Alert archive / California / Mesoscale Discussions in 2014

Mesoscale Discussion 1547

August 11, 201410 counties in California; Storey County, Washoe County, Nevada; 8 counties in Oregon

The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2014, 2:42 PM PDT for 10 counties in California; Storey County, Washoe County, Nevada; 8 counties in Oregon. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Aug 11, 2014, 2:42 PM PDT (21:42 UTC)
Expired
Aug 11, 2014, 4:45 PM PDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Butte County, CA, Lassen County, CA, Modoc County, CA, Nevada County, CA, Placer County, CA, Plumas County, CA, Shasta County, CA, Sierra County, CA, Siskiyou County, CA, Tehama County, CA, Storey County, NV, Washoe County, NV, Crook County, OR, Deschutes County, OR, Jackson County, OR, Jefferson County, OR, Klamath County, OR, Lake County, OR, Wasco County, OR, Wheeler County, OR

The radar

The Medford radar (KMAX), 168 km from the middle of the area, began a volume at 21:42 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, 9.7 hours before the alert went out and 182 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, Medford/Jackson, OR at 12:00Z on 2014-08-11Temperature 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, Medford/Jackson, OR at 12:00Z on 2014-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 31 square meters per square second.193958Sfc1 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
2730 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
31 m²/s²
0-3 km storm-relative helicity
11 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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Nearby

Mesoscale Discussions in California, 2014Mesoscale Discussions in Oregon, 2014Mesoscale Discussions in Nevada, 2014Every mesoscale discussion 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.