Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 81, NWS Philadelphia/Mount Holly

July 1, 2001Chester County, Montgomery County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 1, 2001, 5:15 PM EDT for Chester County, Montgomery County, Pennsylvania. It was in force for 45 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jul 1, 2001, 5:15 PM EDT (21:15 UTC)
Expired: Jul 1, 2001, 6:00 PM EDT
In force: 45 min
Issued by: NWS Philadelphia/Mount Holly
Area: Whole counties

Counties Chester County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 99 km from the middle of the area, began a volume at 21:14 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 1, 12:00 PM EDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 1, 4:30 PM EDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.3 hours before the alert went out and 203 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: 737 J/kg
Mixed-layer CIN: -52 J/kg
Mixed-layer LCL: 1231 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 28 m²/s²
0-3 km storm-relative helicity: 145 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS51 KPHI 012117
SVRPHI

NJC021-023-PAC017-029-091-012200-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
515 PM EDT SUN JUL 1 2001

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  MERCER COUNTY IN CENTRAL NEW JERSEY.
  MIDDLESEX COUNTY IN NORTHERN NEW JERSEY.
  NORTHERN CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA.
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA.
  BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA.

* UNTIL 600 PM EDT.

* AT 509 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM... ALONG A LINE EXTENDING FROM 2 MILES EAST OF
  MILLSTONE TO HONEY BROOK...MOVING EAST AT 40 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  EDISON...HOPEWELL...NEW BRUNSWICK...COLLEGEVILLE AT 520 PM.
  KENDALL PARK...NORTH BRUNSWICK...ROCKY HILL...PHOENIXVILLE AT 525
  PM.
  PERTH AMBOY...PENNINGTON AT 530 PM.

THIS STORM HAS A HISTORY OF PRODUCING DAMAGING WINDS AND LARGE HAIL.
NUMEROUS TREES AND WIRES HAVE BEEN KNOCKED DOWN. SEEK SHELTER INDOORS
IMMEDIATELY.

FOR THE LATEST STORM INFORMATION...PLEASE TUNE TO NOAA WEATHER
RADIO...YOUR LOCAL RAuDIO OR TELEVISION STATION...OR YOUR CABLE
TELEVISION OUTLET.
 
$$

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 30, 10:53 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	52 min
Jul 1, 1:09 PM EDT	Severe Thunderstorm Warning	PHI	Monroe	36 min
Jul 1, 1:20 PM EDT	Severe Thunderstorm Warning	PHI	Carbon	25 min
Jul 1, 1:26 PM EDT	Severe Thunderstorm Warning	PHI	Berks	64 min
Jul 1, 2:03 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Lehigh	42 min
Jul 1, 2:44 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Northampton	61 min
Jul 1, 4:06 PM EDT	Severe Thunderstorm Warning	PHI	Northampton	39 min
Jul 1, 4:35 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Bucks, Montgomery	40 min
Jul 1, 5:15 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	45 min
Jul 1, 6:31 PM EDT	Severe Thunderstorm Warning	PHI	Philadelphia	29 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2001 Every severe thunderstorm warning in 2001

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.