As we say good by to Spring….The next transition will be from the current Spring like pattern of weak migratory trofs moving into the pacific NW, modulating our local Zephyr, to a pattern highlighted by a strengthening continental high over the four corner states.

It is always fun to watch this transition from a global model point of view, as Climatology points the way, with the models usually following. Currently, the models are showing the first real development of a toasty pattern that brings the warmest weather to the Sierra of the year. The models are timing it to build about July 2nd through the 4th of July Holiday Weekend, as the ECMWF has the toasty 594DM Height isohyet into the Eastern Sierra for the 4th of July holiday itself. I would suspect that the heat will continue well into that following week, unless we get an early season TSRW outbreak.

It is at this time within the first 10 days of July that the highest temps over the Eastern Sierra usually occur.  Why? Not only is the Sun the highest in the sky, The strongest surface heating/convergence and diffluent thicknesses process is occurring to the SE over the Desert Southwest. A strengthening continental upper high is occurring, while SE flow usually does not really established itself in early July. Thus our air mass is initially stable. With a favorable pattern, temperatures can reach into the upper 80s and sometimes low 90s in Mammoth depending on where the core of the upper high sets up. Thereafter, The Desert Monsoon Season kicks in. Easterly waves forming in the underbelly of the continental high, pushing westward or northwestward, occasional moisture advection and most importantly favorable surface convergence over our elevated heat source can trigger thunderstorms.  So while the Cap of an upper high allows heat to build within the air mass, once that cap weakens or shifts east, the lid comes off allowing an outbreak of thunderstorms. Thus the 2nd week of July is most favorable for a heat wave related thunderstorm outbreak pattern over the Eastern Sierra. This is the Climatology of that time here in Mammoth. With that said, that is climatology and what we expect, weather as we well know is what we get. So Thunderstorms may erupt over the July 4th holiday, providing a little of mother natures own fireworks as well.


In the meantime, say good by to Spring today…..1st day of summer arrives Saturday at 3:51AM…..  Highs in Mammoth now in the mid 70s jumping to the low 80s by Monday or Tuesday. There is expected to be one more brief pull back in temps going into the following weekend of the 26-28th….Then Mother Nature cranks up the heat…for the July 4th Holiday weekend and beyond…..


Dr Howard and the Dweebs…………………..:-)