Alert archive / California / Mesoscale Discussions in 2003

Mesoscale Discussion 528

April 21, 200311 counties in California

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2003, 11:48 AM PDT for 11 counties in California. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Apr 21, 2003, 11:48 AM PDT (18:48 UTC)
Expired
Apr 21, 2003, 2:45 PM PDT
In force
3 hr
Issued by
the Storm Prediction Center

Counties Butte County, CA, Colusa County, CA, Glenn County, CA, Merced County, CA, Sacramento County, CA, San Joaquin County, CA, Solano County, CA, Stanislaus County, CA, Sutter County, CA, Yolo County, CA, Yuba County, CA

The nearest sounding before it

Oakland, CA (KOAK), launched 12:00Z, 6.8 hours before the alert went out and 92 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 2003-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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 2003-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -53 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
865 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
-53 m²/s²
0-3 km storm-relative helicity
48 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.

130 
ACUS11 KWNS 211848
SWOMCD
SPC MCD 211848 
CAZ000-212145-

MESOSCALE DISCUSSION 0528
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CDT MON APR 21 2003

AREAS AFFECTED...CENTRAL CA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 211848Z - 212145Z

COVERAGE OF CONVECTIVE CELLS IS EXPECTED TO INCREASE ACROSS THE
INTERIOR VALLEYS OF CENTRAL CA THIS AFTERNOON. ISOLATED SEVERE
HAIL IS POSSIBLE WITH STRONGER CORES...PARTICULARLY DURING THE
MID AFTERNOON THROUGH EARLY EVENING PERIOD /21-01Z/. 

UPPER LOW CENTER EVIDENT ACROSS THE NRN SACRAMENTO VALLEY ON
VISIBLE IMAGERY AT 1830Z IS EXPECTED TO DRIFT SSEWD THROUGH THIS
EVENING. ONGOING INSOLATIONAL HEATING ACROSS THE SACRAMENTO AND
NRN SAN JOAQUIN VALLEYS COMBINED WITH VERY COLD AIR ALOFT /-24C
TO -28C AT 500MB/ SPREADING EWD ACROSS THE REGION WILL
SIGNIFICANTLY STEEPEN LOW TO MID LEVEL LAPSE RATES DURING THE
NEXT FEW HOURS. MODIFIED RUC FORECAST SOUNDINGS OVER THE INTERIOR
VALLEYS THIS AFTERNOON SUGGEST MUCAPE TO 1000 J/KG GIVEN MID 40S
SURFACE DEWPOINTS. SMALL/LOW-TOPPED CONVECTIVE CELLS WILL LIKELY
INCREASE IN COVERAGE ACROSS THE REGION THIS AFTERNOON.
INSTABILITY COMBINED WITH 850-500MB LAPSE RATES AROUND 8C/KM AND
VERY LOW WBZ HEIGHTS AROUND 4 KFT SUGGEST SMALL HAIL IS
LIKELY...WITH SEVERE HAIL POSSIBLE WITH STRONGEST
CORES...PARTICULARLY WHEN INSTABILITY IS MAXIMIZED DURING THE
21-01Z PERIOD. ACTIVITY WILL LIKELY WEAKEN BY LATE THIS EVENING. 

..BANACOS.. 04/21/2003

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

ATTN...WFO...HNX...STO...MTR...

38162208 38532230 39052250 39322262 39782258 39952209
39902144 39292111 38772093 38232061 37962051 37312013
37001995 36321977 36372047 36902115 37342150 38182210

Nearby

Mesoscale Discussions in California, 2003Every mesoscale discussion in 2003

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.