Alert archive / Pennsylvania / Special Weather Statements in 2021

Special Weather Statement, NWS Philadelphia/Mount Holly

August 1, 2021Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this special weather statement at Aug 1, 2021, 8:29 PM EDT for Chester County, Montgomery 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 1, 2021, 8:29 PM EDT (00:29 UTC)
Expired: Aug 1, 2021, 9:15 PM EDT
In force: 46 min
Issued by: NWS Philadelphia/Mount Holly

Counties Chester County, PA, Montgomery County, PA

The radar

The Dover AFB radar (KDOX), 130 km from the middle of the area, began a volume at 00:32 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 00:00Z, 0.5 hours before the alert went out and 166 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: 324 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 1223 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: -4 m²/s²
0-3 km storm-relative helicity: 8 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

289 
WWUS81 KPHI 020029
SPSPHI

Special Weather Statement
National Weather Service Mount Holly NJ
829 PM EDT Sun Aug 1 2021

PAZ060-101>104-020115-
Eastern Montgomery-Western Montgomery-Western Chester-Eastern
Chester-Berks-
829 PM EDT Sun Aug 1 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN BERKS...
CENTRAL MONTGOMERY AND CHESTER COUNTIES...

At 827 PM EDT, radar indicated strong thunderstorms were located
along a line extending from near Cedarville to Paradise to near
Smithville. Movement was southeast at 25 mph.

Wind gusts up to 45 mph and pea size hail are possible with these 
storms.

Locations impacted include...
West Chester, Norristown, Pottstown, Phoenixville, Lansdale, West
Norriton, East Norriton, Coatesville, Downingtown, Ambler, Kennett
Square, Birdsboro, Collegeville, Oxford, Royersford, Parkesburg,
Trappe, West Grove, Honey Brook and Schwenksville.

This includes the following highways...
 Pennsylvania Turnpike between mile markers 296 and 332.
 Northeast Extension between mile markers 21 and 30.
 Interstate 76 in Pennsylvania between mile markers 327 and 329.
 Interstate 176 in Pennsylvania between mile markers 1 and 3.

If outdoors, consider seeking shelter inside a building.

LAT...LON 3974 7612 3973 7610 3974 7610 3976 7606
      3983 7604 3987 7599 3995 7600 4004 7593
      4011 7594 4014 7588 4018 7594 4032 7569
      4021 7514 3972 7589 3972 7613
TIME...MOT...LOC 0027Z 297DEG 24KT 4026 7570 4001 7612 3989 7630 

$$

Staarmann

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.