Alert archive / California / Mesoscale Discussions in 2012
Mesoscale Discussion 502
The Storm Prediction Center issued this mesoscale discussion at Apr 12, 2012, 3:08 PM PDT for 9 counties in California. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Apr 12, 2012, 3:08 PM PDT (22:08 UTC)
- Expired
- Apr 12, 2012, 4:45 PM PDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
Counties Colusa County, CA, Glenn County, CA, Merced County, CA, Sacramento County, CA, San Joaquin County, CA, Stanislaus County, CA, Sutter County, CA, Tehama County, CA, Yolo County, CA
The radar
The Beale AFB radar (KBBX), 80 km from the middle of the area, began a volume at 22:09 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, 10.1 hours before the alert went out and 146 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.
- Mixed-layer CAPE
- 4 J/kg
- Mixed-layer CIN
- -2 J/kg
- Mixed-layer LCL
- 657 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- 221 m²/s²
- 0-3 km storm-relative helicity
- 308 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
976
ACUS11 KWNS 122208
SWOMCD
SPC MCD 122208
CAZ000-122345-
MESOSCALE DISCUSSION 0502
NWS STORM PREDICTION CENTER NORMAN OK
0508 PM CDT THU APR 12 2012
AREAS AFFECTED...COASTAL RANGES INTO SACRAMENTO VALLEY
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 122208Z - 122345Z
STRONG STORMS WERE MOVING ONSHORE NEAR EUREKA THIS AFTERNOON AND MAY
DEVELOP S/SEWD INTO THE SACRAMENTO VALLEY. THE MAIN THREAT WILL BE
MARGINALLY SEVERE HAIL BUT A BRIEF TORNADO CAN NOT BE RULED OUT.
STORMS CURRENTLY MOVING ONSHORE NEAR EUREKA WERE SHOWING SIGNS OF AT
LEAST WEAK LOW AND MIDLEVEL ROTATION AS DEEP LAYER SHEAR HAS BEEN
INCREASING THROUGH THE DAY AS UPPER LEVEL WAVE APPROACHES THE PAC NW
COAST. BULK SHEAR VALUES NEAR 35 KT HAVE FAVORED SOME ISOLATED
INTENSE CELLS AND WITH STEEP MIDLEVEL LAPSE RATES NEAR 7-7.5 DEG C
PER KM AND COLD TEMPERATURES ALOFT...MARGINALLY SEVERE HAIL WILL BE
POSSIBLE THROUGH THE EVENING HOURS. IN ADDITION TO THE HAIL
POTENTIAL...WSR-88D VAD WIND PROFILES FROM KDAX AND KBHX INDICATE
FAVORABLE LOW LEVEL HODOGRAPHS WITH 0-1 KM SRH 300 M2/S2 AT
KBHX...DIMINISHING TO CLOSER TO 50 AT KDAX. THUS...A WATERSPOUT OR
BRIEF TORNADO CAN NOT BE RULED OUT THROUGH THE EARLY EVENING HOURS.
THE ONLY LIMITING FACTORS AT THIS TIME APPEAR TO BE
INSTABILITY...WITH SBCAPE VALUES CURRENTLY LESS THAN ABOUT 500 J/KG
IN ADDITION TO SOME WEAK MIDLEVEL RIDGING. THIS COULD LIMIT
SUSTAINED UPDRAFTS AND THEREFORE ANY SEVERE POTENTIAL. THEREFORE
CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED FOR POTENTIAL WW
ISSUANCE.
..LEITMAN.. 04/12/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...HNX...STO...MTR...EKA...
LAT...LON 40712457 40672353 40402219 38842109 37712028 37251993
36892030 36752084 38132181 39612304 39722392 40092441
40712457SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 12, 11:11 AM PDT | Mesoscale Discussion | SPC | Amador, Calaveras, Colusa, Glenn, Humboldt, Sacramento and 7 more | 64 min |
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.