Irma's continued trek west across the ocean was guided by a strong ridge of high atmospheric pressure over the Atlantic, which prevented the storm from curving north and away from North America. (usatoday.com)
In 2013 and 2014, a vast region of persistently high atmospheric pressure over the northeastern Pacific Ocean — known as the «Ridiculously Resilient Ridge» — prevented typical winter storms from reaching California, bringing record - low precipitation and record - high temperatures. (weatherwest.com)
The proximal cause of the precipitation deficits was the recurring poleward deflection of the cool - season storm track by a region of persistently high atmospheric pressure, which steered Pacific storms away from California over consecutive seasons (8 ⇓ ⇓ — 11). (pnas.org)