Is This Weather Normal? – January 2019

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The main weather stories in Terrace, BC for January 2019:

  • Higher than average temperature
  • Higher than average precipitation
  • Lots of rain (at least for January)

Temperature:

January temperature was the 8th warmest on record, averaging +0.3°C, which is 4.0°C warmer than the 1971-2000 baseline climate. Most of the month had temperatures well above average with only a couple days near the beginning of the month that had temperatures near average (Fig. 1).

 

Figure 1: Daily average temperature for January 2019 in Terrace, BC (red line). The black line shows the 1971-2000 average. The two gray lines show plus/minus one standard deviation.

Precipitation:

Precipitation in January was the 31st most on record, totaling 195mm, which was 20mm more than the 1971-2000 average. This provided a brief respite from the longer-term drought in northwest BC, but much of this precipitation (105mm, 54%) fell as rain. The cumulative values show this (Fig. 2), with total rain in 2019 (dark blue, dotted) above the 1971-2000 normal (dark blue, solid), whereas total snow in 2019 (light blue, dotted) is below normal (light blue, solid). This isn’t unheard of in January, but certainly not the norm. While high elevations mostly received snow – helping to build the winter snowpack – liquid precipitation at lower elevations isn’t available during the spring melt to come. This also made for some wet ski days at Shames Mountain!

Figure 2: Cumulative precipitation – where total precipitation (green), rain (dark blue), and rain (light blue) are added throughout the year. Solid lines show the 1971-2000 average. Dotted lines show the 2019 totals to date.

Links:

Terrace, BC Weather Forecast (Environment Canada), All data presented in this post is freely available here.

 

Is This Weather Normal? – 2018 Overview

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The weather in Terrace, BC for 2018 can be summed up in a few primary stories:

  • A winter story: Higher than average snowfall at low elevations.
  • A temperature story: Warmer than average, and with the 3rd warmest summer on record.
  • A summer/fall drought story: Record-setting dry conditions from July through October.

But first, some annual averages and totals for 2018:

  • 2018 was the 25th warmest year on record, averaging 7.1°C, which is 0.7°C warmer than the 1971-2000 baseline climate.
  • 2018 was the 7th driest year on record, with a total of 934mm of precipitation, which is 439mm below the 1971-2000 average, or 68% of normal.

While these annual values tell part of the story of 2018 weather, they mask some of the truly weird weather that we experienced in 2018. Figure 1 shows average monthly temperature for 2018 (blue dots) in comparison with all years on record. February was quite a bit colder than average, July and August were much warmer than average.

Figure 1: 2018 average monthly temperature for Terrace, BC. The dotted blue curve is 2018, the 10 red lines are the ten warmest years on record, every other year is in gray. The black line is the long-term average, and the error bars mark plus/minus one standard deviation.

A Winter Story:

Conditions in Terrace, BC during the winter of 2018 were noteworthy in that we had a large early snowfall in November (2017) followed by colder than average temperatures and more snow through February, leading to snow persisting through the winter at lower elevations. It was the 31st coldest winter (Dec. – Feb.) on record, with temperatures 1°C below the 1971-2000 average. Even with this cold, and the persistent snow on the ground, it was the 15th driest Dec. – Feb. on record with total precipitation 190mm less than average. This significantly lower than average precipitation (61% of normal) meant that while we had lots of snow at low elevations, the mountain snowpack was unremarkable. Looking at total snowfall for the months Nov. – Mar. reveals that it was the 19th snowiest winter on record in Terrace.

Some noteworthy winter statistics:

  • 13th coldest February (-5.2°C), 3.9°C colder than average.
  • 19th snowiest winter (Nov. – Mar.):
    • 384cm of snow
    • 105cm more than average
    • Well below the record winter of 655cm (1972).

A Temperature Story:

The main temperature stories for 2018 were the much warmer than normal months of July and August, and a record setting temperature for a day in June. While the year was only the 25th warmest on record, we had the 3rd warmest summer (Jun. – Aug.). Average summer temperature was 17.2°C, 1.7°C warmer than average. The month of June was nearly identical to the average, but we then had the 4th warmest July followed by the 3rd warmest August (Figure 1).

Additional seasonal temperature statistics for 2018:

  • 31st coldest winter, 1°C below average
  • 49th warmest spring, 0.2°C above average
  • 3rd warmest summer, 1.7°C above average
  • 29th warmest fall, 0.7°C above average

Just like the annual average temperature masks seasonal and monthly variability, seasonal and monthly averages hide the day-to-day extremes experienced during the year. Figure two shows the average daily temperatures for the year.

Figure 2: Daily average temperature for 2018 in Terrace, BC (red line). The black line shows the 1971-2000 average. The two gray lines show plus/minus one standard deviation.

Changing temperature between the two gray lines (plus/minus one standard deviation) can be considered average variability. When temperatures go below or above these two lines we’re starting to see conditions that are more out of the ordinary. There were a few such events in 2018.

The colder than average February (roughly between Julian day 30 and 60) stands out pretty clearly, with two peak cold days: -13.4°C on February 10th, and -11.8°C on February 19th. Getting cold days like this isn’t out of the ordinary, and in fact we usually get more such days and the minimum temperature in a given year is usually colder. Only two years had the lowest winter temperatures higher than the -13.4°C recorded in 2018. Or, in other words, 28 out of the 30 years during the climate baseline period (1971-2000) had temperatures colder than our coldest temperature in 2018. Translation: It didn’t get that cold in 2018.

The peak temperature on May 18th of 18.4°C (day 138) wasn’t a record setting temperature for the month of May, but certainly was much higher than the average and within a few degrees of the all-time high for the month of May.

The two times of highest average daily temperature occurred on June 19th (25.3°C) and on July 30th (25.1°C). Only two years during the 1971-2000 baseline climate period had an average daily temperature above 25.3°C. June 19th, 2018 set an all-time record for temperature in June with a high temperature of 34.2°C and an average daily temperature of 25.3°C. The peak summer temperatures of 2018 were well above normal.

A Summer/Fall Drought Story:

The final, and most important weather story of 2018 was the July through October drought. It was the driest Jul. – Oct. on record with a total of 150mm of precipitation (37% of normal), and the driest Jul. – Sep. on record with a total of 56mm of precipitation (26% of normal). None of the individual months were record setting, but taken together they are the driest four-month period on record in Terrace.

  • 9th lowest July precipitation
  • 5th lowest August precipitation
  • 4th lowest September precipitation
  • 9th lowest October precipitation

Figure 3: 1913-2018 total precipitation for the months July – August. The long-term average is in black and dashed. There are two years of missing data (1914 and 1953).

The impacts of the 2018 drought will likely linger, unless the region receives well above normal snowfall and a cool/wet summer in 2019. Watch for analysis for January and February 2019 coming to GlacierChange.org soon, followed by updates at the end of each month.

Some weather-related news stories from 2018 for Terrace and the larger region:

Province Increases Drought Rating in Parts of Northern BC, Terrace Standard

Province Ups Drought Level for Coastal BC, Terrace Standard

‘Unprecedented Low Water Levels’ in Northern, Central BC Raise Fears for Future of Wildlife, CBC

Some weather-related links:

Government of BC Drought Information Portal

Terrace, BC Weather Forecast (Environment Canada), All data presented in this post is freely available here.

 

Is This Weather Normal? – Introduction

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Have you ever wondered if the weather yesterday, last week, or this past month was “normal”? Starting in the coming days, “Is This Weather Normal?” will become a regular blog topic at GlacierChange.org. This series of posts will focus on the weather of Terrace – a town of some 12,000 in the Coast Mountains of British Columbia.

I teach an introductory weather and climate course at Coast Mountain College, and in addition to doing weekly weather forecasts with my class, we’ve also begun looking at our weather in a longer term context. The motivation for bringing these short overviews on the “normality” (or abnormality as the case may be) of our weather, is to provide some quantitative context, some verifiable reference points for what we experience on a daily basis.

Our perception of weather is colored by personal preferences of what constitutes “nice”. And often it has become that “nice” is completely abnormal, and sometimes even threatening to the ecological norms of a region (see here for example). “Sure glad this is all falling as rain. You don’t have to shovel rain!” is a common mid-winter saying during an abnormally warm winter spell. “This fall weather has been incredible! The salmon probably aren’t doing too well though, eh?” was a common refrain in the summer/fall of 2018 here in northwest BC. Our qualified opinions of the weather has us far removed from what “normal” actually is.

My hope is that these posts will help provide some rational footing with respect to our daily experience of the vagaries of our atmosphere – at least in western British Columbia. Watch for the first such post – an overview of 2018 weather – in the coming days, followed by an update each month for 2019.

 

 

 

Gilkey Glacier, AK – 30 Years of Thinning

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gilkey-glacier-1985-2015

This photo pair shows the Gilkey Glacier (main glacier in the valley) in southeast Alaska. It’s hard to get a sense of the enormity of this scene. The distance from the photo location to where the glacier curves around the corner to the left is ~10 km. The amount of thinning of the glacier surface is on the order of 200-300 m.

Gilkey Glacier is one of the largest outlet glaciers of the Juneau Icefield. It is banded by numerous medial moraines and is a world-famous example of ogives (the arcs of alternating lighter and darker ice), which form at the base ice falls. It is named for Arthur Gilkey – mountaineer and early leader of the Juneau Icefield Research Program.

Castle Creek Glacier – 55 Years of Retreat

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By Matt Beedle

The longest continuous record of annual length change for a North America glacier now stands at 55 years (1959-2013).  In 2013 Castle Creek Glacier retreated 26.3 meters, the fifth largest annual measurement since 1959.  Total 1959-2013 retreat now stands at 803 m, with an average annual rate of 14.6 m.

dL-combi_59-13Annual length change of Castle Creek Glacier in meters (top), and cumulative length change in meters (bottom).  Both plots include data from 1959 to 2013.  A full discussion of the methods used to derive this data set can be found here.

Glacier retreat over decades can be dramatic.   For instance, Castle has lost nearly 2 km2 of surface area since 1952, most of it near the terminus.  Repeat photography of glaciers typically uses pairs of images separated by multiple decades, revealing this stunning multi-decade change.

 

castle_1952-2011_aerial-photosTwo aerial photographs of the terminus area of Castle Creek Glacier.  The 1952 image is from the National Air Photo Library, Natural Resources Canada.  The 2011 image includes the near infrared band – vegetation appears red.

In my numerous trips to Castle Creek Glacier over the past six years I’ve been no less moved by the annual changes of a much smaller magnitude, however.  The change we see around us is always in relation to scale, proximity and familiarity.

 

One of my annual tasks at Castle Creek Glacier has been to walk the terminus of Castle Creek Glacier with a high-precision GPS on my pack, mapping the glacier margin and measuring annual change.  This annual walk – often times more of a scramble – reveals a great deal. The revelation is in terms of quantifiable glacier retreat, but also a more subjective experience of glacier landscapes and glacier change.  John Muir – reflecting on a brief exploration of the terminus area of Baird Glacier, Alaska in 1879 – captures this experience well:

“The whole front of the glacier is gashed and sculptured into a maze of shallow caves and crevasses, and a bewildering variety of novel architectural forms, clusters of glittering lance-tipped spires, gables, and obelisk, bold outstanding bastions and plain mural cliffs, adorned along the top with fretted cornice and battlement, while every gorge and crevasse, groove and hollow, was filled with light, shimmering and throbbing in pale-blue tones of ineffable tenderness and beauty.”

-John Muir, Travels in Alaska

Along with mapping the glacier margin and annual retreat, I’ve had the opportunity to observe and photograph Castle Creek Glacier’s annual changes.  With each visit I’m astonished by the volume loss, change in form and alteration in character that is quantified blandly (yet importantly!) in our measurements of change.  These repeat photographs, dating back to 2007, don’t show the marked change of repeat photos separated by decades. They do, however, catalog the more experiential understanding of the annual glacier change of Castle Creek Glacier.  If you’re fortunate enough to have a ‘local’ glacier, make an effort to pay it a visit each year – you will be richly rewarded.