Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 162, NWS Philadelphia/Mount Holly

August 18, 20174 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 18, 2017, 3:46 PM EDT for 4 counties in Pennsylvania. It was in force for 44 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, 2017, 3:46 PM EDT (19:46 UTC)
Expired: Aug 18, 2017, 4:30 PM EDT
In force: 44 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Tornado: Possible
Hail: 1.0 in
Wind: 60.0 mph

Counties Berks County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 115 km from the middle of the area, began a volume at 19:45 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, 3:47 PM EDT	TSTM WND DMG	Wernersville, PA	TREE DOWN AT INTERSECTION OF SADDLEBROOK DRIVE AND DANIEL STREET IN SOUTH HEIDELBERG TWP. TIME ESTIMATED FROM RADAR.
Aug 18, 4:19 PM EDT	TSTM WND DMG	1 Sse Maxatawny, PA	TREE DOWN ON WIRES ON THE 900 BLOCK OF OLD TOPTON ROAD. TIME ESTIMATED FROM RADAR.

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, 2:27 PM EDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 7.8 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-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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1073 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 147 m²/s²
0-3 km storm-relative helicity: 215 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

134 
WUUS51 KPHI 181946
SVRPHI
PAC011-077-091-095-182030-
/O.NEW.KPHI.SV.W.0162.170818T1946Z-170818T2030Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
346 PM EDT FRI AUG 18 2017

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Berks County in eastern Pennsylvania...
  Northwestern Montgomery County in southeastern Pennsylvania...
  Lehigh County in eastern Pennsylvania...
  Southern Northampton County in eastern Pennsylvania...

* Until 430 PM EDT

* At 346 PM EDT, severe thunderstorms were located along a line
  extending from near Claussville to Wernersville, moving east at 25
  mph.

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

  SOURCE...Radar indicated. 

  IMPACT...Minor damage to vehicles is possible. Expect damage to 
           trees and power lines. 

* Locations impacted include...
  Allentown, Reading, Easton, Bethlehem, Forks, Emmaus, Wyomissing,
  Northampton, Wilson, Hellertown, Nazareth, Birdsboro, Kutztown,
  Fleetwood, Sinking Spring, Laureldale, Womelsdorf, Bath,
  Wernersville and Newmanstown.

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.

&&

LAT...LON 4072 7570 4079 7512 4077 7513 4078 7517
      4075 7519 4073 7518 4068 7520 4068 7517
      4064 7519 4019 7583 4023 7602 4035 7620
TIME...MOT...LOC 1946Z 251DEG 23KT 4059 7562 4031 7609 

TORNADO...POSSIBLE
HAIL...1.00IN
WIND...60MPH
 
$$

SFJ

1 follow-up statement

826 
WWUS51 KPHI 182002
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
402 PM EDT FRI AUG 18 2017

PAC011-077-091-095-182030-
/O.CON.KPHI.SV.W.0162.000000T0000Z-170818T2030Z/
Berks PA-Montgomery PA-Lehigh PA-Northampton PA-
402 PM EDT FRI AUG 18 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM EDT
FOR BERKS...NORTHWESTERN MONTGOMERY...LEHIGH AND SOUTHERN NORTHAMPTON
COUNTIES...

At 401 PM EDT, severe thunderstorms were located along a line
extending from near Allentown to Spring Ridge, moving east at 25 mph.

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

SOURCE...Radar indicated. 

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

Locations impacted include...
Allentown, Reading, Easton, Bethlehem, Forks, Emmaus, Wyomissing,
Northampton, Wilson, Hellertown, Nazareth, Birdsboro, Kutztown,
Fleetwood, Sinking Spring, Laureldale, Womelsdorf, Bath, Wernersville
and Newmanstown.

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.

In addition to damaging winds and hail, torrential rainfall is also 
occurring with these storms, and may lead to flash flooding. Do not 
drive your vehicle through flooded roadways.

&&

LAT...LON 4072 7570 4079 7512 4077 7513 4078 7517
      4075 7519 4073 7518 4068 7520 4068 7517
      4064 7519 4019 7583 4023 7602 4035 7620
TIME...MOT...LOC 2001Z 251DEG 23KT 4062 7552 4034 7599 

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

SFJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 3:39 AM EDT	Flash Flood Watch	PHI	Berks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more	18 hr
Aug 18, 4:48 AM EDT	Areal Flood Advisory	PHI	Berks, Lehigh, Northampton	4 hr
Aug 18, 2:10 PM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh	4 hr
Aug 18, 2:21 PM EDT	Special Weather Statement	PHI	Berks	24 min
Aug 18, 2:33 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	42 min
Aug 18, 3:14 PM EDT	Special Weather Statement	PHI	Berks, Lehigh	31 min
Aug 18, 3:15 PM EDT	Areal Flood Advisory	PHI	Berks	4 hr
Aug 18, 3:19 PM EDT	Special Weather Statement	PHI	Northampton	26 min
Aug 18, 3:37 PM EDT	Special Weather Statement	PHI	Carbon	38 min
Aug 18, 3:43 PM EDT	Special Weather Statement	PHI	Berks	32 min
Aug 18, 3:45 PM EDT	Areal Flood Advisory	PHI	Carbon, Lehigh, Monroe, Northampton	4 hr
Aug 18, 4:02 PM EDT	Flash Flood Warning	PHI	Berks	4 hr
Aug 18, 4:24 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Montgomery	51 min
Aug 18, 4:29 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	61 min
Aug 18, 4:57 PM EDT	Areal Flood Advisory	PHI	Bucks, Chester, Montgomery	3 hr
Aug 18, 5:03 PM EDT	Severe Thunderstorm Warning	PHI	Chester	42 min
Aug 18, 5:11 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	49 min
Aug 18, 5:20 PM EDT	Areal Flood Advisory	PHI	Bucks, Delaware, Montgomery, Philadelphia	3 hr
Aug 18, 5:39 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Philadelphia	66 min
Aug 18, 5:54 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	66 min
Aug 18, 6:38 PM EDT	Special Weather Statement	PHI	Delaware, Philadelphia	37 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2017 Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.