Alert archive / Pennsylvania / Areal Flood Advisories in 2020

Areal Flood Advisory 21, NWS Philadelphia/Mount Holly

June 5, 20205 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jun 5, 2020, 3:48 PM EDT for 5 counties in Pennsylvania. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Jun 5, 2020, 3:48 PM EDT (19:48 UTC)
Expired
Jun 5, 2020, 7:17 PM EDT
In force
3 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Bucks County, PA, Chester County, PA, Delaware County, PA, Montgomery County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 74 km from the middle of the area, began a volume at 19:48 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

Brookhaven, NY (KOKX), launched 12:00Z, 7.8 hours before the alert went out and 217 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, Brookhaven, NY at 12:00Z on 2020-06-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 34 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 12:00Z on 2020-06-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 139 square meters per square second.19395878Sfc1 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
34 J/kg
Mixed-layer CIN
-275 J/kg
Mixed-layer LCL
685 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
139 m²/s²
0-3 km storm-relative helicity
150 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

958 
WGUS81 KPHI 051948
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
348 PM EDT Fri Jun 5 2020

PAC017-029-045-091-101-052345-
/O.NEW.KPHI.FA.Y.0021.200605T1948Z-200605T2345Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Bucks PA-Chester PA-Philadelphia PA-Delaware PA-
348 PM EDT Fri Jun 5 2020

The National Weather Service in Mount Holly NJ has issued a

* Flood Advisory for Minor Flooding in Poor Drainage Areas for...
  Southeastern Montgomery County in southeastern Pennsylvania...
  Southeastern Bucks County in southeastern Pennsylvania...
  East central Chester County in southeastern Pennsylvania...
  Northern Philadelphia County in southeastern Pennsylvania...
  Central Delaware County in southeastern Pennsylvania...

* Until 745 PM EDT.

* At 347 PM EDT, Doppler radar indicated heavy rain due to
  thunderstorms. This will cause minor flooding. Overflowing poor
  drainage areas will result in minor flooding in the advisory area.
  Up to one inch of rain has already fallen.

* Some locations that could experience flooding include...
  Philadelphia, Norristown, Chester, Lansdale, West Norriton, East
  Norriton, Yeadon, Doylestown, Conshohocken, Hatboro, Ambler,
  Swarthmore, Jenkintown, Narberth, Chalfont, East Lansdowne,
  Rockledge, Newtown, Abington and Langhorne.

This includes the following highways...
 Interstate 476 in Pennsylvania between mile markers 1 and 19.
 Pennsylvania Turnpike between exits 320 and 353.
 Northeast Extension near exit A20.
 Interstate 76 in Pennsylvania between mile markers 327 and 342.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

LAT...LON 4040 7507 4020 7483 3987 7537 3991 7552
      4005 7562

$$

Kruzdlo
3 follow-up statements
440 
WGUS81 KPHI 052123
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
523 PM EDT Fri Jun 5 2020

PAC017-029-045-091-101-052345-
/O.CON.KPHI.FA.Y.0021.000000T0000Z-200605T2345Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Bucks PA-Chester PA-Philadelphia PA-Delaware PA-
523 PM EDT Fri Jun 5 2020

...THE FLOOD ADVISORY FOR MINOR FLOODING IN POOR DRAINAGE AREAS
REMAINS IN EFFECT UNTIL 745 PM EDT FOR SOUTHEASTERN MONTGOMERY...
SOUTHEASTERN BUCKS...EAST CENTRAL CHESTER...NORTHERN PHILADELPHIA AND
CENTRAL DELAWARE COUNTIES...

At 516 PM EDT, Doppler radar and automated rain gauges indicated
heavy rain due to thunderstorms. This will cause minor flooding.
Overflowing poor drainage areas will result in minor flooding in the 
advisory area. Up to one inch of rain has already fallen. Law 
enforcement has indicated several roads have flooded including 
portions of US Highway 202 in Chester County PA.

Some locations that could experience flooding include...
Philadelphia, Norristown, Chester, Lansdale, West Norriton, East
Norriton, Yeadon, Doylestown, Conshohocken, Hatboro, Ambler,
Swarthmore, Jenkintown, Narberth, Chalfont, East Lansdowne,
Rockledge, Newtown, Abington and Langhorne.

This includes the following highways...
 Interstate 476 in Pennsylvania between mile markers 1 and 19.
 Pennsylvania Turnpike between exits 320 and 353.
 Northeast Extension near exit A20.
 Interstate 76 in Pennsylvania between mile markers 327 and 342.

Additional rainfall of one half to one inch is expected over the 
area. This additional rain will result in minor flooding.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

LAT...LON 4040 7507 4020 7483 3987 7537 3991 7552
      4005 7562

$$

Deal
660 
WGUS81 KPHI 052232
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
632 PM EDT Fri Jun 5 2020

PAC017-029-045-091-101-052345-
/O.CON.KPHI.FA.Y.0021.000000T0000Z-200605T2345Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Bucks PA-Chester PA-Philadelphia PA-Delaware PA-
632 PM EDT Fri Jun 5 2020

...THE FLOOD ADVISORY FOR MINOR FLOODING IN POOR DRAINAGE AREAS
REMAINS IN EFFECT UNTIL 745 PM EDT FOR SOUTHEASTERN MONTGOMERY...
SOUTHEASTERN BUCKS...EAST CENTRAL CHESTER...NORTHERN PHILADELPHIA AND
CENTRAL DELAWARE COUNTIES...

At 626 PM EDT, Doppler radar and automated rain gauges indicated 
heavy rain due to thunderstorms fell earlier this afternoon causing 
minor flooding. While there has been a lull in the heavy rainfall 
over the last hour, there is another round of showers that will 
bring one half to one inch of additional rainfall which will cause 
minor flooding over the advisory area in areas of poor drainage 
areas.

Some locations that could experience flooding include...
Philadelphia, Norristown, Chester, Lansdale, West Norriton, East
Norriton, Yeadon, Doylestown, Conshohocken, Hatboro, Ambler,
Swarthmore, Jenkintown, Narberth, Chalfont, East Lansdowne,
Rockledge, Newtown, Abington and Langhorne.

This includes the following highways...
 Interstate 476 in Pennsylvania between mile markers 1 and 19.
 Pennsylvania Turnpike between exits 320 and 353.
 Northeast Extension near exit A20.
 Interstate 76 in Pennsylvania between mile markers 327 and 342.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Protecting yourself from immediate threats to life and safety shall
take priority.  Whenever possible, as long as it does not cause
greater harm, all COVID-19 protective action guidance should be
followed.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

&&

LAT...LON 4040 7507 4020 7483 3987 7537 3991 7552
      4005 7562

$$

Deal
417 
WGUS81 KPHI 052317
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
717 PM EDT Fri Jun 5 2020

PAC017-029-045-091-101-052324-
/O.CAN.KPHI.FA.Y.0021.000000T0000Z-200605T2345Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery PA-Bucks PA-Chester PA-Philadelphia PA-Delaware PA-
717 PM EDT Fri Jun 5 2020

...THE FLOOD ADVISORY HAS BEEN CANCELLED FOR SOUTHEASTERN
MONTGOMERY...SOUTHEASTERN BUCKS...EAST CENTRAL CHESTER...NORTHERN
PHILADELPHIA AND CENTRAL DELAWARE COUNTIES...

Although some light to moderate rain is expected over the next hour 
or two, the threat of heavy rain has ended. As a result, minor 
flooding is no longer expected.

LAT...LON 4040 7507 4020 7483 3987 7537 3991 7552
      4005 7562

$$

Kruzdlo

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 4, 10:05 PM EDTSpecial Weather StatementPHIChester, Delaware, Montgomery, Philadelphia40 min
Jun 4, 10:31 PM EDTSevere Thunderstorm WarningPHIBucks, Chester, Delaware, Montgomery, Philadelphia46 min
Jun 4, 10:46 PM EDTAreal Flood AdvisoryPHIBerks, Carbon, Lehigh, Monroe, Northampton119 min
Jun 5, 9:47 AM EDTFlash Flood WatchPHIBerks, Bucks, Chester, Delaware, Lehigh, Montgomery and 2 more12 hr
Jun 5, 3:15 PM EDTSpecial Weather StatementPHIBucks, Montgomery30 min
Jun 5, 4:14 PM EDTSpecial Weather StatementPHIBerks16 min
Jun 5, 5:01 PM EDTAreal Flood AdvisoryPHIBucks4 hr
Jun 5, 5:19 PM EDTAreal Flood AdvisoryPHIBucks, Delaware, Philadelphia4 hr

Nearby

Areal Flood Advisories in Pennsylvania, 2020Every areal flood advisory in 2020

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.