Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

August 10, 2021Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 10, 2021, 5:40 PM EDT for Chester County, Pennsylvania. It was in force for 35 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 10, 2021, 5:40 PM EDT (21:40 UTC)
Expired: Aug 10, 2021, 6:15 PM EDT
In force: 35 min
Issued by: NWS Philadelphia/Mount Holly
Hail: 0.25 in
Wind: 40

County Chester County, PA

The radar

The Philadelphia radar (KDIX), 124 km from the middle of the area, began a volume at 21:41 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.7 hours before the alert went out and 192 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: 529 J/kg
Mixed-layer CIN: -120 J/kg
Mixed-layer LCL: 1096 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

076 
WWUS81 KPHI 102140
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
540 PM EDT Tue Aug 10 2021
 
PAZ060-101>103-102215-
Western Montgomery PA-Western Chester PA-Eastern Chester PA-Berks PA-
540 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of southeastern Berks,
west central Montgomery and north central Chester Counties through
615 PM EDT...

At 540 PM EDT, Doppler radar was tracking a strong thunderstorm over
New Morgan, or 10 miles south of Reading, moving southeast at 20 mph.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects. Minor damage to outdoor objects is 
         possible.

Locations impacted include...
Pottstown, Downingtown, Birdsboro, Honey Brook, Elverson, New Morgan,
Glenmoore, Chester Springs, Pughtown, Lionville, Cedarville,
Lionville-Marchwood, Stowe, Spring City, South Pottstown, Kenilworth,
Flying Hills, Amity Gardens, Lorane and Exton.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 314.
 Interstate 176 in Pennsylvania between mile markers 1 and 10.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

&&

LAT...LON 4030 7591 4023 7553 3998 7567 4011 7594
      4014 7588 4020 7597
TIME...MOT...LOC 2140Z 293DEG 16KT 4020 7588 

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

$$

SFJ

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 1:02 AM EDT	Special Weather Statement	PHI	Burlington	28 min
Aug 10, 3:33 AM EDT	Excessive Heat Warning	PHI	Burlington, Camden, Gloucester, Hunterdon, Mercer, Middlesex and 5 more	4 days
Aug 10, 3:33 AM EDT	Heat Advisory	PHI	Atlantic, Cape May, Cumberland, Monmouth, Ocean, Salem and 2 more	4 days
Aug 10, 3:54 AM EDT	Areal Flood Advisory	PHI	Atlantic	80 min
Aug 10, 4:59 AM EDT	Areal Flood Advisory	PHI	Burlington	60 min
Aug 10, 5:58 AM EDT	Flash Flood Warning	PHI	Burlington, Mercer	2 hr
Aug 10, 2:07 PM EDT	Special Weather Statement	PHI	Salem	38 min
Aug 10, 4:52 PM EDT	Special Weather Statement	PHI	Monmouth	23 min
Aug 10, 4:54 PM EDT	Special Marine Warning	PHI		26 min
Aug 10, 5:05 PM EDT	Special Weather Statement	PHI	Somerset, Warren	25 min
Aug 10, 5:09 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Hunterdon, Mercer, Somerset, Warren	51 min
Aug 10, 5:30 PM EDT	Special Weather Statement	PHI	Warren	30 min
Aug 10, 5:58 PM EDT	Special Weather Statement	PHI	Mercer, Middlesex, Morris, Somerset, Warren	32 min
Aug 10, 6:27 PM EDT	Special Weather Statement	PHI	Burlington, Mercer, Middlesex, Monmouth, Morris	33 min
Aug 10, 6:59 PM EDT	Special Weather Statement	PHI	Middlesex, Monmouth	31 min
Aug 10, 7:09 PM EDT	Special Marine Warning	PHI		66 min
Aug 10, 7:27 PM EDT	Special Weather Statement	PHI	Monmouth	33 min
Aug 9, 10:10 PM EDT	Areal Flood Advisory	PHI	Carbon	3 hr
Aug 10, 3:06 PM EDT	Special Weather Statement	PHI	Berks	24 min
Aug 10, 3:33 PM EDT	Special Weather Statement	PHI	Berks	27 min
Aug 10, 3:52 PM EDT	Special Weather Statement	PHI	Berks, Carbon, Lehigh	23 min
Aug 10, 4:01 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Carbon, Chester, Lehigh, Montgomery, Northampton	44 min
Aug 10, 4:18 PM EDT	Areal Flood Advisory	PHI	Berks, Carbon, Lehigh	3 hr
Aug 10, 4:33 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Carbon, Chester, Lehigh, Monroe and 2 more	42 min
Aug 10, 5:11 PM EDT	Special Weather Statement	PHI	Chester, Montgomery, Philadelphia	34 min
Aug 10, 6:36 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester	39 min
Aug 10, 7:10 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	65 min
Aug 10, 7:54 PM EDT	Severe Thunderstorm Warning Considerable damage threat	PHI	Chester	51 min
Aug 10, 7:12 PM EDT	Special Weather Statement	PHI	Kent, Queen Anne's	33 min
Aug 10, 7:42 PM EDT	Special Weather Statement	PHI	Kent, Queen Anne's, Talbot	33 min

Nearby

Special Weather Statements in Pennsylvania, 2021 Every special weather statement in 2021

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.