Based on today's GFS 06Z my vague analysis of tomorrow's snowfall ~ Early afternoon.
Although first I will be taking aboard a few rules of thumb.........
Temperature is probably one of the most crucial factors when determining whether or not snow is likely to fall. As a general rule of thumb, snow in the UK tends to fall when the temperature is 2C or less.
You may be wondering how snow can fall when the temperature is above freezing? Well the temperature of the air several metres above the surface is colder than at ground level. This snowfall can easily remain intact down to the surface, but does start to melt which is why it tends to be fluffy and wet (sleet and wet snow).
When temperatures remain at or below freezing the snow doesn't melt and therefore drier and more powdery..... great for snowboarding!
Temperatures of 2 - 4C will likely result in sleet or rain, although if it falls for long enough the air temperature will fall (evaporative cooling) eventually turning the sleet to snow.
The higher up you are, the colder it gets (hills and mountains) roughly by 1C for each 100m.
The UK is surrounded by relatively warm water, which means that in Winter temperatures in Coastal areas are kept slightly higher than further inland.
With temperatures being so crucial in determining snow, it means that whilst snow falls inland, locations 5 - 10 miles from the coast will see rain or sleet instead.
To add...... evaporative cooling is more likely under a slack and filled low pressure as winds don't mix in warmer moist air.
This chart will help those trying to determine if it will snow tomorrow in there location.
As for tomorrow early afternoon...... and will likely change so nowcasting is probably a better option.
Based upon this mornings GFS 06Z.........
Winds look slack which is good news for evaporative cooling (Rain turning to snow)
Dew points look very good across eastern England (Subzero).
Maximum temperatures under 2C across eastern England....... which is good news for snowfall and not rain.
Good thickness heights for eastern England - within the 528.
Precipitation down the spine of the Country and highly likely to change come the 12Z in a few hours
Based on the above information/data I would be forecasting moderate to heavy snowfall for eastern England no further south than London. Central, southern and southeastern England starting off as rain/sleet (snow chilterns etc) but readily turning to snow after dusk when air and ground temperatures fall away.
If I had to choose a prime A1 spot for tomorrows snowfall, I would be going for Cambridgeshire.
NH