Alert archive / Pennsylvania / Tornado Warnings in 2011
Tornado Warning 4, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this tornado warning at May 18, 2011, 1:52 PM EDT for Bucks County, Montgomery County, Philadelphia County, Pennsylvania. It was in force for 24 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- May 18, 2011, 1:52 PM EDT (17:52 UTC)
- Expired
- May 18, 2011, 2:16 PM EDT
- In force
- 24 min
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
Counties Bucks County, PA, Montgomery County, PA, Philadelphia County, PA
The radar
The Philadelphia radar (KDIX), 73 km from the middle of the area, began a volume at 17:54 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
Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 5.9 hours before the alert went out and 113 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
- 79 J/kg
- Mixed-layer CIN
- -31 J/kg
- Mixed-layer LCL
- 561 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 66 m²/s²
- 0-3 km storm-relative helicity
- 169 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted, in the capitals the NWS used until 2016.
994 WFUS51 KPHI 181752 TORPHI PAC017-091-101-181830- /O.NEW.KPHI.TO.W.0004.110518T1752Z-110518T1830Z/ BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 152 PM EDT WED MAY 18 2011 THE NATIONAL WEATHER SERVICE IN MOUNT HOLLY NJ HAS ISSUED A * TORNADO WARNING FOR... CENTRAL BUCKS COUNTY IN SOUTHEAST PENNSYLVANIA... EAST CENTRAL MONTGOMERY COUNTY IN SOUTHEAST PENNSYLVANIA... NORTHEASTERN PHILADELPHIA COUNTY IN SOUTHEAST PENNSYLVANIA... * UNTIL 230 PM EDT * AT 150 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR BRYN ATHYN...OR 9 MILES NORTHEAST OF PHILADELPHIA...MOVING NORTHWEST AT 30 MPH. THIS THUNDERSTORM IS SHOWING SIGNS OF STRONG ROTATION ON DOPPLER RADAR. * THE TORNADO WILL BE NEAR... HATBORO...WILLOW GROVE AND IVYLAND BY 200 PM EDT... CHALFONT AND LANSDALE BY 220 PM EDT... FRICKS AND HATFIELD BY 225 PM EDT... PRECAUTIONARY/PREPAREDNESS ACTIONS... THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS. IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW JERSEY. && LAT...LON 4026 7537 4035 7518 4013 7500 4007 7505 TIME...MOT...LOC 1752Z 137DEG 27KT 4012 7505 $$ GORSE
2 follow-up statements
917 WWUS51 KPHI 181759 SVSPHI SEVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 159 PM EDT WED MAY 18 2011 PAC101-181808- /O.CAN.KPHI.TO.W.0004.000000T0000Z-110518T1830Z/ PHILADELPHIA PA- 159 PM EDT WED MAY 18 2011 ...THE TORNADO WARNING FOR NORTHEASTERN PHILADELPHIA COUNTY IS CANCELLED... THE THUNDERSTORM WITH ROTATION ON DOPPLER RADAR HAS MOVED OUT OF THE AREA, THEREFORE THE WARNING HAS BEEN CANCELLED. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW JERSEY. LAT...LON 4026 7537 4035 7518 4016 7503 4011 7511 TIME...MOT...LOC 1758Z 137DEG 27KT 4016 7511 $$ PAC017-091-181830- /O.CON.KPHI.TO.W.0004.000000T0000Z-110518T1830Z/ MONTGOMERY PA-BUCKS PA- 159 PM EDT WED MAY 18 2011 ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 230 PM EDT FOR CENTRAL BUCKS AND EAST CENTRAL MONTGOMERY COUNTIES... AT 154 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO INDICATE A TORNADO. THIS TORNADO WAS LOCATED NEAR BRYN ATHYN...OR 10 MILES NORTH OF PHILADELPHIA...MOVING NORTHWEST AT 30 MPH. THE TORNADO WILL BE NEAR... MAPLE GLEN AND SPRING HOUSE BY 205 PM EDT... MONTGOMERYVILLE...BRITTANY FARMS-HIGHLANDS...CHALFONT AND LANSDALE BY 215 PM EDT... FRICKS...HATFIELD AND KULPSVILLE BY 220 PM EDT... PRECAUTIONARY/PREPAREDNESS ACTIONS... WHEN A TORNADO WARNING IS ISSUED BASED ON DOPPLER RADAR...IT MEANS THAT STRONG ROTATION HAS BEEN DETECTED IN THE STORM. A TORNADO MAY ALREADY BE ON THE GROUND...OR IS EXPECTED TO DEVELOP SHORTLY. IF YOU ARE IN THE PATH OF THIS DANGEROUS STORM...MOVE INDOORS AND TO THE LOWEST LEVEL OF THE BUILDING. STAY AWAY FROM WINDOWS. IF DRIVING...DO NOT SEEK SHELTER UNDER A HIGHWAY OVERPASS. THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS. IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW JERSEY. && LAT...LON 4026 7537 4035 7518 4016 7503 4011 7511 TIME...MOT...LOC 1758Z 137DEG 27KT 4016 7511 $$ GORSE
353 WWUS51 KPHI 181816 SVSPHI SEVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 216 PM EDT WED MAY 18 2011 PAC017-091-181824- /O.CAN.KPHI.TO.W.0004.000000T0000Z-110518T1830Z/ MONTGOMERY PA-BUCKS PA- 216 PM EDT WED MAY 18 2011 ...THE TORNADO WARNING FOR CENTRAL BUCKS AND EAST CENTRAL MONTGOMERY COUNTIES IS CANCELLED... THE THUNDERSTORM THAT HAD STRONG ROTATION ON DOPPLER RADAR HAS WEAKENED, THEREFORE THE TORNADO WARNING HAS BEEN CANCELLED. HOWEVER, LOCAL WIND GUSTS UP TO 40 MPH ARE POSSIBLE WITH THIS STORM. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 900 PM EDT WEDNESDAY EVENING FOR DELAWARE AND NORTHEASTERN MARYLAND AND SOUTHERN NEW JERSEY. LAT...LON 4026 7537 4035 7518 4016 7503 4011 7511 TIME...MOT...LOC 1814Z 137DEG 27KT 4025 7522 $$ GORSE
The office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 18, 4:00 AM EDT | Coastal Flood Advisory | PHI | Delaware, Philadelphia | 25 hr |
| May 18, 1:01 PM EDT | Special Weather Statement | PHI | Bucks, Montgomery, Philadelphia | 59 min |
| May 18, 2:45 PM EDT | Areal Flood Advisory | PHI | Monroe, Northampton | 6 hr |
| May 18, 3:05 PM EDT | Areal Flood Advisory | PHI | Bucks, Montgomery | 115 min |
Nearby
Tornado Warnings in Pennsylvania, 2011Every tornado warning in 2011Tornadoes in 2011
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.