A “Major” Sudden Stratospheric warming event is underway over the Arctic at the moment. One that may change the course of one the driest beginnings of Winter to the Central and Southern Sierra in years…..  The SSW, (Sudden Strato Warming Event) is a process that can rapidly warm the stratosphere of over 100F at times, caused by planetary wave breaking (Rossby Waves) that propagate up into the Stratosphere. The sudden heating of the Stratophere creates high pressure over the polar region that can dislodge the polar vortex or even breaking it up into smaller vorticies sending them south “toward” the mid latitudes. All in all, the main effect is a southward adjustment to the Polar Jet, which is in the end, what we want to get winter going!   Thus far this winter, the polar jet has been over the Pacific Northwest, south to Northern CA.,   This is a reason why Mammoth has not received much in the way of precipitation. La Nina has effectivly blocked and/or weakend the MJO from periodically forcing the usual wet patterns that develop along the southern and central west coast, The SSW may be our savior that adds a northern latitude variable to the equation of getting the upper jet well south into CA.   Here is a link to more information on the SSW; https://www.severe-weather.eu/global-weather/stratosphere-major-winter-warming-watch-january-2021-fa/   

COMMENT:    By the looks of what is going on over the Arctic with its strong height rises in the global models and a massive PV headed south over East Asia, this is going to be a big deal for the Central West Coast this January, as the Extension of the East Asian Jet progresses to the west coast with some very signifacant “Atmospheric Rivers”.

The Screaming message here is that Winter is coming!!


Dr Howard and the Dweebs……………….:-)