U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 220100 
Storm Prediction Center ac 220059 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0759 PM CDT Wed Mar 21 2018 

Valid 220100z - 221200z 

..no severe thunderstorm areas forecast... 

a few thunderstorms will continue this evening across parts of 
central and northern California and the Great Basin. 

Evening raobs, convective/lightning behavior, and latest satellite 
and surface observations all confirm prior expectations for limited 
heating, and thus meager cape to persist through the afternoon and 
into the evening across the northern Central Valley of California. 

Despite the limited cape, strong low-level and deep-layer shear is 
indicated across the region. This has allowed a few 
organized/rotating low-topped storms to evolve, in a narrow band 
near and to the north of Sacramento. Radar-indicated updraft 
circulations suggest that funnel clouds -- or perhaps a very 
brief/weak tornado -- may occur over the next 1-2 hours until storms 
diurnally weaken. However, very limited potential -- both in terms 
of intensity and areal coverage -- does not appear to warrant 
introduction of a risk area. 

.Goss.. 03/22/2018 


Mesoscale Discussion

acus11 kwns 220057 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 220057 

Mesoscale discussion 0165 
National Weather Service Storm Prediction Center Norman OK 
0757 PM CDT Wed Mar 21 2018 

Areas affected...northeast New Jersey...New York City...Long 
Island...southern New England 

Concerning...heavy snow 

Valid 220057z - 220700z 

Summary...heavy snowfall will develop from northeastern New Jersey 
northeastward into southern New England this evening. Snowfall rates 
are expected to reach 1 inch per hour with locally higher rates in 
some locations. 

Discussion...the latest water vapor imagery shows an upper-level low 
centered over the mid-Atlantic region. A pronounced dry slot is 
located off shore and is wrapping around the northeastern periphery 
of the upper-level system. A deformation zone is located along the 
leading edge of the dry slot from just off the New Jersey coast 
northeastward to just near the southern coast of Long Island. This 
band is being supported by a low-level speed Max of 40 to 50 kt 
which is just offshore from southern New England and oriented 
parallel to the coast. In response, isentropic lift is maximized 
across the mesoscale discussion area and short-term model forecasts suggest that this 
environment will be maintained this evening into the early overnight 
period. Heavy snowfall with 1 inch per hour rates will be possible 
from the Newark, New Jersey and New York City areas over the next 2 
to 4 hours. This heavy snowfall will spread northeastward into 
southern New England later this evening as the upper-level system 
continues to east-northeastward drift. Snowfall rates could locally 
exceed 1 inches per hour within the heaviest part of the band. 

.Broyles.. 03/22/2018 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 41747052 41237163 40717274 40177396 40287434 40567450 
40937421 41687291 42297103 41747052