097 FXUS65 KREV 122030 AFDREV Area Forecast Discussion National Weather Service Reno NV 130 PM PDT Sat Aug 12 2023 .SYNOPSIS... Our lingering low near the California coast will bring daily chances for showers and thunderstorms across the Sierra and western Nevada. Thunderstorm potential will be highest south of Highway 50 through the weekend, then spread northward Monday. Temperatures over the next week will remain near to slightly above average, with the warmest days most likely Wednesday and Thursday. && .DISCUSSION... No significant changes to the thunderstorm potential. Looking ahead to the upcoming week, we are still anticipating daily chances for showers and thunderstorms. Thunderstorm potential will shift from day-to-day as the low pressure wobbles off the California coastline. Let's glance at the details. * Weekend Storm Potential: Best moisture and instability will remain along and south of highway 50 for this weekend. Once thunderstorms initiate in the afternoons, outflow boundaries may allow more isolated storms to kick off and surge farther north towards I-80. Localized heavy rain will be confined mainly to the eastern Sierra of Mono County while lightning and gusty winds accompany all storms. Storm motions today and Sunday will generally be from east to west as well, which may result in storms anchoring or pushing west of the Sierra crest through the evening. Overnight light showers are possible (10-20% chances), but high resolution simulations show much of the activity kicking off across Mineral county and sweeping west across Mono/Alpine counties by early Sunday morning. * Widespread Coverage Monday: The low slowly progresses north on Monday, sweeping moisture and storm potential along with it across the Sierra and western Nevada. Widespread chances (25-40%) for showers and thunderstorms arrive by midday Monday (Mono/Mineral) and spread northward to the Oregon border by Monday evening. Latest simulations show a decent shortwave spinning around the easternmost edge of the low, which would help to kick off stronger storms. The strength of the storms will rely heavily on the placement of incoming shortwaves with the low. All the ingredients are in the vicinity (moisture, instability, trigger) it is just a matter of where they align. * Thunderstorm Train: Tuesday through most of next week, a 10-20% chance sticks around for much of the Sierra, NE CA, and far western NV. Blended guidance continues to highlight Friday as the next "bigger" thunderstorm day with around 25% chances for much of the Sierra and NE CA. Our slowly exiting low will be contending with an incoming trough dropping out of the Pac NW, which is introducing a bit more uncertainty into forecast days 5-7. Some simulations show the Pac NW trough placing the region under a drier, cooler southwest flow as it drops southward towards the weekend. * Hot, then Cool? Temperatures are expected to remain near or a few degrees above average for the upcoming week. The blended guidance has remained consistent with signaling Wednesday-Thursday as the hottest days of the next week, with a 20-25% chance for some western NV valleys hitting 100 degrees. -Edan && .AVIATION... * Almost daily thunderstorm chances through at least Monday, especially for the Sierra terminals. KMMH continues to have the highest thunderstorm potential at 30-40% chances with KTVL/KMEV/KRNO sitting at 10-20% chances through Sunday then 20-30% chances Monday as the low off the CA coast meanders slightly northward. * Plan on typical thunderstorm impacts for aviators, including lower CIGS/VIS with terrain obscuration during heavier rainfall, gusty and erratic outflow winds, frequent lightning and small hail. Gusty and erratic thunderstorm outflow winds may also spread isolated thunderstorm potential farther north late this afternoon and evening (towards I-80), as well as kick up desert playa dust across western NV. -Edan && .FIRE WEATHER... * While dewpoints are climbing across many areas along and south of Interstate 80, dewpoints across the northern portion of the region (NE CA + NV) are still in the lower 30s. High pressure across the Pac NW is having some influence on the northern portion of the forecast area and producing lower RH and poor/moderate RH recoveries overnight as well. * Thunderstorm potential is still on track for much of the upcoming week, mainly south of Hwy 50 through Sunday then spreading northward. There will be some dry lightning strikes possible outside of the wetter rain cores, but generally we aren't expecting a lot of fire starts. Dewpoints in the 50s and precipitable water around 0.75" are indicative of a rather moist atmosphere, which will allow wetting rains to occur with storms this weekend. While shower and thunderstorm coverage will be more widespread on Monday, storms will be trending wetter as well. * Forecast winds continue to be lighter than our typical afternoon breezes. However, thunderstorms will produce gusty, erratic outflows/downdrafts 40+ mph, especially with more hybrid storm activity across the Basin and Range. * Over the next few days, recent (2-3 years old) major wildfire burn areas will need to be monitored due to the enhanced flash flood risk. This will be true for areas south of US-50 in the eastern Sierra and western Nevada as well. We will be keeping a close eye on steep terrain locations and flood prone areas since there will be an enhanced flash flood risk, and especially since some of these locations may see several rounds of shower and thunderstorm activity over the upcoming week. -Edan && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$