Special Weather Statement, NWS North Platte, NE

Area Forecast Discussion
National Weather Service North Platte NE
722 PM CDT Mon Aug 23 2021

.SHORT TERM...(This evening through Tuesday night)
Issued at 207 PM CDT Mon Aug 23 2021

The main focus of the short term is the storm chances tonight.

A low pressure system has troughing that extends British Columbia SE
into Kansas. Along with a sfc boundary and aid from the ever present
LLJ, this will be the trigger for storms tonight. Ample moisture
remains in the region, evident by dwpts in the 60s/70s, and above
avg PWATs of 1.25". The worry however, is that lifting will not be
strong enough to break the capping in place. If the cap can be
broken, storms will have plenty of MLCAPE to tap into (~2000J/kg or
more), thanks to daytime heating steepening the lapse rates, and
about 40 kts of bulk shear. Expecting the main focus area to reside
in the eastern Panhandle to north central Nebraska, where isolated
strong to severe storms are most likely. SPC suggests the main
hazards will be large hail (up to 2") and damaging winds.

Eventually, the system will move east a bit, and leave tomorrow in
WNW flow at the sfc. This will usher in a bit cooler air (with
modest CAA at 850) and limit highs from getting beyond the 90s. The
flow will also help usher in a bit drier air with dwpts ranging from
the 40s in the Panhandle to 60 in central Nebraska.

.LONG TERM...(Wednesday through Monday)
Issued at 207 PM CDT Mon Aug 23 2021

As the trend has proven, long term upper levels look to be covered
by a ridge oriented SW to NE...centered generally over Oklahoma at
500mb. A UL jet will reside just north of this feature over the
ND/Canada border. At lower levels, a LLJ over Nebraska looks to
strengthen Wednesday and into Thursday, and shift a bit east into
Friday, but remain over central to eastern Nebraska. This feature
looks to remain throughout the forecast. At the sfc, the low looks
to have moved far enough SE to reside over western KS.

This low pressure system will be the focus for precip and storm
chances Wednesday evening. It looks as though lapse rates will
steepen into the afternoon, but as with the short term, will need to
deduce in with newer model forecasts if instability will be enough
to overcome the capping. As such, have left the inherited CHC PoPs
in the forecast ATTM.

Beyond Wed, at upper levels, a closed low over British Columbia will
push the upper level jet off to the NE, and ridging more into ESE
CONUS. The corresponding sfc closed low will move SE over Nebraska
TH and into Fri. This system will be the focus for more precip/storm
chances given the aid from the stagnant LLJ.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 715 PM CDT Mon Aug 23 2021

Skies should remain VFR through the TAF period. There is an
outside chance for an ISOL TSTM or two but chances are slim and
will not be included in the VTN and LBF terminal forecast. Winds
will be light, generally less than 10 kts. A weak cold front will
switch winds to the north to northwest on Tuesday, and some gusts
could approach 20 kts Tuesday afternoon across north central
Nebraska.

&&

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

SHORT TERM...Sinclair
LONG TERM...Sinclair
AVIATION...Taylor

Hazardous Weather Outlook
National Weather Service North Platte NE
310 PM CDT Mon Aug 23 2021

NEZ004>010-022>029-035>038-056>059-069>071-094-242015-
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-
310 PM CDT Mon Aug 23 2021 /210 PM MDT Mon Aug 23 2021/

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

.DAY ONE...TONIGHT.

Isolated thunderstorms are possible this evening, generally
affecting areas along and north of highway 20 across northern
Nebraska. An isolated severe storm may form and the primary severe
weather hazard is very large hail, 2 inches in diameter or
greater. Wind damage is a secondary concern.

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

Chances for showers and thunderstorms will increase for the
middle of the week with a marginal threat for severe storms
generally north of Interstate 80 again on Wednesday into Thursday.
Additional thunderstorms are possible heading into the weekend
but the severe weather threats uncertain at this time.

.SPOTTER INFORMATION STATEMENT...

Please relay any information about observed severe weather to the
NWS.

&&

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

Special Weather Statement
National Weather Service North Platte NE
755 PM MDT Mon Aug 23 2021

NEZ004-240245-
Sheridan NE-
755 PM MDT Mon Aug 23 2021

...A strong thunderstorm will impact portions of southeastern
Sheridan County through 845 PM MDT...

At 755 PM MDT, Doppler radar was tracking a strong thunderstorm near
Antioch, or 18 miles east of Alliance, moving northeast at 30 mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Ellsworth, Antioch, Snow Lake, Watson Lake, Lakeside, Wolf Hill,
Kennedy Lake and Argo Hill.

This includes the following highways...
 Highway 250 between mile markers 1 and 18.
 Highway 2 between mile markers 99 and 122.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4246 10227 4228 10205 4210 10206 4208 10207
      4202 10228 4201 10261 4205 10268
TIME...MOT...LOC 0155Z 221DEG 27KT 4206 10252

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Taylor