FXUS65 KCYS 242312

Area Forecast Discussion
National Weather Service Cheyenne WY
512 PM MDT Thu May 24 2018

.SHORT TERM...(This evening through Friday)
Issued at 148 PM MDT Thu May 24 2018

Latest visible satellite and radar obs showed a few showers
developing under a shortwave ridge of high pressure aloft. These
showers are likely tapping into a bit of residual CAPE and fairly
steep midlevel lapse rates left over from yesterdays shortwave
trough. A brief shower was recorded at the CYS ASOS, however,
very little except for a brief downpour and possibly a rumble of
thunder is expected with these showers as they slowly drift
northeast over the next few hours. POPS were increased slightly
for the extra shower activity. Precip should die quickly as the
Sun sets this evening, bringing an end to any significant chances
for precipitation through the next few days. A stray shower cant
be ruled out over the next few days, but chances are low. Mostly
clear skies on Friday will allow daytime high temperatures to warm
up quite a bit in the afternoon. Much of southeastern Wyoming
will see temperatures in the middle to upper 80s. Farther east
into the Panhandle, temperatures will climb into the lower 90s
during the afternoon hours.

.LONG TERM...(Friday night through Thursday)
Issued at 148 PM MDT Thu May 24 2018

Upper level ridging continues on Saturday with temperatures
climbing a few degrees higher than Friday. Most of the Panhandle
should be well into the 90s with a few spots pushing toward 95
degrees by late afternoon. To the west, a few showers could
develop with residual moisture along the higher terrain to the
west. Model signals are pretty dry and show little QPF with any
storm that does get going.

Things begin to change on Sunday as an upper low approaches from
the Great Basin region. Temperatures will be cooler Sunday as a
Vort lobe rotates around the upper low. Lee cyclogenesis will
help bring moisture westward as a weak cold front moves out of
the northwest and stalls. Forcing along the frontal boundary and
orographic lift will fire several clusters of thunderstorms along
the Laramie Range in the afternoon. Models show decent MLCAPE
values around 1500 J/kg in the afternoon. The airmass should also
be weakly to moderately sheared, with 25 to 35 kts of bulk shear.
This suggests there is some potential for a few stronger storms
but overall severe potential should be somewhat tempered by the
lack of deep layer shear. Regardless, several rounds of storms
through Tuesday should produce some heavy rain across southeastern
Wyoming and western Nebraska. Cooler temperatures continue for
Tuesday as the main brunt of the upper low opens up and begins to
eject over the plains. A few more showers and storms will be
possible, although coverage is expected to be more isolated and
further east.

The long term period looks a bit more active as the polar jet dips
back across the CONUS. Models diverge on the specifics but show
several periods of active weather continuing through next week and
into the first part of June.


.AVIATION...(For the 00Z TAFS through 00Z Friday afternoon)
Issued at 510 PM MDT Thu May 24 2018

VFR. VCSH at KCYS, KBFF and KSNY through 02Z as isolated SHRA
develop in wake of northward moving outflow boundary. Convection
dissipates followed by SKC. Breezy west winds will diminish after
02Z at KLAR and KRWL. Light and variable winds prevail elsewhere.


Issued at 313 AM MDT Thu May 24 2018

Fire weather concerns should remain low for the next few days. High
Lowest afternoon humidities will fall to under 20 percent over
western areas Friday and Saturday but winds will be light. Cooler
temperatures will return Sunday with scattered showers and
thunderstorms Sunday into early next week.




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