Area Forecast Discussion
Issued by NWS Cheyenne, WY

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FXUS65 KCYS 031730

Area Forecast Discussion
National Weather Service Cheyenne WY
1130 AM MDT Wed Jun 3 2020

.SHORT TERM...(Today through Friday night)
Issued at 235 AM MDT Wed Jun 3 2020

Forecast concerns this morning deal with severe thunderstorms
chances today and Thursday.

Currently...Surface low pressure analyzed just south of Casper
this morning. Warm front extends southeastward to Cheyenne and
south into central Colorado. To the east of this warm
front...dewpoints observed in the upper 50s east of the Laramie
Range out into the Panhandle. Still seeing a little convection
across northern Dawes County north of Chadron this morning at 2
AM. Rest of CWA PPINE at this time.

Guidance continues to show the warm front surging east later this
morning as a dry line. Mesoscale guidance showing convection
developing along and east of this dry line after 18Z
today...becoming most widespread around 20Z/21Z. MUCAPE east of
the dry line up to 2000/2500 J/KG out across the Panhandle. Ample
shear with 0-6km 45-50kts on forecast soundings for a few
supercells to develop. SPC`s Slight Risk looks good for the
Panhandle through 00Z this afternoon before the dry air surges
east through the panhandle.

NAM...GFS and SREF develop some convection Thursday along the I-80
Corridor...while ECMWF keeps CWA dry. Did maintain some low
chances POPs as the ECMWF may be the outlier tomorrow. Very dry
Thursday afternoon with humidity well down into the mid
storms Thursday (if they develop) will be high based storms with
wind downdrafts the major concern.

.LONG TERM...(Saturday through Tuesday)
Issued at 235 AM MDT Wed Jun 3 2020

Decent upper shortwave swings northeast across the region late
Saturday and should produce pretty widespread convection as it
does so. Sunday should be warm and mainly dry in the wake of the
shortwave with some drier air advecting into the area ahead of the
main upper trough that will be over the western CONUS. This trough
will move slowly east and across the CWA Monday and Monday night
with a pretty good cold front passing across early on Monday.
Significantly cooler conditions returning Monday and Tuesday
along with some showers and maybe a few storms over the CWA


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1126 AM MDT Wed Jun 3 2020

Cigs should lower slightly as the afternoon progresses, but VFR
flight categories are still anticipated. The semi-stationary
frontal boundary will continue to keep winds elevated for the
terminals across the forecast region. Due to the nearby frontal
boundary, VCSH and VCTS are likely this afternoon through 0Z. Wind
gusts of 20-30 knots are also likely, especially when VCTS is the
present weather at terminals.


Issued at 235 AM MDT Wed Jun 3 2020

Very dry and breezy conditions likely to continue across areas
west of the Laramie Range today...spreading eastward Thursday.
Afternoon humidity below 15 percent with wind gusts to 30-35 mph
for FWZs 303 through 308 will result in elevated to locally
critical fire weather conditions. Begin to see showers and
thunderstorms returning to all FWZs Saturday as a low pressure
system tracks west to east across the area.


Issued at 235 AM MDT Wed Jun 3 2020

High water flows will continue through late this week due to rapid
mountain snowmelt. The upper North Platte River near Saratoga,
Encampment river, and the Little Laramie River west of Laramie are
observing elevated flows in action stage at this time. However,
rivers and streams are not forecast to go above flood stage at
this time due to the lack of precipitation.




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