574 
FXUS65 KCYS 290523
AFDCYS

Area Forecast Discussion
National Weather Service Cheyenne WY
1123 PM MDT Sun Jun 28 2020

.SHORT TERM...(This evening through Tuesday night)
Issued at 127 PM MDT Sun Jun 28 2020

Tonight...Based on the HRRR, NAM and GFS, expect the first broken 
line of isolated to scattered showers and thunderstorms to move 
across mainly our northern half of counties by late afternoon, with 
another batch early this evening. CAPE of 500 to 1000 J/kg along 
with wind shear only around 25 knots suggests limited chances for 
severe thunderstorms, though a few storms could produce strong wind 
gusts of 50 to 60 mph based on strength of winds aloft and the deep 
dry adiabatic layer in the atmosphere. Most storms should be over 
around or shortly after sunset. 

Monday...Similar setup to today with strong south southwest flow 
aloft and warm temperatures aloft limiting convective potential. 
However, with strong surface heating and steep lapse rates, along 
with some mid level moisture, we could see isolated to widely 
scattered thunderstorms in the afternoon from Laramie to Douglas and 
Lusk. Continued hot temperatures, though somewhat cooler at Rawlins 
in the wake of the slow moving cold front.

Monday night...As the cold front progresses eastward across our 
counties, and with increasing low and mid level moisture, expect to 
see scattered to numerous showers and thunderstorms in the evening, 
most numerous across our northern counties. Will see a decrease in 
coverage after midnight, with the main chance for showers and 
thunderstorms north of a Rawlins to Scottsbluff line.

Tuesday...Cooler in the wake of the cold front. With cyclonic flow 
aloft and another passing shortwave trough aloft, along with some 
mid level moisture, will see scattered afternoon showers and 
thunderstorms. 

Tuesday night...After a chance of evening showers and thunderstorms 
mainly east of Interstate 25, will see a drying trend. Cooler 
overnight temperatures compared to the previous few nights.

.LONG TERM...(Wednesday through Sunday)
Issued at 127 PM MDT Sun Jun 28 2020

An uncertain forecast for Tuesday. The upper-level trough axis and
associated cold frontal passage should yield the best chance for a
fairly widespread precipitation event during the next several days
across the CWA. However, the models continue to advertise very dry
profiles with minimal QPF. The GFS/ECM both heavily favor areas to
the east of the CWA for convective development w/ gusty winds over
our area. Otherwise, generally cooler for Tuesday and Wednesday as
the area will be influenced by troughing aloft. We should begin to
trend warmer and drier later in the week with the return of large-
scale ridging. 

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1123 PM MDT Sun Jun 28 2020

VFR conditions expected to persist through the overnight period.
Models have some fog east of the NE sites so some monitoring will
be needed to see if westward expansion occurs. Showers and 
thunderstorms possible Monday afternoon that will need to be 
addressed as better guidance comes in this morning. 

&&

.FIRE WEATHER...
Issued at 127 PM MDT Sun Jun 28 2020

Minimum humidities will continue to be rather low Monday, 
Wednesday, Thursday and Friday afternoons. Gusty winds are 
expected west of I-25 on Monday, with lesser winds Wednesday into 
the weekend.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&

$$

SHORT TERM...RUBIN
LONG TERM...CLH
AVIATION...WM
FIRE WEATHER...RUBIN