Alert archive / Washington / Flash Flood Warnings in 2021

Flash Flood Warning 1, NWS Spokane, WA

July 8, 2021Okanogan County, Washington

NWS Spokane, WA issued this flash flood warning at Jul 8, 2021, 6:07 PM PDT for Okanogan County, Washington. It was in force for 113 min. 1 report 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: Jul 8, 2021, 6:07 PM PDT (01:07 UTC)
Expired: Jul 8, 2021, 8:00 PM PDT
In force: 113 min
Issued by: NWS Spokane, WA
Area: Storm-based polygon
Flood severity: None

County Okanogan County, WA

The radar

The Seattle radar (KATX), 154 km from the middle of the area, began a volume at 01:06 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
Jul 8, 7:00 PM PDT	FLASH FLOOD	12 Sw Mazama, WA	FOREST SERVICE REPORTED A FLASH FLOOD / DEBRIS FLOW THAT BLOCKED THE NF-4440 ROAD 1 MILE EAST OF THE GILBERT TRAILHEAD. FLOW WAS APPROXIMATELY 4 FEET DEEP AND STRANDED 2 VEHICLES OVERNIGHT. TIME IS ESTIMATED BASED ON RADAR.

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

The nearest sounding before it

Spokane, WA (KOTX), launched 00:00Z, 1.1 hours before the alert went out and 311 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 3320 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 18 m²/s²
0-3 km storm-relative helicity: 75 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

074 
WGUS56 KOTX 090107
FFWOTX
WAC047-090300-
/O.NEW.KOTX.FF.W.0001.210709T0107Z-210709T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Spokane WA
607 PM PDT Thu Jul 8 2021

The National Weather Service in Spokane has issued a

* Flash Flood Warning for...
  West central Okanogan County in north central Washington...

* Until 800 PM PDT.

* At 606 PM PDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area.  Flash flooding is ongoing or
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar indicated.

  IMPACT...Flooding of small creeks and streams, urban areas, 
           highways, streets and underpasses as well as other 
           drainage and low lying areas.

* Some locations that will experience flooding include...
  Mystery Campground, South Creek Campground, War Creek Campground
  and Poplar Flat Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The affected areas are in and below Crescent Mountain Fire burn scar
above and along Twisp River Road.  High intensity rainfall on the
burned area may cause flash flooding, mud slides and rock slides.
Campers, hikers, and motorists in and below the Crescent Mountain
Fire burned area should take immediate precautions to protect life
and property.

Move away from recently burned areas. Life-threatening flooding of
creeks, roads and normally dry arroyos is likely. The heavy rains may
trigger rockslides, mudslides and debris flows in steep terrain,
especially in and around these areas.

&&

LAT...LON 4844 12036 4830 12038 4836 12054 4855 12057

FLASH FLOOD...RADAR INDICATED

$$

JW

The office that day

Everything else NWS Spokane, WA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 9, 2:42 AM PDT	Heat Advisory	OTX	Adams, Asotin, Douglas, Garfield, Grant, Lincoln and 3 more	41 hr
Jul 9, 8:03 AM PDT	Red Flag Warning	OTX		37 hr

Nearby

Flash Flood Warnings in Washington, 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.