Alert archive / Pennsylvania / Areal Flood Advisories in 2021

Areal Flood Advisory 20, NWS Philadelphia/Mount Holly

June 8, 20214 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jun 8, 2021, 1:18 PM EDT for 4 counties in Pennsylvania. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jun 8, 2021, 1:18 PM EDT (17:18 UTC)
Expired: Jun 8, 2021, 4:30 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

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

The radar

The Philadelphia radar (KDIX), 76 km from the middle of the area, began a volume at 17:20 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.3 hours before the alert went out and 211 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: 254 J/kg
Mixed-layer CIN: -121 J/kg
Mixed-layer LCL: 1088 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -39 m²/s²
0-3 km storm-relative helicity: 23 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

697 
WGUS81 KPHI 081718
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
118 PM EDT Tue Jun 8 2021

PAC029-045-091-101-082030-
/O.NEW.KPHI.FA.Y.0020.210608T1718Z-210608T2030Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Chester PA-Delaware PA-Montgomery PA-Philadelphia PA-
118 PM EDT Tue Jun 8 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  Southeastern Chester County in southeastern Pennsylvania...
  Delaware County in southeastern Pennsylvania...
  Southeastern Montgomery County in southeastern Pennsylvania...
  Philadelphia County in southeastern Pennsylvania...

* Until 430 PM EDT.

* At 118 PM EDT, Doppler radar indicated heavy rain due to 
  thunderstorms. Minor flooding is ongoing or expected to begin 
  shortly in the advisory area. Between 1 and 1.5 inches of rain 
  have fallen.

* Some locations that may experience flooding include...
  Philadelphia, Camden, West Chester, Norristown, Chester, 
  Phoenixville, Lansdale, West Norriton, East Norriton, Yeadon, 
  Westtown, and Conshohocken.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 317 and 346.
	Interstate 95 in Pennsylvania between mile markers 0 and 33.
	Interstate 76 in Pennsylvania between mile markers 327 and 351.
	Interstate 676 in Pennsylvania between mile markers 0 and 1.
	Interstate 476 in Pennsylvania between mile markers 0 and 19.
	Northeast Extension between mile markers 21 and 31.

This includes the following DSS Events...
	Philadelphia Flower Show.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3984 7586 4031 7530 4012 7496 4010 7496
      4006 7498 4005 7497 4001 7505 3998 7507
      3996 7513 3991 7513 3988 7515 3988 7519
      3985 7524 3985 7534 3980 7542 3983 7550
      3984 7558 3983 7564 3980 7571

$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 8, 11:54 AM EDT	Areal Flood Advisory	PHI	Monroe	2 hr
Jun 8, 12:34 PM EDT	Flash Flood Warning	PHI	Monroe	2 hr
Jun 8, 12:40 PM EDT	Special Weather Statement	PHI	Monroe	35 min
Jun 8, 1:09 PM EDT	Special Weather Statement	PHI	Monroe	21 min
Jun 8, 1:17 PM EDT	Special Weather Statement	PHI	Chester	13 min
Jun 8, 1:24 PM EDT	Special Weather Statement	PHI	Delaware	21 min
Jun 8, 1:27 PM EDT	Areal Flood Advisory	PHI	Carbon, Lehigh, Monroe, Northampton	3 hr
Jun 8, 1:35 PM EDT	Flash Flood Warning	PHI	Chester, Delaware, Montgomery	5 hr
Jun 8, 2:07 PM EDT	Special Weather Statement	PHI	Bucks	23 min
Jun 8, 2:19 PM EDT	Areal Flood Advisory	PHI	Bucks	2 hr
Jun 8, 2:43 PM EDT	Special Weather Statement	PHI	Montgomery	32 min
Jun 8, 3:15 PM EDT	Special Weather Statement	PHI	Chester	30 min
Jun 8, 3:21 PM EDT	Flash Flood Warning	PHI	Chester, Montgomery	3 hr
Jun 8, 3:43 PM EDT	Special Weather Statement	PHI	Chester	32 min
Jun 8, 4:20 PM EDT	Special Weather Statement	PHI	Chester	25 min
Jun 8, 4:25 PM EDT	River Flood Warning	PHI	Chester	11 hr
Jun 8, 6:21 PM EDT	Areal Flood Warning	PHI	Chester, Delaware	15 hr
Jun 8, 7:14 PM EDT	River Flood Warning	PHI	Chester, Delaware	18 hr

Nearby

Areal Flood Advisories in Pennsylvania, 2021 Every areal flood advisory 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.