Long-standing dry pattern may be coming to an end in Los Angeles.
Within the past few days, long-range weather models have begun to hint at major changes in hemispheric upper wind patterns potentially affecting western U.S. weather in January.
Persistent strong high pressure has consistently blocked moisture-bearing storms far to the north of the Golden state for the past two months, and this pattern may be coming to an end within in the next two weeks.
Upper air projections for the next 16 days continue to suggest a strong west to east (zonal) component developing across the Pacific Ocean from eastern Asia stretching possibly all the way to California. In addition, the strong well-entrenched blocking western U.S. high pressure ridge in place since November may be finally pushed north into the Gulf of Alaska, allowing a moisture-laden flow of subtropical air to begin its eastward trek into California. This “undercutting” current also has the potential to push cold arctic air over other regions of the country back north into Canada, allowing for relief from bitterly cold conditions causing misery and distress across parts of the Midwestern U.S.
This major change often does occur in any January following two months of what meteorologists refer to as a “high amplitude meridional flow” pattern over the country.
Statistically, it is unusual for any weather pattern to remain stagnant for two months or longer; the longer it remains in place; the greater are the chances that it will be finally be pushed out, and for a longer period of time. Such was the case in some of California's wettest years, in the late 1970s and early 1980's.
But because of the absence of favorable oceanic temperature patterns, a sudden and prolonged extremely wet pattern isn't probable for Los Angeles, perhaps just a reversion to a more normal rainfall pattern starting in the first week of 2014.
Meanwhile, the short term outlook is for another episode of moderate Santa Ana winds in greater Los Angeles and vicinity through early Monday as yet another passing weak disturbance is followed by re-strengthening high pressure over the interior west.
But some relief from unseasonably warm and dry conditions here locally stands a good chance of taking place within the next two weeks.