Storm Clouds Clear Out to leave cool crisp morning in Mammoth with Icy Conditions and Clear Skies…..Westerlies continue to slowly strengthen as well as El Nino…..The week ahead looks seasonal and dry….However….Toward the end of next week, Stormy….
Monday October 19, 2015
Posted at 8:43 am by Howard
Chatted with one of the Leed’s this morning and the upshot was that too much is going on at this time to make an accrete QPF forecast for the Wednesday night-Friday system. There are two tropical storms out over the pacific. One that is phasing with the westerlies over the western pacific, but that should be well into the guidance by tomorrow AM. Over the eastern pacific, tropical storm Olaf is being picked up by the next wave approaching the west coast.
I will make a guess at this point but there is not a great amount of confidence. Maybe by tomorrow morning things will be different?
For what ever it worth, it appears that chances are decent that some light snow to fall…..between Wednesday afternoon through Friday night. The snow level will begin about 8000 to 8500 feet Wednesday night but will come down Thursday and down further Friday/Ngt. The wettest model tries to bring in close to an “inch of QPF” over the west side of the sierra, over the 3 day period Wednesday night through Friday night. The driest model brings in about .25 during the same period. That is quite a big spread but that is what I am working with. October is a tough month for forecasting….It should be easier later in November though the Winter. Next update in the morning…
Longer range is not convincing enough to get excited about anything yet…..However, hemisphere is chilling fast and so it is just a matter of a few weeks to start seeing in the models some significant storms headed for the west coast….
OCTOBER 24th Update:
Models are diverging from earlier prongs for a storm capable of delivering several inches of snowfall to the eastern sierra. I still expect some light snowfall Wednesday over the higher terrain but it is not looking as favorable now as 3 days ago.
I will have a complete update Sunday on next weeks weather and beyond…
Oct 21st, Wednesday AM:
There appears this morning, to be the possibility of a decent storm, sometime between next Wednesday and Halloween.
Here are the ingredients:
- Typhoon Champi was located some 500Mi due south of Tokyo this morning
A. Over the next 5 days Champi will be totally extra tropical and merging with the westerlies as it moves NE
- A moderate trough will move off the Asian coast this Saturday AM and constructively phase with Champi over the following 24 hours building a strong ridge down stream on a longitude between the Dateline and the Hawaiian Islands.
- That amplified ridge deepens a new trof down stream over the East Pac tapping cold from the GOAK.
- This eastern pacific trof entrains now Hurricane OLAF as a extra tropical storm which spins up the jet in the negative tilt system. This builds an upper ridge over the pacific NW while the upper trof digs into California “”About”” next Thursday the 29th. This timing is subject to the scenario over the western pacific.
- Climo wise, this will bring the possibility of our All Hallows eve storm, even through the storm may come a day or two sooner. The models also suggest that the leading trof may be just the 1st in a series into that following 1st week of November.
Wednesday PM Update:
It should be noted that in advance of the system next week, there is a mid latitude upper low north of Hawaii this afternoon that will bring clouds and possibly some showers this Sunday….
Once again another interesting 5 day period of weather over the southern half of the state of CA. Precipitation amounts ranged mostly between 1.25 to 2.00 inches in the sierra with some isolated amounts of 3.00+ inches, especially in the mountains north of Santa Barbara. The weather has been greatly influenced by the highly anomalous sea surface temps off the Southern California Coast this Summer, and now Fall. The positive phase indices of the PDO for the month of September reached 1.95. Comparing that to September of 1997 was 2.19. A moderate weakening began in October of 97, before rapid weakening the end of that year. The PDO in its positive phase is responsible for a lot of heat in the oceans along the west coast the past 12+ months. Oceanic Kelvin Waves have added to that heat this year allowing SSTA to reach record levels west of Southern CA beaches. Sea Surface temps according to buoys, recorded temps just over 80F is some cases this past September.
The Quite Giant:
El Nino’s effect upon our current weather is quite incipient now compared to what is likely to happen this Winter as the East Asian Upper jet strengthens and migrates south and splits eastward from the Subtropics. Its split southern branch associated with the +PNA teleconnection pattern will likely bring a lot of beneficial rains to the Southern half of our state. In the case of strong El Niño’s like this one, even the more northerly portions of the state that are often times absent from the effects of El Nino’s wet pattern may benefit.
The Dweebs are following the RIMM phase space that are at least suggestive of a strong MJO to develop over the Indian Ocean with the potential to flip the PNA to negative in the coming weeks. . As mentioned in my last discussion, there appear to be an emerging signal over the east coast of Africa in the Eastern Indian Ocean. As of late, the Ensemble Global Forecast System may be hinting at an Equatorial Rossby Wave or tropical Storm or KV because of the emergence is followed by an Eastward shift with the convection. That is not all that encouraging….
The ECMF is progressive and needs to be followed…..As strong Convection between 70E and 100E over the Indian Ocean is often associated with a flip in the PNA to negative and long wave trofing over the Eastern pacific. This looks like sometime between week 2 and 3. I will update Wednesday AM after the CPC update….
As mentioned last August, the warm water along the west coast is reminiscent of the winter of 1957-58 El Nino year. However, the strength of El Nino this year is stronger, but the SSTA structure along the west coast is similar. That allowed a winter of 140% of normal to Mammoth Lakes. With as much energy (Heat) that is trapped in the tropical oceans over the EQ eastern pacific, there is likely going to be some pretty intense precip events this winter. The CFS VS2 is calling for a November that has normal amounts of precipitation for Mammoth Lakes. December on through the Winter is expected to be much wetter than normal. I have given up on following the ECMWF monthly guidance for precipitation as it preformed so poorly last winter and several winters back. To me it does not make much sense to try to predict 3 months of precipitation on a monthly basis, let alone a month’s worth of precip for area’s like Mammoth Mt, when you have to consistently update those figures during the month. The best forecasts will be the ones with the best guidance 7 to possibly as much 10 days out, once we get into the meat of the winter.
Although, this winter looks quite wet snowfall wise with snow to ratios low, and the likelihood of the Platinum Powder Criteria not being reached until late winter like late February or March. Nevertheless the Dweebs will still hope for a good cold one at some point! In the meantime, for those that have signed up for the Platinum Powder alert system, I will make good use of email by offering you all some very good forecast information well before the weekends, so you can plan accordingly before coming to Mammoth. In addition, if the Dweebs see an opportunity to advise for a Platinum Powder advisory or alert, you will benefit from the timing to cut up some amazing powder…… As a reminder, Platinum Powder criteria is 12 inches or more of light snowfall which for the majority of it is at ratios of 15 inches of snow to one inch of water at 10,000 feet and above….
Dr Howard and the Dweebs……………………..:-)