


Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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737 FXUS65 KRIW 270856 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 256 AM MDT Fri Jun 27 2025 .KEY MESSAGES... - Elevated to critical fire weather is likely across much of the area this afternoon and evening. - Elevated fire weather remains likely on Saturday. - Showers and thunderstorms are possible each afternoon across northern Wyoming, but the chance is generally less than 1 out of 5 at any particular location. && .DISCUSSION... Issued at 250 AM MDT Fri Jun 27 2025 Sometimes as shift workers, we work long stretches of shifts. This is my seventh in a row. And sometimes, things get a bit redundant. It turns out that this one of those days. All in all, there is little change in the reasoning of the forecast this morning when compared to yesterday. The main concern of the day is fire weather, both of the elevated and critical variety. The set up looks the same, with a weak shortwave moving across the area and a jet streak across Montana, putting the area in the right front quadrant, enhancing downward forcing. This will mix some mid level wind to the surface, bring breezy conditions to much of the area. If this was August, we would likely have fairly widespread Red Flag warnings. However, most locations don`t have critical fuels yet. So, these will be limited. Natrona County still looks good for the Red Flag Warning, so we continued it pretty much as is. We did given some thought to the other critical zone, 282, A.K.A. Washakie and Hot Springs county. However, humidity will be a bit higher here and wind will be more borderline. A spot or two may get Red Flag conditions but most shouldn`t so we won`t issue. Critical conditions are likely in southern Wyoming and portions of central Wyoming where humidity will fall toward 10 percent as well. As for convection, a few thunderstorms are possible along the northern border but the chance is less than 1 out of 5. Any shower or thunderstorm would be high based though, and with very high dew point depressions, any shower or thunderstorm could have a wind gust of 50 mph. The next question was if we should extend the Red Flag Warnings to Saturday. For now,we held off. Most guidance is showing dew points running 5 to 10 degrees above those on Friday. In addition, the jet will shift a bit further north and wind should be a bit lighter, making conditions more borderline. If trends favor warnings, we can issue this afternoon or tomorrow morning. Another shortwave moving through will bring a somewhat higher chance of showers and storms across the north. However, the chance will again be less than 1 out of 4. A weak cold front then moves across the area Sunday. Moisture is limited, but it could again bring isolated storms, with the best chance in eastern portions of the area. It will knock temperatures down a few degrees East of the Divide and raise dew points a bit more, so the chance of Fire Weather headlines looks unlikely at this point (less than a 1 out of 3 chance). Ridging then builds back northward over the area for early next week. Monday at this point looks like a nice day with near normal temperatures and little chance of storms. Chances may increase Tuesday and especially Wednesday as deeper moisture may try to return to the area. Details are impossible to hash out this far out, but POPs have increased on these days. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1035 PM MDT Thu Jun 26 2025 VFR conditions throughout the period for all TAF sites remaining dry throughout. Light winds and scattered mid to upper level clouds overnight. Winds will start to increase after 15Z-17Z then pick up with gusts up to 25 kt at all locations after 18Z-19Z due to the stronger mixing with peak heating of the afternoon. Winds will diminish after 01Z-02Z towards sunset becoming around 8-12 kt through the end of the period and overnight into Saturday morning. Mid to upper level clouds remain scattered to broken throughout the day Friday remaining above the 10-12kft mark. No other weather elements are expected at this time. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .FIRE WEATHER... Issued at 250 AM MDT Fri Jun 27 2025 A weak weather system moving to the north will bring humidity under 15 percent across much of the area. With a gusty wind developing this afternoon, elevated to critical fire weather is likely across much of the area this afternoon and evening, with the worst conditions across central and southern Wyoming. Elevated fire weather remains likely on Saturday afternoon although somewhat less wind and somewhat higher humidity may improve conditions somewhat. && .RIW WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from noon today to 9 PM MDT this evening for WYZ280. && $$ DISCUSSION...Hattings AVIATION...LaVoie/Lowe FIRE WEATHER...Hattings