Videocast: Cooler, Breezy Sunday
After a gorgeous Saturday with temps in the 60s and even some 70s near Morgan Hill (and a glorious 49ers win!) Sunday will turn progressively breezy and cooler as a case of “Canadian A/C” drops in over the Bay Area. Highs should stay in the low to mid 50s for most places, but given the source of the air it will probably feel colder than that outside. Rainfall chances increase rapidly by Wednesday for areas north of San Francisco as a robust Pacific jet stream races into Northern California, but never really crosses south of the Bay Area. While there will be plenty of moisture to work with to produce heavy rain (thanks to the westerly moisture-rich airflow) its still looking like most of the moisture and best upper level lift will be aimed in from north of the Golden Gate into midday Thursday before rain does begin to move south. Friday is trending wetter for most areas and certainly more windy – the computer models are hinting at 20-40 mph winds possible late Friday into early Saturday accompanying the rain. It may seem harsh compared to what we’ve been used to – but after all it *is* mid January and this is the weather we’re *supposed* to be seeing – windy/wet/snowy Sierra. There’s good news regarding that last topic. With plenty of moisture to work with and mid/upper level winds hitting the Sierra at nearly a perpendicular angle – this should maximize mountain-force lift (orographic lift as mets like to say) and produce some really solid snow totals above 6,000 ft. The pattern doesn’t appear cold enough to drop snow levels too much further than that, but hopefully as the jet digs a little further south and cooler air following behind the individual cold fronts sweeps in, this should help drive snow levels down even more into next weekend. At the same time, that same mountain-forced lift to the moisture can yield some very heavy rain totals along the coastal range. With the jet stream holding its position over Northern California, just north of the Bay Area, it would seem the heaviest rains will fall from Marin county northward, possibly localized roadway, hillside runoff issues for Sonoma County northward at times – but from Santa Clara county southward there doesn’t look to be nearly as much rain – at least until Friday when that windier storms barrels through. Bottom line – the storm door is swinging back open and the Sierra ski season seems primed for a restart by this time next week. Oh, an about that amazing 49ers… should the NY Giants win on Sunday, the 49ers would host the Giants at 3:30pm next Sunday the 22nd. Its looking like rain at times for that with temps in the mid 50s, possibly breezy. We’ll keep an eye on it for you should the NFC championship game be hosted here at Candlestick. If its at Lambeau Field, we’ll our 49ers should prepare for snow showers, breezy with temps in the upper 20s and wind chill index probably in the upper teens – classic “Frozen Tundra” weather for January! Enjoy your Sunday! – Rob Mayeda
