Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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006 FXUS65 KRIW 310325 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 925 PM MDT Thu May 30 2024 .KEY MESSAGES... - Daytime high temperatures 5-10F above normal Saturday through Monday initiate another period of active snow melt in the mountains. Foothill creeks and streams will see daily diurnal water rises. - Breezy west to southwest wind on Monday and Tuesday could heighten rangeland fire conditions over central and southern Wyoming. - Ensemble forecasts are in agreement with a ridge of high pressure developing over the western United States by the middle of next week. Temperatures will be well-above normal. && .DISCUSSION... Issued at 101 PM MDT Thu May 30 2024 Mid-level moisture within cyclonic flow draped over the northern half of the forecast area has allowed for isolated showers and cloud cover over the northern mountains today. Otherwise, plenty of sunshine and more seasonable temperatures across the the remainder of the forecast area Thursday afternoon. The cyclonic flow persists across the north overnight enabling a few showers to linger over the northern mountains into Friday morning. The parent trough over the Canadian Prairie Provinces lifts northeast by midday Friday. This leaves the forecast area with a mostly clear sky Friday afternoon and night. There will be a breezy west wind across southern Wyoming, but nothing out of the ordinary. Temperatures warm to at or just above seasonal normals regionwide. Zonal flow is found across the region through the weekend. Temperatures will be running 5-10F above normal both days, which allows for a period of active mountain snowmelt. Much of the snowpack is now confined to elevations above 9K feet. Foothill creeks and streams will see daily diurnal rises, but available channel capacity and the fact this will be higher elevation melt should limit flooding concerns. The exceptions would be the Salt and Snake drainages where lower snow has yet to melt, and those drainages fed by the northern Bighorn Mountains. Mid-level moisture sneaks into southwest Wyoming Saturday and ignites isolated afternoon and early evening showers and storms in that region. A better plume of mid-level moisture arrives from the west Saturday night and Sunday, leading to better coverage over the northwest-quarter of the state during that time period. A deepening trough off the Pacific Northwest coast generates southwest flow aloft Monday leading to even warmer temperatures. The above normal temperatures combined with a breezy southwest wind and a drier airmass elevates rangeland fire weather concerns Monday. However, many areas are still in greenup. The flow flattens Tuesday as shortwave energy rolls through the Northern Rockies with little noticeable impacts to sensible weather. It may be a bit breezier Tuesday as the pressure gradient tightens. Attention then turns to a building ridge across the western United States. Much above normal temperatures in the 80s and even lower 90s look increasingly likely. Current projections have daily highs the latter half of next week falling short of record highs that run in the lower to mid 90s. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 921 PM MDT Thu May 30 2024 VFR conditions prevail at all terminals throughout the TAF period. Winds will gradually decrease overnight with many terminals seeing light and variable winds into Friday morning. Skies clear out overnight with a lingering SCT/BKN080-100 cloud deck at KCOD and KWRL through the night. SKC prevail across all terminals by Friday morning and remain into the end of the period. West- northwest winds develop by early Friday afternoon with periodic gusts of 20 to 25 knots. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Jones AVIATION...Dziewaltowski