I get the best forecast information from the "forecast discussion" page. Here's what is coming......
EXTENDED DISCUSSION (Monday THROUGH Thursday)...
Our attention then turns toward a strong weather system expected
Monday-Tuesday, with lingering chances into Wednesday. A low
pressure system will drop from the Gulf of Alaska and eventually
become a closed low somewhere off the NorCal coast early next
week. As this low strengthens and digs off the NorCal coast, broad
upper-level lift will tap into some low-end moisture, producing
widespread precipitation and heavy mountain snow. Clusters still
indicate some variation in the location of the low center, which
would influence exactly how much winds and precipitation we could
see with this system. Even so, ensembles have been fairly
consistent on the timing, and recent runs depict the low center
digging further east, ending up over the Bay Area before digging
southeast. Latest forecast is every similar to the previous
forecast, but doubled since 24 hours ago. Storm total precip is
now 1"-3" in the Valley, 2-3.50" in the foothills, and 3-5" in
the mountains. Snow levels will be fairly low initially Monday
morning at 1500-2500 feet, increasing to 3,000-4,000 feet by
Monday afternoon. Total snow amounts of 3-5 feet are possible for
elevations above 4000 feet, locally up to 6+ feet. The heaviest
is expected to be Monday night through Tuesday. In addition to
precipitation, we will also see some gusty winds as pressure
gradients tighten in response to the closed low, how strong those
winds will be is very unclear at this point given the variation
in the low center, but at least gusts to 30-40 mph appears likely
for portions of the region. Given the synoptic set-up, there will
likely be periods of thunderstorms possible sometime Tuesday as
well, but those details will become more clear the closer we get.
Ensembles are indicating the low will be slowly moving southeast
through the middle of the week, keeping some chances in the forecast
through much of Wednesday. There is still some discrepancies in
the timing of how quickly the low will move out, so confidence is
fairly low beyond Tuesday.
//Peters
