"This set up is often referred to as the "Beast from the East".
Forecasters admit it is still unclear who will be affected and how much will fall.
Mr Walker said, however, that widespread snow is not expected.
He added: "But it is quite unusual, particularly as it's quite late in the season".
What does the yellow alert mean?
Kerala tribal youth's death: Government announces Rs 10 lakh compensation
Madhu, who was said to be mentally unsound, was living in a cave in the forest for the past several months, his family said. The lynching incident occurred at Attapady in Palakkad district on Thursday night after a mob accused Madhu of theft.
Snow showers, already affecting eastern parts of England early on Monday, are expected to become more persistent and more widespread through the afternoon and evening.
Forecasters say the white stuff could cause travel chaos on roads and rails, stranding vehicles and passengers and causing delays and cancellations.
Snow showers are expected to develop widely, with some places seeing 5 to 10 cm of snow.
Dorset Highways has started preparations ahead of the cold weather and has warned scheduled surfacing work may be cancelled and rescheduled.
You can check that here - but Spirit FM has done some of the hard work for you in terms of temperatures.
Muirhead mistake proves crucial as Great Britain miss out on curling final
Muirhead narrowly missed a double take-out in the second end as Hasselborg drew Sweden into a 2-0 lead. Japan tied the game for the first time in the contest with the stolen point.
"Cold weather is now established across the country with widespread overnight frosts", said Paul Gunderson, chief operational meteorologist at the Met Office. Max 0C during the day and min -4C at night.
And it will turn even colder on Sunday night, reaching lows of 0C to -3C.
By Wednesday next, day-time temperatures in Dublin will hover around freezing.
A blast of weather all the way from Siberia in Russian Federation could be set to hit Ireland over the coming days according to the latest Irish and United Kingdom forecast as Spring sunshine is replaced by a sub-zero eastern weather front.
At present, Met Eireann is forecasting that it will be extremely cold with penetrating severe frosts and temperatures struggling to get above zero by day especially in eastern counties from Wednesday through Friday.
Flood Watch: Greatest Risk Along E and SE Slopes
Residents in Mattawan, in southwestern MI , used sandbags to protect homes and businesses as a river rose above its banks. A 52-year-old Bourbonnais, Illinois, woman was found dead Tuesday in a submerged auto in Peotone, south of Chicago.