U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 231624 
Storm Prediction Center ac 231623 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1123 am CDT Fri Mar 23 2018 

Valid 231630z - 241200z 

..there is a slight risk of severe thunderstorms Kansas/NE border 

..there is a marginal risk of severe thunderstorms central Great 

Isolated large hail and strong wind gusts are expected between 6 to 
11 PM CDT along parts of the Kansas-Nebraska border. 

..KS/NE border area... 
Have upgraded to a narrow slight risk for large hail given the 
potential of a persistent supercell or two developing this evening 
in association with an eastward-moving surface cyclone. 

A surface cyclone over northeast Colorado should peak in intensity across 
northwest Kansas at 00z, in response to Lee cyclogenesis and forcing for 
ascent downstream of a low-amplitude shortwave trough approaching 
from the eastern Great Basin. This will draw a modifying Gulf air 
mass (boundary-layer dewpoints in the low-mid 50s) northward beneath 
an elevated mixed layer, resulting in a capped warm sector east of a 
sharpening dryline. However, deep mixing and forcing for ascent near 
the triple point (close to the Kansas/NE/co border region) should Foster 
high-based convection in the late afternoon. Strong deep-layer shear 
yielding elongated hodographs amid very steep mid-level lapse rates 
around 8-8.5 c/km from 700-500 mb could support a moderate-lived 
discrete supercell or two in the early to mid evening, capable of 
large hail and strong outflow winds. This activity may be maintained 
into the late evening via elevated parcels in a zone of robust 
low-level warm advection northeast of the eastward-moving surface 
cyclone. Elevated storms will weaken overnight given a cluster 
convective Mode on the periphery of weak buoyancy. 

.Grams/Mosier.. 03/23/2018 


Mesoscale Discussion

acus11 kwns 222006 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 222005 

Mesoscale discussion 0166 
National Weather Service Storm Prediction Center Norman OK 
0305 PM CDT Thu Mar 22 2018 

Areas affected...central California 

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 California. 

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 California 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... 


Latitude...Lon 37592127 38032154 38462168 38862161 39072114 38952073 
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36601918 36141957 36482050 37592127