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000
acus01 kwns 241957
swody1
Storm Prediction Center ac 241955
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
0255 PM CDT Thu may 24 2018
Valid 242000z - 251200z
..there is a slight risk of severe thunderstorms across parts of
the Great Plains and upper Mississippi Valley...
...
Isolated to scattered strong to severe thunderstorms are expected
across the Great Plains and upper Mississippi Valley this afternoon
and evening.
...
Several changes have been made to the outlook for this issuance. The
first change is to extend the slight risk westward into eastern
Colorado where thunderstorms are currently developing. This
convection is expected to have a severe threat as it moves eastward
into increasing instability later this afternoon. The second change
to the outlook is to expand the slight risk area westward across
parts of northern Nebraska and east-central South Dakota. A maximum
of instability is analyzed by the rap to the southeast of Pierre, South Dakota
where a severe threat would be possible if storms can develop. The
third change to the outlook is to adjust the thunder line further
north across the mid Mississippi Valley where convection is ongoing
in northeast Arkansas.
.Broyles.. 05/24/2018
Previous discussion... /issued 1142 am CDT Thu may 24 2018/
Models are rather inconsistent today regarding location/timing and
intensity of convection later today. This leads to a relatively
low-confidence outlook. Nevertheless, a few changes have been made
to the marginal/slight areas based on 12z cam consensus.
..ND/SD/MN this afternoon/evening...
Water vapor loop shows a strong upper trough rotating northward
across Montana/ND into Manitoba. Most of the lift associated with this
system will move into Canada by this afternoon, but some potential
for organized severe storms will be present across parts of
northern/northeastern ND and eastern South Dakota. Those storms that form
along a weak surface boundary/dryline will be in an environment of
at least moderate cape and sufficient vertical shear for
Bow/supercell structures. Large hail and damaging winds will be
possible in the strongest cells. This activity should spread
eastward across Minnesota through the evening.
...
Strong heating will yield steep lapse rates and minimal cap this
afternoon over parts of central NE into central Kansas. Forecast
soundings suggest a very unstable air mass is also likely, with
sufficient mid/upper level flow for some convective organization.
The main forecast uncertainty is the extent of convective
development. About half of the morning cam solutions suggest storms
will form over north-central NE. If this occurs, damaging winds and
hail would be possible. A more consistent convective signal is
apparent over far eastern Colorado into western KS, where parameters
appear favorable for damaging wind gusts.
..West Texas/southeast nm...
Once again today, a few thunderstorms are expected to form in the
hot/unstable air mass in place across southeast nm and West Texas.
Shear profiles are a little weaker than yesterday and upper forcing
is minimal. Nevertheless, a few storms could produce hail and gusty
winds.
...
A large upper trough is digging into CA, with height falls expected
to commence along the Sierra later today. A cluster of
thunderstorms is forecast to develop over northwest NV, spreading
northward into southern or tonight. Forecast soundings show
inverted-v profiles and sufficient steering flow for some risk of
gusty/damaging wind.
..MN/northern WI/western Upper Michigan...
A decaying cluster of thunderstorms over northern WI will leave a
remnant outflow boundary, possibly focusing redevelopment of storms
later today. If so, the strongest cells could produce hail and
gusty winds.
$$
Mesoscale Discussion
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acus11 kwns 242048
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 242047
nvz000-caz000-242245-
Mesoscale discussion 0512
National Weather Service Storm Prediction Center Norman OK
0347 PM CDT Thu may 24 2018
Areas affected...western Nevada and vicinity
Concerning...severe potential...watch unlikely
Valid 242047z - 242245z
Probability of watch issuance...20 percent
Summary...a threat for damaging wind gusts exists this afternoon
into the evening. A ww is not anticipated at this time.
Discussion...visible satellite imagery has indicated towering
cumulus developing along the Sierra. Krgz has steadily shown an
increase in reflectivity values over the past half hour. Given these
trends and the approach of a mid-level trough, more wide-spread
initiation is likely in the next hour or so. A modified rev 18z
sounding shows modest SBCAPE values approaching 1000 j/kg. A
relatively dry sub-cloud layer indicates that a risk of severe wind
gusts will be the main threat with any storms. Shear will be
sufficient for storm organization -- currently at 20-30 kts per rap
analysis -- and should improve with the approach of the mid-level
wave. Given the expected limited storm coverage and modest buoyancy,
a ww is not expected at this time.
.Wendt/Hart.. 05/24/2018
..please see www.Spc.NOAA.Gov for graphic product...
Attention...WFO...lkn...rev...
Latitude...Lon 41091994 41161948 41151898 40921853 40551832 39991835
39451840 39361848 38721866 38391899 38331936 38701974
39142010 39832013 41091994
