Alert archive / New Jersey / Areal Flood Advisories in 2021

Areal Flood Advisory 89, NWS Philadelphia/Mount Holly

July 17, 2021Somerset County, New Jersey

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jul 17, 2021, 5:52 PM EDT for Somerset County, New Jersey. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jul 17, 2021, 5:52 PM EDT (21:52 UTC)
Expired
Jul 17, 2021, 8:00 PM EDT
In force
2 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

County Somerset County, NJ

The radar

The Philadelphia radar (KDIX), 78 km from the middle of the area, began a volume at 21:56 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, 9.9 hours before the alert went out and 157 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 2021-07-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1203 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Brookhaven, NY at 12:00Z on 2021-07-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 35 square meters per square second.1939Sfc1 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
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.

050 
WGUS81 KPHI 172152
FLSPHI

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

NJC035-180000-
/O.NEW.KPHI.FA.Y.0089.210717T2152Z-210718T0000Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Somerset NJ-
552 PM EDT Sat Jul 17 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  Somerset County in northern New Jersey...

* Until 800 PM EDT.

* At 552 PM EDT, Doppler radar indicated heavy rain due to 
  thunderstorms. Minor flooding is ongoing or expected to begin 
  shortly in the advisory area. Up to 0.5 inches of rain have 
  already fallen in spots with an additional 1.0 to 1.5 inches 
  possible.

* Some locations that may experience flooding include...
  Somerville, Bridgewater, Manville, Mendham, Peapack And Gladstone, 
  Far Hills, Rocky Hill, Millstone, Flagtown, Belle Mead, 
  Cloverhill, and Skillman.

This includes the following highways...
	Interstate 78 in New Jersey between mile markers 27 and 34.
	Interstate 287 in New Jersey between mile markers 16 and 27.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4076 7456 4040 7461 4041 7474 4051 7480
      4050 7478 4058 7471 4059 7472 4060 7472
      4062 7470 4063 7473 4065 7472 4067 7473
      4068 7472 4069 7472 4070 7472 4072 7473

$$

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 17, 12:55 PM EDTSpecial Weather StatementPHIHunterdon50 min
Jul 17, 1:05 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer40 min
Jul 17, 1:31 PM EDTAreal Flood AdvisoryPHIHunterdon97 min
Jul 17, 1:50 PM EDTSpecial Marine WarningPHI40 min
Jul 17, 1:56 PM EDTSevere Thunderstorm WarningPHIHunterdon, Morris, Somerset, Warren36 min
Jul 17, 2:02 PM EDTAreal Flood AdvisoryPHIMonmouth, Ocean92 min
Jul 17, 2:56 PM EDTSevere Thunderstorm WarningPHIMiddlesex, Somerset49 min
Jul 17, 3:06 PM EDTSevere Thunderstorm WarningPHIWarren39 min
Jul 17, 3:09 PM EDTTornado WarningPHIMiddlesex21 min
Jul 17, 3:38 PM EDTAreal Flood AdvisoryPHIMiddlesex40 min
Jul 17, 3:51 PM EDTSevere Thunderstorm WarningPHIMiddlesex24 min
Jul 17, 4:55 PM EDTSevere Thunderstorm WarningPHIHunterdon, Somerset50 min
Jul 17, 5:13 PM EDTAreal Flood AdvisoryPHIHunterdon4 hr
Jul 17, 5:19 PM EDTTornado WarningPHIHunterdon14 min
Jul 17, 5:25 PM EDTFlash Flood WarningPHIHunterdon6 hr
Jul 17, 5:30 PM EDTSevere Thunderstorm WarningPHIHunterdon, Warren19 min
Jul 17, 6:02 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer, Somerset43 min
Jul 17, 6:15 PM EDTFlash Flood WarningPHIMorris, Somerset5 hr
Jul 17, 6:39 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer, Middlesex, Morris, Somerset51 min
Jul 17, 6:51 PM EDTSevere Thunderstorm WarningPHIBurlington39 min
Jul 17, 6:59 PM EDTSmall Craft AdvisoryPHI7 hr
Jul 17, 7:01 PM EDTSevere Thunderstorm WarningPHIHunterdon, Somerset44 min
Jul 17, 7:12 PM EDTAreal Flood AdvisoryPHIMercer, Somerset3 hr
Jul 17, 7:26 PM EDTSevere Thunderstorm WarningPHIHunterdon, Mercer, Middlesex, Morris, Somerset49 min

Nearby

Areal Flood Advisories in New Jersey, 2021Every 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.