Alert archive / Pennsylvania / Areal Flood Warnings in 2025

Areal Flood Warning 21, NWS Philadelphia/Mount Holly

May 31, 2025Lehigh County, Pennsylvania

NWS Philadelphia/Mount Holly issued this areal flood warning at May 31, 2025, 8:42 AM EDT for Lehigh County, Pennsylvania. It was in force for 4 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: May 31, 2025, 8:42 AM EDT (12:42 UTC)
Expired: May 31, 2025, 12:45 PM EDT
In force: 4 hr
Issued by: NWS Philadelphia/Mount Holly
Area: Storm-based polygon
Flood severity: None

County Lehigh County, PA

The radar

The Philadelphia radar (KDIX), 120 km from the middle of the area, began a volume at 12:44 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, 0.7 hours before the alert went out and 233 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: 41 J/kg
Mixed-layer CIN: -265 J/kg
Mixed-layer LCL: 625 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 88 m²/s²
0-3 km storm-relative helicity: 73 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

568 
WGUS41 KPHI 311242
FLWPHI

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Flood Warning
National Weather Service Mount Holly NJ
842 AM EDT Sat May 31 2025

PAC077-311645-
/O.NEW.KPHI.FA.W.0021.250531T1242Z-250531T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
842 AM EDT Sat May 31 2025

...FLOOD WARNING IN EFFECT UNTIL 1245 PM EDT THIS AFTERNOON...

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

* WHERE...A portion of east central Pennsylvania, including the 
  following county, Lehigh.

* WHEN...Until 1245 PM EDT.

* IMPACTS...Flooding of rivers, creeks, streams, and other low-lying 
  and flood-prone locations is imminent or occurring.

* ADDITIONAL DETAILS...
  - At 842 AM EDT, gauge reports indicated heavy rain due to
    thunderstorms. Flooding is ongoing or expected to begin
    shortly in the warned area. Between 1 and 2 inches of rain
    have fallen.
  - Additional rainfall amounts up to 0.5 inches are possible in
    the warned area.
  - For Little Lehigh at Trexlertown near Little Lehigh Creek:
    At 8:15am the stage was 3.5 feet.
    Flood Stage is 4.5 feet.
    ...
    For Spring Creek at Trexlertown at Spring Creek:
    At 8:30am the stage was 4.47 feet.
    Flood Stage is 4.5 feet.
  - http://www.weather.gov/safety/flood

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4050 7559 4051 7563 4056 7564 4057 7560
      4056 7556 4052 7555


$$

Staarmann

1 follow-up statement

619 
WGUS81 KPHI 311635
FLSPHI

Flood Statement
National Weather Service Mount Holly NJ
1235 PM EDT Sat May 31 2025

PAC077-311645-
/O.EXP.KPHI.FA.W.0021.000000T0000Z-250531T1645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lehigh PA-
1235 PM EDT Sat May 31 2025

...FLOOD WARNING WILL EXPIRE AT 1245 PM EDT THIS AFTERNOON...

The Flood Warning will expire at 1245 PM EDT this afternoon for 
South Central Lehigh County.

Flood waters are receding along Little Lehigh Creek. Flooding is no 
longer expected to pose a threat. Please continue to heed remaining 
road closures.

&&

LAT...LON 4050 7559 4051 7563 4056 7564 4057 7560
      4056 7556 4052 7555


$$

Staarmann

The office that day

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

Issued	Product	Office	Counties	Lasted
May 30, 11:12 PM EDT	Flash Flood Warning	PHI	Chester, Delaware	3 hr
May 30, 11:36 PM EDT	Flash Flood Warning	PHI	Bucks, Chester, Delaware, Montgomery, Philadelphia	4 hr
May 31, 12:34 AM EDT	Flash Flood Warning	PHI	Bucks	3 hr
May 31, 1:04 AM EDT	Flash Flood Warning	PHI	Berks, Bucks, Lehigh, Montgomery	4 hr
May 31, 5:06 AM EDT	Areal Flood Warning	PHI	Lehigh, Montgomery	5 hr

Nearby

Areal Flood Warnings in Pennsylvania, 2025 Every areal flood warning in 2025

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.