Archive for October, 2016

Height Rises to provide warmer days and a bit of a break in the wind later today and into Wednesday….Next short wave to tap Bonanza of subtropical moisture from north of ITZ and remains of Hurricane Seymour with potential for another rain event for the high country Thursday into Friday…….Cooler system to move in Late Saturday night with the chance of some snowfall to the Towns of Mammoth and June Sunday AM….

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.



Another Active 2nd half of the week is expected with the potential of more heavy rain Thursday Night into Friday….October rainfall records look to be in jeopardy….

The front left exit region of the subtropical jet is creating the lift this morning to produce some light rainfall in the Town of Mammoth. Once this wave passes we will have lots of clouds the next couple of days but dry weather.  A long wave trof has taken up residence over the Eastern Pacific. However,  too far west for cold enough air to bring snowfall to the Town of Mammoth. Heights remain in the low 570s DM at 500MB, so we are in the sweet spot for rain and tropical moisture but little in the way of snowfall at the 7000 to 8000 foot level. This large-scale adjustment wave will continue to send several shot of energy into the west coast over the next 6 to 10 days affecting the central sierra periodically.  The most significant development is hurricane Seymour off the coast of Central Mexico. This moist system will be moving over colder waters soon…thereby dissipating and releasing its moisture into the surrounding area. With the long wave located at 135 west and a rather sharp short wave progged Thursday AM, no doubt that there will be some heavy rainfall headed for the Sierra Thursday afternoon into Friday AM.  The PWAT from that fetch is forecasted to be as high as 2.00 inches Thursday AM just off the central coast.  Rainfall amounts may tally similar amounts that occurred weekend before last, tying all time October rainfall records for the Central and Northern Sierra.

As far as snowfall, most of it will be above 9500 to 10,000 feet again. At the moment, the OIP looks to be Thursday night into Friday AM.


+SSTA’s are still warmest in the North Pacific. If they remain their, that would lend bias to some mighty cold weather later in December and January.  As mentioned in a past discussion, this is a winter that will be difficult to forecast as the climate models have not done a good job so far.  I would not put .02 cents on any long-range forecast at this time.  As an example Scripps forecasted a “strong La Nina” last Summer and that goes against most climate models now. The PDO as become neutral the past 2 months and there is only speculation on what it will do this winter.  If the Warm Blob backs into the NE Gulf of AK again, there goes our winter. If it remains weak, with anomalous SSTA warmth continuing over the north pacific, that would be more interesting for a normal to wetter than normal winter. The Climate models can forecast all they want but if they do not pan out, they are worthless. Best to stick to the week one and week 2 forecasts and track the MJO for highlighted weather events this winter….


Note; the Dweebs will take a hard look at things later in November to see if there is more consistency in the climate models and at the least, the forecast of the PDO and ENSO.

October Precipitation off to a grand start with 4.03 inches of rain here at the Village at Mammoth over the weekend….For some areas it is the 3rd wettest Oct on record already…..Still lots more time this month to set all time October Precipitation Record……While we wait….Another warm up is in store with temps in the upper 60s Friday…….Is another AR event in the cards for Northern and Central CA this month?

A great storm for the trees!  They need water just like we do. Four inches of rain will certainly help the forest but unfortunately it is too late for many of our giant pines…. Some are now widow makers so be sure to check out carefully around your residence’s. If the’re up wind and dead, get a professional to inspect them and cut down if necessary.

The absolute most dangerous time for tree damage is when we have heavy wet snow that clings to the upper tree followed by rapidly falling temps, and gusty winds.  So if the forecast is for heavy wet snow followed by a quick drop in temps such as after a cold front passage, along with strong gusty winds post frontal….beware! 


This is a different fall. And anything different is a good thing compared to the past 5 years. What is different?  For one, the westerlies were exceptionally strong across the north pacific over the past week.  This was due to the block over AK and the undercutting of the westerlies. Add the tremendous latent heat from not one, but two typhoon’s and Northern and Central California hit the Jackpot! The upper jets strength was spun up more from the tropical systems than cold air advection as is usually the case in winter.

Although we have some fine weather shaping up the next few days….Next week could prove to be interesting and active again. Although no typhoons are expected to become extra tropical over the central or western pacific, the upper pattern does amplify due to a shot of cold air coming off of Eastern Asia. The location of the deepening trof off the North Eastern Asian coast suggest strong amplification of the westerlies downstream with an upper ridge building out at 170west. This is a little west of where the Dweebs would like it to be…..So the upper trof sets up at 140west.   However, in that there is no high latitude block this time, Short wave energy will likely over run the central pacific ridge with time, and either cut the eastern pacific trof off or deepening it SW/NE, which may set up another AR for Northern and Central CA within the next 6 to 10 days…. The AR if it does develop, it does not look as wet or protracted as last weekend. Nevertheless, it may be enough to set an all time precipitation record for October for parts of California and Northwestern NV.

In the meantime, LA is expected 100 degree heat Thursday from a hot *Santana and Mammoth temps will climb into the upper 60s.  All areas will expect cooling late in the weekend with the pattern change expected.  The Dweebs will have a better handle on the prospect’s for more rain or snow early next week or before.

North Pacific Sea Surface Temperatures:

Biggest anomalies are in the Bering Sea now about 170West.  Is it coincidence that the mean pacific ridge is now about 170west?  Is the position of the Anomalous SSTA the Chicken or the Egg?

Also there is a cold pool developing between 160East and 160West, between 40 and 50 north.   Could this be the beginning of the resurgence of the dreaded +PDO?


Stay tuned…….


*Santana = Devil Wind