Few showers of the frozen variety, then warmer and drier

Filed in Uncategorized by on January 16, 2007 2 Comments

A very weak upper low is currently diving down the CA coast. The low is expected to track just inland from the coast overnight and approach SoCal with mainly overland trajectory. This system will be somewhat similar to the one that moved in at the end of last week, except that the air aloft will not be quite as cold (-2 to -4 degrees C at 850 mb vs. -6 to -7 C) and there will be a little more moisture associated with it (0.45 PW vs. 0.15 PW). Still, given the cold air already present over CA, still expect some low snow levels (500 feet in the far north; 1000-1500 feet in the Bay Area) with the scattered showers. There is actually a small chance of freezing rain (not to be confused with sleet) late tonight in the Sacramento Valley with any showers that do fall as overnight breaks in the clouds allow for surface air temperatures to fall to near freezing (and ground temperatures to fall to 29/30). Don’t expect an ice storm, but it would certainly be wise to watch for icy roadways early tomorrow. Less than 0.10 inches is still expected, however, and aside from some isolated snow showers near the Grapevine tomorrow afternoon the weather looks to clear up very quickly. A couple of colder nights will be on tap again after skies clear tomorrow, but certainly not to the record-breaking and locally damaging magnitude we have experienced recently. 850 mb temps will begin a slow rise thereafter, climbing well above zero and possibly exceeding 12 C by early next week. In fact, we could be looking at a favorable scenario for record-breaking warm temperatures (80s or even 90s in SoCal, 70s to locally 80s in NorCal) by week 2. Rather alarmingly, the GFS is currently indicating a completely dry period across the West–not just in CA, but in NV, UT, AZ, NM and nearly all of OR, with less than 0.35 falling even in WA, MT, and WY! Watch for the new CPC Drought Monitor graphic this Thursday–I think D0 will be expanded to nearly all of CA and the D1 and D2 areas will cover a much larger area of the Southwest. The ground up here is caked dry–and that’s saying a lot in an area that often sees upwards of 40 inches annually. We normally see (in my gauge) about 25 inches between October and the end of Jan. Currently, we have seen less than 9 in., and we’ll probably see less than an additional0.25 before the end of the month. Stay tuned…