Moisture Updates - August 23, 2023

Synopsis

Map 1: Since the last report (August 16) rains have continued throughout a large swath of the North West, North East and Eastern Peace Regions with many lands receiving well over 40 mm in recent days, and in some areas ranging to well over 80 mm (Map 1). Elsewhere along the foothills and extending eastward into the Central and Southern Regions and along the USA border, upwards of 20 mm fell on moisture stressed lands. Unfortunately dry conditions prevailed elsewhere, with less than 10mm falling across wide swaths of land though parts of the Central, Southern and Peace Regions. However, for most of these parched areas 5 to 10 mm was welcome and should have minimal impact on harvest activities which are now ramping into full gear throughout the Southern Region. Excess moisture may be a pressing issue across much of the North West and North East Regions and a long stretch warm dry weather would be welcome here in the coming days.

90-day Precipitation Patterns as of August 23, 2023

Maps 2 & 3: Over the past 90 days, much of the North West Region has been persistently wet with many areas seeing this much rain on average less than once in 12 to 25 years and some isolated areas are near once in 50-year wets (Map 2). In sharp contrast, most of the Central, Southern and northern Peace Regions have been chronically dry with many lands in the less than once in 12 to 25 year low category and several isolated pockets tending towards once in 50-year lows.

Rainfall totals over the last 90-days are now well over 400 mm across much of the North West with relatively few areas receiving less than 300 mm (Map 3). A total of eight stations have recorded more than 500 mm with the greatest amount (592 mm) recorded at the Mayberne Auto station, located in the Forest Protection Area, roughly 50 km NNW of Edson. In contrast parts of the Central Region and most of the Southern Region were dry, receiving less than 120 mm. Drier still were lands across much of the east-half of the Southern Region where less than 80 mm fell. Currently there are 14 stations that have received less than 50 mm in 90-days, with the lowest accumulations (40.5 mm) being recorded at the Buffalo AGCM station about 100 KM ENE of Brooks. In comparison, average rainfall accumulations for this location are in the 170 mm range. This is in the heart of Alberta’s dry belt and growing reasonable crops even with average rainfall is in itself challenging. Persistent above average temperatures have only added to the chronic moisture stress.

Lack of moisture across many parts of the South and Central Regions have been occurring since at least the beginning of July last year, following a relatively wet June that helped immensely. Looking back as far as August of 2020 many of these lands have remained persistently dry and are now struggling with precipitation deficits in the range of -500 mm. This is far more than a “normal” years’ worth of precipitation, lost in the space of only three years, which in the driest areas, ranges on average from 325 to 350 mm annually.

Soil Moisture Reserves Relative to Normal as of August 23, 2023

Maps 4, 5 & 6: With recent rains across many locales, soil moisture reserves have recovered substantially (Map 4). Bear in mind that at this time of year they are generally quite depleted and as such it’s “normal” for soils to be near their historically driest point in the year (Map 5). That being said, this serves as a good start for the soil moisture recharge cycle ahead of next year’s cropping cycle. However, there are still significant shortages across much of the Central Region and parts of the south, with many lands needing roughly 50 to 75 mm of rain to bring current reserves to near normal for this time of year (Map 6).