September 30, 2019 – Cooler weather along with a chance of showers continues today. Gradually milder temperatures are expected through the week with highs returning to around average by the end of the week.
Scattered to numerous showers indicated on radar across the foothills and west slopes of the northern Sierra Nevada ahead of the next upstream vort moving into northwest California. Elsewhere, skies are clear to partly cloudy across the region. Current temperatures are milder compared to 24 hours ago and range from the 30s in the mountains to the upper 40s to lower 50s across the Central Valley.
Shower chances will continue today, most numerous over the foothills and mountains, as the vort swings through the region. 1 to 3 inches of snowfall accumulation will be possible across the higher passes with locally higher accumulations over the peaks. Dry weather will return tonight and Tuesday as the trough shifts east.
Highs today will remain 15-25 degrees below average. Temperatures will gradually moderate the next several days, but won’t return to near average until the end of the week.
Extended Discussion (Friday through Monday)
A rather tranquil period ahead with lower heights exiting the region on Friday morning. As the associated longwave trough accelerates toward the Rockies, heights will build over the eastern Pacific affording a gradual warm up into the weekend. A broad upper low across the subtropical Pacific could lift toward the state by Sunday. However, even if this verifies, it will encounter a broad upper ridge which would likely shear/weaken the system. Ensemble means maintain ridging to some extent into the following week before a potential break in this pattern. Until then, expect daily highs in the low/mid 80s across the Valley while 50s and 60s can be found across the mountains. It is forecast to remain dry through the period.