134 FXUS65 KCYS 020511 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1111 PM MDT Sun Jun 1 2025 .KEY MESSAGES... - A passing weather disturbance and relatively strong cold front for early June will move across the forecast area on Monday, producing widespread showers and scattered thunderstorms Monday afternoon and night. Some of the thunderstorms south of a Cheyenne to Chadron line may become severe Monday afternoon and evening. - Cooler and wetter weather will prevail for Tuesday and Wednesday before a warming trend develops for Thursday through Saturday, with chances for late day showers and thunderstorms each day. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 147 PM MDT Sun Jun 1 2025 Tonight...Visible satellite imagery, WSR-88D reflectivity and model guidance suggests isolated to widely scattered showers and thunderstorms through early this evening, mainly for southeast Wyoming. As the cold front approaches our northern counties, we may see an uptick in shower coverage late this evening across Converse County. Relatively quiescent weather after midnight in advance of the cold front. Monday...Quite an active day expected. As the progressive shortwave trough aloft moves into the Dakotas, its associated cold front will sweep southward across our counties, ushering in cooler north winds and widespread low clouds. With strong frontal lifting and a deep moist airmass, we anticipate numerous showers and thunderstorms to develop, especially in the afternoon along and near the cold front. With the combination of shear and instability, some of the thunderstorms will likely become severe from Laramie County of southeast Wyoming across the southern two-thirds of the Nebraska Panhandle, where the Storm Prediction Center has their slight risk area. Maximum temperatures will be tough to call based on the strength of the cold front and cloud cover. Monday night...As the cold frontal band is overridden by moist flow aloft, numerous showers and scattered thunderstorms will continue into the evening hours, most numerous south of a Laramie to Alliance line. Some of the storms may be severe early in the evening in this corridor. Scattered to possibly numerous showers will continue after midnight in the moist airmass, with chilly temperatures as 700 mb temperatures fall to -2 Celsius. There may be some areas of fog development in areas where rain decreases in coverage. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 147 PM MDT Sun Jun 1 2025 Multiple shortwaves will gives us precipitation chances throughout the work week mainly in the afternoon and evening. However, starting Wednesday we begin to have our westerly downslope become the predominant pattern allowing temperatures to rise from the mid 60`s and into the 70`s Thursday with more widespread 70`s on Friday into the weekend. Tuesday, another shortwave swings through the intermountain west from the early afternoon and into the evening. There looks to be a vort max associated with this shortwave that may be the primary means for lift. On top of the vort max there will be a little bit of some residual moisture for the vort max to lift for some light showers. Given the lack of real synoptic support anything severe is not likely, however some lightning and thunder may be possible. Wednesday into Thursday, A midlevel trough pushes through continuing the rain chances for the Intermountain west. There should be enough synoptic lift and well as the vorticity gradient to produce stronger storms than Tuesday. However, model guidance shows dry air filling into the region potentially cutting off any convection into the overnight hours or evening if that dry air arrives sooner. Thursday into Friday, westerly flow starts to dominate the pattern allowing us to get a small break from the precipitation chances. Dry air looks to start filing into the lower elevations giving us a dry layer near the surface that may possibly not allow precipitation from reaching the surface. && .AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1107 PM MDT Sun Jun 1 2025 Isolated showers and storms have come to an end across southeast Wyoming and western Nebraska with a calm night and early morning expected. A brief period of patchy fog is possible around KCYS, but confidence in this fog developing is low. Winds remains light and variable overnight into the early morning hours before increasing with the passing cold front later this afternoon and evening. This cold front will initiate strong to severe storms across the region with all terminals potentially seeing impacts from storms. Gusty, erratic winds and large hail will be possible in and around all storms that develop. Storms will come to an end in the evening with low ceilings moving in overnight. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...RUBIN LONG TERM...MM AVIATION...AM