Alert archive / Oregon / Severe Thunderstorm Warnings in 2014

Severe Thunderstorm Warning 7, NWS Portland, OR

August 12, 2014Clackamas County, Multnomah County, Oregon

NWS Portland, OR issued this severe thunderstorm warning at Aug 12, 2014, 12:58 PM PDT for Clackamas County, Multnomah County, Oregon. It was in force for 23 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 12, 2014, 12:58 PM PDT (19:58 UTC)
Expired: Aug 12, 2014, 1:21 PM PDT
In force: 23 min
Issued by: NWS Portland, OR
Area: Storm-based polygon

Counties Clackamas County, OR, Multnomah County, OR

The radar

The Portland,OR radar (KRTX), 63 km from the middle of the area, began a volume at 19:58 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

Medford/Jackson, OR (KMFR), launched 12:00Z, 8.0 hours before the alert went out and 336 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: 39 J/kg
Mixed-layer CIN: -585 J/kg
Mixed-layer LCL: 2152 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 52 m²/s²
0-3 km storm-relative helicity: 61 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The office that day

Everything else NWS Portland, OR issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 11, 8:30 PM PDT	Special Weather Statement	PQR	Lane	30 min
Aug 12, 12:50 PM PDT	Special Weather Statement	PQR	Clackamas	25 min
Aug 12, 1:05 PM PDT	Special Weather Statement	PQR	Yamhill	25 min
Aug 12, 1:17 PM PDT	Severe Thunderstorm Warning	PQR	Clackamas, Hood River, Multnomah	28 min
Aug 12, 2:01 PM PDT	Special Weather Statement	PQR	Hood River	29 min
Aug 12, 2:40 PM PDT	Small Craft Advisory for Rough Bar	PQR		18 hr
Aug 12, 2:47 PM PDT	Special Weather Statement	PQR	Skamania	43 min
Aug 12, 3:12 PM PDT	Areal Flood Advisory	PQR	Skamania	2 hr
Aug 12, 3:29 PM PDT	Special Weather Statement	PQR	Skamania	46 min

Nearby

Severe Thunderstorm Warnings in Oregon, 2014 Every severe thunderstorm warning in 2014

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.