"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?
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.
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.
Aruna Budda Reddy Wins Bronze At 2018 Gymnastics World Cup
The gold medal of the event was bagged by Tjasa Kyaslef of Slovenia while the bronze was taken by Australia's Emily Whitehead. In men's artistic gymnastics, India's Rakesh Patra made it to the final in rings but finished fourth with a score of 13.733.
"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.
Ben Stokes to return for first England-New Zealand ODI
The allrounder was forced to miss the Ashes tour, where his absence was felt as England were beaten 4-0 by Australia . England one-day captain Eoin Morgan will be happy to cut Ben Stokes some slack.