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Monday, June 5, 2017

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

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 the ice shelf more frequently and going more zonal with less amplitude in the planetary waves. This flattening of the Rossby or Planetary waves in the Southern Ocean/hemisphere seems to allow the Northern Hemispheres jet stream to find a lower latitudinal flow regime in the North Pacific thus as the Southern Hemisphere approaches Winter with the storm path stacked against the ice shelf the Northern hemispheres Westerlies have more flexibility to move toward lower latitudes like Tahoe.

Another interesting attribute to our atmospheric behavior lately is the global "Specific" humidity (amount of water vapor in atmosphere) levels and "relative" humidity (how close the air is to being completely saturated with water vapor) levels. As our earth warms with increasing levels of Carbon Dioxide the science is showing that specific humidity levels are on the rise and especially rising since the strong El Nino of 1997-1998! This makes since as C02 levels rise and the earth warms that the earths heat budget and equilibrium will have to relinquish its heat by water evaporation and/or the phase changes of water from liquid to gas phase or cloud development. This is what NASA has to say about these changing humidity levels:

Overall, water vapor in the surface atmosphere has increased over land and ocean relative to the 1970s (specific humidity is rising), while the atmosphere over land is becoming less saturated (relative humidity is dropping). At first glance, that seems impossible. How can the atmosphere be getting less saturated if there is more water vapor in the air?

The drivers of this are not yet well understood but differences in rate of warming between land and ocean, and land surface water availability may be factors. Saturation—the point at which water vapor condenses back into water or ice, often forming clouds—depends on the air temperature, and air temperature around the world is also rising. Over many land areas, it’s getting warmer faster than it is getting wetter, which means the air is less saturated (relative humidity goes down), even as specific humidity goes up.

This is very complex science to understand how these changes are going to influence our climate systems, but what seems plausible is that with increasing specific humidity levels and more cloud producing nuclei (CPN's) would be conducive for more low pressure development globally meaning increasing likelihood for cyclones, hurricanes, typhoons, Noreasters, Atmospheric Rivers etc. However, the temperature of the land masses that are warming- especially along the southern extent of the Jet stream (i.e. central California)- will dictate whether the low pressures have the ability to stay intact and utilize the increasing specific humidity levels to rain out over the land and interior mountains like the Sierras. This brings me back to the Arctic and North Atlantic Oscillation I spoke of in my last post and how it relates to these wetter air masses impacting land and mountain terrain. When the Arctic Oscillation or North Atlantic Oscillation swings negative and allows colder air to spill downward into California or Europe it supports the low pressures to rain out and redistribute the water that has been transpired/evaporated from the oceans and the increasing specific humidity levels above the oceans thus allowing the air mass to reach 100% relative humidity above the land mass and begin to rain. My point here is that California weather and the Arctic Oscillation are very closely linked as specific humidity levels rise and our land masses warm.

Bottom line these increasing levels of specific humidity are going to be very important to study and relate to the teleconnective global patterns that allow the moister ocean based atmosphere to transport the overseas low pressures into regions like Central California, and not forgetting that California has the ability to generate extremely warm temperatures due to our geology and latitude geographic placement. Who is going to win the battle between warming land masses and increasing specific humidity levels? Last Winter we all know who won!!!

Stay Tuned ...

Monday, May 15, 2017

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 ...

Thursday, May 11, 2017

7 Days of Bad Weather Starts Tomorrow

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 ...

Sunday, April 30, 2017

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

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 Oscillation which is going negative also.

I have listed some of these complex teleconnections below.

1.) El Nino becoming new Normal- the oceanic sea surface temperatures are very supportive for a very active energized North Pacific jet stream and lower latitude storm track, meaning the east equatorial Pacific is anomalously warm (positive ENSO values).

2.) Indian Ocean Dipole- the Indian Ocean dipole is in neutral/positive phase allowing the thunderstorm belt/low pressure area to find a quasi equilibrium in east equatorial Pacific. This dipole has been in negative phase for the last two years or so and is moving toward positive now or a cooler sea surface temperature regime in the East Indian Ocean and has big impacts on the Madden Joulian Oscillation and intensity of El Nino rains during our Winters in Central California.

3.) North Pacific "Blob"-  the North Central Pacific Ocean where the " warm blob" was at fault for ridging during the drought is staying cool with below normal sst's. This cooler surface water weakens the North Pacific high and allows the storms drop south into California instead of being deflected into Canada .

4.) Sun Phase-Our solar disk or sun phase continues to show the "sleep of the sun" or the lowest sun spot/solar activity we have witnessed in possibly hundreds of years or maybe thousands. This low sun spot phase is effecting the tropopause (layer of atmosphere between Troposphere and Stratosphere) and the upper level temperatures of the Troposphere, thus influencing the high pressure or warming of the arctic (more ozone is a function of less incoming solar radiation creating a heat sink during the Winter and higher pressure over the Arctic).

5.) Pacific North America Pattern-The strong Arctic High this winter responsible for record warmth in the Arctic is also exerting forcing on the Northern Hemispheric jet stream supportive of a positive Pacific North America Pattern or lower warmer jet stream entering the West Pacific Ocean from southern Eurasia. This jet stream pattern is also related to the positive ENSO values taking hold in a large portion of the east equatorial Pacific Ocean.

6.) Hadley Cell- Lastly the Hadley Cell circulation properties at the present-conducive of Solar Minimum- is relinquishing the equator warmth into a lower latitude than normal (reason we had so many atmospheric rivers this Winter I'm hypothesizing). Hadley Cells play a major role in earths thermodynamics and its heat budget and equilibrium. It seems with a warming planet from natural and man made influences along with the very low solar minimum levels could be a perfect combination for a wetter climate along the West Coast of North America.

Bottom line our weather pattern or global climate system is in territory we have never seen especially with the very high human induced CO2 levels thus "normal" is no longer going to be "normal" and we need to prepare for weather patterns we have never seen or experienced since weather record keeping began.

*Fantasy forecast seeing next Winter looking extremely active again and could be one of wettest years since floods of 1862 and yes i mean wetter than this year with no break in March next Winter. Bit worrisome to be honest!

Stay Tuned ...

Sunday, April 16, 2017

3 Weak, Moisture Starved Systems Heading Our Way

We have 3 systems that will move quickly through and have a slight impact on the area. I do not see any major snowfall amounts in any one given time period, however the total of all 3 systems will leave us with more snow in the Carson Range and Sierra.

Let's focus on the total precip and snow levels. Mt. Rose will receive all snow. For the most part snow levels will be around 6,500-7,000 feet. However, the 2nd system could bring in some warmer air and snow levels could jump to 7,500 feet late tomorrow or early Tuesday.

Here is the precip forecast:

Some areas of the High Sierra, around the western crest could see as much as 3 additional feet. Those areas, above 9,000 feet have picked up so much snow this season, that 3 feet is like a few inches anywhere else. It is interesting that Mt. Rose has led North America in snowfall amounts, because the highest peaks, west of Lake Tahoe at the crest of the Sierra have picked up much more snow, perhaps some areas in the 1,000 inch range ... uninhabitable!

I do see 9-18 inches of additional snowfall for Mt. Rose by late next Wednesday.

After that, high pressure begins to dominate and we will see a fairly significant warming trend. How significant? There is a chance of 80 degrees for the leeward valleys, next Saturday.

Stay Tuned ...

Sunday, April 9, 2017

Next Storm Coming Late on Wednesday

We are tracking 3 storms right now for next Wednesday, then a week from today and then, perhaps, the 21st of April. The last storm hooked up nicely with a moisture tap and we see something similar for the storm next week, although probably not as much moisture by about half.

Here is the forecast for late Wednesday night:

A decent moisture connection, but nothing like what we saw in the last storm. Snow levels for this one should be around 6,500 at the start and fall to around 5,000 feet as the cold front passes through. That means the leeward foothills can expect more snow on the ground.

The following Sunday night see's the next storm come in. This storm does not have the moisture associated with it and will only bring in more cool air. I see light amounts of snow and lot of wind. Here is the forecast for Sunday afternoon as the storm approaches:

The last storm we are tracking could show up on the 21st and may bring a return to the moisture tap, we will have to wait and see.

Here is the moisture forecast for the next two systems, as you can see nothing like this last system:

I am thinking 9-18 inches of snow for Mt. Rose by Friday morning with an additional 2-6 on Sunday night.

Stay Tuned ...

Thursday, April 6, 2017

Storm Track Shifts North, Storms Stacking Up

The storm track for our latest weather system has shifted north and Tahoe is now right in the bullseye of the storm. This is a major storm for this time of year and will last through most of Saturday with high winds and lots of precip, mostly snow above 7,000 and perhaps lower.

Most of the major precip should be over by late Saturday afternoon. However, we are talking about a lot of rain and mountain snow between now and then. The possibility exists for a major snow event for the leeward foothills around 5,500 feet and above as the NWS is having difficulty pinpointing snow levels with this very unusual storm. If you live in one of those areas, be prepared.

The next storm we are tracking comes in next Wednesday, April 12th. This looks like an abnormally large spring storm again:

This storm has adequate moisture and will come in warm we believe right now. Our best guess is 7,500 feet. This system will stick around until late Friday afternoon.

We are tracking another abnormally large spring storm that could come in around Tuesday the 18th. It appears to be following in the footsteps of the first two storms. Speaking of the first two storms, here is the precip forecast:

Folks, there is a good chance that Mt. Rose could pick up an additional 3-7 feet of snow in the next week with what appears to be more on the way.

Nice to have Paul Huntington back, his crystal ball seems to see just a little further out than others! If you have not read his post from last column, you should.

Stay Tuned ...