U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 230546 
Storm Prediction Center ac 230544 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1244 am CDT Fri Mar 23 2018 

Valid 231200z - 241200z 

..there is a marginal risk of severe thunderstorms across portions 
of the central u... 

Strong thunderstorms may impact portions of the Central Plains 
vicinity this evening/overnight. A few of these could be 
accompanied by a risk for hail this evening. 

Very slow progression of the upper pattern across the U.S. Is 
expected this period, with troughs affecting the west and east 
coasts and a ridge over the center of the country. The main feature 
with respect to stronger thunderstorm activity will be a 
smaller-scale wave shifting quickly northeast across The Four 
Corners area/southern rockies and into the plains during the second 
half of the period. 

At the surface, a Lee low over Colorado early is forecast to advance 
east across Kansas as the upper wave approaches the plains, with a 
warm front extending east-southeast across the Ozarks through the 
period. Elsewhere, a cold front is forecast to cross the Great 
Basin ahead of the main western upper trough, while high pressure 
prevails over most of the eastern states through Saturday morning. 

..portions of the Central Plains/mid Missouri Valley... 
Showers and a few thunderstorms are forecast to evolve during the 
afternoon across northeast Colorado and the Nebraska Panhandle 
vicinity, with convection increasing/expanding eastward with time, 
within a zone of warm advection north of the surface low/warm front 
across Kansas. With the warm-sector boundary layer expected to 
remain capped, convection will be confined to the zone of elevated 
instability north of the baroclinic zone. 

While rather modest cape is generally expected, moderate mid-level 
westerlies will provide sufficient shear in the cloud-bearing layer 
to support a few stronger storms. With marginally severe hail 
possible, will maintain a 5% hail area straddling the 
Nebraska/Kansas border and extending into southwest Iowa/northwest 
Missouri into the overnight hours. 

.Goss/Gleason.. 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