Los Angeles Basin Heat Waves Likely To Continue
Discussion: The departure from normal for July (so far) at Burbank, CA is +6.2F. Last year and 2016 were also hot with departures of +4F and +3F respectively. This year July will produce 11 days with a maximum temperature >95F compared to just 3 last year and 6 in 2016. July 2018 is not only hotter than the last 2 (July’s) but the extreme (hot) character of July 2018 is sharply stronger than 2016 and 2017.
The cause of the extreme heat is a widespread intense drought across the southwest quarter of the U.S. During summertime LARGE AREAS OF SOIL MOISTURE DEFICIT have a tendency to maintain subtropical ridge areas aloft causing a feedback mechanism to the atmosphere to intensify drought. Unlikely is a scenario (through early October) in which the high pressure area causing the anomalous heat breaks down to bring a persistent cooler pattern change. Forecast models indicate a wet monsoon bias for Arizona leaving the Los Angeles basin on the dry (and hot) side of such a regime.
From a climate perspective a large area of warmer than normal sea surface temperature anomalies (SSTA) southwest of California and Baja California is regaining strength and correlate to continued high pressure over California and much of the West the remainder of summer 2018.
There is an El Nino Watch in-place although this regime has been slow to develop. During El Nino the eastern tropical Pacific is warmer than normal and produces above normal tropical cyclone activity. Heat relief from a north turning tropical cyclone (clouds and/or rain) might be the only way to break the heat.
The 16-day forecast indicates the current heat wave lasts a little longer, into the weekend before cooling a bit next week followed by another heat wave August 8-10 (and possibly longer).
The August 2018 monthly temperature departure from normal is projected near +3F to +4F. August 2015 was similar (+4.3F) when 5 days exceeded 100F.
Summary: The torrid heat breaks this weekend especially near the coast. Another heat wave occurs beginning August 8. August could produce another 4-5 days >100F. Anomalous heat continues into early autumn.