Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 1994

Severe Thunderstorm Warning 58, NWS Philadelphia/Mount Holly

July 2, 1994Chester County, Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Jul 2, 1994, 4:58 PM EDT for Chester County, Pennsylvania. It was in force for 47 min.

The area

The counties it named.

The facts

Issued
Jul 2, 1994, 4:58 PM EDT (20:58 UTC)
Expired
Jul 2, 1994, 5:45 PM EDT
In force
47 min
Issued by
NWS Philadelphia/Mount Holly
Area
Whole counties

County Chester County, PA

The nearest sounding before it

Atlantic City In, NJ (KACY), launched 12:00Z, 9.0 hours before the alert went out and 122 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-pSkew-T log-p diagram, Atlantic City In, NJ at 12:00Z on 1994-07-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 634 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Atlantic City In, NJ at 12:00Z on 1994-07-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 14 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
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
634 J/kg
Mixed-layer CIN
-18 J/kg
Mixed-layer LCL
922 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
14 m²/s²
0-3 km storm-relative helicity
35 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
WUUS1 KPHL 022101 RRA
SVRPHL
PAC029-022145-
 
BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PHILADELPHIA/MOUNT HOLLY NJ
458 PM EDT SAT JUL 2 1994
 
THE NATIONAL WEATHER SERVICE IN PHILADELPHIA/MOUNT HOLLY HAS EXTENDED
THE SEVERE THUNDERSTORM WARNING EFFECTIVE NOW UNTIL 545 PM EDT
FOR PEOPLE IN THE FOLLOWING LOCATION...
 
IN SOUTHEAST PENNSYLVANIA
 
   ...EASTERN CHESTER COUNTY
 
A NATIONAL WEATHER SERVICE EMPLOYEE HAS JUST REPORTED PENNY SIZED HAIL
WITH THIS SEVERE THUNDERSTORM IN DOWNINGTOWN.  IN ADDITION TORRENTIAL
HEAVY DOWNPOURS WERE REPORTED WITH IT.  THE THUNDERSTORM WAS DRIFTING
SLOWLY SOUTHEAST AT 5 TO 10 MPH AND WILL CONTINUE TO POSE THE MULTIPLE
THREATS OF DAMAGING WIND GUSTS...LARGE HAIL AND TORRENTIAL DOWNPOURS
ACROSS EASTERN CHESTER COUNTY.
 
HEAVY RAINS WITH THIS THUNDERSTORM MAY CAUSE FLOODING OF SMALL
STREAMS AND UNDERPASSES VERY QUICKLY.  DO NOT DRIVE YOUR CAR INTO
AREAS WHERE THE WATER COVERS THE ROADWAY.  THE WATER MAY BE DEEPER
THAN YOU THINK.  IF CAUGHT IN RISING WATERS...ABANDON YOUR CAR
QUICKLY.  MOVE TO HIGHER GROUND.
 
 
 
&

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, Jul 2, 4:06 PM EDT, 52 minutes before
PAZ067>071-NJZ015>019-032200-

SPECIAL WEATHER STATEMENT/SHORT TERM FORECAST - THUNDERSTORMS
NATIONAL WEATHER SERVICE PHILADELPHIA/MT HOLLY
400 PM EDT SAT JUL 2 1994

...THUNDERSTORMS DEVELOPING IN THE NORTHERN AND WESTERN SUBURBS OF
PHILADELPHIA...

AT 355 PM EDT DOPPLER RADAR SHOWED TWO INTENSIFYING THUNDERSTORMS OVER
CHESTER COUNTY PENNSYLVANIA.  ANOTHER THUNDERSTORM WAS ALSO DEVELOPING
NEAR DOYLESTOWN IN BUCKS COUNTY.  MOVEMENT WAS SLOWLY EAST TO SOUTHEAST
AT 10 TO 15 MPH.

PERSONS IN THE PHILADELPHIA NORTHWESTERN SUBURBS SHOULD BE ON THE ALERT
FOR THUNDERSTORMS.  PLEASE GET OUT OF THE WATER AND HEAD INDOORS WITH
THE FIRST CRACK OF THUNDER.  OTHER THUNDERSTORMS ARE EXPECTED TO DEVELOP
ACROSS THE REMAINDER OF THE GREATER PHILADELPHIA METROPOLITAN AREA THE
REST OF THE AFTERNOON AND EVENING.

YOUNG/GIGI
Special weather statement, Jul 2, 4:30 PM EDT, 28 minutes before
NJZ019>026-501-022100-

SPECIAL WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE ATLANTIC CITY NJ
430 PM EDT SAT JUL 2 1994

...ISOLATED THUNDERSTORMS POP-UP IN THE HUMID AIRMASS...

AT 430 PM...THE ATLANTIC CITY WEATHER RADAR SHOWED TWO ISOLATED
THUNDERSTORMS SHOWING UP ON THE OLD (WRS-57) RADAR NEAR PHILADELPHIA
IN CHESTER COUNTY AND THE OTHER ONE WAS NEAR ANNAPOLIS MARYLAND.

AS WITH ANY THUNDERSTORM...THEY HAVE THE POSSIBLY OF GIVING BRIEF
HEAVY DOWNPOURS AND GUSTY WINDS.

THE MOVEMENT WAS TOWARD THE EAST NORTHEAST AROUND 25 MILES AN HOUR.

PM
Special weather statement, Jul 2, 4:44 PM EDT, 14 minutes before
NJZ019>026-501-022100-

SPECIAL WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE ATLANTIC CITY NJ
430 PM EDT SAT JUL 2 1994

...ISOLATED THUNDERSTORMS POP-UP IN THE HUMID AIRMASS...

AT 430 PM...THE ATLANTIC CITY WEATHER RADAR SHOWED TWO ISOLATED
THUNDERSTORMS SHOWING UP ON THE OLD (WRS-57) RADAR NEAR PHILADELPHIA
IN CHESTER COUNTY AND THE OTHER ONE WAS NEAR ANNAPOLIS MARYLAND.

AS WITH ANY THUNDERSTORM...THEY HAVE THE POSSIBLY OF GIVI(NG BRIEF
HEAVY DOWNPOURS AND GUSTY WINDS.

THE MOVEMENT WAS TOWARD THE EAST NORTHEAST AROUND 25 MILES AN HOUR.

PM

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 2, 4:28 PM EDTSevere Thunderstorm WarningPHIChester32 min

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 1994Every severe thunderstorm warning in 1994

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.