SPC Forecast Products

Storm Prediction Center

03/21/2018 07:03 PM
SPC - No watches are valid as of Thu Mar 22 01:04:01 UTC 2018
No watches are valid as of Thu Mar 22 01:04:01 UTC 2018.

03/21/2018 07:03 PM
SPC Mar 22, 2018 0100 UTC Day 1 Convective Outlook
SPC 0100Z Day 1 Outlook
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0759 PM CDT Wed Mar 21 2018

Valid 220100Z - 221200Z


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

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03/21/2018 06:58 PM
SPC MD 165
MD 0165 Image

Mesoscale Discussion 0165
NWS 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 MCD 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...


LAT...LON   41747052 41237163 40717274 40177396 40287434 40567450
            40937421 41687291 42297103 41747052 

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