Alert archive / California / Mesoscale Discussions in 2018
Mesoscale Discussion 166
The Storm Prediction Center issued this mesoscale discussion at Mar 22, 2018, 1:05 PM PDT for 8 counties in California. It was in force for 115 min.
The area
The outline as issued.
The facts
- Issued
- Mar 22, 2018, 1:05 PM PDT (20:05 UTC)
- Expired
- Mar 22, 2018, 3:00 PM PDT
- In force
- 115 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 5%
Counties Amador County, CA, Calaveras County, CA, Fresno County, CA, Madera County, CA, Merced County, CA, Sacramento County, CA, San Joaquin County, CA, Stanislaus County, CA
The radar
The Sacramento radar (KDAX), 120 km from the middle of the area, began a volume at 20:05 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, 8.1 hours before the alert went out and 142 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 634 m above ground
- 0-6 km bulk shear
- 64 kt
- 0-1 km storm-relative helicity
- 130 m²/s²
- 0-3 km storm-relative helicity
- 129 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
237
ACUS11 KWNS 222006
SWOMCD
SPC MCD 222005
CAZ000-222200-
Mesoscale Discussion 0166
NWS Storm Prediction Center Norman OK
0305 PM CDT Thu Mar 22 2018
Areas affected...Central CA
Concerning...Severe potential...Watch unlikely
Valid 222005Z - 222200Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated hail and perhaps a brief tornado possible for the
next few hours across portions of central CA.
DISCUSSION...Recent radar imagery has shown a subtle increase in
storm strength over the past hour. This increase is likely tied to
increased forcing for ascent from the shortwave trough currently
traversing the region. Cloud cover has also thinned across the
region, allowing for more diurnal heating and a resulting increase
in instability. Current mesoanalysis estimated MUCAPE over 500 J/kg
throughout much of the central CA valleys.
Winds throughout the Sacramento Valley have veered southwesterly,
reducing the low-level shear and overall tornado potential in that
area. However, given the strong mid/upper-level flow, 0-6 km bulk
shear remains strong (i.e. over 50 kt), and the potential for
transient storm organization still exists. Given the veered
low-level flow, the primary severe threat in this area is hail, some
of which may approach severe thresholds. An isolated tornado cannot
be completely ruled out, especially in areas of localized stronger
and/or backed surface winds. Winds are still a bit more
southeasterly across the San Joaquin Valley, which favors more
low-level shear and a relatively higher (albeit still low) tornado
threat. Overall, the isolated nature of the threat will preclude the
need for a watch.
..Mosier/Guyer.. 03/22/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...HNX...STO...
LAT...LON 37592127 38032154 38462168 38862161 39072114 38952073
38782058 38462048 38232036 37862019 37411983 37011953
36601918 36141957 36482050 37592127Nearby
Mesoscale Discussions in California, 2018Every mesoscale discussion in 2018
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.