Special Weather Statement, NWS Cheyenne, WY

Area Forecast Discussion
National Weather Service Cheyenne WY
1245 PM MDT TUE JUL 26 2016

.UPDATE...

&&

.SHORT TERM...(Today through Wednesday night)
Issued at 304 AM MDT Tue Jul 26 2016

Main forecast concerns Today and Wednesday will be the threat of
thunderstorm activity and the position/speed of a surface cold
front forecast to push into the forecast area. A broad upper level
high pressure south of Wyoming will continue to retrograde
westward into the eastern Great Basin region today. This will
allow some jet energy and a weak frontal boundary to drift a bit
further south across central Wyoming today. Surface trough
currently extends from north of Douglas near Gillette...southward
along the Front Range of the Rockys. This surface trough will
serve as a weak dryline with a high moisture gradient along the
boundary. LAPS surface analysis shows a surface low over northeast
Wyoming. This low will slowly drift southeast across the area
today and will aid the development of thunderstorms. A few strong
to marginally severe thunderstorms are expected east of a line
from Lusk to Scottsbluff Nebraska where the highest instability
will be along with the most favorable shear profiles. Strong
winds/hail/frequent lightning are the main concerns into this
evening. Further south...just a general risk of thunderstorms is
expected along the dryline-like boundary as it gradually moves
eastward through the afternoon. Activity is expected to move east
of the forecast area while another round of showers and isolated
thunder is possible further west tonight as a 700KT jet max and
surface cold front begins to move south into east central Wyoming
and the northern Nebraska panhandle. Kept POP around 15 to 20
percent after midnight...mainly well north of I80.

For Wednesday...Models all show the surface cold front pushing
southward and eventually stalling along the Laramie Range
Wednesday night. With cooler air aloft moving into the area under
northwest flow and some jet energy...expect a pretty good chance
of widely scattered or scattered thunderstorms along and east of
the Laramie Range/I-25 corridor Wednesday afternoon through late
Wednesday evening. Strong to severe thunderstorms are also
possible in these areas as well...especially if there is limited
cloud cover. Kept POP between 25 to 40 percent across the eastern
plains into western Nebraska with a better chance at organized
sustained convection through Wednesday evening. Temperatures will
begin to lower a few degrees on Wednesday...but highs will remain
in the mid to upper 80's before lowering late in the afternoon.

.LONG TERM...(Thursday through Tuesday)
Issued at 304 AM MDT Tue Jul 26 2016

The upper ridge sets up shop over the desert southwest through
Tuesday with periodic shortwave energy moving east across Wyoming
and western Nebraska. With the upper high over central Nevada on
Thursday we see a shortwave driving southeast across Wyoming and
western Nebraska Thursday afternoon producing scattered showers
and thunderstorms during the afternoon and evening hours.
Weak shortwave ridging Friday results in lower PoPs in the
isolated category through the weekend for afternoon convection,
then we see the upper ridge start to move east with southwesterly
upper flow returning by Tuesday as a stronger shortwave starts to
drive east from Idaho possibly resulting in eventual higher PoPs
by early next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1222 PM MDT Tue Jul 26 2016

Main concern to aviation ops will again be trying to pin timing
and strength of thunderstorm activity this afternoon and early
evening. Thunderstorm coverage will be isolated. Sites with the
best chance to see thunderstorms will be the western Nebraska
Panhandle, but still not confident enough to elevate to anything
above VCTS. A few storms may become strong-severe in this same
area later today. Convection will wane by 02-03z.

&&

.FIRE WEATHER...
Issued at 304 AM MDT Tue Jul 26 2016

Fire weather concerns will be low across the majority of the area
today...but near critical conditions are possible across portions
of FWZ 301 and western 303 and 304 due to low humidities and west
to northwest winds gusting between 20 to 25 MPH at times. Coverage
of showers and thunderstorms will increase over the next few days
through Friday with minimal concerns for the rest of the week.

&&

.CYS Watches/Warnings/Advisories...
WY...None.
NE...None.
&&

SHORT TERM...TJT
LONG TERM...JG
AVIATION...CAH
FIRE WEATHER...TJT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHEYENNE WY
424 AM MDT TUE JUL 26 2016

WYZ101>119-271215-
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-
424 AM MDT TUE JUL 26 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
WYOMING.

.DAY ONE...TODAY AND TONIGHT

WIDELY SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS THE MOUNTAINS
AND I-25 CORRIDOR EARLY THIS AFTERNOON. THESE THUNDERSTORMS WILL
GRADUALLY MOVE EAST ACROSS THE HIGH PLAINS THROUGH THIS EVENING.
BRIEF HEAVY RAINFALL...FREQUENT LIGHTNING...AND GUSTY WINDS ARE
POSSIBLE WITH THESE THUNDERSTORMS THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THUNDERSTORMS WILL INCREASE IN COVERAGE BY MID TO LATE WEEK WITH
AN INCREASING THREAT OF SEVERE THUNDERSTORMS ON WEDNESDAY AND
THURSDAY...ESPECIALLY ALONG AND EAST OF INTERSTATE 25.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE REQUIRED.

NEZ002-003-019>021-054-055-095-096-271215-
DAWES-BOX BUTTE-SCOTTS BLUFF-BANNER-MORRILL-KIMBALL-CHEYENNE-
NORTH SIOUX-SOUTH SIOUX-
424 AM MDT TUE JUL 26 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WESTERN
NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS EASTERN WYOMING AND
MOVE SOUTHEAST INTO WESTERN NEBRASKA THIS AFTERNOON AND INTO THIS
EVENING. SOME THUNDERSTORMS MAY BECOME STRONG AND CONTAIN
HAIL...STRONG GUSTY WINDS...AND HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THUNDERSTORMS WILL INCREASE IN COVERAGE BY MID TO LATE WEEK WITH
AN INCREASING THREAT OF SEVERE THUNDERSTORMS ON WEDNESDAY AND
THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE REQUIRED.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
214 PM MDT TUE JUL 26 2016

WYZ118-119-262100-
EAST LARAMIE COUNTY WY-CENTRAL LARAMIE COUNTY WY-
214 PM MDT TUE JUL 26 2016

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LARAMIE COUNTY UNTIL
300 PM MDT...

AT 213 PM MDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM NEAR
HILLSDALE...OR 15 MILES EAST OF CHEYENNE...MOVING EAST AT 30 MPH.

NICKEL SIZE HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
PINE BLUFFS...BURNS...HILLSDALE AND CARPENTER.

THIS INCLUDES INTERSTATE 80 IN WYOMING BETWEEN MILE MARKERS 375 AND
402.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

&&

LAT...LON 4106 10458 4124 10458 4129 10406 4100 10407
      4100 10437
TIME...MOT...LOC 2013Z 269DEG 24KT 4115 10448

HAMMER