Special Weather Statement, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
307 PM MDT Mon Jul 3 2017

.SHORT TERM...Tonight through Wednesday Night

The latest KCYS radar loop was indicative of scattered to numerous
showers and thunderstorms across southeast WY. A very dry boundary
layer remains in place across the CWA w/ inverted-V profiles, so a
threat for 40-50 MPH wind gusts will accompany this activity. Rain
amounts should be minimal from these high-based storms. We may see
a few showers linger into the early evening, but in general expect
to see things winding down as a mid-level disturbance continues to
track east into central NE. We could see another round of showers/
thunderstorms on Tuesday afternoon/evening, but rising heights and
resultant subsidence should keep activity quite isolated. The GFS/
NAM are both showing very limited QPF, so it may be tough to get a
storm or two going. The upper ridge axis moves overhead Wed, w/ H7
temperatures ranging from 16-17 deg C over the NE Panhandle, to 20
deg C over western Carbon county. It should be a very hot day over
much of the area with deep subsidence in place and resulting ample
sunshine. We continued to advertise forecast high temperatures 3-5
degrees warmer than consensus model guidance, putting a large part
of the CWA in the 90s, near 100 F in the Platte River Valley.

.LONG TERM...(Thursday through next Monday)
Issued at 250 PM MDT Mon Jul 3 2017

Medium to long range models continue to show a dominant upper
level high pressure building over Utah and Colorado through the
weekend. Model show this high slightly further west compared to
previous model runs with its position closer to the four corners
region by Sunday and next Monday. This will result in a slightly
more favorable environment for convection, especially across
southeast Wyoming due to upslope winds and weak northwest flow
aloft. With limited forcing, was not comfortable going over 30
percent for POP due to timing of shortwave energy. Any convection
that does develop will likely be slow moving with locally heavy
rainfall. Models do indicate a weak front just off the surface
sliding southward along the high plains for Friday and Saturday,
so kept the highest POP and chances for thunderstorms for these
days. By early next week, models show a strong ridge axis
extending into Wyoming on the northern portion of the the main
area of high pressure. Believe this feature will enhance midlevel
subsidence and lower precipitation chances across the area late
Sunday and Monday afternoon. Temperatures will remain well above
normal with highs generally in the middle 80's to middle 90's
across the area, including locations west of the Laramie Range.
Thursday and Monday look like the hottest days during this
forecast period with most places in the 90's, and a few areas
below 4500 feet even hitting the century mark in the afternoon.

&&

.AVIATION...(For the 18Z TAFS through Tuesday morning)

VFR conditions will prevail through tonight with intervals of
midlevel cloudiness. Widely scattered showers and thunderstorms east
of the Laramie Range will continue to develop and move southeast
across the high plains. These showers will spread eastward and
affect the western NE terminals through 00z before diminishing with
the loss of daytime heating. Light winds and clearing skies are
expected tonight.

&&

.FIRE WEATHER...
Issued at 147 PM MDT Mon Jul 3 2017

Near-critical fire weather conditions are ongoing across Carbon Co
this afternoon with occasional wind gusts over 30 MPH at RWL along
with RH values near 10 percent. So far, the sporadic nature of the
wind gusts has precluded the issuance of a Red Flag Warning but we
will continue to monitor. Otherwise, hot and dry weather is likely
to prevail through mid/late week. Light winds should prevent wide-
spread critical fire weather conditions.

&&

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

SHORT TERM...CLH
LONG TERM...TJT
AVIATION...TJT
FIRE WEATHER...CLH

Hazardous Weather Outlook
National Weather Service Cheyenne WY
409 AM MDT Mon Jul 3 2017

WYZ101>119-041015-
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-
409 AM MDT Mon Jul 3 2017

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

.DAY ONE...TODAY AND TONIGHT

Widely scattered thunderstorms are expected once again this
afternoon. A few storms may become strong but widespread severe
weather is not expected.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Isolated to widely scattered showers and thunderstorms are
possible especially Friday through Sunday. At this time widespread
severe weather is not expected.

.Spotter information statement...

Spotter activation will not be needed at this time.

NEZ002-003-019>021-054-055-095-096-041015-
Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne-
North Sioux-South Sioux-
409 AM MDT Mon Jul 3 2017

This hazardous weather outlook is for portions of western
Nebraska.

.DAY ONE...TODAY AND TONIGHT

Widely scattered thunderstorms are expected once again this
afternoon. A few storms may become strong but widespread severe
weather is not expected.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Isolated to widely scattered showers and thunderstorms are
possible especially Friday through Sunday. At this time widespread
severe weather is not expected.

.Spotter information statement...

Spotter activation will not be needed at this time.

Special Weather Statement
National Weather Service Cheyenne WY
414 PM MDT MON JUL 3 2017

NEZ055-032300-
Cheyenne NE-
414 PM MDT MON JUL 3 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN CHEYENNE COUNTY
UNTIL 500 PM MDT...

At 413 PM MDT, Doppler radar was tracking a strong thunderstorm near
Twin Buttes, or 11 miles southeast of Sidney, moving east at 15 mph.

Nickel size hail and wind gusts of 50 to 55 mph will be possible with
this storm.

This storm will remain over mainly rural areas of southeastern
Cheyenne County.

LAT...LON 4104 10262 4100 10263 4101 10290 4104 10290
      4106 10261
TIME...MOT...LOC 2213Z 277DEG 13KT 4100 10282

Rubin

Special Weather Statement
National Weather Service Cheyenne WY
443 PM MDT MON JUL 3 2017

NEZ055-032330-
Cheyenne NE-
443 PM MDT MON JUL 3 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN CHEYENNE COUNTY
UNTIL 530 PM MDT...

At 442 PM MDT, Doppler radar was tracking a strong thunderstorm over
Colton, or 8 miles east of Sidney, moving east at 45 mph.

Another strong thunderstorm was just southeast of Sunol, moving
northeast at 45 mph.

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

This strong thunderstorm will be near...
  Sunol around 445 PM MDT.
  Lodgepole around 455 PM MDT.

This includes Interstate 80 in Nebraska between mile markers 62 and
77.

LAT...LON 4100 10262 4101 10284 4115 10296 4122 10294
      4122 10261
TIME...MOT...LOC 2242Z 287DEG 40KT 4115 10282

Rubin