Area Forecast Discussion
Issued by NWS Cheyenne, WY

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216
FXUS65 KCYS 240227 AAA
AFDCYS

Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
827 PM MDT THU JUN 23 2016

.UPDATE...
Issued at 821 PM MDT Thu Jun 23 2016

Radar trends the past few hours indicated a marked decrease in
coverage and intensity of showers and thunderstorms. With several
convective outflow boundaries still roaming around, cannot rule
out a few weak t-storms with brief gusty winds for a couple more
hours this evening.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 245 PM MDT Thu Jun 23 2016

Showers and thunderstorms have continued to develop along the I-80
corridor this afternoon as a weak disturbance aloft pushes east
across the area. some small hail has been reported with gusts up
to 40 MPH so far early this afternoon. Main concern this afternoon
is severe thunderstorms as this line progresses eastward into the
western Nebraska panhandle. However...shear values are still
marginal which supports the multicell structure developing along
several surface boundaries/outflow further to the west. Will
continue to closely monitor the environment this afternoon since a
few severe Thunderstorms are possible southeast of a line from
Cheyenne to Chadron Nebraska. This activity is expected to move
east out of the forecast area by midnight tonight. Kept fog out of
the forecast for now due to concerns with cloud cover and precip
coverage...although some low clouds and fog are possible by
sunrise from Kimball to Alliance Nebraska.

Friday will be similar with a lower chance for strong to severe
thunderstorms due to the lack of shear over the area. Drier air
will also move into the northwest portion of the forecast area and
mainly central Wyoming...with the attention shifting towards fire
weather by Friday afternoon. Friday will be a few degrees warmer
with highs in the mid 80`s to mid 90`s across most of southeast
Wyoming...warmest across the lower elevations. Hot temperatures
are expected over western Nebraska with readings in the 90`s to
possibly around 100. A cold front associated with the strong upper
level trough currently near the Washington coastline will rapidly
move southeast across the forecast area as the trough moves into
Montana Friday night and Saturday morning. Expect cooler
temperatures for Saturday...with highs ranging between the mid
70`s to mid 80`s. It will be pleasant and breezy/very dry behind
the front...as PW/s lower below one quarter of an inch out west.

.LONG TERM...(Sunday through Thursday)
Issued at 144 PM MDT Thu Jun 23 2016

A fairly active extended forecast period may be in the cards w/quasi
zonal flow atop broad/flat upper-level ridging. The actual timing of
individual disturbances is uncertain...but low-level convergence and
moist upslope should yield at least scattered showers and storms for
Monday and Tuesday. Dew points in the 50s/60s across the high plains
should support CAPES over 2000 J/kg on both days...likely focused in
the western Panhandle on Tuesday. Deep layer shear is expected to be
strong with 30-40 knot flow at H5...so a multi-day severe threat can
be expected. Daytime highs should be near to slightly above seasonal
norms through the period.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 511 PM MDT Thu Jun 23 2016

VFR conditions are expected outside of scattered afternoon/evening
thunderstorms across much of the area. Stronger thunderstorms will
produce brief periods of MVFR visibility and ceilings, heavy rain,
erratic/gusty winds to 40 kt, and small hail. Included TEMPOs at
RWL, SNY and AIA through 03Z this evening, with VCSH/TS elsewhere.
Convection will diminish after 03Z.


&&

.FIRE WEATHER...
Issued at 144 PM MDT Thu Jun 23 2016

Moderate fire weather concerns Friday and potentially Saturday as
well. Dry and windy conditions are expected across east central
Wyoming through Saturday with a higher chance of showers and
thunderstorms further south along the I80 corridor. A Red Flag
Warning has been issued for east central Wyoming from Douglas to
Lusk area for low humidities and gusty afternoon winds...although
the stronger gusts may be delayed until mid to late afternoon. A
cold front will move into the region Friday Night resulting in
gusty south to southwest winds becoming northwest by Saturday.

&&

.CYS Watches/Warnings/Advisories...
WY...Red Flag Warning from noon to 9 PM MDT Friday for WYZ301.

NE...None.
&&

$$

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



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