The Winter Outlook for 2012-13 shows generally normal snowfall for Mammoth Mountain and normal to slightly below normal precipitation elsewhere in California.
The forecast is based upon a neutral state ENSO in the tropical Pacific, but leaning toward toward a weak El Nino during mid-winter.
The other factors taken into account for the winter forecast is the continued negative (cold) phase of the Pacific Decadal Oscillation (PDO) and positive (warm) phase Atlantic Multi-Decadal Oscillation (AMO).
High latitude blocking associated with long standing high pressure ridges in northern Canada stretching eastward into Greenland should force the polar jet stream southward at times this winter, a feature absent from the atmospheric circulation last winter.
This effect is expected to take place by early/mid-winter allowing for earlier snowfall for the Central and Southern Sierra after generally normal snowfall during late Autumn.
There will still be the normal periodic dry spells during the winter with March expected to be the driest overall month of the 2012-13 winter.
Overall, this winter will be snowier that last season by about 100″, but more importantly, the snowfall should come earlier this season and likely will arrive by the end of December as opposed to the end of January like last year. WG
Winter Outlook Month by Month