Alert archive / California / Mesoscale Discussions in 2012

Mesoscale Discussion 582

April 23, 20124 counties in California; Klamath County, Oregon

The Storm Prediction Center issued this mesoscale discussion at Apr 23, 2012, 1:39 PM PDT for 4 counties in California; Klamath County, Oregon. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued
Apr 23, 2012, 1:39 PM PDT (20:39 UTC)
Expired
Apr 23, 2012, 3:15 PM PDT
In force
96 min
Issued by
the Storm Prediction Center

Counties Lassen County, CA, Modoc County, CA, Plumas County, CA, Sierra County, CA, Klamath County, OR

The radar

The Medford radar (KMAX), 182 km from the middle of the area, began a volume at 20:39 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, 8.7 hours before the alert went out and 205 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 2012-04-23Temperature 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 2012-04-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 23 square meters per square second.19395878Sfc1 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
1383 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
23 m²/s²
0-3 km storm-relative helicity
139 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.7

Open this sounding in Storm Lab

The text

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

011 
ACUS11 KWNS 232039
SWOMCD
SPC MCD 232039 
NVZ000-ORZ000-CAZ000-232215-

MESOSCALE DISCUSSION 0582
NWS STORM PREDICTION CENTER NORMAN OK
0339 PM CDT MON APR 23 2012

AREAS AFFECTED...SRN ORE...NRN CA...NW NV

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 232039Z - 232215Z

A MARGINAL WIND DAMAGE AND HAIL THREAT SHOULD EXIST ACROSS NRN
CA...NW NV AND SRN ORE THIS AFTERNOON. THE THREAT SHOULD REMAIN TOO
ISOLATED TO WARRANT WW ISSUANCE.

THUNDERSTORMS ARE DEVELOPING IN NRN CA AND NW NV ALONG THE ERN EDGE
OF MODERATE INSTABILITY WHERE MLCAPE VALUES ARE ESTIMATED FROM 750
TO 1200 J/KG. THE STORMS ARE INCREASING IN COVERAGE DUE TO SFC
HEATING AND TOPOGRAPHIC FORCING FROM THE SIERRA NEVADA. AS THE CELLS
SPREAD NWD INTO THE LOWER ELEVATIONS THIS AFTERNOON...STEEP LAPSE
RATES AND MODERATE DEEP LAYER SHEAR MAY BE ENOUGH FOR A HAIL THREAT.
IN ADDITION...SFC TEMPERATURE-DEWPOINT SPREADS EXCEED 40 DEGREES
ACROSS MUCH OF THE MCD AREA SUGGESTING DOWNBURSTS MAY BE ENHANCED
ENOUGH TO POSE AN ISOLATED WIND DAMAGE THREAT FOR A FEW HOURS THIS
AFTERNOON.

..BROYLES.. 04/23/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...REV...MFR...STO...

LAT...LON   39622013 39552069 40162134 41912213 43062208 43512133
            43112075 42022043 41222016 40321965 39622013

Nearby

Mesoscale Discussions in California, 2012Mesoscale Discussions in Oregon, 2012Every mesoscale discussion in 2012

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.