Thomas Fire in Southern CA becomes 5th largest in state history; 230,000 acres and growing

The Thomas Fire of Ventura and Santa Barbara Counties in Southern California has now become (as of Sunday Night) the 5th largest fire in California State history. And based on trends and fire weather expected, it may go for the state record (273,246 acres).  After winds decreased somewhat Friday afternoon-Saturday, they picked up again on Sunday, causing extreme fire growth to an incredible 50,000 acres and reducing the containment from 15% to 10%.

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Growth of Thomas Fire since last Tuesday’s ignition.
Since the fire developed last early-morning Tuesday, it has exhibited extreme fire behavior in intense Santa Ana winds with gusts of 45-80 mph, fanning flames and, more importantly, embers far downwind of the actual fire. Currently, 790 structures have been destroyed with the evacuation of over 88,000 people. A 70 year old woman died after being overtaken by the fire following suffering severe injuries in a car crash. In San Diego County, another woman was badly burned over 50% of her body in the Lilac Fire while helping horses escape from a thoroughbred training facility.  And speaking of horses…46 horses were confirmed killed at San Luis Rey Downs where the trainer was badly injured. The death toll will likely rise among the horses as 450 horses were there when the fire rapidly struck. Many burned to death refusing to leave their stables or running back into them, while others died from shock even after initially safely away from the fire’s path. Meanwhile, another 29 horses suffered a similar fate at a ranch in Los Angeles County’s Creek Fire.

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Dry or low precipitation conditions expected in mid-range computer models (this forecast depiction by the Global Forecast System; GFS) for much the Southwest US and Great Plains through December 20th.

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Forecast upper-atmospheric wave pattern valid noon CST Monday by the GFS. Powerful ridge of high pressure over the West will continue dry, very abnormally mild conditions while colder weather remains over the eastern US.
Unfortunately, high fire danger will continue through Monday with gusts over 45 mph allowing the Thomas Fire and any other fires which develop to easily spread and do so rapidly. Conditions should relax Monday night before possible re-intensification on Tuesday. As mentioned, the Thomas Fire may reach record territory tomorrow based on trends. And as of now, NO significant measurable rainfall is expected in California (or much of the Southwest US and Great Plains) the next 10 days. A blocking upper-atmospheric high pressure pattern over the Eastern Pacific will certainly allow for intensification of drought conditions and continued dryness and moderate to high fire danger for days to come. I should also note, fire danger will also be elevated on parts of the High Plains. Much of Eastern Colorado into Western Kansas are under red flag warnings for Monday because of expected elevated breezy conditions and low humidity with dry fuels.

—Meteorologist Nick Humphrey

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Key Findings of the US Government’s Climate Science Special Report

Today, the US Global Climate Change Research Program released the Climate Science Special Report, Vol. 1 of the Fourth National Climate Assessment mandated by Congress to provide the latest scientific basis and impacts from climate change on the United States. Climate science continues to evolve, but in the direction of more significant realization of how humans have influenced the climate thus far, as well as how much more influence will come in the not to distant future.

Below are some of the headline findings provided in the rather powerful report (be prepared for a lot of INTENSE info):

    1. Earth’s average temperature has increased by 1 degree C (1.8 F) during the 1901-2016 period. This is faster than any rate known in the last 1,700 years.                 2017TempUpdate_Top10_Global_F_en_title_lg
    2. The average temperature of the contiguous United States has also increased by 1 degree C (1.8 F) during the 1901-2016 period. Satellite and surface observations are consistent in the detection of this rapid rise in temperature. With no change in the rate of greenhouse gas emissions, the CONUS is expected to experience a more abrupt average rise in temperature of 3.2-6.6 degrees C (5.8-11.9 F) between now and 2100.                                                                                 
      figure6_1
      Change in average surface temperature (annual and seasonal) for the period 1986-2016 since the period 1901-1960 (contiguous US; 1925-1960 for Alaska and Hawaii). Data from NOAA.

      figure6_8
      Projected changes in the coldest and warmest daily temperatures (°F) of the year in the contiguous United States. Changes are the difference between the average for mid-century (2036–2065) and the average for near-present (1976–2005) under the higher emissions scenario (RCP8.5). Maps in the top row depict the weighted multimodel mean whereas maps on the bottom row depict the mean of the three warmest models (that is, the models with the largest temperature increase). Maps are derived from 32 climate model projections that were statistically downscaled using the Localized Constructed Analogs technique. Increases are statistically significant in all areas (that is­­, more than 50% of the models show a statistically significant change, and more than 67% agree on the sign of the change). Data by NOAA.
    3. Temperature extremes in the United States are trending significantly toward record high temperatures over record low temperatures. This trend is expected to continue with the number of below freezing days also continuing to decline and days above 32 degrees C (90 F) continuing to rise.
      figure6_5
      Data by NOAA.

      figure6_9
      Projected changes in the number of days per year with a maximum temperature above 90°F and a minimum temperature below 32°F in the contiguous United States. Changes are the difference between the average for mid-century (2036–2065) and the average for near-present (1976–2005) under the higher scenario (RCP8.5). Maps in the top row depict the weighted multimodel mean whereas maps on the bottom row depict the mean of the three warmest models (that is, the models with the largest temperature increase). Maps are derived from 32 climate model projections that were statistically downscaled using the Localized Constructed Analogs technique. Changes are statistically significant in all areas (that is, more than 50% of the models show a statistically significant change, and more than 67% agree on the sign of the change).
    4. The global influence of natural variability is limited to small fraction of observed climate trends. Solar output and the Earth’s internal natural variability have contributed only marginally to the observed changes in the climate system over the past century. There is no convincing evidence for natural cycles in the observational record that could explain the changes in the climate system.                                                                                                                                                         
    5. Heavy precipitation events have increased across the US since 1901. The highest increase over the Northeast and the second highest increase over the Midwest.                                                                                                                                2017ClimateExtremes_Downpours_3_en_title_lg
    6. Northern Hemisphere spring snow cover, North American maximum snow depth and Western US snow-liquid equivalent have all declined since the early 20th century. At current rates of decline and assuming no change in water resource management, chronic, long-duration hydrological drought conditions are possible for portions of the United States by 2100.                                                                                                                                                                                               
    7. Global mean sea-level has risen 7-8 inches (~0.2 m) since 1900 with 3 of those inches since 1993. Relative to the year 2000 is very likely global mean sea-levels will rise up to 0.6 ft (0.18 m) by 2030, 1.2 ft (0.38 m) by 2050 and 4.3 ft (1.3 m)+ by 2100. A more rapid degradation of the West Antarctic Ice Sheet may mean physically possible sea level rise theoretically exceeding 8 ft (2.4 m) by 2100 (confidence is low on this).                                                                                                                2016StateOfClimate_SLR_en_title_lg
    8. The global ocean has absorbed more than 93% of the heat caused by global warming since the mid-20th century. The oceans have warmed by about 0.7 degrees C (1.3 F) during the 1900-2016 period. Assuming no emissions changes, warming of the oceans by an average of 2.7 degrees C (4.9 F) is expected by 2100.                                                                                                                                       2016StateOfClimate_HeatStorage_en_title_lg
    9. The global ocean continues to undergo rapid acidification because of dissolved carbon dioxide from atmospheric emissions. The rate of acidification is unparalleled in the past 66 million years (since the Cretaceous-Paleogene Impact Event). At the current rate, the pH of the global ocean may decline from its current average of 8.1 to as low as 7.8 by the end of the century. Seawater with pH <8 can be corrosive to shellfish, plankton and coral which depend on carbonate structures for their shells, backbones and skeletons. The greatest change in acidity will be in Arctic Ocean.

      figure13_5-1200
      Predicted change in sea surface pH in 2090–2099 relative to 1990–1999 under the higher scenario (RCP8.5), based on the Community Earth System Models–Large Ensemble Experiments CMIP5 (Figure source: adapted from Bopp et al. 2013 ).
    10. The Arctic is warming at a rate approximately twice as fast as the global average with a rapid decline in sea ice volume and extent since satellite observations began in 1979. At the current rate of warming, the Arctic Ocean will be effectively ice-free in the month of September by the 2040s.                       

      siv_annual_max_loss_and_ice_remaining
      Arctic Sea Ice Volume since 1979. Note gradual and accelerating collapse of sea ice volume. Arctic may fall below 1,000 cubic kilometers at some point in the month of September in as early as several years to a decade or so. This will happen when the yearly sea ice maximum and loss of what remains equal.
    11. Global warming has contributed “significantly” to ocean-atmosphere variability in the North Atlantic Ocean; as a result these changes have contributed to the observed upward trend in North Atlantic hurricane activity since the 1970s. North Atlantic hurricanes are expected to increase in intensity (maximum sustained wind potential) with increasing precipitation rates during the 21st century.                                    2017Hurricanes_Info_en_title_lg

      figure9_2-1200
      Tracks of simulated Saffir–Simpson Category 4–5 tropical cyclones for (a) present-day or (b) late-21st-century conditions, based on dynamical downscaling of climate conditions from the CMIP5 multimodel ensemble (lower scenario; RCP4.5). The tropical cyclones were initially simulated using a 50-km grid global atmospheric model, but each individual tropical cyclone was re-simulated at higher resolution using the GFDL hurricane model to provide more realistic storm intensities and structure. Storm categories or intensities are shown over the lifetime of each simulated storm, according to the Saffir–Simpson scale. The categories are depicted by the track colors, varying from tropical storm (blue) to Category 5 (black; see legend). (Figure source: Knutson et al. 2015; © American Meteorological Society).
    12. Large forest fires in the Contiguous US and Alaska have increased since the early-1980s. This increase is expected to continue with “profound” impacts on ecosystems.                                                                                                                           2016Wildfires_temp_WEST_en_title_lg

Some other findings of note:

-For the period 1901-2016, the Dust Bowl Era (mid-1930s) remains the most extreme era for heat. This is thought to be largely the result of significant land-surface feedbacks caused by precipitation deficits and poor land management leading to reduced vegetation and strong surface heating (which in turn promoted further drying and land degradation). However, we are on a path to eclipse this period in US climate history in the coming decades, particularly as colder conditions (more found in 1930s winters for example) continue to decline in a warming climate and extreme heat continues to increase.

-The Climate report explains (as has been explained in previous scientific literature) the period of so-called “global cooling” which occurred from the mid-1940s to mid-1960s: aerosol particles generated by WWII and post-war industrial production (esp. coal power plants) which reflected some solar radiation into space temporarily slowing long-term global warming, even as carbon dioxide concentration in the atmosphere continued to increase.

-The report notes that annual precipitation has decreased over the West, Southwest and Southeast, while increases have occurred over the Plains, Midwest and Northeast. They specifically mention an increase in mesoscale convective systems (organized clusters of thunderstorms which dump significant rainfall) over the Plains and Midwest since 1979. Mesoscale convective systems are expected to increase in frequency and intensity during the 21st century.

-While tornado climatology related to climate change has been difficult to understand because of the reliability of storm reports before the 1990s, scientists involved in the report have concluded one interesting aspect…there is moderate confidence in a decrease in tornado days (day when tornadoes of any number are confirmed), as tornadoes are increasing on those days. Greater volatility in tornado occurrence year-to-year as well as a trend toward an earlier first occurrence during the year have been observed. Studies looking at the ingredients for severe storms with all modes of potential activity (tornadoes, hail, wind) suggest an increased frequency and intensity of severe storms over areas prone to them in the US in a warmer world, but confidence on details is low.

-This report concluded that observed drought and precipitation increases (1901-2016) cannot be confidently attributed human-induced global warming. The Dust Bowl Era remains the benchmark period for extreme drought conditions. However recent negative trends in soil moisture are believed to be attributable to warming temperatures. Although soil moisture projections in climate models are still considered in their “elementary” stages in the science, based on what is known, there appears to be a signal for further decreases in soil moisture over portions of the US (particularly West and Plains) by the end of this century, increasing the risk of chronic hydrological drought.

-I find the key finding #11 I listed particularly important. There has been much debate between scientists (particularly more observational minded meteorologists vs. climatologists) about whether there has been truly observable increase in N. Atlantic hurricane activity seasonally beyond the natural variability, given the limited period of reliable satellite record and intensity measurements. This statement is given MODERATE confidence given that global warming has caused increases in sea-surface temperatures, oceanic heat content and natural cycles on multi-annual and multidecadal time scales involve changes in not only these thermodynamic variables but also dynamic ones in response (vertical wind shear, position/intensity of monsoon troughs, development of tropical waves into organized TCs).

Additional Thoughts:

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Climate change will likely be one of the most difficult challenges the world will face this century (at least). Why? Why should we care?

When it comes to effects on people (which is what people care about), at the end of the day, what matters for the livelihood of people rich or poor? Food, water, living space. If these become challenged, you get human suffering (from economic to health threats) and geopolitical problems. The potential for significant drying and increasing chronic hydrologic droughts from loss of snowpack will lead to increasing populations in demand for resources seriously straining water resources. Crops around the world will face increasing difficulties from heat stress, prolonged droughts mixed with periods of more intense heavy rainfall events. Acidification and warming may threaten marine food resources already strained by overfishing around the world. Living space will become slowly threatened by sea level rise in low-lying areas and island nations…and more readily in the coming decades…by repeated far more extreme heat waves than previously in already hot, humid environments where cooling is not readily available, and possibly by diseases as ecosystems shift to different places, along with pests (which will also impact crops potentially).

Climate change isn’t just about warming, it’s about cascading impacts on the whole of the climate system. Without a drastic global shift to a low-carbon energy sources and the advancement of technology to remove carbon dioxide from the atmosphere, we are in store for a very challenging period in human history. This isn’t worse-case/best case or any of this. This is simply the path that we are on, no over-dramatic statements nor downplaying needed or tolerated. Hopefully we via our governments make the right choices.

–Meteorologist Nick Humphrey

First Game of World Series Tonight…Weather Headline: HOT

The World Series begins tonight in Los Angeles between the LA Dodgers and the Houston Astros. And it begins with record heat in Southern California. Today, in fact, downtown LA is setting a record high for the day and it is the warmest temperature on record for so late in the year. This was after a record high of 102 was set for downtown LA yesterday. So far it has reached 103 downtown and the official high may be higher before the day is done.

First pitch for the World Series is at 5 pm PDT this evening. While temperatures will decrease somewhat by that time, game time temperatures will be in record territory for a World Series Game (95-100 degrees F). The hottest World Series first pitch on record was from a game (cannot remember which) in 2001 in Phoenix when the NY Yankees played on the road against the Arizona Diamondbacks in a starting game temperature of 94 degrees.

In addition to heat, fire danger remains VERY high across Southern California as Santa Ana winds intensified today and will continue into tomorrow. RED FLAG WARNINGS are in effect for parts of SoCal. Gusts of 50-60 mph have caused problems for firefighters as they dealt with brush fires in Granada Hills this morning and Rancho Cucamonga this afternoon (LA Times). 

(Map of Rancho CucamongaMap of Granada Hills)

Game 2 of the World Series (First Pitch at 5 pm PDT Wed) should be slightly “cooler”, but still quite hot…expecting temperatures to start the game in the mid-90s (92-97 degrees F). If you’re going to these games or doing any outdoor activity at all in Southern California…lots of water and be careful with anything that sparks or burns!

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US Global Forecast System forecast temperatures at 5 pm PDT Tuesday.

Enjoy the game! Go American League and go Astros!

–Meteorologist Nick Humphrey

Biggest WxClimo Story of 2017…Wildfires.

Fires have been raging across the world this year with unprecedented scope. Major wildfire outbreaks have been notable from tropical rainforests in Africa and South America to the taiga of Canada and Russia. Even Greenland has seen an unusual amount of fire activity on the edge of the ice sheet. This year, Western North America, and the Iberian Peninsula of Europe have been particularly hard hit with life-threatening fires (see HERE, HERE, and HERE). Although fires occur every year with variable impacts, a significant upward trend can be tied to climate change allowing both natural and human activity to ignite and expand the destructive intensity of wildfires.

This video by Climate Central summarizes the impacts of these fires so far this year and their connection of climate change. This recent article by The Observer also summarizes fires around the world and the impacts of climate change.

 

(The featured satellite image above is from October 9, 2017 courtesy of the European Space Agency).

WxClimoEd Series, Post #1, Part 2: Understanding Global Climate Change Indicators

Hello Weather & Climate News readers! This post will be the first (Part II) in what will be my ongoing education article series WxClimoEd. I hope to write educational posts on various topics related to weather and climate to help enhance your understanding of various phenomena and their impact on the environment, individuals and society. These posts will present key ideas and concepts and provide occasional linked sources to further, more detailed information.

Understanding Global Climate Change (Indicators)

In Part 2 of this article series on Global Climate Change, I’ll discuss the indicators of climate change in progress on  Earth. Even without the global measurements of temperature, there are plenty of signs in the climate system that change toward a warmer world is in progress.

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Earth Undergoing Abrupt Climate Change

While global warming is considered to be detectable since the First Industrial Revolution (after 1750), since the latter half of the 20th century, the environment has begun to exhibit what could be considered “abrupt” changes. Among scientists who study natural abrupt change in the paleoclimate records have had some common thought on what “abrupt” means: 1) Changes in climate which can be witnessed within a human lifetime and 2) the change is very nonlinear; it far exceeds the mechanism which initiated the change in the first place (See this video presentation by Dr. White at the American Geophysical Union Annual Meeting discussing past abrupt climate change in the paleoclimate record). In the past, abrupt change usually occurred as a result of the advance or recession of ice sheets, leading to rapid change in local temperature or regional circulations (or even global distributions of precipitation or temperature patterns). Today, abrupt change is being increasingly witnessed as a result of an already unnaturally fast mechanism (rapid rise in carbon dioxide concentration, resulting in rapid rise in global temperatures relative to natural variability…multi-decadal to centennial  scales vs. multi-millennial).

Here are just some of  the abrupt changes resulting from the changing climate happening now:

  1. Decline in sea ice over the Arctic Ocean

siv_annual_max_loss_and_ice_remaining
Arctic Sea Ice Volume since 1979. Note gradual and accelerating collapse of sea ice volume. Arctic may fall below 1,000 cubic kilometers at some point in the month of September in as early as several years to a decade or so. This will begin the process toward widespread open ocean in the Arctic for a time in September.
2. Rapid increase in air temperature of the Arctic.

The Arctic (64-90N) has warmed around 3-4 degrees C since the 1881-1910 period (based on NASA data). 2-3 degrees C of warming has occurred just since the 1951-1980 period with notable warming since the year 2000. This has led to not only the rapid decline in Arctic sea ice, but the beginning the melting of land permafrost.

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Average air temperatures (over land and ocean) in the Arctic region, relative to 1951-1980 average. Shown is 1984 (year I was born) to 2016. Red box show rapid warming of Arctic since 2000 compared to previous decades. “315” = +3.15 degrees C anomaly. (NASA GISS)
Addendum: The rise in the average temperature of Earth as a whole can count as abrupt, as seen in the earlier graph (farther back up). Most warming has occurred since the 1970s. The top ten warmest years on record going back to 1880 have occurred since 1998 (with 1998 now the last year in the top ten from the 20th century). 2017 is expected to be the 2nd warmest year on record just slightly behind 2016.


3. Increase in Sea Surface Temperatures and Oceanic Heat Content of Global Ocean.

The average sea-surface temperature of the global ocean from 60S-60N has risen around one degree C since the 1881-1910 period. 0.5 degrees C warming has occurred since 1980. Like the global air temperature, SSTs have been most of their record warm years since the turn of the 21st century, with an accelerated pace of warming since 2000 (1.62 degrees C/century currently, compared to 1 degree C/century 1950-2000). 2017 sea surface temperatures are currently running the 2nd warmest on record (NOAA data).

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Sea surface temperature anomalies 1880-2016 for various sectors of global ocean. Values on graph are in degrees F. Oceans have warmed roughly 2 degrees F/1 degree C.
As far as oceanic heat content, the oceans have accumulated over 100 zetajoules (1 x 10^23 joules) of heat energy in the upper 700 meters of the global ocean since 1993. An incredible amount of energy, with increasingly accelerated warming in the deep ocean below 700 meters since 1993.

4. Acidification of the Global Ocean.

Earth’s seawater is slightly basic (basic is ph > 7). The global average ph of the oceans has decreased from 8.25 to 8.069 since the 1750s (ph was 8.104 in the 1990s). This is caused by the oceans dissolving carbon dioxide (30-40% of carbon dioxide released by humans dissolves in the oceans). This interaction forms carbonic acid, with further chemical reactions leading to increasing concentrations of the hydronium ion (H+). This leads to a lowering of the ph. The rate of acidifcation is faster than at anytime in the past 300 million years! The rapid acidification has been more pronounced in the Arctic Ocean because of very cold water (colder water can absorb more dissolved gases). When ph falls under 8 in the coming decades (assuming no mitigation), marine life which depend on carbonate structures (shellfish, sea snails, corals, some types of plankton, etc) begin to suffer from the corrosive effects of less basic waters.

5. Sea Level Rise

rate-of-sea-level-rise-accelerating

Sea levels are rising as a result of meltwater from land and thermal expansion as oceans warm. As the atmosphere and oceans continue to warm and weaken the Arctic and Antarctic Ice Sheets, sea levels will continue to rise, with possible nonlinear positive feedbacks accelerating it. It has already accelerated since the end of the 20th century. “King Tides” have become an increasing problem because of sea level rise in the 21st century.

6. Increase in Extreme Weather and Climate Events

The end of the 20th century into the early 21st century has featured a statistical increase in extreme weather events. Climatologists usually classify “extreme” as being 4-5+ standard deviations from the mean of all events. Such increase in extreme events over the course of years means that natural variability is being dominated by global warming, and causing a continuously shifting climate pattern.

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The shift in the range of meteorological variables across the bell curve because of climate change. The curve represents the normal distribution of events with natural variability (climate teleconnections and seasonal). The small shift of the mean by climate change causes a significant increase in less common events at one tail as well as an increase in truly extreme events not previously observed in the reference climate regime. (Presentation slide by Erick Fernandes, 2015).
Extreme events include heat, flooding, rainfall rates, drought, and wildfires. All of these occurrences have been increasing the frequency and severity around the world because of climate change. In addition, there is evidence that because of the high rate of warming of the Arctic, the mid-latitude jet stream has become weaker with increased amplitude extremes, leading to short-term and longer-term patterns favorable for extreme conditions at the surface. For example, high amplitude ridges of high pressure which do not move much or reform constantly can lead to extended periods of drought and extreme heat (while other areas downstream may receive cooler temps but heavy rainfall and flooding. This is actually something that is observable on meteorological timescales. Dr. Stefan Rahmstorf discusses the increases in extreme events from climate change in a lecture HERE.


One thing I must emphasize with understanding the impacts of global climate change is that it is impacting the environments of our world now and continue to accelerate in the coming years and decades (assuming no major changes are done). Global warming…the primary force of climate change, caused by our immense release of greenhouse gasses from fossil fuels…is the dominate force behind the rate of change in climate behavior. According to the Intergovernmental Panel on Climate Change in their 5th assessment, the world should actually be experiencing anomalous COOLING right now, but instead we have warmed Earth above and beyond natural long term global temperature variability. So when people ask “Did global warming cause (insert extreme weather event)?”, it is the wrong question. Climate looks at a collection of events for a trend. What is clear is that global warming is NOW causing a statistically significant increase in extreme events and will continue to do so. There is no “new normal” but only a continuous “ramping up” of the Earth’s natural variability toward greater extremes relative to the beginning of the Industrial Revolution, with greater impacts as humanity leaves the stable global climate in existence since the beginning of civilization.

This may be something many do not appreciate, but it is factual. Human civilization has changed Earth’s climate system to the point that we as humans are turning up the “thermostat” and started a multi-centennial experiment in geoengineering. Heat, drought, flooding, rainfall rates, wildfire events, and jet stream amplitudes, as a result, have all increased significantly in just the past 30 yrs.

If the climate were a piece of music…think of Earth’s relatively short-term natural cycles as the melody and global warming as the dominating background harmony from which the melody plays over. If the harmony changes keys, the melody will respond and shift accordingly.

In Part 3, I’ll discuss the projected future impacts of climate change being actively researched (and some already happening) such as food security, human health and living space.

Quick update on Northern California Wildfires (plus weather forecast)

As of now (5:30 pm PDT), the death toll in the California Wildfires is up to 35 and is expected to go up further. 18 in  Sonoma County, 9 in Mendocino County, 4 in Yuba County and 4 in Napa County. 5700 structures have been destroyed and 221,000 acres have been burned. Treating the conglomeration of fires as a single event (as all the Northern CA ones initiated Sunday Night), this is by far the most destructive fire event in state history and one of the deadliest. Simply horrifying and very sad.

Firefighters have begun to have some containment success the past 48 hrs with slower winds and at least some periods of slightly improved humidity. However, tonight-Sunday morning will feature an intensification of extreme fire danger. This is because a strong surface high pressure system will advance toward the central Intermountain West this weekend, intensifying downsloping Diablo winds from the hilly and foothill mountainous terrain of Northern California. North-northeast winds may gust as high as 45-60 mph Saturday, inducing very low humidity values, drying out fuels and potentially promoting extreme fire behavior (high forward speed, rapid growth) in existing fires as well as any new fires. Red Flag Warnings have been issued by the National Weather Service to cover this forecast potential.

95fndfd_init_2017101312
Strong high pressure moving over OR, ID and NV Saturday will promote strong Diablo winds over Northern California. (NWS forecast surface map valid 11 am PDT Saturday).

There are no thunderstorms forecast, so any new fires would be likely started by human activity. So folks in these areas need to very much be careful with anything which can potentially start fire and really…just avoid starting any outdoor fire or using  anything which sparks.

Some good news…mid-range computer model forecasts suggest a pattern shift toward precipitation and cooler weather by the end of next week. Just have to get through the next week of fire activity before some meaningful hydrologic relief to aid the firefighting efforts.

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The Global Forecast System Model forecast accumulated total precipitation valid 8 pm PDT Friday. This is one forecast scenario, but all global models point toward a wetter pattern, beginning the second half of next week into next weekend.

–Meteorologist Nick Humphrey

Fire Conditions expected rest of this week and weekend for California

The fire conditions Wed Night into this morning were not as severe as expected thanks to weaker winds. This allowed firefighters to make some ground against fires through the night, however high fire danger remains and will continue for days into the future, with no rain in sight.

GFSSW_sfc_temp_057
Strengthening pressure gradients along the mountainous terrain of interior California and the warm, very dry air mass will promote high far danger with windy conditions near the mountains and adjacent valleys Fri Night-Sunday. (See tightly packed isobars…lines of equal pressure…on the map in CA just west of Nevada as high pressure shifts SE-ward over the Intermountain West).
GFSSW_sfc_dewp_057
Very low dew points during the day Sat could mean relative humidity values as low as 10-20% across interior California, along with gusty winds for high fire danger.

Air quality remains terrible in the Bay Area. Folks in that region should do what they can to avoid being outside if at all possible.

cur_aqi_sanfrancisco_ca (1)
Unhealthy air quality exists across the entire Bay Area. Expect harmful air quality to be problematic into the weekend.

I’ll add any additional updates related to fires on this post today. Stay safe in these areas!

–Meteorologist Nick Humphrey