Alert archive / Pennsylvania / Areal Flood Advisories in 2021

Areal Flood Advisory 90, NWS Philadelphia/Mount Holly

July 17, 2021Bucks County, Philadelphia County, Pennsylvania; Mercer County, Somerset County, New Jersey

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jul 17, 2021, 7:12 PM EDT for Bucks County, Philadelphia County, Pennsylvania; Mercer County, Somerset County, New Jersey. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jul 17, 2021, 7:12 PM EDT (23:12 UTC)
Expired: Jul 17, 2021, 10:00 PM EDT
In force: 3 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon

Counties Mercer County, NJ, Somerset County, NJ, Bucks County, PA, Philadelphia County, PA

The radar

The Philadelphia radar (KDIX), 50 km from the middle of the area, began a volume at 23:13 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, 11.2 hours before the alert went out and 180 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: 1203 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 1054 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted.

503 
WGUS81 KPHI 172312
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
712 PM EDT Sat Jul 17 2021

NJC021-035-PAC017-101-180200-
/O.NEW.KPHI.FA.Y.0090.210717T2312Z-210718T0200Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mercer NJ-Somerset NJ-Bucks PA-Philadelphia PA-
712 PM EDT Sat Jul 17 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  Mercer County in central New Jersey...
  Southwestern Somerset County in northern New Jersey...
  Southeastern Bucks County in southeastern Pennsylvania...
  Northeastern Philadelphia County in southeastern Pennsylvania...

* Until 1000 PM EDT.

* At 712 PM EDT, Doppler radar indicated heavy rain due to 
  thunderstorms. Minor flooding is ongoing or expected to begin 
  shortly in the advisory area. Between 0.5 and 1 inch of rain has 
  already fallen in spots with another 1 to 2 inches possible.

* Some locations that may will experience flooding include...
  Northeast Philadelphia, Trenton, Bensalem, Ewing, Princeton, 
  Bristol,  Pennington, Rockledge, and Yardley.

This includes the following highways...
	Pennsylvania Turnpike between mile markers 347 and 359.
	Interstate 95 in Pennsylvania between mile markers 29 and 40.
	Interstate 295 in New Jersey between mile markers 58 and 76.
	Interstate 195 in New Jersey between mile markers 0 and 3.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4017 7508 4032 7492 4034 7495 4035 7486
      4038 7487 4038 7480 4042 7481 4042 7475
      4043 7475 4042 7459 4034 7463 4029 7456
      4018 7468 4018 7471 4015 7472 4013 7482
      4008 7486 4001 7504 4005 7512 4014 7502

$$

Iovino

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 16, 8:14 PM EDT	Special Weather Statement	PHI	Montgomery	31 min
Jul 16, 8:41 PM EDT	Special Weather Statement	PHI	Bucks	34 min
Jul 16, 9:07 PM EDT	Special Weather Statement	PHI	Lehigh	23 min
Jul 16, 9:29 PM EDT	Special Weather Statement	PHI	Lehigh	31 min
Jul 16, 10:21 PM EDT	Special Weather Statement	PHI	Lehigh	24 min
Jul 17, 12:55 PM EDT	Special Weather Statement	PHI	Bucks	50 min
Jul 17, 1:05 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	40 min
Jul 17, 1:31 PM EDT	Areal Flood Advisory	PHI	Bucks	97 min
Jul 17, 2:30 PM EDT	Special Weather Statement	PHI	Berks	45 min
Jul 17, 2:36 PM EDT	Severe Thunderstorm Warning	PHI	Berks	39 min
Jul 17, 3:06 PM EDT	Severe Thunderstorm Warning	PHI	Carbon, Lehigh, Monroe, Northampton	39 min
Jul 17, 5:13 PM EDT	Areal Flood Advisory	PHI	Bucks, Montgomery, Philadelphia	4 hr
Jul 17, 5:25 PM EDT	Flash Flood Warning	PHI	Bucks	6 hr
Jul 17, 5:30 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	19 min
Jul 17, 6:02 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	43 min
Jul 17, 6:39 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	51 min
Jul 17, 6:51 PM EDT	Severe Thunderstorm Warning	PHI	Bucks, Montgomery, Philadelphia	39 min
Jul 17, 7:01 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	44 min
Jul 17, 7:26 PM EDT	Severe Thunderstorm Warning	PHI	Bucks	49 min
Jul 17, 7:36 PM EDT	Special Weather Statement	PHI	Carbon	54 min
Jul 17, 1:50 PM EDT	Special Marine Warning	PHI		40 min
Jul 17, 1:56 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Morris, Somerset, Warren	36 min
Jul 17, 2:02 PM EDT	Areal Flood Advisory	PHI	Monmouth, Ocean	92 min
Jul 17, 2:56 PM EDT	Severe Thunderstorm Warning	PHI	Middlesex, Somerset	49 min
Jul 17, 3:09 PM EDT	Tornado Warning	PHI	Middlesex	21 min
Jul 17, 3:38 PM EDT	Areal Flood Advisory	PHI	Middlesex	40 min
Jul 17, 3:51 PM EDT	Severe Thunderstorm Warning	PHI	Middlesex	24 min
Jul 17, 4:55 PM EDT	Severe Thunderstorm Warning	PHI	Hunterdon, Somerset	50 min
Jul 17, 5:19 PM EDT	Tornado Warning	PHI	Hunterdon	14 min
Jul 17, 5:52 PM EDT	Areal Flood Advisory	PHI	Somerset	2 hr
Jul 17, 6:15 PM EDT	Flash Flood Warning	PHI	Morris, Somerset	5 hr
Jul 17, 6:59 PM EDT	Small Craft Advisory	PHI		7 hr

Nearby

Areal Flood Advisories in Pennsylvania, 2021 Areal Flood Advisories in New Jersey, 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.