Severe Thunderstorm Warning 108, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
324 PM MDT Tue Aug 15 2017

.SHORT TERM...(This evening through Thursday)
Issued at 250 PM MDT Tue Aug 15 2017

Shortwave trough currently across southeast Utah is fcsted to swing
northeastward through the evening.  Large scale ascent and
associated cooling/destabilization aloft is causing scattered to
numerous showers and storms to develop across southeast WY.  With
good bulk shear (30-40 kts) and CAPE of 500-1000 J/kg, a few of the
storms could be stronger with small hail across southeast WY.  Still
think that the best chance of more severe storms will be over the
southern Nebraska Panhandle in areas along I-80.  This is where
instability is greatest (SBCAPE of 2000-2500 J/kg) and any discrete
storm would have the potential of producing large hail.  The HRRR
has been consistent at showing widespread rain with embedded tstms
across areas much of the plains through the evening so have PoPs of
50-60 through 06Z.  The strong/severe storm threat will mostly
diminish by mid evening as the activity becomes more less discrete
and more multicell.

Precip chances will diminish after 06Z as the best large scale
ascent ahead of the shortwave moves eastward into central Nebraska.
Overnight fropa will usher in cooler temps for Wednesday with highs
dropping into the 70s over lower elevations.  The cool and stable
post frontal airmass will keep storm chances minimal over much of
the CWA.  Warming will occur on Thursday with dry westerly boundary
layer flow across southeast WY.  An isolated storm may develop in
the better instability to the east of the sfc trough across the
Panhandle.

.LONG TERM...(Thursday night through Tuesday)
Issued at 250 PM MDT Tue Aug 15 2017

Drier conditions are anticipated this weekend as the upper level
flow turns to the northwest behind a departing shortwave across
the northern Plains. This will allow for a nice warmup with
afternoon highs starting to climb into the 80s both Saturday and
Sunday. The upper level flow is progged to turn more to the
southwest early next week which will help draw some more moisture
into the area. This will make things tricky on precipitation and
cloud cover chances especially on Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1200 PM MDT Tue Aug 15 2017

The main concern with this forecast package will be the timing of
the convection this afternoon.

Latest visible imagery was showing convection already developing
along the Laramie Range/Snowy Ranges, and between Rock Springs and
Wamsutter. This convection is progged to continue developing during
the course of the afternoon and move east-northeast at speeds at 15
to 20 kts. However, some of the stronger stronger storms may move in
a more easterly fashion. This convection should begin to affect the
CYS/LAR/RWL TAF sites between 20-23z. The Nebraska TAF sites may see
some stronger convection, but the convection will probably be mainly
after 22Z. We will have to keep an eye on how things evolve today
and make adjustments as necessary. Most of the convection should
clear out by around sunset.

&&

.FIRE WEATHER...
Issued at 250 PM MDT Tue Aug 15 2017

Minimal fire weather concerns through Friday. We expect good chances
for showers and thunderstorms through this evening. Some of the
storms will produce brief heavy rain and wetting rains.  A warming
and drying trend will occur Thursday into this weekend.  Afternoon
humidities could drop down to 15-20 percent across portions of
southeast Wyoming by this weekend.

&&

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

SHORT TERM...ZF
LONG TERM...REC
AVIATION...REC
FIRE WEATHER...ZF

Hazardous Weather Outlook
National Weather Service Cheyenne WY
432 PM MDT Tue Aug 15 2017

NEZ002-095-096-WYZ101>119-162245-
Dawes-North Sioux-South Sioux-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-
432 PM MDT Tue Aug 15 2017

This hazardous weather outlook is for portions of western
Nebraska...east central Wyoming...south central Wyoming and
southeast Wyoming.

.DAY ONE...THIS AFTERNOON AND TONIGHT

Scattered thunderstorms will be possible through the evening.
While the probability for severe storms is low, a few strong
storms will be capable of producing small hail, gusty winds, and
brief heavy rain.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

The probability for widespread hazardous weather is low.

.Spotter information statement...

Spotter activation will not be needed.

NEZ003-019>021-054-055-162245-
Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne-
432 PM MDT Tue Aug 15 2017

This hazardous weather outlook is for portions of western
Nebraska.

.DAY ONE...THIS AFTERNOON AND TONIGHT

Scattered thunderstorms are expected this afternoon into the
evening. A few severe storms will be possible with large hail and
gusty winds along with brief heavy rain. A Severe Thunderstorm
Watch is in effect through the evening for the southern Panhandle.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

The probability for widespread hazardous weather is low.

.Spotter information statement...

Spotter activation may be needed from this afternoon into the
evening across the southern Panhandle.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
432 PM MDT TUE AUG 15 2017

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

0420 PM     HAIL             4 E CHEYENNE            41.15N 104.72W
08/15/2017  E0.88 INCH       LARAMIE            WY   PUBLIC

            NICKEL SIZED HAIL IN THE SADDLE RIDGE SUBDIVISION.

&&

JG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
500 PM MDT TUE AUG 15 2017

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

0500 PM     HEAVY RAIN       5 NW HARRISBURG         41.60N 103.81W
08/15/2017  M1.60 INCH       BANNER             NE   BROADCAST MEDIA

&&

MJAMSKI

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
521 PM MDT TUE AUG 15 2017

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

0518 PM     HAIL             14 N KIMBALL            41.44N 103.66W
08/15/2017  M1.00 INCH       BANNER             NE   BROADCAST MEDIA

&&

MJAMSKI

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
522 PM MDT TUE AUG 15 2017

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

0518 PM     TSTM WND GST     14 N KIMBALL            41.44N 103.66W
08/15/2017  E58 MPH          BANNER             NE   BROADCAST MEDIA

            ESTIMATED GUSTS 55-60 MPH.

&&

MJAMSKI

Special Weather Statement
National Weather Service Cheyenne WY
522 PM MDT TUE AUG 15 2017

NEZ054-160000-
Kimball NE-
522 PM MDT TUE AUG 15 2017

...SIGNIFICANT WEATHER ADVISORY FOR KIMBALL COUNTY UNTIL 600 PM
MDT...

At 522 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 11 miles north of Kimball to near Pine Bluffs.
Movement was southeast at 20 mph.

Dime size hail and wind gusts of 50 to 55 mph will be possible with
these storms.

Strong thunderstorms will be near...
  Panorama Point around 540 PM MDT.
  Kimball around 550 PM MDT.
  Dix around 600 PM MDT.

Other locations impacted by these storms include Bushnell.

This includes Interstate 80 in Nebraska between mile markers 2 and
35.

A severe thunderstorm watch remains in effect until 1100 PM MDT for
the Panhandle of Nebraska.

LAT...LON 4101 10339 4100 10405 4117 10405 4139 10380
      4139 10338
TIME...MOT...LOC 2322Z 315DEG 17KT 4139 10370 4111 10405

Rubin

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHEYENNE WY
524 PM MDT TUE AUG 15 2017

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

0523 PM     HAIL             7 SE HARRISBURG         41.48N 103.64W
08/15/2017  M2.75 INCH       BANNER             NE   LAW ENFORCEMENT

&&

MJAMSKI