Alert archive / California / Mesoscale Discussions in 2012

Mesoscale Discussion 2085

October 22, 20127 counties in California

The Storm Prediction Center issued this mesoscale discussion at Oct 22, 2012, 1:48 PM PDT for 7 counties in California. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued
Oct 22, 2012, 1:48 PM PDT (20:48 UTC)
Expired
Oct 22, 2012, 3:45 PM PDT
In force
117 min
Issued by
the Storm Prediction Center
Chance of a watch
5%

Counties Butte County, CA, Colusa County, CA, Glenn County, CA, Sacramento County, CA, Sutter County, CA, Tehama County, CA, Yolo County, CA

The radar

The Beale AFB radar (KBBX), 38 km from the middle of the area, began a volume at 20:50 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

Oakland, CA (KOAK), launched 12:00Z, 8.8 hours before the alert went out and 204 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, Oakland, CA at 12:00Z on 2012-10-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4 joules per kilogram.LCLLFCEL10008507005003002001001 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, Oakland, CA at 12:00Z on 2012-10-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 276 square meters per square second.1939587897117Sfc1 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
4 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
650 m above ground
0-6 km bulk shear
69 kt
0-1 km storm-relative helicity
276 m²/s²
0-3 km storm-relative helicity
345 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.

113 
ACUS11 KWNS 222048
SWOMCD
SPC MCD 222048 
CAZ000-222245-

MESOSCALE DISCUSSION 2085
NWS STORM PREDICTION CENTER NORMAN OK
0348 PM CDT MON OCT 22 2012

AREAS AFFECTED...SACRAMENTO VALLEY

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 222048Z - 222245Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...ISOLATED STRONG TO MARGINALLY SVR STORMS WILL BE POSSIBLE
THROUGH THE AFTERNOON. THE ISSUANCE OF A WW IS NOT NEEDED.

DISCUSSION...MODEST BOUNDARY-LAYER WARMING OWING TO AREAS OF
INSOLATION BENEATH RELATIVELY COOL MID-LEVEL TEMPERATURES ARE
SUPPORTING MARGINAL INSTABILITY WITH SBCAPE/MUCAPE VALUES FROM 250
TO AROUND 500 J/KG. LOW-LEVEL ASCENT OVER THE WRN FLANK OF CHANNELED
SLY FLOW THROUGH THE SACRAMENTO VALLEY IS SUPPORTING ISOLATED
CONVECTIVE DEVELOPMENT AMIDST 20-25 KT OF EFFECTIVE BULK SHEAR.
MULTICELL TO PERHAPS MARGINAL SUPERCELL STRUCTURES -- AIDED BY
DIRECTIONAL SHEAR EVIDENT IN SACRAMENTO-AREA VWP DATA -- MAY SUPPORT
MARGINALLY SVR HAIL/WIND WITH THE STRONG STORMS. HOWEVER...THE
ABSENCE OF STRONGER BUOYANCY/STRONGER DEEP SHEAR SHOULD MITIGATE THE
OVERALL SVR THREAT.

..COHEN/MEAD.. 10/22/2012

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

ATTN...WFO...STO...

LAT...LON   40702221 39972175 39052127 38402124 38322163 38602193
            38962224 39362244 39782261 40222269 40652261 40702221

Nearby

Mesoscale Discussions in California, 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.