It might be the start of meteorological spring, but winter is definitely fighting back this week.
On Monday night, cold Arctic air pushed southwards across the UK.
Snow has been reported across North East Scotland, the Northern Isles and Northeast England, especially in Northumberland.
But it wasn't just the north of the country. There were even reports of snow as far south as Suffolk, the home counties saw a dusting too—and there's more to come.
This cold Arctic air will remain in place until the weekend as it battles against the mild moist Atlantic air trying to make headway from the south-west.
Where these two airmasses meet, we're likely to see a tricky mixture of rain, sleet and snow.
Forecasting snow is one of the hardest things to do in this set up as it depends on a number of factors:
The extent of the system and if this changes between computer models. This means firming up on the location can be a challenge.
The persistence of the snowfall. Nearly all precipitation in the UK leaves the cloud as snow, before often melting as it gets closer to the ground. Over time, heavy snow cools the atmosphere all the way to the surface, allowing snow to fall to ground level
The intensity of the snowfall determines how quickly the air cools to sustain the snow
The question of whether any snow will accumulate on the ground is linked to ground surface temperature and the variables already mentioned
So, as you can see, it really is difficult to forecast rain, sleet and snow when the conditions are marginal. Hence we're not just hedging our bets!
What can we expect?
Before we get into the detail, the story for this week is split in two. Snow showers will affect Scotland, Northern Ireland and North East coastal districts until Thursday, ahead of the main low centre pushing in from the west.
Meanwhile, the south of the country has a complex 48 hours of weather, as a daisy chain of fronts skirts southern England.
Through much of Tuesday night a front will push across the southern counties of England and south Wales. Arriving into the south-west around 9pm before moving eastwards. A mixture of rain, sleet and snow will sweep through.
There is a large degree of uncertainty in how far north the snow will develop. Accumulations will mainly be focused over higher ground, however some at lower levels are still possible.
Further snow and hail showers will impact northern coastal counties, including Northern Ireland and Scotland. Clear skies will develop elsewhere allowing a widespread harsh frost with the risk of ice too.
Wednesday will see a brief lull before it turns interesting again with mostly crisp sunny weather.
As Tuesday night's low pulls away to the south, most of the country will escape with a quiet day. Cloud amounts will start to increase from the south-west.
Some wintry showers will continue to impact northern areas and where these line up, accumulations of snow will continue.
Meanwhile in the south-west, the next system arrives, driving moisture into the cold arctic air once again, but this time it makes more northern progress.
The onset is likely to arrive after 4pm from the south-west, moving into south-west England and south Wales seeing a mixture of rain, sleet and snow.
Depending on its intensity will determine how quickly the snow reaches the surface and how long it is sustained.
Through Wednesday evening, as the sun loses strength and temperatures start to fall, a wintry mix is more likely.
The low pressure moves in and advances further north and east. At this stage, the focus for the higher snow accumulations is across England south of the M4, where there is a chance some places could see 5-10 cm falling in just a few hours.
From midnight and during the early hours of Thursday, the low pressure clears eastwards, leaving clear skies and sub-zero temperatures for many.
This will lead to the risk of ice on untreated roads and surfaces.
Again, there are uncertainties regarding the exact track, the northern extent, intensity and how much snow will actually accumulate.
Met Office have a yellow weather warning for snow and ice, in force from 12am Wednesday to 9am Thursday for the south of the country to cover this.
Thursday and Friday
By Thursday, a deep low pressure system which has been developing in the Atlantic will swiftly plough into the cold air, but this time will push across the whole country.
Strong winds will accompany this ,bringing the risk of gales, blizzards for parts of northern areas and blowing lying snow.
On its leading edge, rainfall will readily turn to snow across northern England, north Wales, Northern Ireland and Scotland. Significant disruption is likely in places.
The Met Office have a yellow weather warning for snow valid from 3am Thursday until 6pm Friday.
For central and northern areas snow will persist through much of Friday, while across the southern portion of the waring area, snow will turn back to rain during Thursday afternoon and evening.
How much snow will Thursday's system bring?
3 to 5 cm widely through the warning zone
5 to 10 cm of snow likely, even at low elevations
Potentially 15 to 20 cm will accumulate across central and northern areas
Above 150m, of the North Pennines, Southern Uplands, parts of the Central Belt and southern Highlands, there is scope for 30 to 40 cm.
The snowfall is likely to bring severe disruption for the north of the country with long delays and cancellations to travel.
Roads are likely to become blocked and passengers could become stranded and some communities could become cut off and power outages may occur too.
Remember the five Ps in cold weather:
People - especially the elderly, if you can please check in on your neighbours and check if they are OK and need anything
Pets - in cold weather, animals that may usually be outside, it's worth considering bringing them inside or ensuring they have somewhere warm to shelter. And don't forget that salt spread on the roads can be irritating to your furry friends paws, remember to rinse them in warm water
Pavements - remember icy paths and pavements are likely so be careful of slips, trips and falls
Pipes - cover your pipes and protect your outside taps from freezing over to help prevent water leaks
Plants - cover and protect cold sensitive plants
Is there anymore after Friday?
Although a way off as yet, there looks to be some further snowfall possible for the north of the country on Saturday night and into Sunday.
Until then, stay up to date with the latest forecast and Met Office warnings which you can find here