Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 281125 CCA

Area Forecast Discussion...Corrected
National Weather Service Cheyenne WY
319 AM MDT Sun May 28 2017

.SHORT TERM...(Today and tonight)
Issued at 315 AM MDT Sun May 28 2017

GOES-R water vapor loop depicted a well-defined circulation moving
across northern MN, with a trailing trough axis southwestward
through central NE, northwest KS and into southwest CO. A weak short
wave was moving southeast across east-central MT and far northern
WY, accompanied by widely scattered showers. A surface ridge axis
extended from western MT through the central Rockies to the TX/OK
panhandles. Skies were mostly clear with temperatures in the 30s
and 40s. Winds were variable less than 10 mph.

Most of the models show the weak disturbance continuing to track
southeast across eastern WY and western NE today. High-Resolution
Rapid Refresh (HRRR) model develops widely scattered convection
across the high plains and mountains this afternoon. CAPE values
peak from 300-500 j/kg with weak 0-6 km shear, so strong tstorms not
expected. High temperatures this afternoon will be 5-10 degrees
warmer with highs in the 60s-low 70s outside the mountains. It will
be breezy across the plains as northwest winds gust to 30 mph.
Shower activity will diminish this evening as the atmosphere
stabilizes. A weak front will push south late tonight and stall over
the mountains Memorial Day. Moisture convergence, upslope, CAPE
values 500-1000 j/kg, and 25-30 kt 0-6 km shear indicate more
scattered convective coverage Monday afternoon, especially along and
west of I-25. The stronger tstorms may produce hail up to nickel
size, brief heavy rain and wind gusts of 40-50 mph. It will be a tad
cooler Monday, mainly over the plains, with highs in the 60s to
around 70. Convection ends by mid-evening Monday. Highs Tuesday will
be about 5 degrees warmer than Monday with mid 60s-mid 70s. Isolated
afternoon convection Tuesday will be confined to the Snowy, Sierra
Madre, southern Laramie ranges, and adjacent valleys and foothills.

.LONG TERM...(Tuesday night through Saturday)
Issued at 300 AM MDT Sun May 28 2017

A few showers are possible near the Colorado border Tuesday evening
otherwise it looks dry overall into early Weds afternoon with an
upper ridge poised to the west of the CWA. A weak impulse passing by
late Weds may set off a few showers and tstms again mainly near the
Colorado border. The upper ridge will slip across the area Thursday
with temperatures likely the warmest for the week on that day. A
little cooler Friday and Saturday behind a weak cool front moving
by early Friday. Widely sctd mainly afternoon and evening showers
and tstms expected Thursday through saturday as weak and hard to
time shortwaves move across and interact with some instability.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 300 AM MDT Sun May 28 2017

VFR expected through the period. Isolated showers and a few tstms
around this afternoon into early this evening.


Issued at 235 AM MDT Sun May 28 2017

Fire weather concerns will be minimal through early this week. Isolated
afternoon and early evening showers and thunderstorms will develop
with the passage of a weak upper level disturbance. A weak front will
drop south and stall along the Front Range Memorial Day. A moist upslope
flow and instability will favor scattered shower and thunderstorm
development during the afternoon and early evening along and west of
Interstate 25. More widely scattered showers and thunderstorms will
be possible Tuesday afternoon over the southeast Wyoming mountains
and foothills. Warmer and mostly dry conditions will prevail Wednesday
and Thursday. The exception may be isolated afternoon thunderstorms
over the mountains.




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