Area Forecast Discussion
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
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961 FXUS65 KRIW 142108 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 308 PM MDT Fri Jun 14 2024 .KEY MESSAGES... - Isolated thunderstorms will produce 45 to 55 mph outflow wind gusts this evening through sunset, after which time storms will dissipate. - Temperatures continue to run 10 to 15 degrees above seasonal normals through the day Saturday. - Breezy winds are expected on Saturday combined with temperatures well above normal, leading to elevated fire weather conditions. Shower and thunderstorm activity will be minimal. - Temperatures begin cooling on Sunday, and below average temperatures are expected by Tuesday as the next weather system moves through. && .DISCUSSION... Issued at 255 PM MDT Fri Jun 14 2024 A strong ridge of high pressure continues to dictate the weather pattern for Wyoming over the next 36 hours, with temperatures remaining 10 to 15 degrees above normal. As a trough slowly pushes onto the West Coast this afternoon, a shortwave focused over Montana has provided lift for some thunderstorms, primarily across southern Montana, just north of the Wyoming border. Over western and central Wyoming, dynamics are not as favorable, but scattered diurnal-heating-based "garden variety" thunderstorms will still produce gusty outflow winds on the order of 45 to 55 mph due to the large temperature-dew point spreads (indicative of efficient evaporation and cooling of downdraft air parcels). After sunset storms will quickly dissipate. Overnight RH recovery will be relatively poor and thermal belts are likely for midslopes. Any fire activity is likely to be more vigorous than on a typical overnight. On Saturday, the trough over the Pacific Northwest will continue inching eastward, tightening the pressure gradient. Most areas across Wyoming will see strong sustained westerly winds develop by noon, with gusts in the 35 to 50 mph range. The higher gusts will be focused over the wind corridor from Sweetwater to Natrona County. Isolated thunderstorms are again possible on Saturday afternoon, but these will be focused over the Powder River Basin and quickly move into eastern Wyoming by mid- afternoon. Gusty outflow winds are again the main threat with any of this convective activity. Sunday and into early next week the trough to the west will begin to influence sensible weather more. Temperatures will cool to seasonal normals, and areas along the northern third of the state will likely (40 to 70% chance) see light measurable rain Monday into Tuesday. Tuesday will even feature temperatures below seasonal normals for the first time in over a week. Temperatures moderate for the second half of the week, with above average highs again in the forecast by Friday. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1124 AM MDT Fri Jun 14 2024 VFR conditions are expected to prevail across all terminals through the TAF period. The only exception to this would be a brief thunderstorm moving over a terminal this afternoon/evening creating a short period of MVFR or even IFR conditions. All terminals except KBPI and KJAC have a (10-20%) chance for a thunderstorm today. KWRL and KCOD have the best chance of seeing thunderstorms/showers this afternoon/evening. Winds will increase this afternoon across all terminals with most seeing gusts of 20-25 knots. Gusty outflow winds are possible at most terminals depending on the vicinity of any developing convection. Winds along with any lingering convection will begin to dissipate around sunset. Winds become light and variable overnight. Saturday morning will see winds begin to gradually increase with breezy conditions starting to develop near the end of the period at most terminals. 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...VandenBoogart AVIATION...Dziewaltowski