Alert archive / Pennsylvania / Flash Flood Warnings in 2021

Flash Flood Warning 35, NWS Pittsburgh, PA

August 26, 2021Clarion County, Jefferson County, Pennsylvania

NWS Pittsburgh, PA issued this flash flood warning at Aug 26, 2021, 10:31 PM EDT for Clarion County, Jefferson County, Pennsylvania. It was in force for 3 hr. 3 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 26, 2021, 10:31 PM EDT (02:31 UTC)
Expired: Aug 27, 2021, 1:30 AM EDT
In force: 3 hr
Issued by: NWS Pittsburgh, PA
Area: Storm-based polygon
Flood severity: None

Counties Clarion County, PA, Jefferson County, PA

The radar

The State College radar (KCCX), 102 km from the middle of the area, began a volume at 02:30 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.

What was reported inside it

Time	Report	Where	Remark
Aug 26, 10:50 PM EDT	FLASH FLOOD	1 Nnw Alaska, PA	ROUTE 36 FLOODED NEAR NORTH 36 AUTO SALES. ROADWAY IS COMPLETELY FLOODED AND WITH DEBRIS. ALSO POSSIBLE FLOODING INSIDE ANOTHER NEARBY BUSINESS.
Aug 26, 11:30 PM EDT	FLASH FLOOD	1 Nnw Alaska, PA	ROUTE 36 NEAR DALE SMITH CAMPER SALES IS FLOODED AND BLOCKED WITH DEBRIS.
Aug 26, 11:35 PM EDT	FLASH FLOOD	1 Nnw Clarion, PA	N 5TH AVE CLOSED DUE TO HIGH WATER RUSHING OVER IT.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 00:00Z, 2.5 hours before the alert went out and 122 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: 822 J/kg
Mixed-layer CIN: -17 J/kg
Mixed-layer LCL: 1171 m above ground
0-6 km bulk shear: 4 kt
0-1 km storm-relative helicity: 3 m²/s²
0-3 km storm-relative helicity: 7 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

412 
WGUS51 KPBZ 270231
FFWPBZ
PAC031-065-270530-
/O.NEW.KPBZ.FF.W.0035.210827T0231Z-210827T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Pittsburgh PA
1031 PM EDT Thu Aug 26 2021

The National Weather Service in Pittsburgh has issued a

* Flash Flood Warning for...
  East Central Clarion County in west central Pennsylvania...
  Northwestern Jefferson PA County in west central Pennsylvania...

* Until 130 AM EDT.

* At 1031 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Clarion, Brookville, Strattanville and Corsica.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 4114 7923 4117 7940 4121 7942 4124 7943
      4125 7936 4124 7926 4125 7910 4133 7902
      4136 7896 4133 7888 4132 7887 4119 7885
      4113 7904

FLASH FLOOD...RADAR INDICATED

$$

Brown

2 follow-up statements

588 
WGUS71 KPBZ 270428
FFSPBZ

Flash Flood Statement
National Weather Service Pittsburgh PA
1228 AM EDT Fri Aug 27 2021

PAC031-065-270530-
/O.CON.KPBZ.FF.W.0035.000000T0000Z-210827T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clarion PA-Jefferson PA PA-
1228 AM EDT Fri Aug 27 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 130 AM EDT EARLY THIS 
MORNING FOR EAST CENTRAL CLARION AND NORTHWESTERN JEFFERSON PA 
COUNTIES...

At 1228 AM EDT, local officials reported flooding due to 
thunderstorms producing heavy rain across the warned area. Between 1 
and 3 inches of rain have fallen. Flash flooding is already 
occurring.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Law enforcement reported.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Clarion, Brookville, Strattanville and Corsica.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 4114 7923 4117 7940 4121 7942 4124 7943
      4125 7936 4124 7926 4125 7910 4133 7902
      4136 7896 4135 7892 4133 7888 4132 7887
      4119 7885 4113 7904

FLASH FLOOD...OBSERVED

$$

Brown

524 
WGUS71 KPBZ 270522
FFSPBZ

Flash Flood Statement
National Weather Service Pittsburgh PA
122 AM EDT Fri Aug 27 2021

PAC031-065-270532-
/O.EXP.KPBZ.FF.W.0035.000000T0000Z-210827T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clarion PA-Jefferson PA PA-
122 AM EDT Fri Aug 27 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 130 AM EDT EARLY THIS MORNING 
FOR EAST CENTRAL CLARION AND NORTHWESTERN JEFFERSON PA COUNTIES...

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

LAT...LON 4114 7923 4117 7940 4121 7942 4124 7943
      4125 7936 4124 7926 4125 7910 4133 7902
      4136 7896 4135 7892 4133 7888 4132 7887
      4119 7885 4113 7904

$$

Brown

Nearby

Flash Flood Warnings in Pennsylvania, 2021 Every flash 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.