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Case Study: May 4, 2018 Destructive Southern Ontario Wind Storm

Please click the button at the end of the article to download the full case study.

A historic damaging wind event occurred in southern Ontario on 4 May 2018. The event was notable for its impacts, including downed trees and power lines and three fatalities. In some locations, these winds were the strongest ever recorded in the month of May. Wind gusts reached over 100 km/h in many areas, with a maximum measured gust of 126 km/h. The damage from this event totalled over $380 million in Ontario, making it the costliest event since the 2013 Toronto floods, according to Catastrophic Indices and Quantification Inc. The map below shows the locations of all measured wind gusts on 4 May 2018 that were at least 87 km/h.

This was a unique event because record-setting wind speeds occurred with both weak thunderstorms and no thunderstorm activity at all. In this case study we examine the meteorological mechanisms that produced the damaging winds. To view the case study, simple click the link below to visit the download page.

What Makes Our Agriculture Weather Forecasts Different?

At Weatherlogics, we strive to provide accurate, detailed, and reliable weather forecasts to the agriculture industry. We understand your frustration with traditional sources of forecasts which can be confusing and lack detail and consistency, which is why we’ve developed our own forecasting service.

At Weatherlogics, our in-house meteorologists produce our own independent, daily forecasts by utilizing various tools such as radar, satellite, surface weather observations, upper-air observations and weather models. This contrasts to many other forecasts which tend to be automated using weather models, rather than allowing trained meteorologists to produce the forecast by utilizing all available tools. While computer models are a great tool to assist in the forecasting process, relying solely on them will inevitably lead to inconsistent and inaccurate forecasts, especially for high-impact weather events. Weather models can also update up to four times per day, causing the forecast to change often, making it difficult to know what to believe.

Weatherlogics’ meteorologists carefully analyze the weather.

The forecasting service provided by Weatherlogics is used by the agriculture industry in all corners of Manitoba. Some reasons why so many have chosen Weatherlogics include:

  • Detail – By providing more detail, our clients are fully aware of what weather is coming before it arrives. We don’t just give the forecast, we explain why the weather is behaving the way it is and also address uncertainties in the forecast.
  • Proven accuracy – In 2017, our temperature forecasts were 30% more accurate than the public forecasts.
  • Meteorologists – Our forecasts are made by real meteorologists. This reduces variability in day-to-day forecast updates and increases confidence because the forecast process is guided by experienced meteorologists.
  • Communication – The uncertainties in the weather forecast are communicated to provide a better idea of where the weather may differ from the forecast
The error in Weatherlogics’ 2017 agriculture forecasts was lower than public forecasts.

Our agriculture forecasts are sent out by email 6 days a week to subscribers. Features of these forecasts include:

  • 5-day forecasts of temperature, precipitation, cloud cover, and wind.
  • Maps of precipitation amounts for the next 3 days.
  • Maps of wind speed and temperatures.
  • A short-term outlook discussing the weather and its uncertainties over the next few days.
  • A long-range outlook discussing the pattern over the next 1-3 weeks.
  • Email updates when significant weather has developed or there is a note-worthy change in the forecast.
An example of a wind map included in every forecast.

In addition to our daily weather forecasts, we also provide other services that help our clients prepare for future weather events:

  • Seasonal outlooks, such as our annual summer forecast.
  • Fully quality-controlled climate data with no missing values.
  • Road weather services to help our clients plan for inclement weather conditions which may affect travel.
Weatherlogics’ summer 2018 precipitation forecast

We currently offer our subscription service only in Manitoba, however we plan to expand our service to other provinces in Canada. We can offer customized weather forecasting services for any location in Canada, just let us know what your needs are! If you live outside of Manitoba, please feel free to contact us to show your interest!

To download a sample forecast, or to learn more, visit our agriculture solutions page. If you have any questions, feel free to contact us!

Hail series (Part 3): Forecasting hail and insurance implications

When forecasting the potential for hail, the first thing we look for is the potential for thunderstorm activity and the type of thunderstorms that are expected to develop. As mentioned in part 2 of this series, supercell thunderstorms tend to produce the largest hail and thus, there is a greater risk for hail damage when there is the potential for supercell thunderstorms. This is because supercells tend to have stronger updrafts, which are required to keep hailstones in the cloud for sufficient amounts of time for them to grow. Supercells tend to develop in a highly unstable atmosphere with adequate wind shear to separate the downdraft and updraft regions, which promotes longevity of the storm.

The life cycle of a thunderstorm, with the wet-bulb zero shown (source: NOAA NSSL).

The depth of the melting layer is also an important factor for determining if hail will melt completely before reaching the surface. The height of the wet-bulb zero can help with forecasting the potential for hail to reach the surface in thunderstorms. The wet-bulb temperature is the temperature at which a surface has cooled due to evaporation of liquid water. Thus, the wet-bulb temperature can be an estimate of the temperature of a precipitation particle as it falls through the atmosphere. We use the wet-bulb temperature because as the particle falls, evaporation is occurring on the wet surface of the particle. Generally, a height of about 2.1 km to 3.2 km (9,000-10,5000 ft) of the wet-bulb zero correlates well with large hail at the surface (source: NOAA Glossary). In the tropics, where the melting layer is deeper, large hail is less common than in the mid-latitudes.

The presence or absence of a layer of dry air in the middle part of the atmosphere is also taken into consideration when forecasting hail. Cooling from evaporation of water and melting of hailstones in this dry layer can lower the wet-bulb zero height inside a thunderstorm cloud, decreasing the depth of the melting layer and increasing the likelihood of large hail.

Hail is common along the Alberta foothills.

Surface elevation also affects the likelihood of hail. Higher elevations, such as the Alberta Foothills, result in thinner melting layers and less time for hailstones to melt. Hail is more frequent in these regions as a result.

Finally, the amount of water vapour in the atmosphere is considered. Generally, lower amounts of water vapour combined with a highly unstable atmosphere are more favourable for large hail. A highly moist atmosphere results in more liquid being present in the storm cloud, which reduces the speed of the updraft, thereby not allowing hail to remain suspended for as long.

A severe weather forecast graphic produced by Weatherlogics.

By considering all these factors, the meteorologists at Weatherlogics are able to produce daily hail forecasts. We identify where hail is likely to occur, and how large it could get. The image above shows one of our severe weather outlook graphics from 2017. That graphic indicates the potential for hail, in addition to damaging winds, heavy rain, and tornadoes. Each forecast graphic is accompanied by a synopsis which describes the meteorological conditions.  This information helps give hail-exposed sectors advance warning of damage potential. Once a hail storm has developed, we track the storm closely and gather information about it. Our hail data can be used to verify insurance claims and identify which areas were most impacted by a storm.

Thank-you for reading this series about hail. If you’d like to continue the conversation, feel free to contact us at info@weatherlogics.com. You can also visit our insurance page for more information about our hail data. We would love to show you how our hail data and forecasts can help you manage your weather risk.

Hail series (Part 2): Storm patterns

Viewed from the air, we can see that hail falls along paths known as hail swaths. These can be quite small – a hectare or so (a few acres) in area – or quite large, 16 kilometres (10 miles) wide by 160 kilometres (100 miles) long. Hail swaths that persist over large distances are often produced by supercell thunderstorms.

Hail swath on the ground near Airdrie, Alberta Canada. Credit: Cpt. Daryl Frank, Jazz Aviation.

Generally, supercell thunderstorms are the most frequent hail producers and produce the largest hail sizes. Supercells are rotating thunderstorms that almost always produce hail. Supercells have the greatest potential for damaging hail because of their stronger updrafts, allowing hail stones to remain lofted inside the storm cloud for longer periods of time. They are also longer-lived storms, allowing them to cause significant hail damage over longer distances.

A June 23, 2007 supercell storm which produced very large hail (Source: U of M Weather Central).

The radar image above shows an example of a supercell thunderstorm southwest of Brandon, Manitoba on June 23, 2007. Not only did the storm produce tornadoes, but it also produced large hail. Notice the V-shape appearance of the storm on the radar image and the hook-like feature on its southern side. These are some of the features on radar often associated with supercells. The region above the hook with the strongest radar returns (bright purples) is the most likely location of very large hail, sometimes as large as softballs.

Other thunderstorm types, such as single-cell or multi-cell storms, usually do not produce hail as large as in supercells. Single-cell storms tend to last less than an hour before fizzling out. This reduces their ability to cause widespread damage and their weaker updrafts tend to produce smaller hail, as compared with supercell thunderstorms. This is not to say that severe hail can never occur under single-cell thunderstorms, but the incidence of large hail is less frequent.

Radar image of a squall line in northern Minnesota (Source: NOAA).

Multi-cell storms last longer because they are continually regenerated along the storm’s boundary of outflow winds. However, their updrafts are also often weaker than in supercell thunderstorms. Squall lines (pictured above), which are lines of multi-cell thunderstorms, often occur late in the day or overnight, producing damaging straight-line winds. Again, large hail can still occur in multi-cell storms but it tends to be less frequent and lesser in size.

A photo of a supercell storm in southern Manitoba (Source: Scott Kehler)

Hail outbreaks can occur if multiple supercell thunderstorms develop along a frontal boundary (such as a cold front). Once these storms develop, large hail will begin to fall not too long after the storms develop (sometimes in as little as 30 minutes), given their intense updrafts. As the day wears on, these storms will either die out when the sun sets, or if the atmospheric conditions are right, the storms may develop into a line of storms, such as a squall line, which races eastward producing damaging straight-line winds and smaller hail.

If you’d like to continue the conversation, feel free to contact us at info@weatherlogics.com. You can also visit our insurance page for more information about our hail data. We would love to show you how our hail data and forecasts can help you manage your weather risk.

In our final post of this hail series next week we will discuss how Weatherlogics forecasts hail storms and impacts of these storms on various industries.

Hail series: What is hail and where does it come from?

Source: NOAA Photo Library

Hail is frozen precipitation, born of the updrafts of thunderstorms. Updrafts are rising air currents, which combined with cold temperatures and water droplets, are the primary forces that create hail. Such conditions are frequently present in the middle and upper portions of thunderstorms.

Hailstone embryos form inside storm clouds on small frozen raindrops and on “snow pellets” called graupel. They grow into true hailstones by accumulating ice through a process called accretion, by capturing supercooled (below 0 °C) water droplets in cloud regions with temperatures below the freezing point, 0 °C (32 °F). Hailstones sometimes contain pebbles, leaves, twigs, nuts, and insects that have been lofted into the clouds by strong updraft winds.

For the hail embryos to grow, they must remain in a layer of supercooled water for a length of time — the longer they stay there, the larger the size. They are kept in this layer by strong updrafts that construct the great towers of the cumulonimbus (Cb) clouds. The updrafts push the Cb cloud tops high into the atmosphere, creating the environment for lightning, thunder, and the various wind characteristics of thunderstorms.

Rising air (updraft) of at least 60 km/h (40 mph) is required to form dime-size hail. Golf-ball size stones (4.5 cm diameter) form when updrafts reach approximately 100 km/h (60 mph), and softball-size hail forms inside updrafts reaching 160 km/h (100 mph; NWS). To form hailstones the size of golf balls, over ten billion supercooled droplets must be accumulated, and thus the hailstone must remain in the storm cloud for at least 5 to 10 minutes. Once a hailstone has reached a weight which the updraft can no longer support, it falls to the ground.

Hailstones form in onion-like layers of opaque and clear ice. Clear layers form when colliding water droplets freeze slowly in cloud layers that are slightly below freezing, allowing air bubbles to escape. This process is termed “wet growth”. Opaque layers, with a “milky” texture, form when colliding water droplets freeze rapidly in cloud layers that are well-below freezing. The rapidity of the freezing prevents air bubbles from escaping. This process is termed “dry growth”.

When hailstones collide inside the thunderstorm, they may break into smaller pieces or become welded together into larger irregular shapes. Large hailstones can fall at a maximum speed of 170 km/h (105 mph).

Hailstones don’t have to travel up and down in a thunderstorm cloud however.  Sometimes they drift slowly downward through the storm, accumulating water droplets and growing as they pass through supercooled water layers. These stones will have a more uniform structure, rather than layered.

Source: NOAA Photo Library

Not all hailstones survive that downward trip. Forty to seventy percent of the hailstones that form within a thunderstorm cloud melt before reaching the ground.

A series of descriptor terms are used to communicate the size of hailstones, ranging from pea-sized to softball-sized. The best way to report the size of a hailstone is to measure it with a ruler or to compare it with a commonly-known object that does not vary in size, such as a coin. Marbles, although often used as a descriptor, is not a great object to compare to due to the varying sizes of marbles.

One of the largest hailstones ever documented occurred on July 23, 2010 in South Dakota. The hailstone had a diameter of 8-inches, or about 20 cm (NWS). Jim Scarlett, meteorologist in charge at the National Weather Service in Aberdeen, SD remarked “I described this one as cantaloupe-size.” The July 23 storm sent hailstones that broke through roofs, leaving fist-size holes in interior ceilings, smashing through windshields and causing at least five injuries to stranded motorists on I-90. Dents in the ground were still visible the following day.

Weatherlogics predicts the locations of future hail storms and collects data on hail events. This information is critical to ensure we have an accurate understanding of hail risk. For more information about these services, click here.

In our next article in this series on hail, we’ll be discussing the characteristics of hailstones, storm patterns associated with hail, and weather forecasting and hail damage assessments.

Hail Series Introduction

Over the next few weeks we’ll be publishing a series about hail. Hail affects nearly everyone at one time or another. Throughout the summer months, farmers, car dealers, insurance professionals, and many others, scan the sky daily. They are watching for towering cumulus clouds that may suddenly explode with thunder and lightning, and occasionally rain down a destructive blanket of hail stones.

The annual economic impact of hail storms runs into billions of dollars. In 2012, Alberta alone experienced $700 million in insured losses due to hail (source: Insurance Bureau of Canada). Insurance companies do have a direct interest in understanding the patterns of hail so that they can better predict losses and manage their claims process more efficiently.

For the rest of us, curiosity drives our desire to understand this fascinating and ever present natural phenomena.

Over the next three weeks we’ll explore the insides of hail stones, the behaviors of hail storms, and some of the economic and social implications of this fascinating phenomena. The first post on April 23, 2018 will discuss what hail is, and how it forms.

If you have questions about this topic or would like to suggest topics for future weather-related stories, please contact us at info@weatherlogics.com.

One of the Driest Meteorological Winters on Record Across Much of the Prairies – Except Southern Alberta

*Note: these statistics do not include the early March 2018 winter storm across the Prairies, which was technically part of meteorological spring.

It was a very dry meteorological winter (DJF) across much of the Prairies this year. Widespread parts of southern Manitoba had less than 50% of normal precipitation. The same can be said for much of southern Saskatchewan, particularly in the Regina area, and for eastern Alberta.

The contrary was true in southern Alberta, where snowfall was well above average this winter. At Calgary International Airport, 77 mm of precipitation and 87 cm of snow were recorded between December 1 and February 28, making it the 7th wettest and 4th snowiest meteorological winter since 1884. Normal is only 29 mm of precipitation and 45 cm of snowfall.

Data Issues

The precipitation amounts and their rankings are presented with a great degree of uncertainty. The methods used to measure precipitation at Environment and Climate Change Canada’s stations have changed significantly over the period of record and have become automated in the past couple decades. We have found that the new automated methods tend to produce smaller precipitation amounts as compared to previous methods, especially when there are moderate to strong winds present. These differences in methods make it difficult to accurately and confidently compare this year’s data with historical data. Nonetheless, this past winter was certainly a dry one throughout much of the southern Prairies, despite the data issues.

Another issue with the weather data in the past couple decades has been the presence of missing observations. Missing observations have occurred quite frequently at some major stations. Often times, the missing data can be retrieved in raw data formats, but sometimes an estimate must be assigned. In the case of Regina, a snowstorm on December 4-5, 2017 of this past winter was not recorded. As a result, by comparing with nearby CoCoRaHS stations, we were able to assign an estimated precipitation amount of 3 mm for the event.

Outlook

In southern Alberta, a lingering deeper-than-normal snow pack may result in a delayed start to spring with cooler than normal temperatures to start the month of March, before a warming trend occurs later in the month. In southern Saskatchewan and Manitoba, an early March winter storm has increased snow depth from near record lows, to fairly healthy levels. This increase in the snow pack will be helpful in replenishing moisture in the soil, but additional spring rains will be needed to fully recover from the dry conditions last summer.

For more information about the forecast for the upcoming summer/growing season, check out our official forecast here: https://www.weatherlogics.com/weatherlogics-summer-forecast-for-2018/.

Weatherlogics’ Summer Forecast for 2018

Our summer forecast for temperature, rainfall, and thunderstorms in 2018.

While it may not seem like it right now, spring is just around the corner. Meteorological spring begins on March 1, which has many people wondering what the upcoming summer has in store. We have prepared our outlook for this summer across western Canada – read on to find out more!

The weather pattern during the summer of 2017 was very dry across the southern Prairies. Rainfall totals in Winnipeg and Regina for 2017 were the 2nd or 3rd lowest on record, at only 333.7 mm (13.1 in) and 152.2 mm (6.0 in), respectively. The outlook for 2018 is a continuation of this dry pattern, but we do not expect it to be as dry as last year. The northern Prairies were on the wet side last year, and we expect this to be the case again this summer. The outlook graphic below shows our prediction for rainfall trends for the upcoming summer/growing season across the Canadian Prairies.

Weatherlogics’ summer 2018 precipitation forecast.

In terms of temperature, 2017 was warm across the western Prairies, but near- to slightly-below normal in the eastern Prairies. Like precipitation, this trend is forecast to continue in 2018, with warm conditions again in the southwestern Prairies and near-normal temperatures in the eastern Prairies. The graphic below displays our temperature forecast.

Weatherlogics’ summer 2018 temperature forecast.

Lastly, we have made our prediction for trends in thunderstorm activity across the Prairies. Overall, 2017 was a fairly quiet year for storms relative to 2015 and 2016 on the eastern Prairies. Conversely, the western Prairies were more active, seeing fairly typical thunderstorm activity. The Alberta foothills are an active thunderstorm region almost every year, so this is not an abnormal situation for that region. This year, our forecast for thunderstorms shows a slight rebound in activity across the eastern Prairies, with more activity than 2017. The western Prairies should again be active, with a similar number of storm days to last year.

Weatherlogics’ summer 2018 thunderstorm forecast.

Unfortunately, the impact of this forecast on the growing season is expected to be mostly negative, especially over southern Saskatchewan and into southern Manitoba. Last year was very dry in these regions, but crops remained surprisingly healthy as they were able to draw on residual soil moisture from previous years. This year, the situation will be different, as last year’s dry conditions depleted the reserves of soil moisture. In addition, snowfall this winter has been near record lows across a large swath of the southern Prairies, especially in southern Saskatchewan and southern Manitoba. Therefore, if significant rains do not occur at opportune times this year, crops will definitely struggle. Our best hope is for a wet spring to help replenish soil moisture before the heat of summer begins to dry the ground out once again.


The meteorologists at Weatherlogics are experts in weather forecasting and climate analysis. Don’t hesitate to contact us at info@weatherlogics.com if you would like to inquire about our weather solutions.

Freezing Rain Vs. Freezing Drizzle: What’s the difference?

In the winter months, one of the most feared weather conditions is freezing rain. It causes ice to accumulate on roads and sidewalks, making travel treacherous. While we all know freezing rain is dangerous, what makes it different from freezing drizzle, or even black ice? In this blog post, we investigate that question!

When you consider the difference between freezing rain and freezing drizzle, the easiest way to visualize the difference is to think of the difference between rain and drizzle. Rain consists of large drops, while drizzle is made up of much finer drops, almost like a mist in some cases. This probably gives the impression that freezing drizzle is just describing freezing rain at a lighter intensity. However, there is more to it than that.

Drizzle consists of water droplets that are less than 0.5 mm in diameter (image from: https://www.weather.gov/jetstream/preciptypes)

 

Rain consists of water droplets that are more than 0.5 mm in diameter (image from: https://www.weather.gov/jetstream/preciptypes)

To understand the difference between freezing rain and freezing drizzle, we actually need to briefly discuss a complex topic called precipitation microphysics. In short, this is referring to the very small-scale processes in clouds that cause precipitation to develop. One key concept regarding this topic is the fact that liquid water can actually exist in the atmosphere down to -40C, and the atmosphere is all liquid water at temperatures above -4C. Between -4 and -40C, there is a mix of ice and liquid, with more ice the closer the temperature gets to -40C. While a discussion about why this occurs is beyond the realm of today’s topic, keep this in mind as you continue reading.

To the average person, freezing drizzle is just low-intensity freezing rain. However, to a meteorologist the difference is much larger. Freezing rain occurs when snow is generated high up in the atmosphere, then falls through a warm layer above the ground (with temperatures above freezing), causing the snow to melt into liquid water. Before the now liquid drop of water reaches the ground, the temperature suddenly falls back below freezing, but not quickly enough for the water droplet to refreeze. As a result, the water droplet hits the ground as liquid, but immediately freezes because the ground is below-freezing. If the water droplet did have enough time to refreeze, it would be called an ice pellet (aka sleet), but that is a discussion for another day.

Freezing rain occurs when snow melts on its way to the ground and then freezes when it hits the surface (Image from: https://www.skybrary.aero/index.php/Freezing_Rain)

So if freezing rain is caused by snowflakes melting before they reach the ground, how is freezing drizzle different? The difference goes back to the microphysics that were discussed earlier. In the case of freezing drizzle, a low-level cloud deck is usually present in an atmosphere where the temperature is between 0 and -10C. Since the cloud in this case is not far below freezing, it is almost entirely (if not entirely) made of liquid water. Therefore, if the cloud contains enough moisture to produce drizzle, those small liquid particles will be supercooled – below freezing – as they head toward the ground. Once they reach the ground, the drizzle droplets are deposited as ice, sometimes called “glaze” because it is often a very thin layer of ice.

Freezing drizzle occurs when the entire atmosphere is below freezing (Image from: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/prcp/zr/prcs/swrp.rxml).

So we’ve learned about freezing rain and freezing drizzle, but what about black ice? Black ice isn’t actually a weather phenomena, but rather a road phenomena. According to the American Meteorological Society:

A popular alternative for glaze. A thin sheet of ice, relatively dark in appearance, may form when light rain or drizzle falls on a road surface that is at a temperature below 0°C. It may also be formed when supercooled fog droplets are intercepted by buildings, fences, and vegetation.

Black ice can form in numerous different ways. It can be the result of freezing rain or freezing drizzle, but could also be from existing water on the road freezing, or even the deposition of ice onto the road from vehicle exhaust. Regardless of its source, black ice is a very dangerous road condition because it can easily be mistaken for a wet road, or even a dry road!

When producing winter weather forecasts, the professional meteorologists at Weatherlogics closely monitor the potential for freezing rain, freezing drizzle, and black ice. While to the average person there may not seem to be much difference between freezing rain and freezing drizzle, the difference is quite important to meteorologists. The impacts are also different, as freezing rain events can be quite significant (e.g. the 1998 Eastern Canada Ice Storm), while freezing drizzle events are usually much less severe. It is especially important to consult a professional meteorologist if you are affected by these types of precipitation, since they are among the most difficult aspects of weather to predict. Our Road Weatherlogics service also provides future predictions of all winter precipitation types, including snow, freezing rain, and blowing snow.

La Niña Watch Issued; Is a Cold Winter Coming?

A La Niña Watch was issued by the Climate Prediction Center (CPC) last week. According to the CPC website, a La Niña Watch is issued when conditions are favourable for the development of La Niña conditions within the next six months.

As you’ve probably heard before, La Niña, or its “brother” El Niño, can have a big impact on winter weather in North America. In the Canadian Prairies region, La Niña usually means colder and snowier winter conditions. The graphic below summarizes why that is the case.

 

A typical La Niña winter brings colder conditions to the Canadian Prairies.

In La Niña years, the jet stream tends to be quite strong and remains consolidated in one band, rather than splitting into multiple streams. This tends to make it easier for frigid air to plunge down from the arctic across the Prairies. The presence of a strong jet stream in our region also allows weather systems to pass through frequently, making snow a common occurrence.

While it’s too early to say for sure whether a La Niña event will develop this winter, it is the most likely outcome at this point. The International Research Institute for Climate and Society at Columbia University has put together a graphic that shows the likelihood of various outcomes this winter. As you can see in the image below, La Niña is most likely, followed by neutral conditions (no El Niño or La Niña).

A La Niña event is currently the most likely outcome for this winter.

If you’d like more details on what to expect this winter, or need winter weather forecasts, our professional meteorologists would be happy to assist your business. Visit the contact us page to get in touch.