Alert archive / Pennsylvania / Flash Flood Warnings in 2026

Flash Flood Warning 121, NWS Pittsburgh, PA

August 20, 20265 counties in Pennsylvania

NWS Pittsburgh, PA issued this flash flood warning at Aug 20, 2026, 10:05 AM EDT for 5 counties in Pennsylvania. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Aug 20, 2026, 10:05 AM EDT (14:05 UTC)
Expired
Aug 20, 2026, 12:51 PM EDT
In force
3 hr
Issued by
NWS Pittsburgh, PA
Area
Storm-based polygon
Flood severity
None

Counties Allegheny County, PA, Fayette County, PA, Greene County, PA, Washington County, PA, Westmoreland County, PA

The radar

The Pittsburgh radar (KPBZ), 50 km from the middle of the area, began a volume at 14:07 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

Pittsburgh, PA (KPIT), launched 12:00Z, 2.1 hours before the alert went out and 33 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, Pittsburgh, PA at 12:00Z on 2026-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 39 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, Pittsburgh, PA at 12:00Z on 2026-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -25 square meters per square second.19395878Sfc1 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
39 J/kg
Mixed-layer CIN
-43 J/kg
Mixed-layer LCL
765 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
-25 m²/s²
0-3 km storm-relative helicity
32 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The office that day

Everything else NWS Pittsburgh, PA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 20, 9:40 AM EDTFlash Flood WarningPBZGreene, Washington3 hr
Aug 20, 9:59 AM EDTFlash Flood WarningPBZArmstrong, Clarion, Jefferson3 hr
Aug 20, 11:10 AM EDTFlash Flood WarningPBZArmstrong, Fayette, Indiana, Westmoreland3 hr
Aug 20, 11:29 AM EDTFlash Flood WarningPBZArmstrong, Indiana, Jefferson, Westmoreland3 hr
Aug 20, 12:43 PM EDTAreal Flood WarningPBZGreene, Washington3 hr
Aug 20, 12:51 PM EDTAreal Flood WarningPBZAllegheny, Beaver, Fayette, Greene, Washington, Westmoreland3 hr
Aug 20, 1:51 PM EDTAreal Flood WarningPBZAllegheny, Armstrong, Fayette, Indiana, Westmoreland3 hr
Aug 20, 2:12 PM EDTAreal Flood WarningPBZArmstrong, Indiana, Jefferson, Westmoreland3 hr
Aug 20, 7:05 AM EDTFlash Flood WarningPBZGuernsey, Muskingum3 hr
Aug 20, 7:48 AM EDTFlash Flood WarningPBZBelmont, Guernsey, Harrison, Monroe, Noble3 hr
Aug 20, 8:18 AM EDTFlash Flood WarningPBZBelmont, Harrison, Jefferson3 hr
Aug 20, 9:34 AM EDTAreal Flood WarningPBZMonroe, Noble24 hr
Aug 20, 10:57 AM EDTAreal Flood WarningPBZGuernsey, Muskingum, Noble11 hr
Aug 20, 10:58 AM EDTAreal Flood WarningPBZBelmont, Guernsey, Harrison, Monroe, Noble, Tuscarawas11 hr
Aug 20, 11:00 AM EDTAreal Flood WarningPBZBelmont, Harrison, Jefferson, Monroe11 hr

Nearby

Flash Flood Warnings in Pennsylvania, 2026Every flash flood warning in 2026

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.