‘Wavy’
jet stream to bring warm weather to north-west Europe
Warm air
from south to deliver above-average temperatures – but heavy rain expected to
follow
Brendan Wood
(Metdesk)
Mon 14 Oct
2024 15.05 BST
North-west
Europe is forecast to experience a burst of autumn warmth this week, thanks to
warm air from southern Europe spreading northwards. This brief episode of
warmer-than-average conditions will be driven by an amplified, or “wavy”, jet
stream, which will allow warm air to push farther north.
Daytime
temperatures across much of France are forecast to reach the mid-20s on Tuesday
and Wednesday, with some areas in the south-west potentially exceeding this.
Meanwhile, the Benelux area and south-east England are expected to reach the
low-20s by midweek.
However, the
most notable temperature anomalies will occur during Tuesday night, when
temperatures will stay in the high teens for areas of north-west Europe, 5-10C
above October averages. In parts of southern France the temperature may not
drop below 20C, a phenomenon known in meteorology as a “tropical night”.
Although an
amplified jet stream can sometimes result in a blocked pattern, in which
conditions persist for several days, this warm period is expected to be more
short-lived, ending with a bang as heavy rain and thunderstorms push in from
the south-east.
Significant
rainfall is possible over France’s Massif Central, with forecast models
suggesting more than 100mm (3.9in) could fall within 24 hours over Wednesday
and Thursday.
Recent
weather patterns have also been unusual in the Sahara desert. While rain in the
Sahara is not uncommon, there have been higher-than-average amounts in recent
months, with some parts of the desert receiving five times their usual
precipitation in September. The deserts of south-eastern Morocco – usually one
of the driest regions on Earth – had two days of torrential rain that exceeded
the yearly average.
Some areas
recorded more than 100mm within 24 hours, with downpours unleashing destructive
flood waters that resulted in 20 fatalities and devastated local agriculture,
as many farmers’ harvests were washed away.
However,
after six years of drought, this rainfall has brought some relief for some,
replenishing groundwater aquifers vital to desert communities and refilling
reservoirs at record rates.
Meteorologists
suggest the increase in rainfall may be linked to a northward shift in the
intertropical convergence zone (ITCZ), a low-pressure band circling the Earth
near the equator, where winds from the northern and southern hemispheres
converge. Although there is no clear explanation for the shift in the position
of the ITCZ, some climate models have linked it to higher air and ocean
temperatures owing to the climate crisis.
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