Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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691 FXUS65 KRIW 181726 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 1126 AM MDT Wed Sep 18 2024 .KEY MESSAGES... - Strong winds off the east slopes of the Absarokas and Bighorns through midday. - Widely scattered rain showers (snow for higher terrain) for the northern half of the CWA off and on all day Wednesday. - Dry conditions Thursday with cooler temperatures and sporadic precipitation chances Friday and over the weekend. && .DISCUSSION... Issued at 1234 AM MDT Wed Sep 18 2024 IR currently depicts a classic comma cloud signature from the high plains to the northern Rockies with much of the colder cloud tops out of the state. Radar shows some lingering rain showers and light snow for the higher terrain across northern parts of the CWA that will continue to wrap around off and on throughout Wednesday. The cold front is now well to the east with ample CAA pushing into the state reinforcing the gusty westerly winds through the morning hours. Boundary layer winds have 50 plus knots that could mix to the surface under the ample cloud cover not capped aloft. The main focus areas for any high winds will be off the east slopes of the Absarokas funneling through the Cody foothills, as well as across the Rattlesnakes to Natrona County. Winds will finally start diminishing towards noon Wednesday and into the afternoon hours as the gradient weakens in wake of the occluded front exiting to the east with the main upper level low. Behind it will be induced ridging for Thursday that will dry out the state but continue with the cooler, more seasonable temperatures to end the work week and over the weekend for the long term. Next up will be another upper level low making its way down the west coast towards the Four Corner Region. Models are now indicating more alignment with one another pushing it further south with less of an impact to the CWA. Cooler temperatures will still be had with breezy winds Friday and into the weekend, but precipitation chances look to be more minimal as the shortwaves spin around the aforementioned low. Higher terrain look to be most impacted with some weak mountain snow as well as some rain showers for south central Wyoming as the low tracks east across the southern states. The main jet will be cut off to the north keeping the more potent lows with much colder air near the Canadian border and into Canada. Longer term forecasts have much model disagreement with some interesting weather patterns to come by mid next week all dependent on some trough/low tracks coming down from the Gulf of Alaska through the Pacific northwest. Time will tell, so stay updated in the coming days. All in all, once this current upper level low track eastward later today, expect calmer yet somewhat unsettled weather to come keeping the cooler temperatures going forward. && .AVIATION /18Z TAFS THROUGH 18Z THURSDAY/... Issued at 1126 AM MDT Wed Sep 18 2024 Cloud cover and areas of light rain have been wrapping into northwest and northern Wyoming Wednesday morning within counter- clockwise flow around an upper-level low over Montana. Also, gusty southwest surface wind 30G50kts has plagued KCPR and similar speeds are likely to prevail there through about 22Z/Wednesday before slowly decreasing by 02Z/Thursday. The counter-clockwise flow leads to gusty westerly surface wind 15-30kts until around 01Z/Thursday at most other terminals, with 10-20kt winds lingering longest at KRIW in favored west-northwest flow. As for precipitation, KJAC will continue to flirt with MVFR/VFR threshold of 030AGL through mid-afternoon, with VFR likely to prevail after 21Z/Wednesday. All other terminals to be VFR. Scattered light rain showers remain favored at KJAC in west- northwest flow until 03Z/Thursday. KWRL has a less than 30 percent chance of seeing a brief light rain shower from 21Z- 24Z/Wednesday. Other terminals to remain dry. Cloud cover gradually dissipates and ceilings rise from south to north tonight. Any lingering light showers decrease between 06Z-12Z/Thursday. Mountain tops frequently obscured above 10K feet MSL until 06Z/Thursday across the northwest quadrant of Wyoming. 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... High Wind Warning until noon MDT today for WYZ003-019-020. && $$ DISCUSSION...Lowe AVIATION...CNJ