Access background information for how and why wind trajectories are monitored in this post.
1. REVERSE TRAJECTORIES (RT)
Since May 1, 2021 the majority of reverse trajectories that have crossed the prairies originated from the Pacific Northwest (Idaho, Oregon and Washington). For the past two weeks there have been an increasing number of reverse trajectories that moved north from Texas, Oklahoma, Kansas and Nebraska (Fig. 1). Compared to previous years, the number incoming trajectories (May) has increased. Though these US regions can be a source of diamondback moths, the ECCC models predict air movement, not actual occurrence of diamondback moths. It should also be noted that host plants of diamondback moth include all plants in the Brassicacea family, including cruciferous weeds and volunteer canola. These plants are suitable hosts until canola emerges.
a. Pacific Northwest (Idaho, Oregon, Washington) – This week there have been 36 trajectories (44 last week) that have crossed Alberta, Manitoba and Saskatchewan. In previous years, the majority of Pacific Northwest reverse trajectories usually have been reported to pass over southern Alberta. This growing season, PNW trajectories have crossed all parts of the prairies (Fig. 2). Compared to this time last year there has been a significant increase in the number of trajectories that have crossed Manitoba and eastern Saskatchewan.
b. Mexico and southwest USA (Texas, California) – Compared to previous years, there has been a noticeable increase in number of trajectories from the southern US. This week there have been 54 trajectories (15 last week) that originated in Mexico and the southwestern US that have crossed the prairies (Fig. 3).
c. Oklahoma and Texas – This week there have been 51 trajectories (16 last week) that have passed over Manitoba, Saskatchewan and eastern Alberta that originated in Oklahoma or Texas (Fig. 4).
d. Kansas and Nebraska – This week there have been 63 trajectories (35 last week) that originated in Kansas or Nebraska that have passed over the prairies (Fig. 5). Relative to the reverse trajectories associated with Oklahoma and Texas, the trajectories from Kansas and Nebraska have crossed further into Alberta.
2. FORWARD TRAJECTORIES (FT)
a. Forward trajectories, originating from Mexico and USA, have crossed a number of prairie locations since May 1, 2021. This week there has been a decrease in the number of trajectories that are predicted to cross the prairies (Fig. 6). The dates on the graph report when the trajectories originated in the USA (blue bars). These trajectories generally require 3-5 days to enter the prairies (red line). The data suggests that, compared to this week, there may be increased potential for the introduction of DBM to the prairies.