Alert archive / California / Mesoscale Discussions in 2011
Mesoscale Discussion 231
The Storm Prediction Center issued this mesoscale discussion at Mar 18, 2011, 11:37 AM PDT for San Mateo County, Santa Cruz County, California. It was in force for 53 min.
The area
The outline as issued.
The facts
- Issued
- Mar 18, 2011, 11:37 AM PDT (18:37 UTC)
- Expired
- Mar 18, 2011, 12:30 PM PDT
- In force
- 53 min
- Issued by
- the Storm Prediction Center
Counties San Mateo County, CA, Santa Cruz County, CA
The radar
The San Francisco radar (KMUX), 36 km from the middle of the area, began a volume at 18:37 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, 6.6 hours before the alert went out and 102 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
- 21 J/kg
- Mixed-layer CIN
- -28 J/kg
- Mixed-layer LCL
- 757 m above ground
- 0-6 km bulk shear
- 68 kt
- 0-1 km storm-relative helicity
- 203 m²/s²
- 0-3 km storm-relative helicity
- 285 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
355
ACUS11 KWNS 181837
SWOMCD
SPC MCD 181837
CAZ000-181930-
MESOSCALE DISCUSSION 0231
NWS STORM PREDICTION CENTER NORMAN OK
0137 PM CDT FRI MAR 18 2011
AREAS AFFECTED...COASTAL SECTIONS OF W-CNTRL CA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 181837Z - 181930Z
SCATTERED LOW-TOPPED CONVECTION WILL POSE A LOW THREAT FOR ISOLATED
WIND DAMAGE THIS AFTERNOON ACROSS COASTAL SECTIONS OF W-CNTRL CA.
STRONG LOW-LEVEL FORCING IN ASSOCIATION WITH A COLD FRONT DROPPING
SEWD ALONG THE WRN COAST OF CA WILL SUPPORT LOW-TOPPED SCATTERED
CONVECTION INTO THIS AFTERNOON. LIMITED PRE-FRONTAL INSOLATION WILL
KEEP ANY SURFACE-BASED INSTABILITY VERY MARGINAL...PRECLUDING A MORE
SUBSTANTIAL SEVERE WEATHER THREAT. HOWEVER...STRONG SWLY FLOW JUST
ABOVE THE SFC /30-40 KT AT 925 MB PER RUC ANALYSIS/ WILL YIELD AN
ISOLATED WIND DAMAGE THREAT WITH ANY OF THE STRONGER CONVECTIVE
CORES. ADDITIONALLY...STRONG LOW-LEVEL WIND SHEAR COULD PROMOTE WEAK
ROTATION /POSSIBLY A WATERSPOUT POTENTIAL/ WITH SOME OF THE
CONVECTION OFFSHORE...WHERE SLIGHTLY GREATER UPWARD BUOYANCY
EXISTS...AND LEWP STRUCTURES HAVE BEEN NOTED IN RECENT RADAR
IMAGERY. HOWEVER...AS THIS CONVECTION MOVES ONSHORE...IT WILL LIKELY
WEAKEN AS IT ENCOUNTERS THE LIMITED INSTABILITY.
..COHEN.. 03/18/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MTR...
LAT...LON 36082180 36532201 36772206 36972220 37082232 37322242
37472238 37692216 37432193 36922160 36482141 36032145
36082180SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 18, 9:26 AM PDT | Mesoscale Discussion | SPC | Alpine, El Dorado, Nevada, Placer, Plumas, Sierra and 1 more | 4 hr |
Nearby
Mesoscale Discussions in California, 2011Every mesoscale discussion in 2011
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.