Alert archive / Pennsylvania / Areal Flood Warnings in 2021
Areal Flood Warning 36, NWS Philadelphia/Mount Holly
NWS Philadelphia/Mount Holly issued this areal flood warning at Sep 1, 2021, 11:38 PM EDT for New Castle County, Delaware; 4 counties in Pennsylvania. It was in force for 10 hr. 11 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
- Sep 1, 2021, 11:38 PM EDT (03:38 UTC)
- Expired
- Sep 2, 2021, 10:00 AM EDT
- In force
- 10 hr
- Issued by
- NWS Philadelphia/Mount Holly
- Area
- Storm-based polygon
- Flood severity
- None
Counties New Castle County, DE, Berks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA
The radar
The Philadelphia radar (KDIX), 122 km from the middle of the area, began a volume at 03:42 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 |
|---|---|---|---|
| Sep 2, 12:00 AM EDT | HEAVY RAIN 4.91 | King Of Prussia, PA | 24 HOUR TOTAL. |
| Sep 2, 12:10 AM EDT | HEAVY RAIN 7.7 | Eagleville, PA | STORM TOTAL. |
| Sep 2, 12:39 AM EDT | FLASH FLOOD | Chadds Ford Twp, PA | FLASH FLOODING ON BRANDYWINE CREEK CLOSED U.S. HIGHWAY 1 IN CHADDS FORD. TIME BASED ON DISPATCH REPORT. |
| Sep 2, 1:15 AM EDT | FLASH FLOOD | 1 Ne Newark, DE | THE GAUGE ON WHITE CLAY CREEK AT NEWARK (NEKD1) REACHED FLOOD STAGE AT 115 AM 9/2, CRESTING AT 13.08 FEET (MINOR FLOODING) AT 400 AM 9/2. |
| Sep 2, 1:19 AM EDT | FLASH FLOOD | Avondale, PA | FLASH FLOODING ON THE EAST BRANCH WHITE CLAY CREEK FORCED THE CLOSURE OF STATE HIGHWAY 41. TIME BASED ON DISPATCH REPORT. |
| Sep 2, 2:30 AM EDT | FLOOD | 1 Wnw Talleyville, DE | THOMPSON BRIDGE ROAD CLOSED FROM FLOODING ON BRANDYWINE CREEK. TIME BASED ON GAUGE REPORTS. |
| Sep 2, 2:45 AM EDT | FLOOD | 3 Nw Talleyville, DE | SMITH BRIDGE ROAD CLOSED FROM FLOODING ON BRANDYWINE CREEK. TIME BASED ON GAUGE REPORTS. |
| Sep 2, 3:00 AM EDT | FLOOD | Henry Clay, DE | THE GAUGE ON BRANDYWINE CREEK AT WILMINGTON (WMND1) REACHED FLOOD STAGE AT 300 AM 9/2, CRESTING AT 23.14 FEET (MAJOR FLOODING) AT 915 AM 9/2. |
| Sep 2, 3:30 AM EDT | FLOOD | Henry Clay, DE | RISING SUN LANE CLOSED OVER BRANDYWINE CREEK FROM FLOODING. TIME BASED ON DISPATCH REPORT. |
| Sep 2, 3:30 AM EDT | FLOOD | Westfield, DE | CORRECTS PREVIOUS FLOOD REPORT FROM WESTFIELD. THE GAUGE ON RED CLAY CREEK AT STANTON (STND1) REACHED FLOOD STAGE AT 330 AM 9/2, CRESTING AT 17.66 FEET (MINOR FLOODING) AT 515 AM 9/2. |
| Sep 2, 4:58 AM EDT | HEAVY RAIN 5.63 | Pike Creek, DE |
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 00:00Z, 3.6 hours before the alert went out and 172 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 569 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 14 m²/s²
- 0-3 km storm-relative helicity
- 167 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
118
WGUS41 KPHI 020338
FLWPHI
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
1138 PM EDT Wed Sep 1 2021
DEC003-PAC011-029-045-091-021400-
/O.NEW.KPHI.FA.W.0036.210902T0338Z-210902T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Berks PA-Chester PA-Delaware PA-Montgomery PA-
1138 PM EDT Wed Sep 1 2021
The National Weather Service in Mount Holly has issued a
* Flood Warning for...
Northwestern New Castle County in northern Delaware...
Southeastern Berks County in eastern Pennsylvania...
Chester County in southeastern Pennsylvania...
Western Delaware County in southeastern Pennsylvania...
Central Montgomery County in southeastern Pennsylvania...
* Until 1000 AM EDT Thursday.
* At 1138 PM EDT, local law enforcement reported widespread flooding
continuing in Chester, Montgomery, and northern New Castle
Counties. Numerous roads remain closed, with several rivers and
streams in flood. Avoid travel in the warning area. Flooding is
expected to continue through the night.
* Some locations that may experience flooding include...
Wilmington, Newark, West Chester, Norristown, Pottstown,
Phoenixville, Lansdale, West Norriton, East Norriton, Coatesville,
Westtown, and Downingtown.
This includes the following highways...
Pennsylvania Turnpike between mile markers 298 and 331.
Interstate 95 in Delaware between mile markers 0 and 19.
Interstate 76 in Pennsylvania between mile markers 327 and 330.
Northeast Extension between mile markers 23 and 30.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around...don't drown when encountering flooded roads. Most
flood deaths occur in vehicles.
&&
LAT...LON 3972 7610 3979 7604 3983 7604 3983 7602
3985 7602 3987 7599 3993 7598 3995 7599
4004 7593 4011 7594 4014 7587 4016 7590
4027 7575 4027 7541 4022 7524 3991 7545
3972 7551 3962 7573 3963 7579 3972 7579
$$
CMS1 follow-up statement
889
WGUS81 KPHI 021353
FLSPHI
Flood Statement
National Weather Service Mount Holly NJ
953 AM EDT Thu Sep 2 2021
DEC003-PAC011-029-045-091-021403-
/O.EXP.KPHI.FA.W.0036.000000T0000Z-210902T1400Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
New Castle DE-Berks PA-Chester PA-Delaware PA-Montgomery PA-
953 AM EDT Thu Sep 2 2021
...FLOOD WARNING WILL EXPIRE AT 10 AM EDT THIS MORNING FOR
NORTHWESTERN NEW CASTLE, SOUTHEASTERN BERKS, CHESTER, WESTERN
DELAWARE, AND CENTRAL MONTGOMERY COUNTIES...
This flood warning will be allowed to expire. Other flood warnings
remain in place across the area. The Schuylkill River and Brandywine
Creek remain in flood as does the White Clay Creek in northern New
Castle county.
LAT...LON 3972 7610 3979 7604 3983 7604 3983 7602
3985 7602 3987 7599 3993 7598 3995 7599
4004 7593 4011 7594 4014 7587 4016 7590
4027 7575 4027 7541 4022 7524 3991 7545
3972 7551 3962 7573 3963 7579 3972 7579
$$
KruzdloThe office that day
Everything else NWS Philadelphia/Mount Holly issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 10:23 PM EDT | Coastal Flood Statement | PHI | Sussex | 13 hr |
| Sep 2, 2:23 AM EDT | Areal Flood Warning | PHI | New Castle | 9 hr |
| Sep 1, 8:29 PM EDT | River Flood Warning | PHI | Lehigh | 10 hr |
| Sep 1, 9:47 PM EDT | River Flood Warning | PHI | Berks | 18 hr |
| Sep 1, 10:24 PM EDT | Flash Flood Warning | PHI | Bucks, Philadelphia | 4 hr |
| Sep 1, 10:29 PM EDT | River Flood Warning | PHI | Bucks | 49 hr |
| Sep 1, 10:32 PM EDT | River Flood Warning | PHI | Bucks | 31 hr |
| Sep 1, 10:42 PM EDT | Areal Flood Warning | PHI | Berks, Bucks, Montgomery | 12 hr |
| Sep 1, 10:47 PM EDT | Areal Flood Warning | PHI | Bucks, Carbon, Lehigh, Northampton | 23 hr |
| Sep 1, 10:52 PM EDT | Areal Flood Warning | PHI | Bucks | 12 hr |
| Sep 2, 12:01 AM EDT | Areal Flood Warning | PHI | Monroe, Northampton | 40 hr |
| Sep 2, 2:29 AM EDT | Areal Flood Warning | PHI | Bucks, Philadelphia | 5 hr |
| Sep 2, 2:41 AM EDT | Areal Flood Warning | PHI | Bucks | 14 hr |
| Sep 2, 3:52 AM EDT | Areal Flood Warning | PHI | Bucks | 8 hr |
| Sep 2, 4:45 AM EDT | River Flood Warning | PHI | Bucks | 37 hr |
| Sep 2, 4:45 AM EDT | River Flood Warning | PHI | Northampton | 37 hr |
| Sep 2, 4:45 AM EDT | River Flood Warning | PHI | Bucks | 37 hr |
| Sep 2, 4:45 AM EDT | River Flood Warning | PHI | Bucks | 33 hr |
| Sep 2, 4:45 AM EDT | River Flood Warning | PHI | Bucks | 34 hr |
| Sep 2, 4:45 AM EDT | River Flood Warning | PHI | Monroe, Northampton | 5 hr |
| Sep 2, 5:02 AM EDT | River Flood Warning | PHI | Lehigh | 11 hr |
| Sep 2, 6:05 AM EDT | Coastal Flood Warning | PHI | Bucks, Delaware, Montgomery, Philadelphia | 6 hr |
| Sep 2, 6:44 PM EDT | Coastal Flood Advisory | PHI | Bucks, Delaware, Philadelphia | 7 hr |
Nearby
Areal Flood Warnings in Pennsylvania, 2021Areal Flood Warnings in Delaware, 2021Every areal flood warning in 2021
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.