Alert archive / Washington / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 2, NWS Seattle, WA

August 3, 2021King County, Washington

NWS Seattle, WA issued this severe thunderstorm warning at Aug 3, 2021, 4:49 PM PDT for King County, Washington. It was in force for 26 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
Aug 3, 2021, 4:49 PM PDT (23:49 UTC)
Expired
Aug 3, 2021, 5:15 PM PDT
In force
26 min
Issued by
NWS Seattle, WA
Area
Storm-based polygon
Hail
1.75 in
Wind
50.0 mph

County King County, WA

The radar

The Seattle radar (KATX), 116 km from the middle of the area, began a volume at 23:52 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

Quillayute State, WA (KUIL), launched 12:00Z, 11.8 hours before the alert went out and 248 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, Quillayute State, WA at 12:00Z on 2021-08-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Quillayute State, WA at 12:00Z on 2021-08-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -29 square meters per square second.1939Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1940 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
-29 m²/s²
0-3 km storm-relative helicity
17 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

933 
WUUS56 KSEW 032349
SVRSEW
WAC033-040015-
/O.NEW.KSEW.SV.W.0002.210803T2349Z-210804T0015Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Seattle WA
449 PM PDT Tue Aug 3 2021

The National Weather Service in Seattle has issued a

* Severe Thunderstorm Warning for...
  Northeastern King County in west central Washington...

* Until 515 PM PDT

* At 449 PM PDT, a severe thunderstorm was located 8 miles northeast
  of Snoqualmie Pass, moving north at 25 mph.

  HAZARD...Golf ball size hail. 

  SOURCE...Radar indicated. 

  IMPACT...People and animals outdoors will be injured. Expect 
           damage to roofs, siding, windows, and vehicles. 

* Locations impacted include...
  Skykomish and Stevens Pass.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Prepare immediately for large hail and deadly cloud to ground
lightning. Seek shelter inside a well-built structure. Stay away from
windows.

&&

LAT...LON 4769 12110 4768 12113 4764 12113 4757 12118
      4757 12122 4753 12124 4751 12129 4749 12130
      4747 12133 4748 12139 4774 12140 4773 12108
TIME...MOT...LOC 2349Z 189DEG 20KT 4753 12131 

HAIL...1.75IN
WIND...<50MPH
 
$$

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 3, 2:28 AM PDTGale WarningSEW24 hr
Aug 3, 2:28 AM PDTSmall Craft AdvisorySEW18 hr

Nearby

Severe Thunderstorm Warnings in Washington, 2021Every severe thunderstorm 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.