Area Forecast Discussion
Issued by NWS Reno, NV
Issued by NWS Reno, NV
786 FXUS65 KREV 172008 AFDREV Area Forecast Discussion National Weather Service Reno NV 108 PM PDT Fri May 17 2024 .SYNOPSIS... Unseasonably warm temperatures along with afternoon breezes will persist through Saturday. Shower and thunderstorm chances return for the Eastern Sierra this afternoon and for areas south of Highway 50 on Saturday. The weather pattern shifts late Sunday bringing cooler temperatures, enhanced winds and potential for intermittent wet weather next week. && .DISCUSSION... Quick Points: * Daytime highs running 5-15 degrees above average through Saturday. Cooling trend to follow Sunday into next week with temperatures hovering near to below seasonal averages by Monday and Tuesday. * Typical afternoon breezes develop daily through the weekend. Brief periods of locally choppy conditions on area lakes late in the afternoons. * Thunderstorms and Showers: 10-20% chance along the Sierra crest from Alpine to Mono counties late this afternoon. On Saturday, plan on 20-30% chances for areas south of Hwy 50, including western NV. Otherwise, dry conditions prevail elsewhere through the weekend. If you want more: A dry, cool front dropping through the Sierra and western Nevada today will bring a touch of a cooldown along with a shift in the winds. Temperatures will still be a bit above normal today and Saturday, but will cool noticeably by Sunday into Monday to near or even slightly below normal averages. With the front passage today our typical westerly afternoon winds will have a substitute of northerly breezes. The north winds won`t persist for long as the west zephyr winds (gusts up to 30 mph) make a comeback Saturday and Sunday afternoons. So far today, some cumulus development is already occurring along the Sierra in Mono county where the greatest potential (10-20%) exists for shower and thunderstorm development. If you`re outdoors recreating or working this afternoon, be aware of when the clouds mature vertically as your initial sign to make your way indoors soon. Always remember when thunder roars, go indoors or when you see a flash, dash inside. The cool front pushes southward and will help to kick off storms a bit early along the Eastern Sierra for Saturday. Showers will initiate around 11am along the crest from Tahoe southward with the most shower coverage in Mono and Alpine counties. When our typical westerly afternoon winds develop around 1pm then shower and thunderstorm coverage will trek eastward into western Nevada areas south of Highway 50. CAPE EFI values showing a decent signal for areas from Tahoe southward into Mono County. By Sunday into Monday, ensemble clusters have been highlighting a trend toward a trough dropping into the Great Basin resulting in further cooling along with continued north to possible northeast breezes. Blended guidance has a large spread in forecast temperatures, so there is still a bit of uncertainty in the depth and westward extent of the trough`s influence as of right now. There is medium confidence that Monday will be the coolest day of the next week with temperatures then resettling around seasonal averages the remainder of next week. -Edan && .AVIATION... * VFR conditions for main terminals through the forecast period. A few cumulus buildups will develop along the higher terrain late this afternoon and evening. After 21z, there will be a 10-20% chances for a showers or thunderstorm for KBAN and KMMH. * FL100 winds have begun to shift across N.CA/NV from the west 15- 25kts kts shifting to the north-northwest. North to northwest surface winds of 10-20 kts are possible through 03Z. * Saturday: Typical westerly afternoon breezes up to 25 kts for all terminals. Thunderstorms and showers will develop along the Sierra by 19z and shift eastward into Wrn NV between 20-22z. -Edan && .HYDROLOGY... Unseasonably warm daytime temperatures and mild nights, combined with higher solar angles, longer days, and limited cloud cover will continue to increase snowmelt rates through the weekend. Even the higher elevation deeper snow areas have begun to melt in earnest. This rapid melt will lead to elevated flows with rivers and streams running cold and fast, most notably in areas draining significant terrain over ~7500 feet from Lake Tahoe south through Mono County. Rivers and streams in this area will remain high through the weekend, with the highest flows likely through Saturday. Cooler temperatures and a depleting snow-covered contributing area will help reduce flows by Sunday into early next week. For areas in the Eastern Sierra, runoff may not taper off until Sunday or Monday when the cooler temperatures finally arrive. While these high and cold flows can be hazardous to recreationalists, flooding is very unlikely. Please use extra caution around local rivers and streams which will be running fast and cold and can be very hazardous if entered. Remember the highest flows are significantly lagged from the heat of the day and can often occur at night. Consistent and steady high flows will continue along the Lower Humboldt, with additional rises likely later in May or early June. TB && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$