Eurasian extremes

Over the last two weeks, even with only a casual perusal of the news, it would be difficult to escape noticing how extreme weather has caused great disruption to many lives.

I’ve outlined here some of the causes of the weather disasters currently affecting large numbers in Russia and Pakistan. You can see that while they are separate events, there are some common physical factors.

Russian heatwave

Global wheat futures have spiked over the last week with much of the activity stemming from crop losses in Russia. Stories of parched fields and decimated crops are everywhere.

Part of the price spike came on the heels of a Russian export ban, but nonetheless, this event has a weather origin. Temperatures in and around Moscow are making the mini heatwaves in the US seem trivial.

One of the reasons why it has stayed so hot for so long is the persistent high pressure system centered over Eastern Europe, coupled with changes in the pattern of the jet stream.

When this high is as entrenched as it has been, it serves to do two things. First it diverts a jet that would normally bring with it cooler air into the region, steering this air into parts of central Russia and northeastern Africa.

Second, it blocks moist air from the southeast, which is exacerbating the dryness. In addition, there is an active west to east jet stream that travels above western Russia, which typically exhibits a seasonal eastward shift, allowing moist air from the west to migrate into the region. This July, the jet did not shift, and the result was a prolonged period of moisture-free air.

When this combines with a strong high, the region experiences weather like it has seen over the last month. And when there is a high pressure system in one region, there is often a corresponding low elsewhere.

Flooding in Pakistan

The low in this case, has been over the mountainous region over northern Pakistan. And this cold low has been the catalyst for a good portion of the excess rains.

So, while located in distinct climatic zones, the heat and dryness in Russia has a connection to the floods in Pakistan.

But there is more to this puzzle. Every year, the annual Indian Monsoon is eagerly anticipated throughout India and Pakistan, as much of the commercial activity that takes place in both countries is agrarian in nature, and therefore, dependent upon healthy seasonal rains.

Another area of high pressure over northeast India has, thus far, kept northern states in India dry. But in the process, this high has diverted even more moisture into central/western India and Pakistan. Added to that, stronger winds from the southeast are also actively driving the moisture into areas that need it the least.

Making the rainfall situation for Pakistan worse is the condition of drainage infrastructure, so when excess rains fall, it takes much longer to drain off. Unfortunately, any excess rains in the coming weeks will likely be met with more problems for the population.

Estimates on the number of flood related deaths are at around 1300, with over 14m having been affected; both of these figures are expected to rise.

Dr. Michael Ferrari, is the Vice President of Applied Technology & Research at Weather Trends International
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