Alert archive / Pennsylvania / Severe Thunderstorm Warnings in 2009
Severe Thunderstorm Warning 171, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this severe thunderstorm warning at Aug 2, 2009, 10:24 AM EDT for New Castle County, Delaware; Chester County, Delaware County, Montgomery County, Pennsylvania. It was in force for 66 min. 2 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 2, 2009, 10:24 AM EDT (14:24 UTC)
- Expired
- Aug 2, 2009, 11:30 AM EDT
- In force
- 66 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
Counties New Castle County, DE, Chester County, PA, Delaware County, PA, Montgomery County, PA
The radar
The Philadelphia radar (KDIX), 105 km from the middle of the area, began a volume at 14:28 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 2, 10:39 AM EDT | TSTM WND DMG | West Chester, PA | NUMEROUS TREES DOWN COUNTY-WIDE. |
| Aug 2, 11:05 AM EDT | TSTM WND DMG | Hockessin, DE | TREES AND WIRES DOWN IN HOCKESSIN. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 2.4 hours before the alert went out and 194 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.
- Mixed-layer CAPE
- 633 J/kg
- Mixed-layer CIN
- -76 J/kg
- Mixed-layer LCL
- 689 m above ground
- 0-6 km bulk shear
- 0 kt
- 0-1 km storm-relative helicity
- 0 m²/s²
- 0-3 km storm-relative helicity
- 0 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000 WUUS51 KPHI 021424 SVRPHI DEC003-PAC029-045-091-021530- /O.NEW.KPHI.SV.W.0171.090802T1424Z-090802T1530Z/ BULLETIN - EAS ACTIVATION REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 1024 AM EDT SUN AUG 2 2009 THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... NORTHEASTERN NEW CASTLE COUNTY IN NORTHERN DELAWARE... CHESTER COUNTY IN SOUTHEAST PENNSYLVANIA... THIS INCLUDES THE CITY OF WEST CHESTER... DELAWARE COUNTY IN SOUTHEAST PENNSYLVANIA... SOUTHERN MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA... * UNTIL 1130 AM EDT * AT 1022 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING NICKEL SIZE HAIL...AND DAMAGING WINDS IN EXCESS OF 60 MPH. THIS STORM WAS LOCATED NEAR GLENMOORE...OR 12 MILES NORTHWEST OF WEST CHESTER...AND MOVING NORTHEAST AT 35 MPH. * THE SEVERE THUNDERSTORM WILL BE NEAR... LIONVILLE AROUND 1030 AM EDT... CHESTER SPRINGS AND PUGHTOWN AROUND 1035 AM EDT... PHOENIXVILLE AND 6 MILES NORTHWEST OF VALLEY FORGE AROUND 1045 AM EDT... COLLEGEVILLE AROUND 1050 AM EDT... PRECAUTIONARY/PREPAREDNESS ACTIONS... THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER... PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS. ALL THE HEAVY RAIN WILL MAKE IT EASIER FOR TREES TO COME DOWN EVEN IF WINDS DO NOT REACH 60 MPH. && LAT...LON 4022 7574 4020 7515 3976 7547 3978 7606 TIME...MOT...LOC 1424Z 244DEG 32KT 4009 7574 $$ TFG
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 2, 2:19 AM EDT | Flash Flood Watch | PHI | New Castle | 13 hr |
| Aug 2, 10:08 AM EDT | Flash Flood Warning | PHI | New Castle | 9 hr |
| Aug 2, 10:08 AM EDT | Severe Thunderstorm Warning | PHI | New Castle | 67 min |
| Aug 2, 10:32 AM EDT | Tornado Warning | PHI | New Castle | 28 min |
| Aug 2, 10:39 AM EDT | Severe Thunderstorm Warning | PHI | Kent, New Castle | 96 min |
| Aug 2, 10:53 AM EDT | Severe Thunderstorm Warning | PHI | New Castle | 67 min |
| Aug 2, 12:13 PM EDT | Areal Flood Advisory | PHI | Kent, Sussex | 3 hr |
| Aug 2, 12:53 PM EDT | Severe Thunderstorm Warning | PHI | Kent, Sussex | 67 min |
| Aug 2, 3:29 AM EDT | Areal Flood Advisory | PHI | Berks | 3 hr |
| Aug 2, 5:54 AM EDT | Areal Flood Advisory | PHI | Chester | 3 hr |
| Aug 2, 7:34 AM EDT | Areal Flood Advisory | PHI | Bucks, Montgomery, Philadelphia | 3 hr |
| Aug 2, 7:51 AM EDT | Areal Flood Warning | PHI | Chester | 4 hr |
| Aug 2, 9:04 AM EDT | Areal Flood Warning | PHI | Montgomery, Philadelphia | 4 hr |
| Aug 2, 9:06 AM EDT | Flash Flood Warning | PHI | Berks, Carbon, Chester, Lehigh, Monroe, Northampton | 4 hr |
| Aug 2, 11:14 AM EDT | Severe Thunderstorm Warning | PHI | Bucks, Lehigh, Montgomery, Northampton | 61 min |
| Aug 2, 11:25 AM EDT | Severe Thunderstorm Warning | PHI | Bucks, Montgomery, Philadelphia | 65 min |
| Aug 2, 11:48 AM EDT | Severe Thunderstorm Warning | PHI | Bucks | 57 min |
| Aug 2, 11:51 AM EDT | Tornado Warning | PHI | Bucks | 24 min |
| Aug 2, 12:33 PM EDT | River Flood Warning | PHI | Bucks | 28 hr |
| Aug 2, 1:25 PM EDT | Areal Flood Warning | PHI | Montgomery, Philadelphia | 6 hr |
| Aug 2, 4:06 PM EDT | Areal Flood Advisory | PHI | Berks, Carbon, Lehigh, Monroe, Northampton | 4 hr |
| Aug 2, 4:21 PM EDT | River Flood Warning | PHI | Chester | 56 min |
| Aug 2, 4:22 PM EDT | Flash Flood Warning | PHI | Berks | 2 hr |
| Aug 2, 6:15 PM EDT | Areal Flood Warning | PHI | Montgomery, Philadelphia | 4 hr |
| Aug 2, 6:25 PM EDT | Areal Flood Warning | PHI | Philadelphia | 4 hr |
Nearby
Severe Thunderstorm Warnings in Pennsylvania, 2009Severe Thunderstorm Warnings in Delaware, 2009Every severe thunderstorm warning in 2009
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.