


Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
682 FXUS65 KCYS 292030 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 230 PM MDT Sun Jun 29 2025 .KEY MESSAGES... - Strong to severe thunderstorms expected this afternoon and evening with a severe thunderstorm watch out. - Elevated fire weather conditions continue for Carbon county - Warm temperatures and daily coverage of isolated to scattered afternoon and evening showers and thunderstorms expected for Tuesday through Sunday. && .SHORT TERM /THROUGH MONDAY/... Issued at 102 PM MDT Sun Jun 29 2025 Mesoscale analysis shows an environment prime for some strong to severe thunderstorm development as of this writing, with CAPE around 1000-2000 J/kg and bulk effective shear of 20-40 knots. A severe thunderstorm watch is in effect through 9 PM tonight for areas east of and around I-25 not including Converse County. The environment is supportive of large hail and damaging wind gusts, but wind may become the more predominant threat as storms shift eastwards through the evening hours. High resolution guidance is in pretty solid agreement on this timeframe, with clustered storms departing the Nebraska Panhandle around 9-10 PM. Overnight activity should wane though a few lingering showers or weak storms may be possible for these areas through the morning hours. Ceilings may also lower and some mist or weak fog could be possible for areas including Cheyenne and Sydney, though confidence is overall low in this. For Monday a few upslope showers or storms may develop off of the high terrain in Wyoming, but probabilities are overall on the low side and we`ll see this quickly wane with the setting of the sun. Otherwise today and tomorrow will be the coolest days of the period, with highs today in the 70`s to 80`s with widespread highs on Monday in the 70`s to low 80`s thanks to the cold front. That will change as we move into the long term though as summer warmth returns. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Issued at 102 PM MDT Sun Jun 29 2025 Tuesday...A warming trend develops as 700 mb temperatures rise to near 15 Celsius. Adequate moisture aloft for isolated to widely scattered late day showers and thunderstorms, mainly over and near the mountains. Wednesday...The warming trend continues as 700 mb temperatures reach 16 Celsius. Moisture availability looks less than Tuesday, thus we anticipate less shower and thunderstorm coverage. Thursday-July 4th...Similar temperatures on Thursday compared to Wednesday with 700 mb temperatures near 16 Celsius. A bit cooler for July 4th, with more cloud cover and moisture aloft. Scattered late day showers and thunderstorms each day. Saturday...Although ridging aloft builds overhead, there should still be adequate low and mid level moisture for scattered afternoon and evening showers and thunderstorms. Slightly cooler temperatures expected for most locations. Sunday...Slightly warmer as the flow aloft turns westerly. Adequate low and mid level moisture for scattered late day showers and thunderstorms, mainly east of Interstate 25. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1151 AM MDT Sun Jun 29 2025 VFR conditions will be prevalent over the next 24 hours, with a handful of exceptions. First, showers and thunderstorms are expected to develop this afternoon and impact all sites through this evening, and any storms could produce locally heavy rainfall and reduce visibilities for brief periods, alongside gusty and erratic winds. Storms could even be strong to severe from KCYS through the Nebraska terminals, with very strong winds and hail possible. Then, cloud bases will remain generally mid level at around 3-6k feet, but later tonight a lowered cloud deck could bring reduced CIGs below 1-2k feet for KCYS and KSNY. Otherwise expect clouds decks outside of this to lift, becoming mid to high level and clearing into tomorrow. Winds will be breezy through this afternoon, around 10-20 knots with gusts 20-30 knots possible outside of the aforementioned storms, weakening into tomorrow morning. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CG LONG TERM...RUBIN AVIATION...CG