Posts

Fall/Winter 2017-2018 Update - Walker Circulation Strengthens Suggesting Wet Cold Start and Drier Late Winter

Image
By Paul Huntington

I just wanted to highlight some recent atmospheric and oceanic observations that point toward a "possible" drier than average Winter for Central California with cooler northern storms (Inside Sliders) rotating down from the Aleutian Islands and less atmospheric rivers than last year, however the Madden Julian Oscillation (MJO)--that has been fairly quiet and inactive recently- is showing signs of waking back up along the Intertropical Convergence Zone (ITCZ) in proximity of the Maritime/Indonesia region or West Pacific along with the upwelling directly off Peru (localized El Nino) slowing down allowing warm sea surface temperatures to establish within the far eastern equatorial Pacific Ocean. Meaning things could change late Fall into Winter and recently our wind patterns/oceans have been showing tendencies toward strong variability in the strengths of El Nino indices- and even going from medium strength La Nina to very strong localized coastal El Nino off…

When Will the Storm Machine Start Cranking?

Image
Although it has been a cool fall, we have not seen any winter storms thus far. Currently we have our persistent ridge of high pressure blocking storms and forcing them north, take a look:



 However, I am seeing a change in that pattern with two storms, one from the south and one from the north, squeezing that ridge out to sea. That change looks to be around the 19th or 20th of October. The massive storm in the image above, will move south and split into a large and small storm. The smaller storm will move way south while the larger storm will come ashore in Washington. Here is a look at the forecast for very early on the 18th:


The storm to the north will drop a wave south, right into the Tahoe area. That will pick up sub-tropical moisture and deliver it to the Sierra. Here is a look at the 19th of October:



I do not expect any major precipitation, but we could see up to a foot in the Carson Range, as this storm's trajectory looks pretty good. This is an early season warmer type of s…

Winter 2017/2018 Outlook

Image
By Paul Huntington

What is next Winter going to bring to the mid latitudes in the Northern Hemisphere and how are the large planetary waves going to behave? Planetary waves are the oscillations in the jet stream around the mid latitudes (Westerlies) that bring either high pressure (ridging) or low pressures (troughing) in the atmosphere and behave much different than the low pressures around the equator that form more from very warm ocean surface water and air condensing into water vapor/clouds and large cumulus thunderstorms/cyclones that create a feedback loop called the Madden Julian Oscillation (MJO), this reverberant affect propagates eastward around the equatorial world kind of like a stack of dominoes folding upon one another. It is very hard to predict when and where it might find a comfortable region stalling out and influencing the Northern Hemispheres Jet stream dynamics but seems to be acting up recently and could be a major player in the extension of the Asia Pacific Jet…

Storm Begins June 8-9, Report on Global Specific Humidity

Image
By Paul Huntington

Starting on June 8 Thursday a big pattern change is taking place with a very unseasonable strong low pressure rotating down from Aleutians and could bring as much as a foot of snow above 8000 ft, adding even more white stuff to our already incredibly large snow pack in the Sierra. The meridional angle (El Nino type trajectory) of the jet stream in the North Pacific is following a very similar path to what brought us saturated air masses throughout the Winter in 2016-2017. Moreover, it seems the Arctic Oscillation is finding a quasi equilibrium more around negative than positive meaning the pressure gradient in the North Pacific on the southerly extent of the northern hemispheric jet stream (westerlies) is lower than average thus allowing the jet stream to dip down into California. Also the Antarctica Oscillation is finding a quasi equilibrium in the positive (climate change and a warming planet could be fueling this pattern change) meaning the jet stream is hugging …

Weak System then Beginning of Summer

A weak, moisture starved system, which is being completely oversold by the local media, will come in tomorrow and clear out by early Wednesday morning. Temperatures will drop, especially in the mountains, but this is nothing like what we have seen this winter.

Starting Wednesday afternoon we see high pressure taking over and we could see our first 90's by late in the weekend or early next week.

Stay Tuned ...

7 Days of Bad Weather Starts Tomorrow

Image
We hope you enjoyed these last few days, because the warm sunshine is going to give way to West  Coast Troughing starting tomorrow. For about the next 7 days temps will struggle to get out of the 50's with cloudy, windy, cool and even rainy conditions. Perfect for getting those last turns of the season at Mt. Rose!

This stormy, cool weather will culminate with at least a reasonable chance for some rain and snow next Tuesday afternoon. Here is the forecast for Tuesday afternoon:


This is a slider type system that will drop out of the north and really make us question if it is really May.

As the season winds down and the weather begins to stabilize, our posts will decrease as there just is not much to talk about. However, rest assured we are keeping a very close eye on next winter. If you read Paul Huntington's post from last week, there are several reasons to believe, that this years record precipitation may also be on tap for next year.

Stay Tuned ...

Cool, Wet Weather to Return Next Weekend. Six Teleconnections that Suggest this Winter's Pattern Continues!

Image
Report by Paul Huntington I am seeing some interesting active late season weather beginning around Saturday May 6 and continuing for a couple weeks into Middle or even late May. These wont be huge storms like this winter but more cool showery lows with embedded thunderstorms and enough to warrant people to question "What is happening to our climate system?"

Once again the global teleconnections are again in perfect alignment for troughing along the West Coast of North America. Yes, I know its time for Spring and warmer weather but we might need to wait- albeit this weeks heat spike- till June. The pattern that is unfolding is very similar to what brought us rains throughout our Winter and doesn't seem to want to budge. The climatic pattern taking shape in the North Pacific is supported by the Negative phase of the Arctic Oscillation or a weakening pressure gradient between the North Polar low and southerly high in the Central North Pacific along with the North Atlantic O…