Special Weather Statement, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
253 PM MDT Tue May 22 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 226 PM MDT Tue May 22 2018

Main concern this evening is the convection evolution tonight.
Latest radar loop was showing some convection developing mainly
west of the Laramie Range. However, there is a good cluster of
storms developing along the Pine Ridge. Latest water vapor loop
was showing the low level clouds tracking from southeast to
northwest. Meanwhile, we are starting to see more of the organized
clusters are starting to track north. Based on this trend, we
would expect the convection to mainly track north this afternoon.
However, we would expect things to evolve further east in response
to the influx of the higher thete air (800-700mb). A few of these
storms may be able to become severe this afternoon based on the
good updraft strength and marginal 0-6km shear around 30 to 35
kts. In addition, we are looking at the potential for heavy
rainfall within some of the stronger storms as the storms slowly
develop eastward. The majority of this convection should lift
north over the forecast area overnight.

Another round of convection is expected to develop over the area
tomorrow along and east of the Laramie Range. Shear potential
looks to be a bit more favorable tomorrow, but the best potential
for convection looks to be in the Panhandle as a potential
vorticity anomaly swings through the area.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 226 PM MDT Tue May 22 2018

Warm and mainly dry weather expected across the CWA Friday through
Saturday as an upper ridge shifts east across the area. There
could be a bit of convection both afternoons over the higher mtns
but warmer mid level temps should keep them limited. An upper low
over the western CONUS will then move slowly towards the CWA
Sunday and Monday and will bring an increase in showers and tstms
both days as weak impulses rotate around this low and over the
region. Best coverage looks like it will be on Monday, aided by
some diffluent upper flow northeast of the upper low. It will be
warm both Friday and Saturday then temperatures trending down some
Sunday and Monday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1152 AM MDT Tue May 22 2018

Main concern on the aviation desk today will be the coverage of
thunderstorms starting 21Z west of Interstate 25 (possibly
affecting Rawlins and Laramie), Cheyenne 21Z-00Z, Scottsbluff,
Alliance and Sidney 00Z-04Z. Right now have a period of MVFR
visibility at all airports except Sidney (where coverage is
expected to be less) during those timeframes. Otherwise, only
other consideration would be lower visibility in fog for Alliance
and Sidney early Wednesday morning, but right now confidence is
not high enough to go below MVFR on visibilities.

&&

.FIRE WEATHER...
Issued at 226 PM MDT Tue May 22 2018

Fire weather concerns will continue to be on the low side during
the next couple of days due to the potential for more convection.
We will have a drying out period on Thursday and Friday which will
cause afternoon humidity values to drop into the teens, but
greenup is expected to persist through the weekend.

&&

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

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

Hazardous Weather Outlook
National Weather Service Cheyenne WY
1000 AM MDT Tue May 22 2018

WYZ101>119-231030-
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-
1000 AM MDT Tue May 22 2018

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

.DAY ONE...REST OF TODAY AND TONIGHT

Scattered to numerous showers and thunderstorms are expected this
afternoon and evening. A few storms could become strong to severe
with hail the main threat.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

Scattered showers and thunderstorms are expected Wednesday, and
again Sunday and Monday. A few storms could become strong to severe
in the Wyoming High Plains east of the Laramie Range.

.Spotter information statement...

Spotter activation is not anticipated.

NEZ002-003-019>021-054-055-095-096-231030-
Dawes-Box Butte-Scotts Bluff-Banner-Morrill-Kimball-Cheyenne-
North Sioux-South Sioux-
1000 AM MDT Tue May 22 2018

This hazardous weather outlook is for portions of western
Nebraska.

.DAY ONE...REST OF TODAY AND TONIGHT

Scattered showers and thunderstorms are expected this afternoon and
evening. A few storms could become strong with gusty winds and small
hail.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

Scattered showers and thunderstorms are expected Wednesday, and
again Sunday and Monday. A few strong to severe storms are
possible Wednesday afternoon with hail the main threat.

.Spotter information statement...

Spotter activation is not expected.

Special Weather Statement
National Weather Service Cheyenne WY
439 PM MDT TUE MAY 22 2018

WYZ110-115-222315-
North Snowy Range Foothills WY-Laramie Valley WY-
439 PM MDT TUE MAY 22 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL ALBANY COUNTY UNTIL
515 PM MDT...

At 438 PM MDT, Doppler radar was tracking a strong thunderstorm 9
miles north of Lake Hattie Reservoir, or 16 miles west of Laramie,
moving north at 15 mph.

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

This storm will remain over mainly rural areas of south central
Albany County.

This includes Interstate 80 in Wyoming between mile markers 286 and
301.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4133 10577 4132 10595 4160 10606 4162 10573
TIME...MOT...LOC 2238Z 174DEG 17KT 4138 10589

Hahn