2018 - Robert's botantical adventures in Northern California

[Robert]

We finally had our first significant snowfall of the season in the Sierra Nevada Mountains. Today I drove up to a few of my observation sites to have a look around.

The first traces of snow appeared at about 2,800 feet (853 meters). At my first stop at 3,625 feet (1,105 meters) I measured 6.5 cm of snow on the ground, with a liquid equivalent of 0.54 inches (13.7 mm) of precipitation. The temperature was 37 F (2.8 C), with low temperatures running 26 F to 22 F (-3.3 C to -5.6 C). Unless there is some warm air advection, the snow should hang around for a while. This would be great and much better than last season when there was very little snow until March.



There was much more snow on the crest of Peavine Ridge, 5,146 feet (1,569 meters). Here I measured a snow depth of 26 cm. Here temperatures have been running 18 F to 13 F (-7.8 C to -10.6 C) the last few nights. Daytime high temperatures have been close to freezing. The temperatures and snow depths are more typical of 20 years ago for this elevation, especially if the snow hangs around and continues to accumulate.



Currently there is a cut-off low moving slowly down the California coast. It appears that it will slowly move inland in Southern California. The dynamics for precipitation are fairly weak in our area. There is a good chance we will see nothing more than overcast skies over the next few days. The best chance of precipitation in our area currently appears to be on Wednesday. There is a bit of warm air advection, so if there is any light precipitation it will be rain at the lower elevations, and snow above maybe 5,500 feet, + or -.

The GFS forecast is for a stronger storm to move into the area Monday and Tuesday. With this storm there will be more warm air advection before colder air arrives. This is all, more or less, a best guess this far out. Conditions change rapidly during the winter months. Tomorrow the forecast could be for clear skies next Monday-Tuesday. Stay tuned…

Anyway, this is a good start to the precipitation and snow season. We are quickly moving back to average precipitation to date. If the current forecast for the ENSO holds we may have a warmer, more southern storm track (southern jet stream) later in the season. If this pans out we could end up with above average precipitation for the season, but with very high snow levels. Low snow levels and snow that lingers is highly beneficial in many ways. The added moisture lingering into the spring would help ameliorate our current wildfire dangers. Of coarse, I record and analysis the interaction of weather/climatic conditions with our native flora and ecosystems. Time will tell.

Stay tuned for the next report…

[Robert]

I was back on Peavine Ridge today measuring the snow.

Over the last 40 to 50 years, snow levels have been rising in our part of California. During the 1970’s it would snow on rare occasions in Sacramento. Thinking about it, the last time it snowed in Sacramento may have been about 1975. At the farm in the Sierra Nevada foothills, it snows less often, the snow does not linger as in the past, and it rarely accumulates over an inch or so.

Despite the fact that it snowed this morning on the crest of Peavine Ridge, the snow depth declined to 20.5 cm. In addition, the liquid equivalent of the snow also declined to 1.20 inches. I have a baseline from last year’s measurements, so I will see how this season compares. The behavior of the winter snow pack influences soil hydrology, the vegetation, and even meso/micro scale weather events in the region.

The good news is that I am not detecting large amounts of pollution in the precipitation in the Sierra Nevada. Sacramento is a mess! The effects of nitrogen oxide compounds (basically auto exhaust) that precipitate out of the atmosphere in the rain can be seen everywhere. Candelaria and Xanthomendoza lichens (they like nitrogen rich environments) are extremely prolific in the Sacramento area. Overgrowth of vegetation on depleted soils is also evident. The excessive nitrogen compounds alter plant metabolism. Stressed trees lead to frequent outbreaks of aphids and other insect pests.

With the recent storms in our area, we are slowly moving toward average precipitation to date. Currently I see mixed signals for more precipitation over the next 7 to 8 days. The AO (Arctic Oscillation) is approaching neutral. Although the ENSO Index (El Niño Southern Oscillation) has advanced, there still does not seem to be a large atmospheric response to the increase in SSTs (Surface Sea Temperatures) at this time. Presently, it appears that two waves with precipitation will move through our area during the Monday – Tuesday time frame. I certainly hope so! We need the rain.

[ArnoldT]

Robert:

Interesting connection.  Nitrogen from car exhaust contributing to increases nitrogen in rainfall increasing  growth of fuel for fires.

[Robert]

Hi Arnold,

Nice to hear from you.     

I have not found any relationship between the nitrogen oxide type components of the air pollution, the overgrowth of grasses, and wildfires in Northern California.

The air pollution problems in the city of Sacramento are glaringly obvious. On many days, a cap or inversion layer can be seen holding a dark grime of polluted air over the city. The symptoms of excessive atmospheric nitrogen oxide type pollutants can easily be observed throughout the area.

There are many variables that interact to create our current wildfire situation. Climatic change and invasive plant species (annual grasses, etc.) are two important variables, however there are additional issues that need to be address.

Here are a few interesting statistics:

In November 2018, the average temperature at the Placerville farm was 51.90 F (11.06 C), 1.58 F (0.88 C) above the 40-year average.

In November 2018, the average temperature at our Sacramento home was 55.10 F (12.8 C), 0.56 F (0.31 C) above the 10-year average.

In November 2018, the average temperature on Peavine Ridge was 46.12 F (7.84 C).

Currently precipitation is running 69% of average to date.

I am hoping that the atmosphere starts responding to the above average SSTs in the eastern equatorial Pacific. This will indicate the onset of El Niño conditions and hopefully above average precipitation in our part of Northern California. The down side of El Niño generated precipitation in our area is above average snow levels. A change back to a consistent snow pack that is thick, low and lingers is desperately needed to help ameliorate our long-standing drought and wildfire issues.

In the short term, a weakening storm system will approach Northern California in the late Sunday – Monday time frame. Currently it appears that we will receive some light precipitation from this storm, however the dynamics do not look promising. Our next chance of precipitation looks to be around 15 December. Much could change between now and 15 December. Currently the AO (Arctic Oscillation) Index is positive 1.5. This is generally not a good indication for much in the way of future precipitation for our part of California. Specific forecasting beyond day 4 is still very problematic. I am hoping for the best.

[Robert]

Friday, 7 December 2018

0600 UTC



It was a pleasant afternoon on Peavine Ridge today. There were high clouds from a storm passing to our north, and it was a comfortable 48 F (8.9 C). The snow is melting, however there was still 17 cm on the ground with a liquid equivalent of 0.97 inches. Another storm will arrive late Sunday into Monday. At this time, it appears that it will be strong enough to produce some rainfall at the lower elevations and snow, perhaps as low as 5,000 feet. I am hoping that we will not lose the snow cover before the next substantial snow-producing storm arrives.



To the south there was still a bit of wrap-around moisture from the cut-off low exiting Southern California. I calculated the LCL at 780 mb and judging from the cloud base this looked correct.

There was also a considerable amount of burning in the forest. This can be seen on the far ridge on the left side of the photograph. With the snow, light winds, and cool temperatures it was a perfect time to burn off excessive fuel in the forest.



I am planning for the next season at this time. For a start, I have a running list of questions that I would like to answer. The relationship and dynamics between our native perennial bunch grasses (and other native perennial species), climate change, and the encroachment of non-native species is of great concern to me. The theory in my head is that to help reduce the proliferation of catastrophic wildfires we need to maintain and enhance our native perennial ecosystems that carpet the forest floor, especially our native bunch grasses.

This is a typical scene on the lower portions of Peavine Ridge. In the foreground are clumps of a native bunch grass, Stipa lemmonii var. lemmonii. Mixed with the Needle Grass are small carpets of Bear Clover, Chamabatia foliolosa, and less amounts of Galium bolanderi. It is not a very diverse mixture of species, however they are well established on the site and more or less free of invasive species.



The great thing about our native bunch grasses is that they stay green during all the seasons. Concerning fire, their flash point is much higher, making them much less susceptible to burning fast and easily.

[Robert]

There is no shortage of invasive grass species at this site. The dominant species in this stand (pictured) is Cynosurus echinatus. Unfortunately, there are many other invasive species in the vicinity and even in this stand. On the top of the list are nasty and aggressive invasive grasses such as Goat Grass, Aegilops triuncialis, Bromus diandrus, B. hordeaceus, B. tectorum, Medusa Head, Elymus caput-medusae, and Poa bulbosa ssp. vivipara. The flash point on these invasive species is very low. Once ignited, fire spreads very quickly and easily through stands of these invasive grass species.



The invasive species issue is not limited to grasses. This stand, at the same site, contains the matted dried remains of Yellow Star-thistle, Centaurea solstitialis, another nasty invasive species. It too can burn easily once it becomes dry.



I understand the principle and reasoning behind mechanical brush clearing. This site is adjacent to dense stands of all of the previously mentioned invasive species. Invasive species will germinate readily in the disturbed exposed mineral soil at this site. I will monitor the situation and see what I can learn from the situation. Perhaps my apprehension concerning the spread of invasive species and the fire dangers that accompany them is unfounded.



In addition, I have to admit that I am concerned about the loss of species diversity. Some native shrubs, such as Indian Manzanita, Arctostaphylos mewukka ssp. mewukka, will stump sprout after being cut or burned to the ground. There are many more species that many never return, especially if sites like this are over run with invasive species.

I even have great concern about the cultivated pines growing throughout the forest. From my perspective the monoculture appears to be very genetically uniform. If so, there could be a risk of an undesirable genetic bottleneck. If the pines share the same, or very similar, maternal parent the genetic risk becomes even greater. What happens when the pines reach reproductive maturity? Do we want highly genetically uniform pollen to dominant the entire forest? I do not think that it is desirable to eliminate all the detrimental genes from a land race. With climate change, what is detrimental now might provide survivability in a new climatic environment.

As you can see, I ask many questions. For me, this is part of what makes outings enjoyable and interesting for me.

[Robert]

Wednesday, 12 December 2018
0500 UTC



I was up on Peavine Ridge again, yesterday, 10 December. As one can see from the photograph the snow is quickly melting. At another location where I measure precipitation and snow depth, there was still 15.5 cm of snow on the ground. Unfortunately, there will be warm and sunny weather for the next two days. The snow is likely to be gone by Thursday. Changes in the patterns of the winter snow pack (and/or the lack of it) are an extremely important variable in the mountain ecology.



A weak storm system was moving through the area, producing a few sprinkles and brief light showers. I measured no precipitation in any of my gauges.

In the next 7 days I do not see much in the way of precipitation for our area. It looks like both Friday and Monday there will be a possibility of some rain and mountain snow. The dynamics at this time do not look very promising for strong vigorous stormy weather.

Through the processes of teleconnction, changes in the atmospheric circulation around the globe can impact our local weather. SSTs in the equatorial central and eastern Pacific are above the El Niño threshold. At this time, the atmosphere is lagging in its response. There are a number of atmospheric indicators that can be monitored, which indicate that we are moving into an El Niño phase. There has not been much change, yet.

There are also other atmospheric patterns that can be monitored. At this time, I see nothing that will move us out of our current generally dryish pattern.



Off to the north, the dynamics of the storm were a bit stronger, with a few rain showers.



In this photograph, clearing skies can be seen on the horizon as the front slid through our region. Also on the far horizon, the top of a cap or inversion can be seen over California’s Central Valley. This is a very common feature of our weather during all seasons. During the winter months the cap can often hold dense fog in the valley, which at times can last for days. In the past, this was a common event during the winter, however patterns have change and persistent valley fog occurs less frequently.



At this time, there is still a fair amount of snow at elevations above 5,000 feet (1,524 meters).

[Robert]

On the lower slopes of Peavine Ridge the snow has melted.

Since the 1860’s there has been an acceleration of anthropogenic induced change on Peavine Ridge that has impacted the ecology and flora. Many of the ingredients for a rich and diverse flora still exist on Peavine Ridge. There has been a great degree of fragmentation of this flora during the past 150, plus years. The introduction and spread of invasive plant species has aggravated the situation. Another variable has been climate change.

Bear Clover, Chamaebatia foliolosa, is a very common understory species on the ridge. The Cleveland Fire, 1992, burned much of the central portion of the ridge. In a few locations, mature forest stands survived the burn. The fire burned much of the understory vegetation at these sites without harming the tall mature conifers. At several of these sites, Bear Clover now carpets the forest floor with a diverse variety of other native species. Very few invasive plant species can be found at these sites. In addition, this vegetation pattern, for a number of reasons, is highly resistant to aggressive wildfires. The diversity, and co-existence, of other native species under these situations is impressive. Nature has her patterns to keep destructive wildfires in check. It seems like it would be wise to try to incorporate these principles into our land management processes.



Hosackia crassifolia var. crassifolia is a fairly common species on Peavine Ridge. The dead stems of this perennial species can be seen throughout the lower and central portions of the ridge.



Iris hartwegii ssp. hartwegii can also be quite common throughout the lower and midsections of the ridge. Plants from the higher elevations endure a lasting snow pack during the winter (or at least they did).



Eriophyllum lanatum var. graniflorum is a beautiful species, especially when in bloom. At times, entire mountainsides can be seen covered with their bright yellow flowers.



I will leave this discussion with a photograph of Phacelia imbricata ssp. imbricata. Both annual and perennial species of Phacelia can be found on Peavine Ridge.

[Robert]

13 December 2018
0400 UTC

It appears that we will get a quick shot of rain on Friday afternoon and then a little stronger storm on Monday. In between there appears that there could be some very warm days for this time of year. A good example will be tomorrow. I checked the 850 mb temperatures for tomorrow and they indeed look on the warm side of things. The 500 mb flow also supports the warm temperatures. I'll check the 15TH tomorrow morning. Heights fell a bit today, however it looks as if this will reverse itself tomorrow.

I was up on Peavine Ridge again today. I have been working out a "best guess" skew-t for the site. So far, this project is generating logical and reasonable readings. It will be nice to have a "best guess" vertical profile of the atmosphere usable and ready to go for the summer monsoon season.

[Robert]

Friday, 14 December 2018
0500 UTC



There has been a marked climatic shift in our portion of Northern California over the past 50 years. After a slowing of the warming trend during the 1990’s, the average annual temperatures, again, began to slowly increase during the 2000’s. For the last 6 years there has been a very marked and rapid increase in our average annual temperatures. June 2014 to July 2015, with an average annual temperature of 62.18 F (16.77 C), was our warmest year since I began keeping records in 1967.

This trend expresses itself in other data. The above graph depicts the number of days at the Placerville farm with low temperatures < or = to 32 F (0 C) each year from 1988-89 to 2017-18. There is a clear trend toward fewer days with temperatures 32 F (0 C) or less each year. So far this winter we have recorded only 5 days with temperatures 32 F (0 C) or less. To date this autumn, the coldest recorded temperature has been 30 F (-1.1 C). This is definitely a highly anomalous event. In the past, temperatures in the mid-20’s F (-3 to -4 C) have been frequent occurrences during late November and early December.

Currently, the snow pack at the 5,000-foot level (1,524 meters) is 16 cm with a liquid equivalent of 1.50 inches. Although this is an improvement over last year (no snow cover at all), this is still much below average.

Over the past 50 years, there has been a marked trend toward warmer storms with higher snow levels in the Sierra Nevada Mountains. One theory I have encountered among climate scientists is that global climate change (warming) is affecting high mountainous regions at a faster rate than lower elevation sites within the same region. This would be something comparable to what we are currently observing in the polar regions of the planet. I recently found an article on the rapid shifts in vegetation in the arctic (when I find it again I will post the link). I have a keen interest in this topic as I have been gathering data in the Sierra Nevada to quantify the changes in ecosystems/vegetation I have been observing of the years. Despite some slowdowns late in this season, I have made good progress at specific sites in detailed mapping of “marker” species. With stormy weather, I will now shift some of my attention to the lower elevations in the Sierra Nevada Foothills. All of this information may be of keen interest to gardeners.

Today was a very interesting weather day here in Northern California. The 1400 UTC Sacramento GOES sounding showed a strong cap (inversion layer) over the Sacramento Valley. The 850 mb temperatures were running 5 C warmer than the valley floor. As the day progressed the cap slowly eased. By the end of the day our Sacramento home recorded a high temperature of 60 F (15.6 C). On Peavine Ridge, 5,146 feet (1,569 meters) the high temperature was also 60 F (15.6 C). Weather phenomena such as this are not uncommon in our area. On this morning, the weather was clear for the most part. If it had been foggy and stayed foggy in the Sacramento Valley, the high temperatures in Sacramento would have been much lower.

Tomorrow will be a busy day.

[Robert]

Ah! 

I found the link to "Shrubs Takeover One Sign of Arctic Change".

https://www.climate.gov/news-features/understanding-climate/shrub-takeover-one-sign-arctic-change

[Robert]

13 December 2018
0400 UTC

It appears that we will get a quick shot of rain on Friday afternoon and then a little stronger storm on Monday. In between there appears that there could be some very warm days for this time of year.

Saturday, 15 December 2018
0400 UTC

The "Friday" front just passed through our area. It appears that parts of Sacramento got a trace of precipitation, Placerville none, as the moisture (what moisture there was  ) was shunted off to the north. After looking at the latest satellite image of the "Monday" storm, well I am not impressed as I see the front shred as it encounters negative vorticity advection, the front extends away from the parent low, and becomes negatively titled. I am sure that the NWS knows much better that I the fate of the next storm as it passes through our area, however the way I see it now we will be fortunate to get any precipitation from this storm. I certainly hope that I am wrong. We are dropping farther below average precipitation to date.

> ah  This morning (1400 UTC) I looked again at the satellite image of the next storm. It is coming together well and it looks like we are finally going to get a goodly amount of precipitation. Right now it appears that snow levels will be a bit high, maybe 5,500 feet. Right now I will take any precipitation that we can get.

[Robert]

I was up on Peavine Ridge both today and yesterday. This photograph was taken on 14 December from the crest of Peavine Ridge. Subtropical moisture was streaming into the area, so it was quite warm, 54 F (12.2 C) for the days high temperature. The moisture from this front was shunted to the north. I did not record any precipitation in any of the gauges, including the Placerville farm. Despite sunny days and warm daytime temperatures the meager snow pack is holding up surprisingly well.



Much farther down on the ridge, I photographed this patch of Bear Clover, Chamaebatia foliolosa, growing under the high shade of a mature coniferous forest canopy. This forest stand escaped intact when the Cleveland Fire (1992) burned the central portion of the ridge.

In areas where the forest ecosystem has not been highly altered, this species is often seen carpeting the forest floor in the Transition Life Zones of the Sierra Nevada Mountains. This species is highly resistant to fire and grows dense enough to out compete invasive annual grasses (which have a very low flash point, i.e. they ignite and burn very quickly and easily when dry). Under ideal conditions (very rare these days), a diverse array of native species can share the same habitat.



Berberis aquifolium is another low creeping species found on Peavine Ridge. This species is even more resistant to fire than Bear Clover. Encouraging the recolonization of this species, as well as many other native species, would certainly help ameliorate our growing wildfire threat. In addition, once established our native species would maintain and propagate themselves with minimal human intervention.



Deer Brush, Ceanothus integerrimus var. macrothyrsus, is a very common species on Peavine Ridge, especially at lower elevation sites. The species is basically deciduous, however the species always seems to retain a few leaves throughout the winter. The dormant seeds can last for years in the soil and germinate in great profusion after a fire. I observed this after both the King Fire (El dorado County) and the Rim Fire (near Yosemite National Park).



Eriodictyon californicum is generally seen growing at lower elevations, predominately in the Sierra Nevada Foothills. There are many thermal belts on Peavine Ridge where species such as this can thrive.

[Robert]

Buckbrush, Ceanothus cuneatus var. cuneatus, is another species at home in the foothill belt of the Sierra Nevada Mountains. As with Yerba Santa, Eriodictyon californicum, this species finds sites within the thermal belts to its liking.



Today, 15 December, the leading edge of overcast from the next storm system started to arrive.



Canyon Live Oak, Quercus chrysolepis, can be found growing on the crest of Peavine Ridge at the 5,000-foot level (1,524 meters). This evergreen species is surprisingly cold hardy. Occasionally I encounter this species at even higher elevations, however always in relatively warm sites. As the name implies, this species is very common in the river canyons of the Sierra Nevada.



This is a close up of the foliage (Quercus chrysolepis). On the crest of Peavine Ridge this species is often seen growing in Andesite rubble where it is very exposed, hot, sunny, and dry during the summer.



Indian Manzanita, Arctostaphylos mewukka ssp. mewukka, can be found growing throughout the Peavine Ridge area. Its gray-green foliage is very beautiful. If one looks closely, the recurved bracts on the inflorescence can be seen. This is one of several characteristics that help identify this species.

[Robert]

Ceanothus cordulatus is found growing at the higher elevations on Peavine Ridge. The species has wicked thorns! Despite this characteristic the blue-green foliage is very attractive. Presently, I do not grow it in our garden, however this situation will change.



Green Leaf Manzanita, Arctostaphylos patula, is another species that is only found at higher elevations on Peavine Ridge. The nascent inflorescences are very attractive as they wait for spring to arrive.