Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 219, NWS Philadelphia/Mount Holly

August 10, 20084 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 10, 2008, 12:21 PM EDT for 4 counties in Pennsylvania. It was in force for 84 min. 6 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 10, 2008, 12:21 PM EDT (16:21 UTC)
Expired: Aug 10, 2008, 1:45 PM EDT
In force: 84 min
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Berks County, PA, Bucks County, PA, Lehigh County, PA, Montgomery County, PA

The radar

The Philadelphia radar (KDIX), 94 km from the middle of the area, began a volume at 16:21 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.

What was reported inside it

Time	Report	Where	Remark
Aug 10, 12:35 PM EDT	HAIL 0.25	2 Nw Pottstown, PA
Aug 10, 12:35 PM EDT	HAIL 0.88	East Greenville, PA
Aug 10, 1:05 PM EDT	HAIL 1	Allentown, PA
Aug 10, 1:20 PM EDT	HAIL 1	Allentown, PA	NICKEL TO QUARTER SIZE
Aug 10, 1:40 PM EDT	HAIL 0.5	Fleetwood, PA	1.25 TO 1.50 INCH HAIL
Aug 10, 1:40 PM EDT	HAIL 1.5	Fleetwood, PA	1.25 TO 1.50 INCH HAIL COVERING THE GROUND

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

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

Issued	Product	Office	Lasted
Aug 10, 10:46 AM EDT	Severe Thunderstorm Watch	SPC	10 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 4.4 hours before the alert went out and 223 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: 771 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 923 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 3 m²/s²
0-3 km storm-relative helicity: 85 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

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

000 
WUUS51 KPHI 101621
SVRPHI
PAC011-017-077-091-101745-
/O.NEW.KPHI.SV.W.0219.080810T1621Z-080810T1745Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1221 PM EDT SUN AUG 10 2008

THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EASTERN BERKS COUNTY IN EASTERN PENNSYLVANIA...
  LEHIGH COUNTY IN EASTERN PENNSYLVANIA...
  BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA...
  MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA...

* UNTIL 145 PM EDT

* AT 1216 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE HAIL.  THIS
  STORM WAS LOCATED NEAR EAST GREENVILLE...OR ABOUT 11 MILES SOUTH OF
  ALLENTOWN...AND MOVING NORTHEAST AT 18 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO      
  SOUDERTON...WILLOW GROVE...ZIONSVILLE...CHALFONT...EMMAUS...
  PERKASIE...QUAKERTOWN...SCHNECKSVILLE...DUBLIN...DOYLESTOWN...
  RICHBORO...  BEDMINSTER AND GARDENVILLE.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 700 PM SUNDAY
EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND NEW JERSEY AND
EASTERN PENNSYLVANIA.

LAT...LON 4071 7558 4056 7538 4054 7533 4027 7491
      4007 7517 4009 7522 4006 7526 4005 7527
      4003 7523 4000 7527 4016 7551 4016 7554
      4023 7561 4022 7562 4025 7567 4025 7570
      4042 7599
TIME...MOT...LOC 1620Z 228DEG 16KT 4044 7549

$$

JJM

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 10, 10:18 AM EDT	Severe Thunderstorm Warning	PHI	Chester	57 min
Aug 10, 10:44 AM EDT	Severe Thunderstorm Warning	PHI	Delaware	61 min
Aug 10, 11:09 AM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware, Montgomery, Philadelphia	66 min
Aug 10, 11:32 AM EDT	Areal Flood Advisory	PHI	Chester, Delaware	3 hr
Aug 10, 11:46 AM EDT	Severe Thunderstorm Warning	PHI	Delaware	59 min
Aug 10, 12:09 PM EDT	Tornado Warning	PHI	Delaware	36 min
Aug 10, 12:17 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery	4 hr
Aug 10, 12:40 PM EDT	Severe Thunderstorm Warning	PHI	Delaware, Philadelphia	95 min
Aug 10, 1:05 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Carbon, Lehigh, Monroe, Northampton	115 min
Aug 10, 1:10 PM EDT	Severe Thunderstorm Warning	PHI	Berks, Chester, Montgomery	65 min
Aug 10, 1:47 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Montgomery	58 min
Aug 10, 3:05 PM EDT	Flash Flood Warning	PHI	Chester	3 hr
Aug 10, 3:35 PM EDT	Severe Thunderstorm Warning	PHI	Berks	40 min
Aug 10, 4:45 PM EDT	Severe Thunderstorm Warning	PHI	Chester	75 min
Aug 10, 5:25 PM EDT	Areal Flood Advisory	PHI	Berks, Montgomery	110 min
Aug 10, 5:45 PM EDT	Severe Thunderstorm Warning	PHI	Chester, Delaware	75 min
Aug 10, 5:59 PM EDT	Areal Flood Advisory	PHI	Chester, Delaware	2 hr
Aug 10, 6:45 PM EDT	Areal Flood Advisory	PHI	Philadelphia	2 hr

Nearby

Severe Thunderstorm Warnings in Pennsylvania, 2008 Every severe thunderstorm warning in 2008

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.