Alert archive / Washington / Areal Flood Advisories in 2021

Areal Flood Advisory 10, NWS Spokane, WA

August 21, 2021Douglas County, Washington

NWS Spokane, WA issued this areal flood advisory at Aug 21, 2021, 12:30 AM PDT for Douglas County, Washington. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued: Aug 21, 2021, 12:30 AM PDT (07:30 UTC)
Expired: Aug 21, 2021, 3:30 AM PDT
In force: 3 hr
Issued by: NWS Spokane, WA
Area: Storm-based polygon

County Douglas County, WA

The radar

The Spokane radar (KOTX), 155 km from the middle of the area, began a volume at 07:31 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

Spokane, WA (KOTX), launched 00:00Z, 7.5 hours before the alert went out and 246 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: 104 J/kg
Mixed-layer CIN: -58 J/kg
Mixed-layer LCL: 1795 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 17 m²/s²
0-3 km storm-relative helicity: 60 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this areal flood advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Spokane, WA wrote its last area forecast discussion before this areal flood advisory went out at Aug 20, 9:50 PM PDT, 2 hours 40 minutes earlier.

Area forecast discussion, Aug 20, 9:50 PM PDT, 2 hours 40 minutes before

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Hazardous weather outlook, Aug 20, 4:40 AM PDT, 19 hours 50 minutes before

Hazardous Weather Outlook
National Weather Service Spokane WA
440 AM PDT Fri Aug 20 2021

IDZ026-027-WAZ031>036-044-211145-
Lewiston Area-Lewis and Southern Nez Perce Counties-
Northeast Blue Mountains-Lower Garfield and Asotin Counties-
Washington Palouse-Moses Lake Area-Upper Columbia Basin-
Spokane Area-Waterville Plateau-
440 AM PDT Fri Aug 20 2021

This Hazardous Weather Outlook is for portions of North Central
Idaho...Central Washington...East Central Washington...Northeast
Washington and Southeast Washington.

.DAY ONE...TODAY AND TONIGHT

No hazardous weather is expected at this time.

Isolated to scattered showers and thunderstorms are expected
this afternoon and tonight, which could produce brief heavy
downpours and create ponding of water on roads, reduce visibility.
Additionally, lightning strikes from thunderstorms are always
dangerous.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

No hazardous weather is expected at this time.

Isolated to scattered showers and thunderstorms are expected
Saturday, which could produce brief heavy downpours and create
ponding of water on roads, reduce visibility. Additionally,
lightning strikes from thunderstorms are always dangerous.

IDZ001>004-WAZ037-038-041>043-211145-
Northern Panhandle-Coeur d'Alene Area-Idaho Palouse-
Central Panhandle Mountains-Northeast Mountains-
Okanogan Highlands-Wenatchee Area-East Slopes Northern Cascades-
Okanogan Valley-
440 AM PDT Fri Aug 20 2021

This Hazardous Weather Outlook is for portions of North Idaho...
North Central Washington and Northeast Washington.

.DAY ONE...TODAY AND TONIGHT

Scattered to numerous showers showers and thunderstorms are
expected this afternoon and tonight. A few storms will be capable
of producing heavy downpours, some which could create dangerous
flash flooding or debris flow near steeper terrain, recently
burned areas or in creeks or small streams areas. Additionally,
lightning strikes from thunderstorms are always dangerous.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

There will be a chance for showers and thunderstorms through
Saturday. A few storms will be capable of producing heavy
downpours, some which could create dangerous flash flooding or
debris flow near steeper terrain, recently burned areas or in
creeks or small streams areas. Additionally, lightning strikes
from thunderstorms are always dangerous.

In the hours before

Local storm report, Aug 20, 7:22 PM PDT, 5 hours 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SPOKANE WA
722 PM PDT FRI AUG 20 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0615 PM     FLOOD            3 NNE ENTIAT            47.72N 120.18W
08/20/2021                   DOUGLAS            WA   LAW ENFORCEMENT

            ROCK SLIDE DUE TO BRIEF HEAVY RAIN PARTIALLY
            BLOCKING ROAD NEAR DESSERT CANYON GOLF
            COURSE.

&&

GK

Special weather statement, Aug 20, 8:37 PM PDT, 3 hours 53 minutes before

Special Weather Statement
National Weather Service Spokane WA
837 PM PDT Fri Aug 20 2021

IDZ002>004-210400-
Central Panhandle Mountains ID-Coeur d'Alene Area ID-
Idaho Palouse ID-
837 PM PDT Fri Aug 20 2021

...A strong thunderstorm will impact portions of western Shoshone,
eastern Benewah and southeastern Kootenai Counties through 900 PM
PDT...

At 837 PM PDT, Doppler radar was tracking a strong thunderstorm 8
miles south of St. Maries, moving north at 40 mph.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
St. Maries, Parkline, Medimont, St. Joe and Santa.

People attending Benewah County Fair should seek safe shelter
immediately!

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4709 11650 4715 11675 4758 11667 4746 11613
TIME...MOT...LOC 0337Z 202DEG 33KT 4719 11659

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

CD

Local storm report, Aug 20, 9:19 PM PDT, 3 hours 11 minutes before

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Local storm report, Aug 20, 10:02 PM PDT, 2 hours 28 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 20, 5:46 PM PDT	Areal Flood Advisory	OTX	Chelan, Douglas	3 hr
Aug 20, 7:17 PM PDT	Areal Flood Advisory	OTX	Okanogan	3 hr
Aug 20, 6:14 PM PDT	Areal Flood Advisory	OTX	Nez Perce	3 hr
Aug 20, 8:37 PM PDT	Special Weather Statement	OTX	Benewah	23 min

Nearby

Areal Flood Advisories in Washington, 2021 Every areal flood advisory 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.