SPC Forecast Products

SPC - No watches are valid as of Tue May 17 13:59:02 UTC 2022

No watches are valid as of Tue May 17 13:59:02 UTC 2022.

SPC MD 799

MD 0799 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL/EASTERN NE...FAR WEST-CENTRAL IA

Mesoscale Discussion 0799
NWS Storm Prediction Center Norman OK
0856 AM CDT Tue May 17 2022

Areas affected...Central/Eastern NE...Far West-Central IA

Concerning...Severe potential...Watch unlikely 

Valid 171356Z - 171600Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated hail possible across central and eastern NE this
morning.

DISCUSSION...A robust elevated thunderstorm continues over northeast
NE, although some modest updraft weakening has been noted recently.
This thunderstorm developed on the far eastern edge of the steep
lapse rate plume and at the nose of the modest low-level jet. Some
limited ascent may have also been provided by a weak shortwave
trough moving into the central Plains. Some additional thunderstorms
have initiated farther west across central NE, although these
updrafts are not as intense as the northeast NE storms yet. Deep
cumulus exists all the way into far southwest NE.

Low-level stability remains in place within the downstream air mass,
although diurnal heating will weaken convective inhibition with
time. Even so, current observational trends and mid-level moistening
noted within forecast soundings suggest these area of storms could
persist. Severe coverage is currently expected to remain isolated,
limiting the need for a watch in short-term, but observational
trends will be monitored closely.

..Mosier/Grams.. 05/17/2022

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...DMX...FSD...OAX...GID...LBF...

LAT...LON   41870071 42379796 42519691 42469613 42169554 41879538
            41439544 41189590 40719660 40379728 40159836 40350003
            41870071 

SPC May 17, 2022 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook
      
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0739 AM CDT Tue May 17 2022

Valid 171300Z - 181200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING
INTO TONIGHT FROM EASTERN NE TO NORTHEAST KS...SOUTHWEST IA...AND
NORTHWEST MO...

...SUMMARY...
Scattered very large hail in excess of 2 inches in diameter,
damaging thunderstorm winds to 70 mph, and a couple of tornadoes
will be possible this evening into tonight from eastern Nebraska
into northeast Kansas, southwest Iowa, and northwest Missouri.

...NE/KS/MO late this afternoon into tonight...
A complex, largely zonal flow regime with subtle embedded speed
maxima will affect the central CONUS through tonight.  A weak
southern stream trough will drift eastward over NM/southern CO,
while a downstream MCVs from overnight convection move eastward from
OK/KS to MO/AR today.  The primary feature of interest this period
is a subtle trough over WY/MT early this morning that will crest the
flat ridge over the High Plains and progress east-southeastward to
the middle MO Valley this evening into tonight.  Associated lee
cyclogenesis is expected today near the CO/KS border, and the
remnant lee cyclone will develop south-southeastward toward the TX
Panhandle tonight as a cold front moves southeastward across
CO/NE/KS.

Some temporary disruptions to the low-level moisture field have
occurred overnight across OK in the wake of weakening convection and
the MCVs with heat bursts, but this drying should wane as storms
dissipate.  Thereafter, a corridor of mid 60s boundary-layer
dewpoints will establish across eastern KS into southeast NE by this
evening.  When the cold front intercepts the richer moisture and
larger buoyancy by late evening from northeastern NE into northern
KS, thunderstorm development is expected.  Storms will subsequently
spread southeastward overnight into the corridor of richer moisture
and MLCAPE of 2000-3000 J/kg, aided by warm advection on the nose of
a 30-40 kt low-level jet.  The large buoyancy and steep midlevel
lapse rates/large DCAPE will favor precipitation-loaded downdrafts
capable of producing wind damage.  Profiles will also potentially
favor very large hail, though this threat depends largely on
maintaining supercell structures within the larger area of
convection.  Any tornado threat will likely depend on at least mid
60s dewpoints making it into NE, and on maintaining semi-discrete
supercells into late evening, or with line-embedded mesovortices.  

...Southeast WY to the southeast TX Panhandle this evening...
A few high-based thunderstorms will be possible this
afternoon/evening in association with surface heating/deep mixing
and the influences of a shortwave trough crossing WY, and a southern
stream trough moving eastward from NM/CO.  Any storms/clusters that
form in this corridor will be capable of producing isolated severe
outflow gusts for a few hours late this afternoon/evening, given
inverted-V profiles.

..Thompson/Leitman.. 05/17/2022


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