Alert archive / Pennsylvania / Areal Flood Advisories in 2021

Areal Flood Advisory 201, NWS Philadelphia/Mount Holly

November 12, 20215 counties in Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood advisory at Nov 12, 2021, 7:34 AM EST for 5 counties in Pennsylvania. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Nov 12, 2021, 7:34 AM EST (12:34 UTC)
Expired
Nov 12, 2021, 10:00 AM EST
In force
2 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon

Counties Berks County, PA, Carbon County, PA, Lehigh County, PA, Monroe County, PA, Northampton County, PA

The radar

The Philadelphia radar (KDIX), 135 km from the middle of the area, began a volume at 12:35 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, 0.6 hours before the alert went out and 229 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 2021-11-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 191 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 2021-11-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 262 square meters per square second.1939587897Sfc1 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
191 J/kg
Mixed-layer CIN
-19 J/kg
Mixed-layer LCL
601 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
262 m²/s²
0-3 km storm-relative helicity
370 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.9

Open this sounding in Storm Lab

The text

As transmitted.

812 
WGUS81 KPHI 121234
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
734 AM EST Fri Nov 12 2021

PAC011-025-077-089-095-121500-
/O.NEW.KPHI.FA.Y.0201.211112T1234Z-211112T1500Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Carbon PA-Lehigh PA-Monroe PA-Northampton PA-
734 AM EST Fri Nov 12 2021

...FLOOD ADVISORY IN EFFECT UNTIL 10 AM EST THIS MORNING...

* WHAT...Flooding caused by excessive rainfall is expected.

* WHERE...
  Berks County in eastern Pennsylvania...
  Lehigh County in eastern Pennsylvania...
  Northampton County in eastern Pennsylvania...
  Carbon County in northeastern Pennsylvania...
  Monroe County in northeastern Pennsylvania...

* WHEN...Until 1000 AM EST.

* IMPACTS...Minor flooding in low-lying and poor drainage areas. 

* ADDITIONAL DETAILS...
  - At 732 AM EST, Doppler radar indicated locally heavy rain.
    Rainfall totals as high as 1.0 to 1.5 inches are expected.
    Minor flooding is ongoing or expected to begin shortly in the
    advisory area. Drains blocked by leaves and other debris will
    result in additional flooding of roadways and areas of
    drainage.
  - Some locations that may experience flooding include...
    Allentown, Reading, Easton, Lehighton, Mount Pocono,
    Bethlehem, Forks, Emmaus, Wyomissing, Northampton, East
    Stroudsburg, and Tobyhanna.
  - http://www.weather.gov/safety/flood

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4073 7576 4074 7576 4091 7600 4101 7573
      4109 7577 4122 7554 4125 7513 4115 7516
      4109 7497 4099 7513 4086 7505 4075 7520
      4061 7520 4042 7548 4045 7553 4024 7570
      4014 7587 4050 7644 4057 7602 4064 7599


$$

Iovino
1 follow-up statement
881 
WGUS81 KPHI 121402
FLSPHI

Flood Advisory
National Weather Service Mount Holly NJ
902 AM EST Fri Nov 12 2021

PAC011-025-077-121412-
/O.CAN.KPHI.FA.Y.0201.000000T0000Z-211112T1500Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Berks PA-Carbon PA-Lehigh PA-
902 AM EST Fri Nov 12 2021

...FLOOD ADVISORY IS CANCELLED...

The Flood Advisory is cancelled for Berks, Lehigh, and Carbon 
Counties.

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

LAT...LON 4122 7554 4125 7513 4115 7516 4109 7497
      4099 7513 4086 7505 4075 7520 4060 7521
      4054 7533 4058 7540 4062 7538 4067 7543
      4066 7548 4074 7553 4075 7560 4079 7561
      4081 7547 4095 7557 4099 7550 4112 7565


$$

PAC089-095-121500-
/O.CON.KPHI.FA.Y.0201.000000T0000Z-211112T1500Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Monroe PA-Northampton PA-
902 AM EST Fri Nov 12 2021

...FLOOD ADVISORY REMAINS IN EFFECT UNTIL 10 AM EST THIS MORNING...

* WHAT...Flooding caused by excessive rainfall continues.

* WHERE...
  Northampton County in eastern Pennsylvania...
  Monroe County in northeastern Pennsylvania...

* WHEN...Until 1000 AM EST.

* IMPACTS...Minor flooding in low-lying and poor drainage areas. 

* ADDITIONAL DETAILS...
  - At 900 AM EST, Doppler radar indicated locally heavy rain.
    Rainfall totals as high as 1.0 to 1.5 inches are expected.
    Minor flooding is ongoing or expected to begin shortly in the
    advisory area. Drains blocked by leaves and other debris will
    result in additional flooding of roadways and areas of
    drainage.
  - Some locations that may experience flooding include...
    Easton, Mount Pocono, Bethlehem, Forks, Northampton, East
    Stroudsburg, Tobyhanna, Wilson, Hellertown, Nazareth, Bangor,
    and Slatington.
  - http://www.weather.gov/safety/flood

LAT...LON 4122 7554 4125 7513 4115 7516 4109 7497
      4099 7513 4086 7505 4075 7520 4060 7521
      4054 7533 4058 7540 4062 7538 4067 7543
      4066 7548 4074 7553 4075 7560 4079 7561
      4081 7547 4095 7557 4099 7550 4112 7565


$$

Iovino

The office that day

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

IssuedProductOfficeCountiesLasted
Nov 12, 6:40 AM ESTSpecial Weather StatementPHIBerks80 min
Nov 12, 9:16 AM ESTSpecial Weather StatementPHIBucks44 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.