Alert archive / Pennsylvania / Areal Flood Advisories in 2021

Areal Flood Advisory 39, NWS Philadelphia/Mount Holly

June 20, 2021Berks County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood advisory at Jun 20, 2021, 10:04 PM EDT for Berks County, Pennsylvania. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued
Jun 20, 2021, 10:04 PM EDT (02:04 UTC)
Expired
Jun 20, 2021, 11:30 PM EDT
In force
86 min
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

County Berks County, PA

The radar

The State College radar (KCCX), 149 km from the middle of the area, began a volume at 02:08 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 00:00Z, 2.1 hours before the alert went out and 195 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, Washington/Dulle, VA at 00:00Z on 2021-06-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 662 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, Washington/Dulle, VA at 00:00Z on 2021-06-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 4 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
662 J/kg
Mixed-layer CIN
-59 J/kg
Mixed-layer LCL
1494 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
4 m²/s²
0-3 km storm-relative helicity
58 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

520 
WGUS81 KPHI 210204
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
1004 PM EDT Sun Jun 20 2021

PAC011-210330-
/O.NEW.KPHI.FA.Y.0039.210621T0204Z-210621T0330Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
1004 PM EDT Sun Jun 20 2021

The National Weather Service in Mount Holly has issued a

* Flood Advisory for...
  West Central Berks County in eastern Pennsylvania...

* Until 1130 PM EDT.

* At 1004 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 2.5 inches of rain 
  have fallen.

* Some locations that will experience flooding include...
  mainly rural areas of West Central Berks County

This includes the following highways...
	Interstate 78 in Pennsylvania between mile markers 10 and 16.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

&&

LAT...LON 4052 7628 4047 7622 4043 7634 4050 7644
      4050 7642 4052 7634

$$

CMS
2 follow-up statements
715 
WGUS81 KPHI 210246
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
1046 PM EDT Sun Jun 20 2021

PAC011-210330-
/O.CON.KPHI.FA.Y.0039.000000T0000Z-210621T0330Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
1046 PM EDT Sun Jun 20 2021

...FLOOD ADVISORY REMAINS IN EFFECT UNTIL 1130 PM EDT THIS EVENING 
FOR WEST CENTRAL BERKS COUNTY...

At 1046 PM EDT, Doppler radar indicated the heavy rainfall had moved 
northeast of the advisory area. However, runoff will likely continue 
to cause minor flooding in the advisory area. Between 1 and 2.5 
inches of rain have fallen.

Some locations that will experience flooding include...
  mainly rural areas of West Central Berks County

This includes the following highways...
	Interstate 78 in Pennsylvania between mile markers 10 and 16.

LAT...LON 4052 7628 4047 7622 4043 7634 4050 7644
      4050 7642 4052 7634

$$

CMS
973 
WGUS81 KPHI 210325
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
1125 PM EDT Sun Jun 20 2021

PAC011-210335-
/O.EXP.KPHI.FA.Y.0039.000000T0000Z-210621T0330Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-
1125 PM EDT Sun Jun 20 2021

...FLOOD ADVISORY WILL EXPIRE AT 1130 PM EDT THIS EVENING FOR WEST 
CENTRAL BERKS COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4052 7628 4047 7622 4043 7634 4050 7644
      4050 7642 4052 7634

$$

Staarmann

The office that day

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

IssuedProductOfficeCountiesLasted
Jun 20, 9:27 PM EDTSpecial Weather StatementPHISchuylkill33 min
Jun 20, 9:55 PM EDTSpecial Weather StatementPHILebanon35 min
Jun 20, 10:27 PM EDTSpecial Weather StatementPHIBerks33 min
Jun 21, 4:35 AM EDTHeat AdvisoryPHIBucks, Chester, Delaware, Montgomery, Philadelphia15 hr
Jun 21, 6:08 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh52 min
Jun 21, 6:21 PM EDTSevere Thunderstorm WarningPHIChester, Delaware54 min
Jun 21, 7:02 PM EDTSevere Thunderstorm WarningPHIBerks, Carbon, Lehigh, Northampton43 min
Jun 21, 7:12 PM EDTSevere Thunderstorm WarningPHIChester, Delaware, Montgomery, Philadelphia48 min
Jun 21, 7:38 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton52 min

Nearby

Areal Flood Advisories in Pennsylvania, 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.