Major pattern change for CA

Dry and warm weather continues over the state of CA. Thursday’s suprise precipitation event in far SoCal notwithstanding (which brought showers and thunderstorms to some coastal areas, areas of heavy precipitation, and a rather impressive dump of snow to the San Diego County mountains, in addition to light snow showers on the valley floor southeast of Bakersfield), February has thus far brought generally normal to above normal temperatures to the entire state along with little to no precipitation. This will change by the middle of next week, as a more zonal jet stream begins to develop and intensify as it sags south into CA by next Tuesday. The first system or two won’t be particularly impressive, as they will meet with a great deal of resistance as they eat away at the persistent ridge and the very dry air aloft curently in place. A potentially very moist plume originating over the Central Pacific will begin to move in by Thursday or so, and some significant precipitation is likely at least in NorCal by that time. 850 mb temperatures will also drop significantly with these systems, from 12 C currently to as low as -3 C by next Friday. This will drop snow levels to well below pass level–eventually to 2500 feet or so. The models are handling this shift very differently with each run, so don’t expect any consistency for at least another 48-72 hours.  The general theme, however, is colder and wetter for CA (probably the entire state, but especially the north). It is interesting to note that La Nina continues to be impresive over the equatorial Pacific, and will likely continue to exert a major influence on the pattern going into the spring. The ongoing ENSO cold event is very likely the cause of the extremely cold and snowy weather over the Middle East and China over the past 2 months. Despite global temperatures being cooler than they have in a while, however, the extent of the Arctic sea ice is still near record-low values, and the total ice content (when thickness is taken into account) is almost certainly the lowest since satellite measurements began and probably much longer than that. It’ll be interesting to see how far the ice recedes this summer…