Alert archive / Pennsylvania / Areal Flood Warnings in 2021

Areal Flood Warning 28, NWS Philadelphia/Mount Holly

August 23, 2021Lehigh County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at Aug 23, 2021, 8:28 AM EDT for Lehigh County, Pennsylvania. It was in force for 7 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 23, 2021, 8:28 AM EDT (12:28 UTC)
Expired
Aug 23, 2021, 3:47 PM EDT
In force
7 hr
Issued by
NWS Philadelphia/Mount Holly
Area
Storm-based polygon
Flood severity
None

County Lehigh County, PA

The radar

The Philadelphia radar (KDIX), 117 km from the middle of the area, began a volume at 12:29 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, 0.5 hours before the alert went out and 225 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 2021-08-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 150 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 2021-08-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 square meters per square second.193958Sfc1 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
150 J/kg
Mixed-layer CIN
-15 J/kg
Mixed-layer LCL
711 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
108 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.7

Open this sounding in Storm Lab

The text

As transmitted.

499 
WGUS41 KPHI 231228
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
828 AM EDT Mon Aug 23 2021

PAC077-231630-
/O.NEW.KPHI.FA.W.0028.210823T1228Z-210823T1630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
828 AM EDT Mon Aug 23 2021

The National Weather Service in Mount Holly has issued a

* Flood Warning for...
  Central Lehigh County in eastern Pennsylvania...

* Until 1230 PM EDT.

* At 828 AM EDT, gauge reports indicated water was rising on the 
  Little Lehigh and Spring Creek. Flooding is ongoing or expected to 
  begin shortly in the warned area. Between 1 and 3 inches of rain 
  have fallen. Due to high water, Spring Creek Road is subject to 
  closures.

* Some locations that will experience flooding include...
  Allentown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most 
flood deaths occur in vehicles.

&&

LAT...LON 4057 7554 4058 7553 4059 7550 4059 7549
      4058 7548 4057 7548 4057 7552 4057 7553

$$

Kruzdlo
2 follow-up statements
148 
WGUS41 KPHI 231616
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
1216 PM EDT Mon Aug 23 2021

PAC077-232030-
/O.EXT.KPHI.FA.W.0028.000000T0000Z-210823T2030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
1216 PM EDT Mon Aug 23 2021

The National Weather Service in Mount Holly has extended the

* Flood Warning for...
  Central Lehigh County in eastern Pennsylvania...

* Until 430 PM EDT.

* At 1216 PM EDT, gauge reports indicated water was still running 
  high on the Little Lehigh and Spring Creek. Flooding is ongoing or 
  expected to begin shortly in the warned area. Between 1 and 3 
  inches of rain have fallen. Due to high water, Spring Creek Road 
  is subject to closures.

* Some locations that will experience flooding include...
  Allentown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around...don't drown when encountering flooded roads. Most 
flood deaths occur in vehicles.

&&

LAT...LON 4057 7554 4058 7553 4059 7550 4059 7549
      4058 7548 4057 7548 4057 7552 4057 7553

$$

Kruzdlo
313 
WGUS81 KPHI 231947
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
347 PM EDT Mon Aug 23 2021

PAC077-231957-
/O.CAN.KPHI.FA.W.0028.000000T0000Z-210823T2030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
347 PM EDT Mon Aug 23 2021

...FLOOD WARNING IS CANCELLED FOR CENTRAL LEHIGH COUNTY...

Flood waters are receding. Please continue to heed remaining road 
closures.

LAT...LON 4057 7554 4058 7553 4059 7550 4059 7549
      4058 7548 4057 7548 4057 7552 4057 7553

$$

Kruzdlo

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 22, 8:11 PM EDTAreal Flood AdvisoryPHICarbon, Monroe, Northampton6 hr
Aug 22, 8:47 PM EDTFlash Flood WarningPHIMonroe, Northampton6 hr
Aug 22, 10:34 PM EDTAreal Flood AdvisoryPHICarbon, Lehigh, Northampton3 hr
Aug 22, 10:53 PM EDTFlash Flood WarningPHICarbon, Lehigh, Monroe, Montgomery, Northampton4 hr
Aug 22, 11:42 PM EDTAreal Flood AdvisoryPHIBerks3 hr
Aug 23, 12:32 AM EDTRiver Flood WarningPHIMonroe10 hr
Aug 23, 12:55 AM EDTRiver Flood WarningPHIMonroe10 hr
Aug 23, 2:36 AM EDTAreal Flood WarningPHICarbon, Monroe21 hr
Aug 23, 3:50 AM EDTRiver Flood WarningPHICarbon3 hr
Aug 23, 3:50 AM EDTRiver Flood WarningPHILehigh, Northampton11 hr
Aug 23, 4:41 PM EDTSpecial Weather StatementPHIMontgomery34 min

Nearby

Areal Flood Warnings in Pennsylvania, 2021Every areal flood warning 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.