


Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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260 FXUS65 KRIW 081558 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 958 AM MDT Wed Oct 8 2025 .KEY MESSAGES... - Dry and warmer conditions prevail across the CWA over the next few days with above normal temperatures for most. - Elevated to near-critical fire weather conditions are expected today from Rock Springs to Casper to Buffalo as a result of gusty winds and low RH. - Chances for precipitation increase by late Thursday through most of the upcoming weekend. - Cooler and unsettled weather prevails through the weekend with the potential for accumulating snow over western mountains by the end of the weekend. && .DISCUSSION... Issued at 229 AM MDT Wed Oct 8 2025 Another chilly start to the day across the Cowboy State. Temperatures this morning are ranging from the mid to upper 20s west of the Divide and mid 30s east of the Divide. Fortunately, a warming trend really kicks into gear today with highs reaching the mid 60s to low 70s. These warm temperatures persist through the rest of the week as high pressure prevails over the region. High pressure will also keep things dry over the next few days, but this may lead to near elevated fire weather conditions today. The main area of concern is along the Wind Corridor from Rock Springs to Casper and into Johnson County. This area will see min RH values around 20 percent with periodic wind gusts of 20 to 30 mph this afternoon. Winds lighten up overnight with dry and mostly quiet weather prevailing through most of Thursday. The forecast starting late Thursday into the weekend remains tricky as cooler and unsettled weather looks to return to the CWA. There are multiple moving parts that will each interact with one another over the next couple days. The first is the area of high pressure that has brought warmer and drier conditions to the region. The second is a large potent low pressure system that moves into the PACNW by the weekend. The third component is an area of tropical moisture that will be moving northward from Mexico. Last, but not least is a trough that will dig south from western Canada into the PACNW by the end of the weekend. Now timing for all these components still remains variable as models have recently been a little too quick in the progression of things. So now, how do all these pieces interact and effect our CWA? Starting with the high pressure that is gradually shifting to the east as we progress through the week. The center of the high will settle over portions of Texas and New Mexico. The anticyclonic flow will funnel tropical moisture associated with Hurricane Priscilla and its eventual remnants across parts of the Desert Southwest by Thursday. This plume of monsoonal-like moisture looks to eventually make its way into the southern CWA late Thursday. This may lead to a few isolated showers and storms Thursday evening across Sweetwater, southern Lincoln, and Sublette Counties and possibly further north by the early hours on Friday. The bulk of the moisture arrives by Friday, spreading further north across nearly all of the CWA. Friday will likely be unsettled with chances for showers and storms as above normal PWATs enter the region. Southwesterly flow persists into Saturday aiding with the funneling of moisture across much of the region. However, by the early hours on Saturday a trough will begin to dig south over northern California/the Great Basin, pushing eastwards through the day. This system should provide some favorable upper level dynamics that look to interact with the tropical moisture. All of this should combine to create a push of precipitation Saturday afternoon and evening across the CWA, starting from the southwest into central basins and possibly northern areas. The nearing trough axis will supply enhanced jet dynamics late Saturday into early Sunday over western WY where flow looks to be the most favorable for a period of upsloping. The trough will also bring with it colder air leading to the possibility for accumulating snowfall over western mountains. Lower elevations of western WY may see a brief transition of cold rain to a wet heavy snow early Sunday morning. It is still too early for an idea of how much snowfall can be expected across the higher elevation, but a better idea of what to expect should come to fruition over the next few days. To summarize, above normal moisture will enter the region late Thursday and early Friday. This will lead to increased chances for precipitation across much of the CWA for most of Friday. Widespread chances for precipitation persist into Saturday with a nearing trough further enhancing precipitation chances. By late Saturday afternoon/early evening, favorable flow will focus across western WY where a period of heavy precipitation may be possible. Colder air is ushered into the area around this time leading to accumulating snowfall across the western mountains. Lower elevations likely see mostly cold rain, but may see a brief period of wet snowfall early Sunday. Showers linger over western WY for Monday with another potential disturbance possible for the first half of next week. Confidence in timing remains low from Saturday onward. && .AVIATION /12Z TAFS THROUGH 12Z THURSDAY/... Issued at 409 AM MDT Wed Oct 8 2025 Dry conditions and SKC skies will continue across the region through the TAF period. The upper flow will begin to back to the southwest today, which leads to breezy southwest surface wind at KCPR and KRKS, as well as KBPI and KJAC at times this afternoon. Otherwise, other terminals will remain 10 kt or less. Patchy fog in the Wind River Basin through 15Z is not expected to impact the KRIW terminal. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Dziewaltowski AVIATION...CNJ/LaVoie