075 FXUS65 KRIW 161711 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1111 AM MDT Thu May 16 2024 .KEY MESSAGES... - A nice today today with mild temperatures. - Elevated fire weather into the weekend, especially on Friday afternoon. - Early next week looks cooler and unsettled. && .DISCUSSION... Issued at 311 AM MDT Thu May 16 2024 The pattern is looking to remain fairly progressive and active into next week. The best day of the period may turn out to be today. Shortwave ridging will be transiting across the area today. And this should bring a pretty nice Spring day to most of the area with some sunshine and mild to warm temperatures. There will be a bit of a breeze in the favored locations, like Rock Springs to Casper, but nothing unusual for May in Wyoming. As for precipitation, the chance is very small. A weak shortwave brushing by to the north could bring an isolated shower or thunderstorm to far northern Wyoming but the chance is less than 1 in 5. These showers should end this evening. Things get more active tomorrow. And we have a few hazards to talk about. The culprit from this will be another shortwave and cold front that will sweep across the area. As for convection, there is a better chance than yesterday. However, this system does not have a ton of moisture to work. Most guidance is showing any showers and storms remaining largely across northern Wyoming and the highest chance is only around 2 in 5, with lesser POPs further south. The concern is the strength of the storms. There will be some upper level divergence and an 100 knot jet approaching. With dew point depressions approaching 50 degrees in some locations along with models soundings with the inverted V signature; many storms could end up high based. This will lead to possible downburst winds of 50 mph or more. The Storm Prediction Center has issued a marginal risk for severe thunderstorms to our east and I could see this extended further westward if trends continue. Further south, the hazards remind me of on my favorite 70s bands; Earth, Wind and Fire. The approaching cold front and the downward forcing from the left front quadrant of the aforementioned jet will bring strong wind across much of the southern two thirds of the area. At this time, the 700 millibar wind does not look quite sufficient for high wind, but it will be close. The day shift may want to consider watches if this trends upward. There is over a 4 in 5 chance of wind gusts past 40 mph in the favored area. And that leads us to the next potential hazard, fire that could scar the earth. Dew points will be very low across much of this area, falling into the teens at times, bringing humidity under 15 percent at times. Fuels are in green up, so no fire warnings are expected. However, elevated fire weather will be a near certainty (over a 4 in 5 chance) across much of the southern half of the area. The main threat will be across the south, which has been dry for a while. In central Wyoming, the area saw decent rain earlier this week and this could mitigate the threat somewhat. Things should quiet down on Saturday, which looks like a somewhat cooler day with less wind, but still breezy at times. Wind increases again on Sunday though as another trough and cold front approach the area. The chance of elevated fire weather looks less though, as temperatures should be somewhat cooler and dew points a bit higher. It will still be rather windy though. This system has a bit more moisture, and will have a better coverage of showers and storms. The chance is only 1 in 3 at best in most locations with exception of the mountains though. The active pattern looks to continue into next week. At this point, Monday and Wednesday look like the best chance of showers. Confidence is not high on this as timing shortwaves this far out is fairly difficult. Temperatures will be cooler behind the front, averaging below normal, especially Monday depending on sky cover. this will be followed by gradual moderation later next week. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1111 AM MDT Thu May 16 2024 VFR conditions through the TAF period. Winds increase this afternoon, with gusts 20 to 25 knots for many locations. Most of these winds decrease by 03Z/Fri. Models are indicating downvalley, northwest winds at KRIW this evening into the night, with winds around 15 knots possible (60%-70%); models show this wind lasting through 07Z to 10Z/Fri. A few showers are possible across the northern Wyoming mountains this afternoon, but no impacts to terminals expected (90%). Friday is a windy day. Gusts begin to increase early morning, increasing further for the afternoon (after the TAF period). Showers are possible across the northern section of Wyoming, but at this distance it is too difficult to pinpoint locations and timings. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .FIRE WEATHER... Issued at 311 AM MDT Thu May 16 2024 No real concerns are expected today. On Friday afternoon, an approaching cold front will bring strong wind to much of the area, with wind gusts over 50 mph possible in central and southern Wyoming. With humidity falling into the teens, elevated fire weather is likely (greater than a 3 in 4 chance). The highest chance is across southern Wyoming, which has been fairly dry over the past week or so. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hattings AVIATION...Wittmann FIRE WEATHER...Hattings