May 25, 2018 - The National Weather Service Hanford Office reports a Winter Weather Advisory for late season snow is in effect for the Sierra Nevada high country above 8,000 feet from Yosemite to Kings Canyon National Parks during Friday morning through Saturday morning.
.SYNOPSIS...Low pressure will move across the area today and then move into Nevada on Saturday. Showers and thunderstorms are expected over the Sierra and parts of even the lower elevations of the north today. Weak high pressure will return by Sunday and Monday with a warming and drying trend. && .DISCUSSION...GOES-16 water vapor imagery shows the center of the incoming Pacific system now about 150 miles west of Monterey. Associated jet stream is well noted pushing north/northeast into the Central California Interior and regional radars show bands of light rain extending into Merced County and increasing echoes of light showers to the south and east, now developing over Western Fresno County. Given the strong dynamics and the incoming low pressure system, showers and even a thunderstorm or two will becoming more widespread as we head through the late night hours from essentially Fresno County north. For today, forecast models bring the center of low pressure onshore in the Bay area and by later this afternoon and evening only slowly move the low center to the southeast. Given the low position and directional shear, expect quite a few thunderstorms over the Sierra and foothills with the threat extending into the San Joaquin Valley from basically Fresno County north through the afternoon and early evening. Meanwhile, over the Sierra, snow will likely fall to around 8000 feet as the colder air aloft associated with the low center arrives. The Winter Weather Advisory is certainly warranted as up to several inches of snow is possible with very cold and winter-like conditions for the hiking and high country enthusiasts. More showers and thunderstorms are likely on Saturday as the low moves into Nevada and cyclonic flow continues in the Sierra. Other areas will likely see any precipitation threat come to an end. On Sunday the low is progged to only move slowly east into western Utah and the last of the wrap around cyclonic flow lingers along the Sierra Crest for one last day of a thunderstorm threat. Models then build a weak ridge over the forecast area on Monday and Tuesday for a warming and drying trend. All in all a very cool and potentially stormy day today to start the Memorial Day Weekend however by Monday, warm and dry conditions will prevail. Next week looks to remain cooler than normal as yet another trough of low pressure develops offshore and then deepens to a closed low by Thursday.
Source: NWS
