Can We Just Get a Freakin Decent Snow Already? Why It's So Hard Getting Snow Here in Richmond

        Time to flip those PJs inside out Richmond area snow lovers, confidence is growing that the region will see at least some wintry weather starting on Sunday night and lasting through Monday night. As is always the case, however, it appears that it will be a nail biter to see who gets the fluffy stuff and who ends up with winters sloppy seconds. Why does it seem like everytime wintry weather comes our way, Richmond is always on the line between igloo building and snowball fights or just a salty, grimy slushy? 

        Though I not a native Richmonder, I've lived here long enough to know to never get too excited about the potential for snow. When I first moved here back in 2015, I got extra excited about the wintry weather possibilities when the Richmond area saw over a foot of snow during the first winter in our new house. Coming from Tennessee, this was a snow lovers paradise comparatively. In recent years, my excitement has turned sour as the party has been reserved primarily to those north of the city. In fact, the snow drought is so bad Richmond hasn't had a measurable 1 inch or greater of snow in nearly three years! So why is it so difficult to see snow around here? 

First, Let's Talk Generally About Sunday-Monday. 

After checking the latest guidance as of 12z, there is still alot of uncertainty that exists. Models are still in heavy disagreement as to how much snow and ice accumulations we could see. Taking a blended look, however, suggests that it is not looking like Richmond will stay as all snow. Instead, the current thinking suggests that Sunday night will start as snow, then transition at some point to a wintry mix or freezing rain, then transition back to snow with a "second thumping" possible on Monday night in response to a developing low off the coast. The positioning of the low pressure and the intrusion of midlevel warm air looks like it keep this storm from being an all snow maker for us. Generally, the further north of town you are, the better your chances of seeing higher snow totals. 

The timing of the transition to wintry mix and how long it lasts will be a big question mark heading into tomorrow. Models are still in disagreement on this as the GFS Model (American) keeps the metro area in a mixture of wintry mix and freezing rain for much of the day with much less snow totals. However, the ECMWF Model (Euro) keeps the metro area in snow for longer and has a smaller period of wintry mix/freezing rain. This results in vastly different snow totals ranging from as little as 1-2 inches of snow + ice to as much as 8-9 inches of snow + ice on the high end. With this much disagreement heading into tomorrow, it is clear that this storm will be a game of inches with little room for error. 

ECMWF (Euro) 12 Z Model Forecast for Monday Morning. This model keeps the Richmond area in all snow for longer and shortens the wintry mix/freezing rain period. The red and blue horizontal lines with numbers indicate the height of the surface to midlevels of the atmosphere, with blue lines indicating lower heights due to cold air (more dense) and red lines indicating higher heights due to warmer (less dense) air. 

  

The GFS Model (American) Forecast for 12 Z at Monday Morning. Unlike the Euro, the GFS has a slightly more northern position for the low pressure, bringing a more mild airmass to the midlevels (notice red lines over the region) and keeping the metro area in a wintry mix/freezing rain for longer. 

Understanding What It Takes... 

The 3 Pillars of Snow...  

        In order to have snow, you need three primary things to all come together at the right time: cold air, moisture, and a way to sandwich those things together. 

Canada Sharing The Love...

To get the cold air south, we typically rely on a "dip" in the upper level jet stream that "unlocks" the cold air contained in Canada and a high pressure system to our north to "feed" our region with the cold air. Getting cold enough air that far south is typically a challenge for this region. Adding further issues, cold air "modifies" as it collides with warmer air to the south, meaning the cold air will warm as it pushes south. Subsequently, the cold air intrusion must contain temps cold enough that even when modified will remain at or below freezing. In most cases, our region is only able to muster "marginal" temps that hover right around freezing. This is not as big of a problem for places north and west of the city as places with higher latitudes and higher elevations are generally cooler. This is one of the main reasons why the Richmond metro struggles oftentimes to get an "all snow" system. 

Graphic From NPR and NOAA. As the strong jet stream winds dip southward, this brings the cold, dry airmass from Canada into the the U.S. This airmass is modified as it marches southward.  

Checking For Tracks... 

With Richmond's proximity to the Atlantic and the Gulf of Mexico, the area already has access to plentiful moisture. Getting the moisture into our region, however, requires a disturbance of some kind to actually move the warmer, moist air northward. This come usually in the form of an area of low pressure tracking near the region at just the right point to bring just enough moisture over the top of the cold airmass. However, getting a track just right is a bit like threading the needle as a track too close to the region will bring too much warm air while a track too far from the region will not bring the necessary moisture.

Typically (though there are exceptions), west-east oriented low pressure tracks are not your friend as these systems may jog too far north or exit the region too quickly. Instead, we typically rely on a particular track of the low pressure that tracks northward just off the Atlantic coast. These storms can originate either from the Gulf (Miller Type A) or develop as a new low pressure right off the coast (Miller Type B). These types of setups are orientated more optimally for our region as they  provide plenty of moisture while allowing enough cold air to wrap in from behind. Most of our region's biggest snowstorms have occurred curtsey of coastal low pressure systems. 

Graphic by Weather Works. This shows the fundamental differences between Miller Type A and Miller Type B setups. 

So What's The Deal? 

        Without getting into specifics of every storm's setup, the main reasons why we haven't seen a big snow in quite sometime is down to two factors: marginal temps and suboptimal storm tracks. Simply put, we have been a bit unlucky in recent years with temps a bit too warm and storm tracks that were less than optimal. Getting snow here is tricky as it requires that the cold air, moisture, and disturbance track all align at the right time. With only marginal temps to work with, a storm tracks are especially critical as a matter of miles can make all the difference between seeing all snow and ending up with plain old rain. 

        In that sense, Sunday's storm is no different as currently both operational models differ on the exact track of the low pressure, with the GFS hanging onto a northward trend while the Euro nudging more southward with the track. Differences also exist in the potential for a "second round" of snow on Monday night in response to the possibility of a developing low pressure off the coast. Regardless,