Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 93, NWS Philadelphia/Mount Holly

July 14, 2017Chester County, Delaware County, Pennsylvania; Cecil County, Maryland; New Castle County, Delaware

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 14, 2017, 2:31 PM EDT for Chester County, Delaware County, Pennsylvania; Cecil County, Maryland; New Castle County, Delaware. It was in force for 59 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 14, 2017, 2:31 PM EDT (18:31 UTC)
Expired: Jul 14, 2017, 3:30 PM EDT
In force: 59 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 18:35 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 14, 2:45 PM EDT	TSTM WND DMG	1 Nw Maple Grove, PA	TREE DOWN BLOCKING HICKORY HILL ROAD. TIME ESTIMATED FROM RADAR.
Jul 14, 2:45 PM EDT	TSTM WND DMG	West Chester, PA	DAMAGE TO CAR WINDOWS.

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
Jul 14, 1:40 PM EDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.5 hours before the alert went out and 157 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: 403 J/kg
Mixed-layer CIN: -72 J/kg
Mixed-layer LCL: 1367 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 52 m²/s²
0-3 km storm-relative helicity: 118 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted.

739 
WUUS51 KPHI 141831
SVRPHI
DEC003-MDC015-PAC029-045-141930-
/O.NEW.KPHI.SV.W.0093.170714T1831Z-170714T1930Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Mount Holly NJ
231 PM EDT FRI JUL 14 2017

The National Weather Service in Mount Holly NJ has issued a

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

* Until 330 PM EDT

* At 231 PM EDT, severe thunderstorms were located along a line
  extending from near Coatesville to near Mount Vernon to near Rock
  Springs, moving southeast at 25 mph.

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

  SOURCE...Radar indicated. 

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

* Severe thunderstorms will be near,
  Coatesville and Downingtown around 235 PM EDT. 
  Oxford, Rising Sun and Marshallton around 245 PM EDT. 
  West Chester, Kennett Square and West Nottingham around 250 PM 
  EDT. 
  Calvert, West Grove, Woodlawn, Lombard, Hockessin, Farmington and 
  North Star around 255 PM EDT. 
  Westtown, Blake, Zion, Ashland and Pike Creek around 300 PM EDT. 
  Fair Hill, Andora, Elam, Pleasant Hill, Kemblesville, Greenville, 
  Concordville, Bay View and Ladenberg around 305 PM EDT. 
  Elsmere, North East, Charlestown, Newport, Talleyville, Appleton, 
  Cherry Hill, Glen Westover and Chelsea around 310 PM EDT. 
  Wilmington, Newark, Arden and Barksdale around 315 PM EDT. 

Other locations impacted by these severe thunderstorms include
Perryville, Chesapeake City, South Coatesville, Modena, Edgemoor,
Marcus Hook, Boothwyn, Trainer, Thorndale and Chester Heights.

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.

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

&&

LAT...LON 3972 7623 3973 7610 3987 7599 3993 7599
      4003 7577 3985 7534 3977 7546 3969 7551
      3967 7551 3965 7547 3966 7552 3961 7556
      3937 7594 3938 7605 3943 7600 3946 7601
      3952 7598 3955 7608
TIME...MOT...LOC 1831Z 306DEG 22KT 3996 7578 3983 7608 3970 7623 

HAIL...0.75IN
WIND...60MPH
 
$$

Robertson

2 follow-up statements

386 
WWUS51 KPHI 141842
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
242 PM EDT FRI JUL 14 2017

DEC003-MDC015-PAC029-045-141930-
/O.CON.KPHI.SV.W.0093.000000T0000Z-170714T1930Z/
New Castle DE-Cecil MD-Chester PA-Delaware PA-
242 PM EDT FRI JUL 14 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 330 PM EDT
FOR NORTHERN NEW CASTLE...CECIL...SOUTHERN CHESTER AND SOUTHWESTERN
DELAWARE COUNTIES...

At 241 PM EDT, severe thunderstorms were located along a line
extending from near Marshallton to Oxford to Conowingo, moving
southeast at 30 mph.

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

SOURCE...Radar indicated. 

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

These severe storms will be near...
  Downingtown and Marshallton around 245 PM EDT. 
  West Chester, Calvert, Kennett Square, West Grove, Lombard and 
  Zion around 250 PM EDT. 
  Westtown, Blake, Hockessin and North Star around 255 PM EDT. 
  Andora, Fair Hill, Pleasant Hill, Kemblesville, Ashland, Bay View, 
  Ladenberg and Pike Creek around 300 PM EDT. 
  North East, Charlestown, Barksdale, Talleyville, Cherry Hill, 
  Elam, Appleton, Glen Westover, Greenville and Concordville around 
  305 PM EDT. 
  Newark, Elkton, Elsmere, Newport, Arden and Chelsea around 310 PM 
  EDT. 
  Wilmington, Brantwood, Chester Township and Wilmington Manor 
  around 315 PM EDT. 
  Hollywood Beach, Glasgow, Bear and Delaware Memorial Bridge around 
  320 PM EDT. 

Other locations impacted by these severe thunderstorms include
Perryville, Chesapeake City, South Coatesville, Modena, Edgemoor,
Marcus Hook, Boothwyn, Trainer, Thorndale and Chester Heights.

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 these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3972 7623 3973 7610 3987 7599 3993 7599
      4003 7577 3985 7534 3977 7546 3969 7551
      3967 7551 3965 7547 3966 7552 3961 7556
      3937 7594 3938 7605 3943 7600 3946 7601
      3952 7598 3955 7608
TIME...MOT...LOC 1841Z 307DEG 26KT 3993 7573 3977 7599 3967 7618 

TORNADO...POSSIBLE
HAIL...0.75IN
WIND...60MPH
 
$$

Robertson

142 
WWUS51 KPHI 141904
SVSPHI

Severe Weather Statement
National Weather Service Mount Holly NJ
304 PM EDT FRI JUL 14 2017

DEC003-MDC015-PAC029-045-141930-
/O.CON.KPHI.SV.W.0093.000000T0000Z-170714T1930Z/
New Castle DE-Cecil MD-Chester PA-Delaware PA-
304 PM EDT FRI JUL 14 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 330 PM EDT
FOR NORTHERN NEW CASTLE...CECIL...SOUTHERN CHESTER AND SOUTHWESTERN
DELAWARE COUNTIES...

At 303 PM EDT, severe thunderstorms were located along a line
extending from near Elam to Fair Hill to Conowingo, moving southeast
at 25 mph.

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

SOURCE...Radar indicated. 

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

These severe storms will be near...
  Westtown, Kennett Square, Barksdale, Appleton, Elam, Cherry Hill, 
  Glen Westover, Greenville, Concordville and Ashland around 310 PM 
  EDT. 
  Newark, Elkton, Elsmere and Talleyville around 315 PM EDT. 
  Arden and Chelsea around 320 PM EDT. 
  Wilmington, Brantwood, Chester Township and Stanton around 325 PM 
  EDT. 
  Pennsville, Charlestown, Glasgow, Bear and Delaware Memorial 
  Bridge around 330 PM EDT. 

Other locations impacted by these severe thunderstorms include
Perryville, Chesapeake City, Edgemoor, Marcus Hook, Boothwyn,
Trainer, Chester Heights, Village Green-Green Ridge, Bellefonte and
Upland.

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 these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3972 7623 3973 7610 3977 7606 3981 7595
      3996 7561 3985 7534 3977 7546 3969 7551
      3967 7551 3965 7548 3966 7552 3945 7581
      3955 7603 3955 7608
TIME...MOT...LOC 1903Z 305DEG 21KT 3986 7560 3970 7586 3969 7615 

TORNADO...POSSIBLE
HAIL...0.75IN
WIND...60MPH
 
$$

Robertson

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 13, 8:17 PM EDT	Special Weather Statement	PHI	Montgomery, Philadelphia	43 min
Jul 14, 7:21 AM EDT	Areal Flood Advisory	PHI	Carbon, Monroe, Northampton	3 hr
Jul 14, 11:40 AM EDT	Flash Flood Watch	PHI	Berks, Chester, Delaware, Montgomery, Philadelphia	11 hr
Jul 14, 12:30 PM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh, Monroe, Montgomery, Northampton	4 hr
Jul 14, 1:58 PM EDT	Special Weather Statement	PHI	Chester	62 min
Jul 14, 2:14 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware, Montgomery, Philadelphia	3 hr
Jul 14, 2:53 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	3 hr
Jul 14, 2:57 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery	3 hr
Jul 14, 3:18 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	12 min
Jul 14, 3:23 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	67 min
Jul 13, 10:03 PM EDT	Special Weather Statement	PHI	Caroline	27 min
Jul 13, 10:15 PM EDT	Areal Flood Advisory	PHI	Caroline, Talbot	4 hr
Jul 14, 9:23 AM EDT	Special Weather Statement	PHI	Cecil	37 min
Jul 14, 12:06 PM EDT	Heat Advisory	PHI	Caroline, Kent, Queen Anne's, Talbot	7 hr
Jul 14, 2:46 PM EDT	Areal Flood Advisory	PHI	Cecil	3 hr
Jul 14, 3:10 PM EDT	Flash Flood Warning	PHI	Cecil	2 hr
Jul 14, 3:52 PM EDT	Flash Flood Warning	PHI	Talbot	53 min
Jul 14, 3:57 PM EDT	Flash Flood Warning	PHI	Cecil, Kent	2 hr
Jul 14, 4:00 PM EDT	Special Weather Statement	PHI	Caroline	45 min
Jul 14, 4:05 PM EDT	Special Weather Statement	PHI	Kent	40 min
Jul 14, 4:48 PM EDT	Special Weather Statement	PHI	Queen Anne's	27 min
Jul 14, 4:59 PM EDT	Flash Flood Warning	PHI	Queen Anne's	4 hr
Jul 14, 5:27 PM EDT	Special Weather Statement	PHI	Queen Anne's	63 min
Jul 14, 5:40 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Kent, Queen Anne's, Talbot	65 min
Jul 14, 5:54 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Talbot	51 min
Jul 14, 5:58 PM EDT	Flash Flood Warning	PHI	Talbot	3 hr
Jul 14, 6:10 PM EDT	Flash Flood Warning	PHI	Caroline	3 hr
Jul 14, 6:20 PM EDT	Severe Thunderstorm Warning	PHI	Caroline, Talbot	40 min
Jul 13, 8:09 PM EDT	Special Weather Statement	PHI	Kent	36 min
Jul 13, 8:29 PM EDT	Special Weather Statement	PHI	Kent	31 min
Jul 13, 10:39 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	51 min
Jul 14, 9:02 AM EDT	Special Weather Statement	PHI	New Castle	28 min
Jul 14, 3:25 PM EDT	Areal Flood Advisory	PHI	New Castle	4 hr
Jul 14, 3:34 PM EDT	Flash Flood Warning	PHI	New Castle	3 hr
Jul 14, 3:54 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	66 min
Jul 14, 5:14 PM EDT	Areal Flood Advisory	PHI	Kent	3 hr
Jul 14, 5:24 PM EDT	Special Weather Statement	PHI	Sussex	36 min
Jul 14, 5:30 PM EDT	River Flood Warning	PHI	New Castle	7 hr
Jul 14, 5:51 PM EDT	Special Weather Statement	PHI	Sussex	39 min
Jul 14, 6:32 PM EDT	Areal Flood Advisory	PHI	Sussex	4 hr
Jul 14, 6:48 PM EDT	Special Weather Statement	PHI	Sussex	42 min
Jul 14, 7:15 PM EDT	Severe Thunderstorm Warning	PHI	Sussex	60 min

Nearby

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