Our very long string of beautiful…warm to hot…late winter-days continued today. The crystal clear skies were marred in parts of NorCal only by the thick creosote smoke originating from the large fire on the railroad trestle over the American River in Sacramento.  Temperatures exhibited a huge diurnal range in inland areas, dropping into the mid 30s and night and rising into the mid 80s during the day time (in interior Moneterey County, the range was from 39-97!!!). Low clouds and fog are currently hugging the coast, bringing an east-west temperature  gradient more characteristic of summer. Warm weather will gradually cool to only slightly above normal levels by late in the weekend, but the weather will still be spectacular. And…on Monday…our weather takes a turn for the climatological mean: cool, with some spring showers. A trough will approach CA from the NW by late Monday afternoon, and may be able to generate some scattered prefrontal convective activity given the very rapid cold air advection aloft and the increasing dynamic lift as the trough approaches…especially in NorCal if the system moves in when there is still some daylight. The front itself will not be too impressive, though it too could have an isolated thunderstorms embedded in it. No heavy rains (except possible local downpours) are expected with this system, but I do expect some sort of cold front to make it all the way south into SoCal on Tuesday. In all likelihood, there will just be some brief light to moderate rain with the front totalling less than 0.25 in., though that would be enought to dampen the ground and lessen the fire threat for awhile. In NorCal, 850 mb temps drop below 0 C by late Tuesday, compared with 21 C currently in place, so a few showers or isolated thunderstorms could develop behind the front even in the absense of any significant large-scale dynamic lift or even much vorticity advection. After a few cool days in the middle of next week, temps rise again to above seasonal norms by next weekend once again. There are some indications that this more typical spring pattern–with occasional chances of precipitation and no more searing heat–will continue for a while. An MJO signal may be developing in the tropical Pacific, and if this develops further and moves east past the Dateline we could be in for some rather active spring weather in the 2-3 week time frame. We can hope, anyway…

 Where has all our rain gone, you might ask? It appears that our share (and then some) of this year’s atmospheric moisture has been transoprted to the French island of Reunion. Tropical Cyclone Gamede set a new world record for 72 hour rainfall earlier this March when it dropped a whopping 154.8 inches (that’s 2.15 inches/hour for three days straight). Even more impressive is the 9 day total of 217.2 inches, which is also a world record. In other terms:  that’s two decades worth of rainfall in San Diego.