Area Forecast Discussion
Issued by NWS Cheyenne, WY

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034
FXUS65 KCYS 221159
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
559 AM MDT FRI JUL 22 2016

.SHORT TERM...(Today thru Sunday)
Issued at 249 AM MDT Fri Jul 22 2016

Today-Tonight:
Latest water vapor loop was showing the tropical plume across
southeast Wyoming. This plume of moisture has produced some thick
cloud cover overnight which has really kept up temperatures.
Latest IR loop was showing these clouds finally starting to lift
northeast which should allow for temperatures to dip towards
daybreak. Water vapor loop was also showing a potential vorticity
anomaly moving through western Wyoming. This feature is progged to
skirt east through central Wyoming this afternoon and help trigger
convection along the Laramie Range this afternoon. Instability
will be somewhat limited with surface based capes generally
ranging from 800-1200 j/kg based on the NAM/RAP soundings and
effective shear values around 25kts. Best instability appears to
be in the panhandle so I Would not be surprised to see a few
strong storms this afternoon with the storm motion generally
northeast at 10 to 15kts. HRRR/Local WRF solutions are showing a
fairly organized cluster of storms pushing through areas east of
the Laramie Range this afternoon with the best coverage mainly
east of a Cheyenne to Wheatland line. This cluster of convection
should push east of the area shortly after 9 pm, and should bring
about clearing skies afterwards.

Saturday-Sunday:
Saturday should be a fairly quiet day as the upper level trof
along the U.S./Canadian border skirts east and drags a frontal
boundary through areas east of the Laramie Range on Saturday
morning. This should tend to dry us out for a short while with
slightly cooler temperatures. The models are trying to hint at
some convection developing along the CO/WY border during the
evening due to the return flow setting up. Went ahead and
introduced pops near Cheyenne Saturday evening, but confidence is
still rather low. Another weak shortwave in Montana is expected to
move through Northern Wyoming on Sunday which may help trigger
some convection east of the Laramie Range. This wave appears to
subtle according to various models solutions, but we will have to
see how this pans out before making large adjustments to precip.
chances.

.LONG TERM...(Sunday night through Thursday)
Issued at 249 AM MDT Fri Jul 22 2016

Subtropical ridge center will be located over Colorado for Monday
with heights aloft rising through the day.  The GFS shows more
convection breaking out across the plains during the aftn/evening
than the ECMWF, with better llvl moisture and instability.  Kept
tstms mostly isolated with the ridging aloft.  The midlvl ridge
center will shift westward toward Utah and the Great Basin by
Wed/Thurs.  It appears that convective chances could increase
especially to the east of the Laramie Range by the middle of next
week as weak shortwaves in northwesterly flow aloft move overhead.
Bulk shear in this pattern is decent (30-40 kts) as are CAPE values,
thus can not rule a strong or svr storm.  Temps through the extended
are expected to be around seasonal norms.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 555 AM MDT Fri Jul 22 2016

VFR. Midlevel clouds will persist over the Nebraska Panhandle for
the next few hours. Isolated to scattered showers and
thunderstorms are expected to develop this afternoon from
southeast Wyoming into the southern Panhandle. Brief gusty winds
and heavy rain could occur with these storms.

&&

.FIRE WEATHER...
Issued at 249 AM MDT Fri Jul 22 2016

No major concerns for fire weather today due to better recovery of
the relative humidities and limited wind speeds. The only factor
could be the potential for thunderstorms this afternoon which may
produce some lightning on dry fuels in the Wyoming and Nebraska
Plains. Critical Fire weather conditions will be more favorable
over areas west of the Laramie Range on Saturday due to stronger
winds near 25 to 30 mph and low relative humidity values. However,
most of the fuels are not favorable for rapid fire growth.

&&

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

$$

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



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