Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 117, NWS Philadelphia/Mount Holly

August 16, 1997Delaware County, Montgomery County, Philadelphia County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 16, 1997, 10:18 PM EDT for Delaware County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 42 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: Aug 16, 1997, 10:18 PM EDT (02:18 UTC)
Expired: Aug 16, 1997, 11:00 PM EDT
In force: 42 min
Issued by: NWS Philadelphia/Mount Holly
Area: Whole counties

Counties Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 77 km from the middle of the area, began a volume at 02:19 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, 2.3 hours before the alert went out and 217 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: 2006 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 1904 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 61 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.5

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KPHL 170220 RRB
SVRPHL
PAC045-091-101-170300-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING...CORRECETD
NATIONAL WEATHER SERVICE PHILADELPHIA/MOUNT HOLLY NJ
1018 PM EDT SAT AUG 16 1997

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A
SEVERE THUNDERSTORM WARNING EFFECTIVE UNTIL 1100 PM EDT FOR PEOPLE IN
THE FOLLOWING LOCATION...

IN  PENNSYLVANIA

   ...SOUTHEASTERN MONTGOMERY COUNTY
   ...DELAWARE COUNTY
   ...PHILADELPHIA COUNTY

AT 1015 PM A LINE OF SEVERE THUNDERSTORMS WAS INDICATED BY DOPPLER
RADAR EXTENDING FROM EASTERN MONTGOMERY COUNTY TO ALONG THE
WESTERN BORDER OF DELAWARE COUNTY. THESE STORMS WERE MOVING TOWARD
THE EAST AT AROUND 35 MPH AND MAY PRODUCE WIND GUSTS TO OVER 55 MPH..
HAIL AND LOCALLY HEAVY DOWNPOURS.

THIS IS A DANGEROUS STORM. MOVE INSIDE A STRONG BUILDING AND DO NOT
STAND NEAR WINDOWS. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON
THE LOWEST FLOOR OF YOUR HOME OR BUSINESS.

DO NOT DRIVE YOUR CAR WHERE WATER COVERS THE ROADWAY. THE WATER MAY
BE DEEPER THAN YOU THINK. IF CAUGHT IN RISING FLOOD WATERS...ABANDON
YOUR CAR QUICKLY AND MOVE TO HIGHER GROUND.

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

NPC

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 16, 11:25 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	35 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 1997 Every severe thunderstorm warning in 1997

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.