Dry and warm weather through Friday with breezy northerly winds. Active weather returns this weekend as a weather system drops down bringing showers, mountain snow, isolated thunderstorms, gusty winds and colder temperatures.
Things remain on track with high confidence of a pretty strong late spring-winter like storm system for the area this weekend. Upper level low system will drop south Friday night then exit the area by Sunday afternoon. EC standard anomaly data showing 500 mb heights impressive at a -2 with return interval of 10 to 20 years for this time of the year.
Ensemble means in good agreement that the upper low will basically slide south across central California with a good period of upper dynamics. Could be stronger if the low was further west but still some good dynamics with this system.
Pretty much a classic winter system originating from the Gulf of Alaska with a nice Atmospheric River and PW plume with climo PW values of 150 to 230% above normal.
System is a pretty quick hitter so biggest challenge is level of impacts with snow and blowing snow above 5000 feet. NBM probabilities showing bullseye of higher snow right in the I80 corridor with 70% to 80% chance of 8″ and about 50% chance of a foot at highest elevations.
Snowfall rates have a chance to exceed an inch an hour in intensity Saturday afternoon and evening.
So with all this the biggest question will be the impacts of this snow and wind. With collaboration with area offices given time of year, sun angle, road and ground temperature and quickness of storm will stick with a winter weather advisory for the event.
In the valley, would expect a band of rain to push across from north to south. NBM QPF probabilities have been pretty consistent for low probs of half an inch and solid chances of quarter of an inch.
High EFI values for cool high temperatures Saturday and Sunday as well with high temperatures dropping a solid 10 to 20 degrees from Friday to Saturday.
Extended Discussion (Monday through Thursday)
Higher confidence above 50% that extended period looks to be fairly dry and on the cool side. Cluster analysis showing majority of solutions point to lower 500 mb heights with dry northerly flow.
Biggest risk would be mid to late week of some northerly flow looks to set up with general troughing across the Great Basin. How amplified that low gets will determine strength of wind which right now probabilities of 40 mph guest are down around 30% to 40%.