As I am writing this, we are just about 2 days out from the start of the event for Maryland. The storm is behaving as expected and is still plotted to track up our gut bringing a slew of winter precipitation. There is still time for wiggle room in the track, but even so, it appears that central Maryland will be experiencing all types of winter precipitation which will cut back on snow totals.
SET UP
Given the forecast I laid out, you need to understand the set-up of this storm so you can see how variable and marginal conditions will be. Some parts of your county may record 6 inches of snow and other parts might get 2 inches and that is just the fact of the matter of this storm. All in all, waking up Monday morning, most of us will see a layer of snow, then ice, then snow as long as a period of regular rain doesn't wash away much.
Frigid Air
Sunday Morning
It will be in the low teens and perhaps in the single digits on Sunday morning. Cold air is dense, and the mountains has a damming effect protecting this air for the incoming storm.
Rotation and Flow of the Storm (Pan Through the 2 Images)
Sunday Night
This storm is extremely strong and will be strengthening in our region. Storms rotate counterclockwise and this storm is violently pulling warm air off the ocean onto land and over the cold air at speeds of 40-70 mph at cloud level.
Usually, these storms track off the coast far enough that the warm air flow overhead doesn't reach our region. However, with this inland track, this warm air is being thrown over the cold dense air (Picture 1) creating large regions of sleet and freezing rain. Falling snow melts entering this over running warm air then freezes when it gets to the cold air at the surface. This can be seen with regions of red and purple on the image (Picture 2)
SNOW, SLEET, OR FREEZING RAIN?
Here is a visual to help you better understand how and when different types of precipitation happen. Not only is it tough to forecast between sleet, snow, or freezing rain, the hard part is determining when and how long it will occur. This is what can aid or kill snow accumulations.
GENERAL TIMELINE OF THE STORM
This is a slider map, click on the arrows to navigate
UPDATED FORECASTED SNOW MAP
This map shows how much snow will be on the ground when the storm finishes up Monday morning. More snow will have fallen that what will be on the ground due to rain fall after midnight washing away some accumulation.
Areas in the 5-8 range will get all snow with some occasional mixing Sunday night.
Areas in the 3-5 range will experience snow, a short period of freezing rain and sleet and rain before changing back to snow for snowfall on the backside of the storm.
Areas in the 1-3 Range will get three to five inches of snowfall followed by a prolonged period of sleet and freezing rain, a period of rain then some snow on the backside of the storm. Expect impactful ice accumulation on trees, sidewalks, and power.
Areas in the trace - inch range will initially get substantial snow, followed by a period of mixed precipitation then rain where most of the snow will be washed away
Areas in the no snow region will likely get a period of snow and mixed precipitation but will all be washed by rain.
THE TWO DETERMING FACTORS OF THE STORM
1. Storm Track
The exact storm track is still up in the air but the most I expect this storm track to wiggle is 50 miles at most. This wouldn't be far enough east to allow a complete snow event for Maryland. What it would do however, is allow the snow to last longer and eliminate any plain rain from occurring in the middle of the storm. So, if the storm track does shift east, less warm air would flow over our region, and we would get snow to sleet to freezing rain back to snow.
2. How long does the cold hold
Barring any changes in storm track, another factor that would effect change in the storm would be the amount of time the cold hangs on for. There will be frigid air on Sunday morning, and I just can't wrap my head around temperatures breaking freezing by midnight. Cold air likes to hang around in our region because it is kept from escaping due to the mountains. The weather models don't usually do the greatest job in recognizing this subtle fact of Maryland weather. I believe there is a good chance cold air will hang around longer for freezing rain to occur for a longer period.
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