Northern California has a below-average first quarter of 2019 Water Year (Photo Credit: NWS)12/30/2018  DISCUSSION: As 2018 draws to a close, so does the first quarter of the water year for Northern California. The water year begins on October 1 and ends on September 30 as set by the United States Geological Survey (USGS) in order to accurately take account of snow that would fall in autumn and winter and not melt until the following summer. So far, across much of Northern California, the amount of precipitation has been below average to date.
A very dry October across much of Northern California has been one of the biggest factors in the below-average rainfall total in the region. In fact, much of the rain that has fallen was early in the month due to a flow of monsoon moisture that reached the San Francisco Bay Area bringing only a few hundredths of precipitation to areas including San Jose and Oakland while not producing any rain in the areas that usually get more such as Napa. The very dry October came as a result of several persistent high-pressure ridges which kept much of the storms from the Gulf of Alaska away from Northern California and steered them towards Oregon and Washington. November began the same way October ended with very dry conditions dominating for most of the month until the day before Thanksgiving, when the first storm from Alaska moved in. This was the first storm in a series which came through for a few days until the end of the month. The storms had brought enough rain to Northern California to help reduce nearly all the deficit from the dry October and even in some places finished above average for the season. However, the Crescent City area near the border of Oregon finished with another below average month which increased its deficits while the other more northern coastal areas like Ukiah and Eureka finished above average. In addition, the precipitation that came at the end of the month was instrumental in helping with the containment of the Camp Fire as well as clearing out the smoke from the Bay Area. December started with the last of the storms from November before having storms come in at a period of once a week. However, these storms produced about the same as November, but it was below average as December is a wetter month for Northern California. Northern California typically gets most of its rain in December through February as the jet stream which helps with the movement of storms is positioned further south. However, this year, the storm track has not moved as far south due to high pressure ridges that lasted longer in between the storm systems. It is only the first quarter of the water year and the months with the typical heaviest rainfall are yet to come for Northern California. To learn more about other high-impact weather events from across North America, be sure to click https://www.globalweatherclimatecenter.com/north-america ! ©2018 Meteorologist JP Kalb
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 California is a world leader in the fight against climate change and harmful polluting emissions, due to a surplus of cutting edge, bold laws put into place by CA governor Jerry Brown. With the signing of SB 100 this past September that commits the state to 100% clean energy by 2045, and the executive order B-55-18 that commits the states entire economy to complete carbon neutrality by 2045, one would think the pollution in California to be quite low in comparison to other states. However, this is not the case as the American Lung Association rated Sacramento the 5th worst city in the nation for ozone pollution. A quick visit to their website, lung.org, reveals that many other prominent CA cities such as Bakersfield, Los Angeles, Modesto, Fresno, and Visalia to be in the top ten worst polluted cities in the US for both short-term and year-round particle pollution. So why does CA, despite its efforts to curb energy and industrial emissions, rank so poorly for air pollution?
Much of the problem has to do with California’s topography. Cities situated in the valley, such as Modesto, Bakersfield, Fresno, Visalia, and Sacramento, are surrounded by mountain ranges like the Sierra Nevadas, the Cascades, Coastal, Klamath, and Transverse. The mountains work as a bowl, in which air is trapped and sits, and little to no air circulation occurs. Here, pollution continually accumulates and compounds bringing it up to unhealthy levels. The problem is then exacerbated in winter as temperature inversions occur, trapping cold stagnant air below a layer of warmer air in which pollutants have no chance to be “vented” out as they might during the summer, thanks to the physical property of heat rising. Another factor in this excessive pollution has been the increase in population throughout California, especially the central valley. This has led to an increase in cars, most of which run off gasoline or diesel combustion engines. These vehicles emit harsh pollutants such as volatile organic compounds, nitrous oxide, carbon monoxide, sulfur dioxide and more. In warmer temperatures, such as the summertime months, some of these pollutants are involved in a series of chemical reactions involving sunlight in which they are transformed into ozone, an extremely corrosive and dangerous pollutant that can cause chest pain, coughing, throat irritation, or even worsen the condition of those with chronic respiratory illnesses such as asthma. These issues are especially common in the more central valley of California. The California central valley, home to cities such as Visalia, Modesto, and Fresno, is one of the most productive agricultural regions throughout the state. Alongside quantities emitted by enormous amounts of diesel guzzling and polluting farm equipment, more pollution occurs when crops are burned at the end of the season, typically in fall, to prepare the land for the next year’s crop. However, aside from the smoke that the burning produces, it leaves another pollution source in its wake, long after the flames and ash have died down: bare soil. In particularly dry and drought-stricken years, wind seamlessly picks up loose soil and dirt, and disseminates the tiny dust and dirt particles throughout the air, adding to the particulate matter. Often this occurs in winter when fields are bare and or left to fallow, as there exists no crop roots to hold down and compact soil. With no rain, soil is parched and easily moved about, pollutants hover and compact in the atmosphere, and residents using wood-burning stoves and fireplaces only exponentiate the issue. With these multiple sources and traps of pollution, it’s no wonder that California has such horrid pollution, enough to classify it as the worst in the United States. Many measures have been passed in order to curb and control these emissions, at least from industry, but it is not nearly enough. Change cannot be made to the California topography. So, it is advisable that going forward, not only industry, but residents take action as well to help reduce these harmful pollutants. Be it switching from gas guzzlers to electric vehicles, replacing wood burning fireplaces for natural gas or electric, or simply using less energy, there is much that can be done to reduce toxic pollution and emissions. To learn more about other high-impact weather events from across North America, be sure to click https://www.globalweatherclimatecenter.com/north-america ! Sources: https://www.lung.org/our-initiatives/healthy-air/sota/city-rankings/most-polluted-cities.html https://www.sfchronicle.com/business/article/California-to-go-100-percent-clean-energy-by-2045-13218236.php https://sacramento.cbslocal.com/2018/04/18/sacramento-air-quality-sucks/ https://airlief.com/air-pollution-during-winter/ https://www.ucsusa.org/clean-vehicles/vehicles-air-pollution-and-human-health/cars-trucks-air-pollution#.W--cvehKjIU https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners http://www.capradio.org/articles/2015/04/29/california-cities-rank-high-on-unhealthy-air-report/ https://www.dmv.ca.gov/portal/wcm/connect/5aa16cd3-39a5-402f-9453-0d353706cc9a/official.pdf?MOD=AJPERES © 2018 Weather Forecaster Alexis Clouser  Discussion: Portions of north-central Montana from time to time experience high wind events. Typically winds downslope off the Northern Rockies creating these downslope wind storms which are high impact events for motorists, pilots, etc. The setup for December 18th-19th showed signs of such an event and prompted high wind warnings by the NWS (light gold color) across a large section of central Montana. This article will examine a way to predict strong downslope winds.  This image above is from the article “An Operational Technique Used to Detect ‘Mountain Wave Signatures’: A Forecast Methodology for Severe Westerly Winds in the Mountains of West Texas” by Todd and Coty Lindley, and Jeffrey Cupo, NWS WFO Lubbock, Midland, TX. One method to forecast a potential downslope wind storm is to take a cross section of the atmosphere perpendicular to the mountain range and analyze the vertical motions present. Based on the article referenced above the vertical cross section should display strong descending air coupled with weaker ascending air just downwind of the mountain peak with an upwind tilt with height. The image above is a cross section down in Texas through the Guadalupe Mountains, notice the upward and downward vertical motions with an upwind tilt in each event with the surface gusts noted below each image.  The cross section starts at point A and runs northeast to point B. Downward vertical motion is represented in grays and whites, upward in pinks. Winds are plotted, equivalent potential temperature, as well as relative humidity. The terrain and elevation are plotted on the bottom of the image with the associated pressure level on the left-hand side. Luckily, tropicaltidbits.com has a function to create cross sections. This cross section is produced from the GFS at 18Z on the 18th (location marked in the upper right corner point A to point B. Right after the start time of the high wind warning the coupled strong downward and upward vertical motion downwind of the highest terrain shows up in the model in a similar fashion to the previous example.   What did the actual wind observations read during this downsloping windstorm? Attached below are the observations from Blackfeet, MT. Surface winds gusted (purple numbers on the right-hand side) into the 40s around 11AM local time, 18Z, with gusts into the 40s and 50s over the next few hours and even a 60-mph reading at 2PM local, 21Z. The setup for downsloping winds also create conditions that result in mountain waves. Not only are the strong surface gusts hazardous to trucks and other vehicles on the roadways but mountain waves are extremely turbulent and dangerous for aircraft aloft. To learn more about high wind events and North American weather in general click here! ©2018 Meteorologist Joe DeLizio |
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