Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 154, NWS Philadelphia/Mount Holly

August 3, 2017Lehigh County, Northampton County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 3, 2017, 8:29 PM EDT for Lehigh County, Northampton 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
Aug 3, 2017, 8:29 PM EDT (00:29 UTC)
Expired
Aug 3, 2017, 9:15 PM EDT
In force
46 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Lehigh County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 114 km from the middle of the area, began a volume at 00:28 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 nearest sounding before it

Brookhaven, NY (KOKX), launched 00:00Z, 0.5 hours before the alert went out and 205 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 00:00Z on 2017-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 87 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 00:00Z on 2017-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 45 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
87 J/kg
Mixed-layer CIN
-92 J/kg
Mixed-layer LCL
937 m above ground
0-6 km bulk shear
13 kt
0-1 km storm-relative helicity
45 m²/s²
0-3 km storm-relative helicity
43 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

642 
WUUS51 KPHI 040029
SVRPHI
PAC077-095-040115-
/O.NEW.KPHI.SV.W.0154.170804T0029Z-170804T0115Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
829 PM EDT THU AUG 3 2017

The National Weather Service in Mount Holly NJ has issued a

* Severe Thunderstorm Warning for...
  Eastern Lehigh County in eastern Pennsylvania...
  Northampton County in eastern Pennsylvania...

* Until 915 PM EDT

* At 828 PM EDT, a severe thunderstorm was located over Allentown,
  moving northeast at 20 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, Easton, Bethlehem, Forks, Emmaus, Northampton, Wilson,
  Hellertown, Nazareth, Wind Gap, Bath, Walnutport, Belfast, West
  Easton, Tatamy, Steuben, Glendon, Neffs, Coffeetown and Lehigh
  University.

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 4078 7515 4075 7519 4073 7518 4068 7520
      4068 7517 4065 7520 4064 7519 4046 7547
      4063 7572 4081 7553 4083 7538 4086 7532
      4086 7528
TIME...MOT...LOC 0028Z 223DEG 19KT 4058 7549 

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

CMS
2 follow-up statements
084 
WWUS51 KPHI 040057
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
857 PM EDT THU AUG 3 2017

PAC077-095-040115-
/O.CON.KPHI.SV.W.0154.000000T0000Z-170804T0115Z/
Lehigh PA-Northampton PA-
857 PM EDT THU AUG 3 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 915 PM EDT
FOR EASTERN LEHIGH AND NORTHAMPTON COUNTIES...

At 857 PM EDT, a severe thunderstorm was located near Coffeetown, or
near Allentown, moving northeast at 10 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, Easton, Bethlehem, Forks, Emmaus, Northampton, Wilson,
Hellertown, Nazareth, Wind Gap, Bath, Walnutport, Belfast, West
Easton, Tatamy, Steuben, Glendon, Neffs, Coffeetown and Lehigh
University.

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 4078 7515 4075 7519 4073 7518 4068 7520
      4068 7517 4065 7520 4064 7519 4046 7547
      4063 7572 4081 7553 4083 7538 4086 7532
      4086 7528
TIME...MOT...LOC 0057Z 238DEG 10KT 4062 7553 

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

CMS
412 
WWUS51 KPHI 040111
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
911 PM EDT THU AUG 3 2017

PAC077-095-040121-
/O.EXP.KPHI.SV.W.0154.000000T0000Z-170804T0115Z/
Lehigh PA-Northampton PA-
911 PM EDT THU AUG 3 2017

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN LEHIGH AND NORTHAMPTON
COUNTIES WILL EXPIRE AT 915 PM EDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore the warning will be allowed to expire.  However gusty winds
and heavy rain are still possible with this thunderstorm.

LAT...LON 4078 7515 4075 7519 4073 7518 4068 7520
      4068 7517 4065 7520 4064 7519 4046 7547
      4063 7572 4081 7553 4083 7538 4086 7532
      4086 7528
TIME...MOT...LOC 0111Z 223DEG 19KT 4067 7547 

$$

CMS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 3, 8:01 PM EDTSpecial Weather StatementPHIBerks44 min
Aug 3, 8:11 PM EDTSpecial Weather StatementPHILehigh49 min
Aug 3, 8:35 PM EDTAreal Flood AdvisoryPHIBerks, Lehigh, Northampton4 hr
Aug 3, 8:54 PM EDTSpecial Weather StatementPHIBerks51 min
Aug 3, 9:11 PM EDTAreal Flood WarningPHIBucks4 hr
Aug 3, 9:20 PM EDTAreal Flood AdvisoryPHINorthampton3 hr
Aug 3, 9:29 PM EDTSpecial Weather StatementPHILehigh, Northampton46 min
Aug 4, 1:25 PM EDTSpecial Weather StatementPHIBerks65 min
Aug 4, 2:49 PM EDTAreal Flood AdvisoryPHIBerks116 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.