Alert archive / Pennsylvania / Flash Flood Warnings in 2021

Flash Flood Warning 29, NWS State College, PA

September 8, 2021Adams County, York County, Pennsylvania

NWS State College, PA issued this flash flood warning at Sep 8, 2021, 10:10 PM EDT for Adams County, York County, Pennsylvania. It was in force for 95 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 8, 2021, 10:10 PM EDT (02:10 UTC)
Expired: Sep 8, 2021, 11:45 PM EDT
In force: 95 min
Issued by: NWS State College, PA
Area: Storm-based polygon
Flood severity: None

Counties Adams County, PA, York County, PA

The radar

The Sterling radar (KLWX), 125 km from the middle of the area, began a volume at 02:14 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 2.2 hours before the alert went out and 125 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: 1652 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 1146 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 115 m²/s²
0-3 km storm-relative helicity: 136 m²/s²
Significant tornado parameter: 1.0
Supercell composite: 7.0

Open this sounding in Storm Lab

The text

As transmitted.

668 
WGUS51 KCTP 090210
FFWCTP
PAC001-133-090345-
/O.NEW.KCTP.FF.W.0029.210909T0210Z-210909T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service State College PA
1010 PM EDT Wed Sep 8 2021

The National Weather Service in State College has issued a

* Flash Flood Warning for...
  East Central Adams County in south central Pennsylvania...
  Northwestern York County in south central Pennsylvania...

* Until 1145 PM EDT.

* At 1010 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. Additional rainfall amounts up to 1 inch are possible 
  in the warned area. 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...
  Weigelstown, Hampton, Manchester, Lake Meade, Dover, East Berlin, 
  Mount Wolf and Heidlersburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4012 7674 4005 7666 3986 7713 3994 7715
      3997 7714

FLASH FLOOD...RADAR INDICATED

$$

KF

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 8, 8:13 PM EDT	Special Weather Statement	CTP	Franklin	17 min
Sep 8, 8:43 PM EDT	Special Weather Statement	CTP	Adams	32 min
Sep 8, 8:55 PM EDT	Severe Thunderstorm Warning	CTP	Adams, Cumberland, York	50 min
Sep 8, 9:39 PM EDT	Special Weather Statement	CTP	York	21 min
Sep 8, 9:48 PM EDT	Areal Flood Advisory	CTP	Adams, York	57 min
Sep 8, 10:22 PM EDT	Areal Flood Advisory	CTP	Lancaster, Lebanon	68 min
Sep 8, 11:24 PM EDT	Areal Flood Advisory	CTP	Lebanon	96 min
Sep 8, 11:45 PM EDT	Areal Flood Advisory	CTP	Adams, York	75 min
Sep 9, 5:00 PM EDT	Special Weather Statement	CTP	Franklin	30 min
Sep 9, 5:15 PM EDT	Special Weather Statement	CTP	Lebanon	45 min
Sep 9, 5:33 PM EDT	Special Weather Statement	CTP	Adams	27 min
Sep 9, 5:57 PM EDT	Special Weather Statement	CTP	Adams	33 min

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.