6 km bulk shear
30 kt
0-1 km storm-relative helicity
103 m²/s²
0-3 km storm-relative helicity
140 m²/s²
Significant tornado parameter
0.1
Supercell composite
2.3

Open this sounding in Storm Lab

The text

As transmitted.

440 
WUUS51 KPHI 132144
SVRPHI
PAC017-091-132230-
/O.NEW.KPHI.SV.W.0088.170713T2144Z-170713T2230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
544 PM EDT THU JUL 13 2017

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...

* Until 630 PM EDT

* At 543 PM EDT, a severe thunderstorm was located over Collegeville,
  or 20 miles northeast of West Chester, moving east at 25 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

  IMPACT...Expect damage to trees and power lines. 

* This severe thunderstorm will be near,
  East Norriton around 550 PM EDT. 
  Lansdale, Souderton and Hatfield around 600 PM EDT. 
  Ambler around 605 PM EDT. 
  Perkasie and Fricks around 610 PM EDT. 
  Chalfont and Dublin around 615 PM EDT. 
  Doylestown and Ivyland around 625 PM EDT. 

Other locations impacted by this severe thunderstorm include
Harleysville, Sellersville, Horsham, Warminster Heights, Evansburg,
Silverdale, Audubon, Telford, Blue Bell and Maple Glen.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

In addition to large 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.

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

&&

LAT...LON 4048 7518 4018 7499 4010 7546 4012 7547
      4013 7546 4013 7547 4028 7555
TIME...MOT...LOC 2143Z 247DEG 23KT 4022 7543 

TORNADO...POSSIBLE
HAIL...<.75IN
WIND...60MPH
 
$$

Robertson
1 follow-up statement
522 
WWUS51 KPHI 132205
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
605 PM EDT THU JUL 13 2017

PAC017-091-132230-
/O.CON.KPHI.SV.W.0088.000000T0000Z-170713T2230Z/
Montgomery PA-Bucks PA-
605 PM EDT THU JUL 13 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 630 PM EDT
FOR EAST CENTRAL MONTGOMERY AND CENTRAL BUCKS COUNTIES...

At 605 PM EDT, a severe thunderstorm was located over Hatfield, or 19
miles north of Philadelphia, moving northeast at 25 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

IMPACT...Expect damage to trees and power lines. 

Locations impacted include...
Lansdale, Doylestown, Hatboro, Souderton, Ambler, Chalfont, Hatfield,
Ivyland, Fricks, Richboro, Willow Grove, Horsham, Telford, North
Wales, New Britain, Warminster Heights, Maple Glen, Brittany
Farms-Highlands, Spring House and Montgomeryville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4038 7512 4018 7499 4014 7525 4031 7537
TIME...MOT...LOC 2205Z 247DEG 23KT 4027 7527 

HAIL...<.75IN
WIND...60MPH
 
$$

MWG

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 13, 3:25 PM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Northampton4 hr
Jul 13, 3:30 PM EDTSpecial Weather StatementPHILehigh, Northampton45 min
Jul 13, 4:06 PM EDTAreal Flood AdvisoryPHIBucks, Lehigh, Monroe, Northampton114 min
Jul 13, 4:06 PM EDTSpecial Weather StatementPHINorthampton39 min
Jul 13, 4:08 PM EDTSpecial Weather StatementPHISchuylkill37 min
Jul 13, 4:09 PM EDTSpecial Weather StatementPHIMontgomery36 min
Jul 13, 4:15 PM EDTSevere Thunderstorm WarningPHIBerks60 min
Jul 13, 4:34 PM EDTSpecial Weather StatementPHIChester41 min
Jul 13, 4:36 PM EDTSpecial Weather StatementPHILehigh24 min
Jul 13, 4:42 PM EDTSpecial Weather StatementPHIMontgomery, Philadelphia48 min
Jul 13, 4:50 PM EDTAreal Flood AdvisoryPHIBerks, Bucks, Chester, Montgomery115 min
Jul 13, 4:50 PM EDTSevere Thunderstorm WarningPHIBucks, Montgomery, Philadelphia40 min
Jul 13, 5:07 PM EDTAreal Flood AdvisoryPHIBucks, Delaware, Montgomery, Philadelphia7 hr
Jul 13, 5:08 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery35 min
Jul 13, 5:08 PM EDTTornado WarningPHIBerks22 min
Jul 13, 5:21 PM EDTSevere Thunderstorm WarningPHIBucks, Philadelphia54 min
Jul 13, 5:25 PM EDTFlash Flood WarningPHIBerks, Lehigh3 hr
Jul 13, 5:26 PM EDTTornado WarningPHIBerks, Chester, Montgomery28 min
Jul 13, 5:30 PM EDTSpecial Weather StatementPHIDelaware, Philadelphia45 min
Jul 13, 5:31 PM EDTFlash Flood WarningPHIBucks3 hr
Jul 13, 5:36 PM EDTSpecial Weather StatementPHIMontgomery39 min
Jul 13, 5:56 PM EDTSpecial Weather StatementPHIBerks34 min
Jul 13, 6:28 PM EDTSpecial Weather StatementPHIBucks47 min
Jul 13, 6:34 PM EDTSpecial Weather StatementPHIDelaware, Montgomery, Philadelphia41 min
Jul 13, 7:03 PM EDTAreal Flood AdvisoryPHIChester, Montgomery117 min
Jul 13, 7:12 PM EDTSpecial Weather StatementPHIPhiladelphia48 min
Jul 13, 7:26 PM EDTSpecial Weather StatementPHIBerks, Montgomery64 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2017Every severe thunderstorm warning in 2017

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.