


Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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790 FXUS65 KRIW 121843 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1243 PM MDT Sat Jul 12 2025 .KEY MESSAGES... - A pleasant, seasonable, dry, and mostly sunny summer day across the Cowboy State today. - Warm temperatures return for Sunday and Monday with above normal highs for much of the area. - Cooler temperatures and precipitation chances return for much of the first half of the upcoming week. && .UPDATE... Issued at 1241 PM MDT Sat Jul 12 2025 The brief break from summer heat we saw on Friday across much of the Cowboy State will come to an end today. Warm July temperatures return with highs in the low to mid 80s west of the Divide and upper 80s to low 90s east of the Divide. Today will be very pleasant overall with plenty of sunshine and dry conditions. Temperatures continue to warm for Sunday with highs back around 90 west of the Divide and in the mid to upper 90s east of the Divide. Conditions remain dry with a small chance for a shower or two across the higher elevations of northern WY. A cold front is expected to near the state by Monday but will remain just out of reach, allowing temperatures to stay warm for another day. Highs for Monday are expected to be similar to Sunday with temperatures in the upper 80s west of the Divide and mid to upper 90s east of the Divide. The nearing front will create some scattered showers and thunderstorms mainly across northern WY. The front will bring increased winds with a breeze developing during the afternoon. Winds will range from 10 to 15 mph with periodic gusts of 15 to 25 mph. These winds combined with low min RH values may create elevated fire weather conditions especially over southern WY. However, with winds remaining mostly marginal the concern for widespread near critical fire weather conditions looks to be low at this time. Model disagreement remains in terms of the timing of the frontal passage and the track of the associated trough. As of today the front will work its way across the state Tuesday, this will lead to cooler temperatures over northern WY with warmer values lingering across central and southern WY. Northern WY will see increased chances for showers and thunderstorms with the frontal passage. The exact extent that precipitation chances spread south will depend on the front speed and track of the trough. Currently, Tuesday looks to see the best chances over northern WY will an isolated shower or two possible for central WY. Widespread chances for showers and thunderstorms arrive by Wednesday after the frontal passage. As mentioned earlier, just how far south these chances spread still remains to be seen. Cooler temperatures are expected for Wednesday but do not look to be to the same degree as originally thought. The current forecast has highs in the upper 70s to mid 80s. Earlier forecasts showed cooler temperatures in the 70s for much of the state. Either way this still does look to be another break from the heat with increased chances for showers and thunderstorms. The rest of the week will see gradual warming return with the possibility of another disturbance by the end of the week into the weekend. && .DISCUSSION... Issued at 325 AM MDT Sat Jul 12 2025 Friday night was one of those nights you really appreciate in the middle of summer. After a couple of really hot days, it was really refreshing stepping outside. Temperatures in the 50s with the nearly full moon out. However, these days are rare in the climatologically warmest time of year, and these will come to an end fairly quickly. The weather will be dominated by dry northwest flow today with convergence aloft. This will lead to a fairly typical summer day across western and central Wyoming. That means a good deal of sunshine, temperatures returning to near normal levels (warm but not overly hot) and light to moderate wind. So, a nice day to start the weekend. We turn the heat machine back on for Sunday through as thicknesses climb across the area. Highs in the lower elevations will see a lot of upper 80s to 90 west of the Divide to 90s to near 100 to the east. There may be just enough mid level moisture returning for a stray shower or thunderstorm of the late day variety in the northern mountains. However, with the chance only around 1 out of 10, we kept the forecast dry for now. Things look to turn more active for the first part of next week. A cold front will move toward the area for Monday but will remain far enough north for another hot day, with temperatures similar to Sunday`s highs. It will be close enough to bring a somewhat better coverage of showers and storms. This would be limited to the northern half of the state. Even here though, the chance is only around 1 out of 3 in the mountains and 1 out of 5 in the lower elevations. The other concern will be elevated fire weather as the pressure gradient tightens a bit. Sustained winds only look to be in the 12 to 15 knot range though across southern Wyoming, where the main concern would be. This makes critical fire weather unlikely at this time (about a 1 in 5 chance at this time) despite humidity under 15 percent. There is more model disagreement for Tuesday and Wednesday in regards to the front and associated trough. Some guidance has trough moving over Wyoming, bringing a rather active 48 hours. Other guidance keeps the main impacts over Montana with only scattered convection. We made few changes at this time as details this far out are nearly impossible to hash out. We do have high confidence in cooler temperatures returning for this period, generally retreating to near to slightly below normal levels. This uncertainty extends into the end of next week as well, as Wyoming will be near the top of the ridge and any shortwaves could bring convection. But timing and position of these waves is hard to predict this far out. So to summarize the next week, there will an increased chance of convection and cooler temperatures, but details of the timing and placement of storms remains highly uncertain. && .AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1107 AM MDT Sat Jul 12 2025 VFR prevails at all terminals through the forecast period. Mid/high clouds drift across the region Saturday afternoon and evening in northwest flow aloft. There appears to be enough moisture and instability to generate a few virga showers over the far southern end of the Wind River Range early Saturday evening. Gusty westerly wind 10-18kts blows most of Saturday afternoon until around 02Z/Sunday at terminals west of the Continental Divide. 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. && $$ UPDATE...Dziewaltowski DISCUSSION...Hattings AVIATION...CNJ