Arctic blast produced ice pellets & wind chill

The very cold air streaming down from the Arctic on Monday meant a cold day with the temperature not getting above 8.2C, which was 6.1C below the April average. However, that was only part of the story as the strong wind, gusting to 24mph, meant there was significant wind chill that for most of the day it felt at least 2C colder outside than indicated on the thermometer.

A band of light precipitation crossed the area at 11.40 and ice pellets were observed. It was not fluffy snowflakes as what fell from the sky was very much smaller than hail and much more irregular and bounced as it hit the ground. Being small and light it was blown around in the wind and could have been mistaken for small snowflakes. Ice pellets form when snowflakes start to melt as they drop from the cloud, then fall through sub-freezing air, whereby they refreeze into grain-like particles.

The thermometer dropped below zero at 22.41 Monday evening and continued downwards unit 07.20 on Tuesday. This produced another hard frost with a minimum of -2.8C at 05.00 on Tuesday. This low was 4.9C below the 37-year average.

Much blue sky and sunshine was in evidence after dawn on Tuesday but shortly after 08.00 cloud began to drift across obscuring much of the sun. By that time the thermometer had recovered to 1.6C. The anticyclone has drifted a little further south so the wind has backed a few degrees and currently coming from the north-northwest. The very dry air continues with humidity at 08.00 as low as 73%.