As the pattern evolves this week, the picture is becoming increasingly clear that another wet storm is in store for the Central and Northern Sierra for Thursday into Friday and a colder system late Saturday night into Sunday with Showers possible Monday. The first system has a big tropical/subtropical tap all the way down to north of the ITZ and no doubt has moisture from Hurricane Seymour. PWAT is forecasted at high as 1.50 to 2.00 inches along the coast of Central CA Thursday AM. A healthy subtropical jet of over 100 knots is associated with it.  The freezing level is expected above 11,000 feet and so for the most part, this is going to be another rain event for Mammoth and the Eastern Sierra Thursday and Friday.  The forecast models are now showing a colder system for Sunday morning that may bring snowfall into the Towns of Mammoth and June Sunday morning and into the afternoon. Amounts are uncertain depending upon how much moisture remains when the cold air arrives Sunday AM.

Back to the details of Thursdays/Friday’s Storm….

A large deep upper low near 50N/132W will initially steer a very dynamic impulse through a deep area of low pressure into the pacific northwest tonight. Thereafter, strong southern stream energy approaches Southern and Central CA later Wednesday. This will provide an extensive surge of pacific moisture directed at much of California. The fetch appears to have both Subtropical moisture from north of the ITZ, combined with eastern pacific tropical storm Seymour inflow. This is not actually an “AR” but the effects would be similar because of the strong moisture transport ahead of the short wave and the subtropical upper jet reaching deep into the subtropics. The big question this morning is….how quickly will the moisture move out or get cut off? This is because, as the long the fetch remains intact, the faster the rainfall totals will accumulate.  Forecast models are not all that good in handling tropical moisture influx in this part of the world. So no doubt they will be playing catch up as time gets closer and the timing becomes more clear.

As a comment……..Burn scar areas along highways 395 dodged a bullet last storm that brought about 4.00 inches of rain to Mammoth Lakes two weekends ago. This coming Thursday into Friday afternoon storm has the potential to bring another 2 to 3 inches of rain at this time.  7 day forecasts of QPF are again in the 4 to 5 inches range again according to WPC’s QPF center.