163 FXUS65 KCYS 120933 AFDCYSArea Forecast Discussion National Weather Service Cheyenne WY 333 AM MDT Fri Sep 12 2025
.KEY MESSAGES...
- Daily chances for afternoon showers and thunderstorms continue through Saturday with gusty winds, downpours, and isolated hail possible.
- A cold front will impact the area Saturday, bringing cooler temperatures through the weekend.
&&
.SHORT TERM /THROUGH SATURDAY/... Issued at 326 AM MDT Fri Sep 12 2025
Current radar shows a few stray light showers across the forecast area early this morning. Some leftover energy from a shortwave that moved through on Thursday has lead to the light showers and will cause these showers to continue through the morning hours. As the upper-level trough over the Great Basin continues to push eastward, more vorticity maxes will be sent into the CWA. This, combined with some 250 mb jet energy will lead to numerous showers and storms developing during the afternoon. Instability is rather lacking so severe storms are unlikely. Although MUCAPE is lacking, DCAPE is still a bit elevated which could lead to some gusty winds in storms. As the day progresses into evening, instability will weaken, turning convection into more stratiform precipitation. PWATs will also increase as the cold front associated with the trough creeps closer. Elevated PWATs will lead to heavy rain at times throughout the afternoon and evening. Hi-Res guidance shows widespread coverage of storms, so it is likely that most locations will see at least some precipitation today. As the trough pushes into the CWA, the cold front will move through the area Friday night. This will cause showers to linger overnight, but overall should not cause any impacts.
With the trough over the Rockies on Saturday and the cold front through the area, high temperatures will be about 5 to 10 degrees cooler than Friday. Highs will be in the 60s for areas west of the Laramie Range and 70s to low 80s for areas to the east. These high temperatures will be near to slightly below normal for mid- September. As the trough axis continues to shift eastward closer to the CWA, more precipitation chances will be possible. Saturday looks like a repeat of Friday with similar instability and PWATs. Showers and storms will develop during the afternoon, once again turning more stratiform by the evening hours as instability dies off. Widespread coverage of precipitation is expected, with most locations likely to see at least some rain by midnight Saturday night.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Issued at 219 PM MDT Thu Sep 11 2025
As we start the long term and progress through the weekend, troughing digs in and slides across our CWA as ridging pushes off to the east. Within the trough, energy aloft will move through our CWA, kicking off a few isolated to scattered thunderstorms along with the potential for heavy rainfall. This trough will slide off to the east through Sunday, bringing the greatest threat of heavy precipitation and thunderstorm potential into the Nebraska panhandle. A brief reprieve Monday as a transit ridge moves in, decreasing precipitation and storm potential. This ridge will bring in the warmest temperatures for the long term period, with highs east of the I-25 corridor soaring once again back into the lower to mid/upper 80s and into the 70s across our western counties. Beginning Tuesday, we will see a return of moisture along with increased precipitation chances that remain possible into Wednesday as another another upper level low rotates across our CWA. At the tail end of next week, northwest flow aloft makes a return, ushering in cooler temperatures that may only top out in the lower to mid 70s. In addition, precipitation chances during this time period previously mentioned, dwindles into next weekend.
&&
.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1143 PM MDT Thu Sep 11 2025
A few stray showers possible overnight, otherwise generally quiet conditions are expected. Winds will be fairly light and variable at night at most terminals. Mid to upper-level clouds will move across the area overnight. More widespread showers and storms can be expected during the day tomorrow with visibility drops possible due to heavy rain.
&&
.CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None.
&&
$$
SHORT TERM...SF LONG TERM...RZ AVIATION...SF
NWS CYS Office Area Forecast Discussion