Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2001

Severe Thunderstorm Watch 708

September 4, 2001New Castle County, Delaware; 11 counties in New Jersey; 13 counties in Pennsylvania

The Storm Prediction Center issued this severe thunderstorm watch at Sep 4, 2001, 3:00 PM EDT for New Castle County, Delaware; 11 counties in New Jersey; 13 counties in Pennsylvania. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Sep 4, 2001, 3:00 PM EDT (19:00 UTC)
Expired
Sep 4, 2001, 9:00 PM EDT
In force
6 hr
Issued by
the Storm Prediction Center
All 25 counties

New Castle County, DE, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Ocean County, NJ, Salem County, NJ, Somerset County, NJ, Berks County, PA, Bucks County, PA, Chester County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Schuylkill County, PA, York County, PA

The radar

The Philadelphia radar (KDIX), 117 km from the middle of the area, began a volume at 18:59 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.

Warnings issued inside it

14 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Sep 4, 3:01 PM EDTSevere Thunderstorm WarningPHIBerks59 min
Sep 4, 3:59 PM EDTSevere Thunderstorm WarningPHIChester61 min
Sep 4, 4:41 PM EDTSevere Thunderstorm WarningPHIDelaware49 min
Sep 4, 4:50 PM EDTSevere Thunderstorm WarningPHIHunterdon40 min
Sep 4, 5:17 PM EDTSevere Thunderstorm WarningPHISomerset43 min
Sep 4, 5:21 PM EDTSevere Thunderstorm WarningPHIGloucester39 min
Sep 4, 5:23 PM EDTSevere Thunderstorm WarningPHIChester52 min
Sep 4, 5:33 PM EDTSevere Thunderstorm WarningPHIMercer, Middlesex42 min
Sep 4, 5:51 PM EDTSevere Thunderstorm WarningPHIMonmouth39 min
Sep 4, 5:58 PM EDTSevere Thunderstorm WarningPHINew Castle47 min
Sep 4, 6:08 PM EDTSevere Thunderstorm WarningPHIOcean52 min
Sep 4, 6:38 PM EDTSevere Thunderstorm WarningPHISalem52 min
Sep 4, 7:04 PM EDTSevere Thunderstorm WarningPHIOcean56 min
Sep 4, 7:11 PM EDTTornado WarningPHIOcean34 min

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.0 hours before the alert went out and 102 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, Phillips Aaf/Abe, MD at 12:00Z on 2001-09-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 35 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, Phillips Aaf/Abe, MD at 12:00Z on 2001-09-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 95 square meters per square second.193958Sfc1 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
35 J/kg
Mixed-layer CIN
-94 J/kg
Mixed-layer LCL
800 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
95 m²/s²
0-3 km storm-relative helicity
80 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 
WWUS9 KMKC 041844
SEL8  
MKC WW 041834
DEZ000-MDZ000-NJZ000-PAZ000-CWZ000-050100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 708
STORM PREDICTION CENTER NORMAN OK
234 PM EDT TUE SEP 4 2001

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   NORTHERN DELAWARE                           
   EXTREME NORTHEAST MARYLAND                           
   NEW JERSEY                         
   EAST CENTRAL AND SOUTHEAST PENNSYLVANIA                       
   COASTAL WATERS                     

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 300 PM UNTIL 900
PM EDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 45 STATUTE MILES
EITHER SIDE OF A LINE FROM 15 MILES NORTH OF HARRISBURG
PENNSYLVANIA TO 20 MILES SOUTHEAST OF LAKEHURST NEW JERSEY.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.  SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.

OTHER WATCH INFORMATION...  CONTINUE...WW 707...

DISCUSSION...STRONG THUNDERSTORMS OVER EAST CENTRAL PA ARE EXPECTED
TO MOVE ESEWD 30-35 KT IN RESPONSE TO STRONG MID LEVEL JET
PROPAGATING ACROSS PA.  AIR MASS HAS DESTABILIZED OVER SRN/ERN PA
INTO NJ WHERE SBCAPE IS IN THE 1500-2500 J/KG RANGE.  DRY AIR ABOVE
THE BOUNDARY LAYER WILL ENHANCE POTENTIAL FOR DAMAGING WIND
GUSTS...WITH ADDITIONAL THREAT FOR LARGE HAIL.  


AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM
MOTION VECTOR 30030.


...WEISS

410,0764 402,0735 391,0741 394,0770

@RUKWBC	.KDENWWUS9 KMKC 041844
SEL8  
MKC WW 041834
DEZ000-MDZ000-NJZ000-PAZ000-CWZ000-050100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 708
STORM PREDICTION CENTER NORMAN OK
234 PM EDT TUE SEP 4 2001

THE STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

   NORTHERN DELAWARE                           
   EXTREME NORTHEAST MARYLAND                           
   NEW JERSEY                         
   EAST CENTRAL AND SOUTHEAST PENNSYLVANIA                       
   COASTAL WATERS                     

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 300 PM UNTIL 900
PM EDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 45 STATUTE MILES
EITHER SIDE OF A LINE FROM 15 MILES NORTH OF HARRISBURG
PENNSYLVANIA TO 20 MILES SOUTHEAST OF LAKEHURST NEW JERSEY.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.  SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE
TORNADOES.

OTHER WATCH INFORMATION...  CONTINUE...WW 707...

DISCUSSION...STRONG THUNDERSTORMS OVER EAST CENTRAL PA ARE EXPECTED
TO MOVE ESEWD 30-35 KT IN RESPONSE TO STRONG MID LEVEL JET
PROPAGATING ACROSS PA.  AIR MASS HAS DESTABILIZED OVER SRN/ERN PA
INTO NJ WHERE SBCAPE IS IN THE 1500-2500 J/KG RANGE.  DRY AIR ABOVE
THE BOUNDARY LAYER WILL ENHANCE POTENTIAL FOR DAMAGING WIND
GUSTS...WITH ADDITIONAL THREAT FOR LARGE HAIL.  


AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.  MEAN STORM
MOTION VECTOR 30030.


...WEISS

410,0764 402,0735 391,0741 394,0770

Nearby

Severe Thunderstorm Watches in Pennsylvania, 2001Severe Thunderstorm Watches in New Jersey, 2001Severe Thunderstorm Watches in Delaware, 2001Every severe thunderstorm watch 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.