Special Weather Statement, NWS Cheyenne, WY

Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
620 PM MDT Sun Aug 5 2018

.UPDATE...
Issued at 601 PM MDT Sun Aug 5 2018

The Severe Thunderstorm Watch has been allowed to expire at 5pm
this evening as overall storm strength has decreased over the past
hour. However, some strong storms remain ongoing across southeast
Wyoming at this time and will shift into Nebraska through 10-11pm
this evening. Pea to isolated quarter hail and wind gusts of 40 to
60 mph will remain possible through the mid to late evening hours.

Atmosphere is becoming more worked over from previous convection
and overall instability is decreasing. None-the-less, more than
supportive wind shear and divergence aloft will aid sustained
updrafts far east WY and into the NE Panhandle. Storm coverage and
strength will diminish fully by late this evening and as storms
exit east into central Nebraska.

&&

.SHORT TERM...(This evening through Monday)
Issued at 257 PM MDT Sun Aug 5 2018

Another active afternoon into the early evening today with
scattered showers and isolated stronger thunderstorms moving
southeastward across the southern half of the forecast area. We
will continue with Severe Thunderstorm Watch number 329 as posted
with the potential of more additional strong to severe storms
developing west of I-25 moving eastward through late afternoon.
This activity continues to generate ahead of a shortwave moving
east out of northern Utah this afternoon, with a general downward
trend on thunderstorm strength expected in the early evening as
the midlevel dynamics start to pull east and we start losing
instability along and just north of the Colorado border. We keep
chance PoPs going for the northern zones into the Nebraska
Panhandle into the early evening, with small PoPs overnight.

Not much in the way of forcing for tomorrow for strong storms.
The weak quasi-stationary boundary stretched roughly along the
Wyoming/Colorado border late today will surge southeastward along
the foothills tonight as the shortwave pulls east of our area.
Most of any synoptic scale forcing for organized severe storms
will be to our east and southeast by tomorrow...although we do
expect to see a few afternoon showers and thunderstorms develop
over the higher terrain west of I-25 by early afternoon spreading
east onto the high plains in the afternoon hours.

.LONG TERM...(Monday night through Sunday)
Issued at 257 PM MDT Sun Aug 5 2018

We are still looking at a gradually warmer and drier period of
weather mid to late week as upper-level ridging builds across the
western CONUS keeping the main track of mid/upper energy to our
north. As midnight shift stated, an occasional disturbance passing
over the northeast side of the ridge could yield a short term
convective risk from time to time, but we still do not expect to
see any organized precipitation chances through the extended
forecast period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 601 PM MDT Sun Aug 5 2018

Ongoing TSRA near KCYS and points east towards KBFF/KAIA/KSNY
where local pockets of MVFR and IFR visibilities are likely with
the stronger storm activity. Highest storm tops are to near FL350
and could cause enhanced turbulence throughout the atmospheric
column. TSRA will be near KSNY near 01-02Z with -TSRA near KBFF
and KAIA next few hours as well. All areas will be clear of the
TSRA activity by 04Z with VFR conditions expected through the
morning hours. Another, but more limited round of TSRA is likely
Monday in the late afternoon near KCYS and points east into the NE
Panhandle.

&&

.FIRE WEATHER...
Issued at 257 PM MDT Sun Aug 5 2018

Scattered showers and a few thunderstorms will persist into the
evening hours before diminishing. Fire weather concerns are
minimal through mid week. Warmer and drier weather returns Tuesday
onward. Relative humidity values will drop to around 15 percent
across western Carbon county Monday through Wednesday, but winds
will remain generally light.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

UPDATE...JSA
SHORT TERM...JG
LONG TERM...JG
AVIATION...JSA
FIRE WEATHER...JG

Hazardous Weather Outlook
National Weather Service Cheyenne WY
738 AM MDT Sun Aug 5 2018

WYZ101>119-061345-
Converse County Lower Elevations-Niobrara County-
North Laramie Range-Ferris/Seminoe/Shirley Mountains-
Shirley Basin-Central Laramie Range and Southwest Platte County-
East Platte County-Goshen County-Central Carbon County-
North Snowy Range Foothills-Southwest Carbon County-
Sierra Madre Range-Upper North Platte River Basin-Snowy Range-
Laramie Valley-South Laramie Range-South Laramie Range Foothills-
Central Laramie County-East Laramie County-
738 AM MDT Sun Aug 5 2018

This hazardous weather outlook is for southeast Wyoming.

.DAY ONE...TODAY AND TONIGHT

Showers and thunderstorms are expected through the day today, with
thunderstorms possibly becoming strong to severe in the afternoon.
Large hail and damaging winds are possible with any thunderstorms
this afternoon and this evening.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

There is a slight chance of thunderstorms early in the week across
far southern Wyoming along the Interstate 80 corridor. Otherwise,
drier weather is expected for the rest of the week.

.Spotter information statement...

Spotter activation will not be required at this time.

NEZ002-003-019>021-054-055-095-096-061345-
Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne-
North Sioux-South Sioux-
738 AM MDT Sun Aug 5 2018

This hazardous weather outlook is for portions of western
Nebraska.

.DAY ONE...TODAY AND TONIGHT

Showers and thunderstorms are expected through the day today, with
thunderstorms possibly becoming strong to severe late in the
afternoon. Large hail and damaging winds are possible with any
thunderstorms through this evening.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

The probability for widespread hazardous weather is low.

.Spotter information statement...

Spotter activation will not be required at this time.

Special Weather Statement
National Weather Service Cheyenne WY
601 PM MDT SUN AUG 5 2018

WYZ101-102-060030-
Converse County Lower Elevations WY-Niobrara County WY-
601 PM MDT SUN AUG 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN NIOBRARA AND
SOUTHEASTERN CONVERSE COUNTIES UNTIL 630 PM MDT...

At 601 PM MDT, Doppler radar was tracking a strong thunderstorm near
Keeline, or 20 miles west of Lusk, moving northeast at 40 mph.

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

Locations impacted include...
Manville, Keeline, Lance Creek and Lost Springs.

LAT...LON 4264 10487 4278 10501 4304 10456 4282 10447
TIME...MOT...LOC 0001Z 233DEG 33KT 4276 10486

Braun

Special Weather Statement
National Weather Service Cheyenne WY
605 PM MDT SUN AUG 5 2018

NEZ020-060030-
Banner NE-
605 PM MDT SUN AUG 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL BANNER COUNTY UNTIL 630
PM MDT...

At 605 PM MDT, Doppler radar was tracking a strong thunderstorm near
Harrisburg, or 22 miles northwest of Kimball, moving east at 45 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Harrisburg.

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 4143 10397 4161 10397 4165 10338 4141 10337
TIME...MOT...LOC 0005Z 268DEG 41KT 4153 10385

Braun

Special Weather Statement
National Weather Service Cheyenne WY
615 PM MDT SUN AUG 5 2018

NEZ054-WYZ118-119-060100-
Kimball NE-Central Laramie County WY-East Laramie County WY-
615 PM MDT SUN AUG 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR KIMBALL AND SOUTHEASTERN LARAMIE
COUNTIES UNTIL 700 PM MDT...

At 614 PM MDT, emergency management reported strong thunderstorms
along a line extending from Albin to 6 miles southwest of Hillsdale.
Movement was southeast at 50 mph.

Dime size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Cheyenne, Kimball, Pine Bluffs, Burns, Dix, Albin, Oliver Campground,
Hillsdale, Panorama Point, Oliver Reservoir, Kimball Airport,
Carpenter and Bushnell.

This includes the following highways...
 Interstate 80 in Wyoming between mile markers 368 and 402.
 Interstate 80 in Nebraska between mile markers 1 and 34.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4115 10473 4148 10410 4138 10406 4123 10338
      4100 10382 4100 10446
TIME...MOT...LOC 0014Z 298DEG 45KT 4141 10412 4117 10459

Braun

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
626 PM MDT SUN AUG 5 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0530 PM     HAIL             6 WSW LORENZO           41.00N 103.15W
08/05/2018  M1.25 INCH       CHEYENNE           NE   STORM CHASER

            A LOT OF HAIL FELL FAST, WITH THE LARGEST STONES MEASURED
            AT 1.25 INCHES.

&&

ABRAUN

Special Weather Statement
National Weather Service Cheyenne WY
635 PM MDT SUN AUG 5 2018

WYZ102-060115-
Niobrara County WY-
635 PM MDT SUN AUG 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL NIOBRARA COUNTY UNTIL 715
PM MDT...

At 634 PM MDT, Doppler radar was tracking a strong thunderstorm near
Lance Creek, or 15 miles northwest of Lusk, moving northeast at 45
mph.

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

Locations impacted include...
Mule Creek Junction, Redbird and Lance Creek.

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 4336 10405 4316 10405 4279 10461 4289 10485
      4348 10424
TIME...MOT...LOC 0034Z 217DEG 40KT 4297 10457

Braun

Special Weather Statement
National Weather Service Cheyenne WY
733 PM MDT SUN AUG 5 2018

NEZ002-060215-
Dawes NE-
733 PM MDT SUN AUG 5 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN DAWES COUNTY UNTIL
815 PM MDT...

At 732 PM MDT, Doppler radar was tracking a strong thunderstorm near
Slim Butte, or 11 miles west of Pine Ridge, moving northeast at 30
mph.

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

This storm will remain over mainly rural areas of northeastern Dawes
County.

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 4300 10294 4300 10279 4294 10279 4294 10280
TIME...MOT...LOC 0132Z 211DEG 27KT 4302 10279

Braun