Special Weather Statement, NWS North Platte, NE

Area Forecast Discussion
National Weather Service North Platte NE
1127 PM CDT Thu Jun 17 2021

.SHORT TERM...(This evening through Friday night)
Issued at 342 PM CDT Thu Jun 17 2021

Isolated showers developed this morning at the cusp of the best mid
level instability which is paired with weak mid level WAA. The AC
associated with the showers has only weak vertical extent in most
cases, however there have been a couple CGs associated with this
area of convection. This all occurring on the edge of the upper
ridge centered over the Great Basin area into the central Rockies.
This area of convection is expected to continue moving further
east this afternoon. The main hazard today lies with Heat Adv area
as mainly sunny skies will lead to heat indices above 100 through
early evening. Weak stationary front lies from southwest through
northeast NE with highest apparent temps south of the front.
Convergence along the front is currently weak as mid level forcing
to promote LL adjustment is also weak.

Attention turns to potential for thunderstorm development this
evening and overnight. AC moving into the Panhandle now suggests
another subtle mid level short wave may be embedded in the flow.
However with morning 700mb temps at a record for this date here at
LBF, and very dry layer from 850-600mb or so coupled with weak deep
layer shear, convective initiation will be tough. Would likely have
to result from terrain forcing further west and move into the area.
A few of the morning deterministic model runs do show this
potential, as do a few CAMs which develop convection near the
WY/CO line and expand into northeast CO by evening helped somewhat
by upslope flow north of the boundary. The sustainability of this
convection into southwest NE is highly in question due to the
above mentioned hindrances, and with RH in the LCL-LFC layer
being 20% or so it would have to be a healthy updraft in the weak
shear to overcome the nearly certain dry air entrainment that any
storm would encounter. Still with slightly better shear this
evening associated with weak height falls and increasing mid level
flow, cannot totally rule out a similar scenario to Wednesday
night in southwest NE this evening so have some slight chcs there.
Anything that would survive should have decent downdraft
potential so some gusty winds would be possible. Further north,
after midnight a decent PV anomaly will drop southeast across the
northern Plains. Thermal advection ahead of this feature paired
with some cooling further north will develop weak mid level FGEN
forcing in north central NE which will likely coincide with good
mid level instability. This should be enough forcing to generate
at least elevated convection overnight, though likely isolated to
widely scattered coverage and low QPF. As a result some POPs
included here mainly after midnight.

Friday will be cooler in the post-frontal environment and may be
hampered slightly by mid level cloud cover in the north associated
with any lingering showers there. Afternoon temps will remain above
average for this time of year but only slightly as the
aforementioned PV anomaly swings through the northern Plains and
pushes the thermal boundary southward into KS. Broad scale
subsidence will overspread the area from late morning on
suggesting a mainly sunny and dry day in store.

.LONG TERM...(Saturday through Thursday)
Issued at 342 PM CDT Thu Jun 17 2021

The upper pattern begins a transition to a northwesterly flow as a
series of short waves carve out a very anomalous upper trough,
eventually residing across the upper Midwest and Great Lakes by the
start of the workweek.

As heights gradually fall through Saturday and zonal flow develops
over the northern High Plains, the low level response will be to
increase southerly flow and resultant moisture back northward as the
next short wave approaches. This should allow a favorable return of
instability to some extent and a better chance for thunderstorm
activity. The more significant PV anomaly and associated frontal
passage looks to come through Sunday, though timing varies among
deterministic models as expected, as well as ensemble systems.
Further, ensemble systems also clustering toward a drier solution
with the passage of the front, however deterministic runs from the
EC/Canadian do suggest post-frontal QPF. The forecast will include
precip chances which seems reasonable given the anomalous nature
of the upper trough.

Beyond Monday, a mainly dry forecast is in store as a transitory
ridge builds into the area by mid week. Temperatures will be
significantly cooler and well below average Monday before moderating
Tuesday and Wednesday back to near or slightly above average for
this time of year.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1126 PM CDT Thu Jun 17 2021

Mostly quiet aviation conditions are expected through Friday. A few
isolated thunderstorms are moving across southwest Nebraska, but are
expected to weaken as they move eastward and shouldn't impact either
terminal. Otherwise, VFR conditions prevail.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

SHORT TERM...Stoppkotte
LONG TERM...Stoppkotte
AVIATION...Kulik

Hazardous Weather Outlook
National Weather Service North Platte NE
833 PM CDT Thu Jun 17 2021

NEZ004>010-022>029-035>038-056>059-069>071-094-190145-
Sheridan-Eastern Cherry-Keya Paha-Boyd-Brown-Rock-Holt-Garden-
Grant-Hooker-Thomas-Blaine-Loup-Garfield-Wheeler-Arthur-McPherson-
Logan-Custer-Deuel-Keith-Perkins-Lincoln-Chase-Hayes-Frontier-
Western Cherry-
833 PM CDT Thu Jun 17 2021 /733 PM MDT Thu Jun 17 2021/

This Hazardous Weather Outlook is for portions of western and
north central Nebraska.

.DAY ONE...TONIGHT.

Isolated thunderstorms remain possible this evening across
southwest Nebraska, with thunderstorms also possible overnight
across north central Nebraska. The potential for severe storms is
low.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

There are additional thunderstorm chances Saturday through Sunday
night. At this time, the threat for severe storms remains
uncertain.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed through tonight.

&&

Get your weather, hydrological, and climate information at
http://www.weather.gov/northplatte

Special Weather Statement
National Weather Service North Platte NE
100 AM CDT Fri Jun 18 2021

NEZ059-180645-
Lincoln NE-
100 AM CDT Fri Jun 18 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN LINCOLN COUNTY UNTIL
145 AM CDT...

At 1259 AM CDT, Doppler radar was tracking a strong thunderstorm over
Wallace, or 23 miles north of Hayes Center, moving east at 20 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Wallace, Wellfleet, Dickens and Somerset.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4074 10123 4092 10124 4098 10071 4071 10069
TIME...MOT...LOC 0559Z 269DEG 17KT 4084 10114

Buttler