Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 134, NWS Philadelphia/Mount Holly

July 24, 2017New Castle County, Delaware; Cecil County, Maryland; Chester County, Delaware County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 24, 2017, 8:08 PM EDT for New Castle County, Delaware; Cecil County, Maryland; Chester County, Delaware County, Pennsylvania. It was in force for 52 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: Jul 24, 2017, 8:08 PM EDT (00:08 UTC)
Expired: Jul 24, 2017, 9:00 PM EDT
In force: 52 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties New Castle County, DE, Cecil County, MD, Chester County, PA, Delaware County, PA

The radar

The Dover AFB radar (KDOX), 99 km from the middle of the area, began a volume at 00:11 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
Jul 24, 8:13 PM EDT	TSTM WND GST 63	North East, MD
Jul 24, 8:42 PM EDT	HAIL 0.25	4 E Elkton, DE

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

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 0.1 hours before the alert went out and 172 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: 1156 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 1330 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 122 m²/s²
0-3 km storm-relative helicity: 177 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 4.0

Open this sounding in Storm Lab

The text

As transmitted.

421 
WUUS51 KPHI 250008
SVRPHI
DEC003-MDC015-PAC029-045-250100-
/O.NEW.KPHI.SV.W.0134.170725T0008Z-170725T0100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service MOUNT HOLLY NJ
808 PM EDT MON JUL 24 2017

The National Weather Service in MOUNT HOLLY NJ  has issued a

* Severe Thunderstorm Warning for...
  New Castle County in northern Delaware...
  Cecil County in northeastern Maryland...
  Southern Chester County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...

* Until 900 PM EDT

* At 807 PM EDT, severe thunderstorms were located along a line
  extending from near Phoenixville to near Riverside, moving east at
  35 mph.

  HAZARD...60 mph wind gusts. 

  SOURCE...Radar indicated. 

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

* Locations impacted include...
  Wilmington, Newark, Middletown, West Chester, Elkton, Calvert,
  Chester, Pennsville, Yeadon, Westtown, Downingtown, Folcroft,
  Swarthmore, Elsmere, Kennett Square, New Castle, Oxford, North
  East, West Grove and Rising Sun.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3980 7604 4012 7558 3997 7525 3988 7526
      3987 7523 3985 7526 3984 7536 3977 7546
      3967 7552 3965 7547 3966 7552 3963 7556
      3960 7555 3960 7552 3938 7575 3939 7604
      3943 7600 3952 7598 3955 7608 3966 7617
TIME...MOT...LOC 0007Z 274DEG 32KT 4013 7556 3945 7626 

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

amc

1 follow-up statement

047 
WWUS51 KPHI 250042
SVSPHI

Severe Weather Statement
National Weather Service MOUNT HOLLY NJ
842 PM EDT MON JUL 24 2017

DEC003-MDC015-PAC029-045-250100-
/O.CON.KPHI.SV.W.0134.000000T0000Z-170725T0100Z/
New Castle DE-Cecil MD-Chester PA-Delaware PA-
842 PM EDT MON JUL 24 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 PM EDT
FOR NEW CASTLE...CECIL...SOUTHEASTERN CHESTER AND DELAWARE
COUNTIES...

At 842 PM EDT, severe thunderstorms were located along a line
extending from near Jenkintown to Cecilton, moving east at 35 mph.

HAZARD...60 mph wind gusts. 

SOURCE...Radar indicated. 

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

Locations impacted include...
Wilmington, Newark, Middletown, Elkton, Chester, Pennsville, Yeadon,
Westtown, Folcroft, Swarthmore, Elsmere, Kennett Square, New Castle,
North East, East Lansdowne, Delaware City, Charlestown, Newport,
Cecilton and Arden.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 3975 7585 4004 7539 3996 7525 3988 7526
      3987 7523 3985 7526 3984 7536 3977 7546
      3967 7552 3965 7548 3963 7556 3958 7554
      3938 7575 3939 7604 3943 7600 3952 7598
      3955 7608
TIME...MOT...LOC 0042Z 274DEG 32KT 4011 7517 3943 7588 

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

amc

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 24, 8:59 PM EDT	Areal Flood Advisory	PHI	New Castle	2 hr
Jul 24, 9:01 PM EDT	Special Weather Statement	PHI	New Castle	59 min
Jul 24, 10:01 PM EDT	Areal Flood Advisory	PHI	New Castle	119 min
Jul 24, 10:06 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	39 min
Jul 24, 10:38 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	52 min
Jul 24, 10:50 PM EDT	Severe Thunderstorm Warning	PHI	Kent	40 min
Jul 24, 11:30 PM EDT	Special Weather Statement	PHI	Kent	45 min
Jul 25, 12:16 AM EDT	Special Weather Statement	PHI	Sussex	44 min
Jul 25, 12:34 AM EDT	Severe Thunderstorm Warning	PHI	Kent, Sussex	41 min
Jul 25, 1:15 AM EDT	Special Weather Statement	PHI	Sussex	45 min
Jul 25, 3:25 PM EDT	Coastal Flood Advisory	PHI	Sussex	11 hr
Jul 24, 9:52 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Kent, Queen Anne's	38 min
Jul 24, 10:02 PM EDT	Special Weather Statement	PHI	Cecil	43 min
Jul 24, 11:10 PM EDT	Special Weather Statement	PHI	Talbot	35 min
Jul 24, 11:55 PM EDT	Areal Flood Advisory	PHI	Caroline, Queen Anne's	2 hr
Jul 24, 8:19 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	116 min
Jul 24, 9:06 PM EDT	Areal Flood Advisory	PHI	Philadelphia	114 min
Jul 24, 9:44 PM EDT	Flash Flood Warning	PHI	Philadelphia	4 hr
Jul 24, 11:11 PM EDT	Areal Flood Warning	PHI	Montgomery	4 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2017 Severe Thunderstorm Warnings in Delaware, 2017 Severe Thunderstorm Warnings in Maryland, 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.