Special Weather Statement, NWS North Platte, NE

Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
630 PM CDT Mon May 7 2018

.SYNOPSIS...
Issued at 314 PM CDT Mon May 7 2018

H5 analysis from this morning had a broad trough of low
pressure across the eastern CONUS. This feature extended from Lake
Ontario, south to the Florida Panhandle. West of this feature, a low
amplitude ridge of high pressure was located from the Nebraska
Panhandle north into the western Dakotas. Upstream of this feature,
a tandem of shortwaves were noted across the western CONUS. The
first shortwave was noted over the Idaho Panhandle. A second
shortwave was located over central California. WV imagery as of
midday had the Idaho shortwave now over swrn Montana, with a second
downstream shortwave noted over central Montana. At the surface: A
trough of low pressure extended south from the Big Horn mountains
south southeast into eastern Colorado. High pressure was present
over eastern Nebraska. Between these two features, across western
and north central Nebraska, southerly winds have increased today and
were gusting up to 40 MPH as of 3 PM CDT. Temperatures as of mid
afternoon ranged from mid to upper 80s.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 314 PM CDT Mon May 7 2018

Tonight and Tuesday...Over the next 24 hours,
precipitation and thunderstorm chances are the main forecast
concern. The shortwave trough aloft will approach eastern Montana
and nern Wyoming around 21z Monday. Mid level warm air advection
will increase downstream of this approaching shortwave. Showers and
thunderstorms will initiate over the higher terrain of northeast
Wyoming and the Black hills then track to the east southeast this
evening. Further south across the northern Nebraska panhandle, the
atmospheric cap appears strong through 00z per fcst soundings. This
CAP finally weakens around 00z Tuesday across the far nw forecast
area. This area of favorable mid level waa, tracks due east across
north central Nebraska overnight. With this in mind, will generally
confine pops to the northern half of the forecast area tonight. As
for the threat for severe storms: Deep layer shear is on the order
of 30-35 KTS tonight in northern Nebraska is favorable for severe
storms. Moisture is lacking today across the forecast area, and this
should limit the coverage of thunderstorms and confine the severe
threat to the early evening hours, mainly over the northwestern CWA
where CAPE is highest through mid evening. Forecast soundings
indicate an inverted V sounding favoring gusty winds as the main
severe threat, however some marginally severe hail is possible given
the steep lapse rates in the elevated moist layer. Lows tonight will
be fairly mild with readings in the lower to middle 50s. On Tuesday,
upper level low pressure will deepen slightly over northwestern
South Dakota. As this feature tracks east along the SD/ND border, it
will drag a trough through the western forecast area Tuesday
morning. This trough axis will be oriented from Valentine to North
Platte by mid afternoon. The main threat for showers and
thunderstorms will be across northern and eastern portions of the
forecast area Tuesday. These locations are in closest proximity to
the upper level low (northern Nebraska) and best low level moisture
(eastern portions of the forecast area). Highs Tuesday will range
from the upper 70s in the north to lower 80s in the south.

.LONG TERM...(Tuesday night through Monday)
Issued at 314 PM CDT Mon May 7 2018

Tuesday night through Thursday...The upper level low
will track from far northeastern South Dakota into central Minnesota
Tuesday night. Showers and thunderstorms will linger in the
northeastern forecast area Tuesday evening before transitioning east
overnight. Wednesday will be dry and seasonal across the forecast
area thanks to subsidence west of the exiting upper level trough and
drier air, with dew points in the 40s. Highs Wednesday will be
around the 80 degree mark. H5 ridging will build into the central
Rockies Wednesday night. This will increase mid level warm air
advection downstream of the ridge. This area of mid level warm air
advection will traverse the forecast area from southwest to
northeast Wednesday night. Pops were introduced late Wednesday night
into Thursday thanks to decent agreement between the NAM12 and GFS
solns. Surface high pressure will build into the northern plains on
Thursday with a frontal boundary stalling out INVOF the SD/NE
border. Low level moisture will increase across Nebraska Thursday
thanks to increasing southerly winds south of the frontal boundary.
Highs will range from the middle 70s along the SD/NE border, to the
upper 80s in SW Nebraska.

Thursday night through Monday...Low pressure will develop across the
Nebraska Panhandle, dragging a cold front through the forecast area
late Thursday night into Friday. Showers and thunderstorms will
accompany passage of the front. The front will be forced south into
Kansas on Saturday, stalling south of the forecast area into Sunday.
Much cooler temperatures are expected for the weekend with highs in
the 50s Saturday and 60s for Sunday. Temps will then rebound back
into the 70s for Monday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 630 PM CDT Mon May 7 2018

VFR is generally expected overnight through Tuesday afternoon.

Isolated thunderstorms are possible in the Nebraska Panhandle
this evening. Storm motion will be east and southeast.

Significant storm coverage is developing along and north of
highway 20 and this should move east along this route overnight
and exit ncntl Nebraska around 09z-11z. There is a chance, less
than 15 percent, that storms could develop as far south as
Nebraska highway 2.

Additional scattered thunderstorms are expected to develop along
highway 20 Tuesday afternoon from 18Z onward.

&&

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

SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC

Hazardous Weather Outlook
National Weather Service North Platte NE
317 PM CDT Mon May 7 2018

NEZ004>010-022>029-035>038-056>059-069>071-094-082030-
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-
317 PM CDT Mon May 7 2018 /217 PM MDT Mon May 7 2018/

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

.DAY ONE...TONIGHT.

Isolated thunderstorms will lift east across into northwestern
Nebraska during the early evening hours. A strong to severe storm
is possible across northwestern Nebraska with the greatest threat
over Sheridan and western Cherry county. Gusty winds will be the
main threat, however hail up to quarter size is possible as well
through mid evening. Activity is expected to traverse east across
north central Nebraska overnight with the threat for severe storms
ending after mid evening.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

Thunderstorms are possible again on Tuesday over northern
Nebraska. A strong to severe storm is possible east of a line
from Naper to Ericson.

Thunderstorms are possible on Thursday across western and north
central Nebraska. Strong storms are possible with the greatest
threat over southwestern and western Nebraska.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight.

&&

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

CLB

Special Weather Statement
National Weather Service North Platte NE
502 PM MDT MON MAY 7 2018

NEZ004-072345-
Sheridan NE-
502 PM MDT MON MAY 7 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN SHERIDAN COUNTY
UNTIL 545 PM MDT...

At 502 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from near White Clay to 7 miles northwest of Hay
Springs. Movement was northeast at 25 mph.

Wind gusts up to 50 mph will be possible with these storms.

Locations impacted include...
White Clay, Pine Ridge, Intersection of Highway 87 and Craven Creek
Road, Metcalf State Wildlife Management Area, Intersection of Beaver
Creek Road and White Clay Creek Road, Intersection of Highway 87 and
Larabee Road and Mount Maria.

This includes Highway 20 near mile marker 74.

LAT...LON 4300 10214 4280 10236 4272 10277 4277 10278
      4278 10277 4279 10279 4288 10280 4300 10276
TIME...MOT...LOC 2302Z 247DEG 29KT 4292 10253 4278 10276

CDC

Special Weather Statement
National Weather Service North Platte NE
619 PM MDT MON MAY 7 2018

NEZ004-080100-
Sheridan NE-
619 PM MDT MON MAY 7 2018

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL SHERIDAN COUNTY UNTIL 700
PM MDT...

At 619 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Hay Springs to near Hemingford. Movement
was east at 25 mph.

Wind gusts up to 50 mph will be possible with these storms.

Locations impacted include...
Rushville, Lone Butte, Highway 27 crossing the Niobrara River, Smith
Lake State Wildlife Management Area, Highway 250 crossing the
Niobrara River, Intersection of Highway 87 and Antelope Road, Walgren
Lake State Recreation Area and Intersection of Highway 27 and Mills
Road.

This includes Highway 250 between mile markers 26 and 48.

LAT...LON 4278 10209 4270 10207 4226 10262 4225 10274
      4266 10277
TIME...MOT...LOC 0019Z 259DEG 32KT 4264 10263 4236 10302

CDC