Final Sunday Storm Update

 There are winter storm warnings for the entire county that starts at 3 AM Sunday and ends at 12PM Sunday, with 3-6 inches, and additional details that will be stated at the end of this post(my opinion and more details). This storm is playing out like a spring storm, as surface temps are marginal due to the temps being in and around the 50s in the past 2 days or so. The timing of this storm is early morning Sunday - Sunday afternoon. It may start as rain, but will turn over into a wet snow. Even so, heavy snowfall will be able to cool the ground fast and will stick on untreated surfaces.

GFS:

The GFS shows the storm starting as rain for southern MoCo, then shows heavy snow taking over any other precipitation for everyone. 

Unfortunately for us, snow lovers, it shows 1-2 inches for the county, with 2 inches in Damascus. This is a huge disappointment compared to the last run of this model. But we still have more models.

European:

The European model shows the storm starting as moderate-heavy snow then shows it transitioning to a mix before it goes off into the ocean. Each picture skips 6 hours though, so we will see more snow than what it seems here.

It shows 4-6 inches for our county, with higher snow accumulation in the southeastern areas. However, in our northern areas, temps will be colder, so more snow will accumulate, whereas, in our southern areas, temps will be warmer, so while there might be more precipitation in general, less snow will accumulate. We will see though.

NAM 12km:

The NAM(12km) shows the storm starting out as rain, which will cool the atmosphere enough to support snow. Then, it turns over to snow and stays that way until the storm is over. It shows heavy rates after the transition to snow.

The NAM shows a good 4-5 inches of snow for our county. It shows more snow west of us than east.

National Weather Service(NWS):

Expected Amounts:

The NWS shows a good 4-6 inches for the whole county, and for our surrounding counties as well. It shows around a 40-50% chance of us seeing 4+ inches.

High-End Totals:

The NWS shows 6-8 inches of snow if a boom were to happen(more snow than expected). This would happen if our bands were widespread and heavy, temps were a little bit colder than expected, and if we see more moisture.

Low-End Totals:

The NWS shows less than 1 inch of snow if we had a bust(less snow than expected). This would happen if temperatures were too warm to support snow, or if we got robbed of our moisture.

Justin Weather:

Justin Berk(he runs Justin Weather) shows us in the 3-6 inches range, and additionally in the "possibly higher" area too(entire county in both). He said that inside the pink circle(possibly higher), where we are, it depends on the heavy bands and local temps for what can accumulate. He also said that thundersnow is possible around daybreak. The "possibly higher" region has the highest chance of seeing very heavy bands and rapid accumulation, increasing the storm total.

Capital Weather Gang:

The Capital Weather Gang shows 1-4 inches of snow for our county, with 4-8 inches if the storm booms, and a coating to one inch if it busts. Overall, with what some of the models have been showing today, I understand why they haven't really increased their totals.

This map from Matthew Cappucci, a meteorologist at the Capital Weather Gang, shows MoCo in the greenish-blue circle, where frontogenesis will enhance snowfall rates, with rapid accumulation and very heavy snowfall rates, for around 3 hours. He also said that thundersnow(mainly for New York) can't be ruled out and is a possibility. That is a rare, yet epic phenomenon in winter storms.

Fox 5:

Fox 5 shows 3-5 inches of snow for the entire county. They stated that snow will come in around 3-5 AM for us and for our surrounding counties and that the heaviest snow will be between 6-10 AM.\

WUSA 9:

WUSA 9 predicts 2-4+ inches of snow for our county, with a small portion of Northern MoCo in the 1-3 inches of snow range. Their map hasn't changed yet, so I will keep updating these maps when new ones are made.

ABC 7:

They didn't give a map, but still gave us a range! For the general area, ABC 7 thinks 2-4 inches of snow. They noted that we might start, and even end as rain.

NBC 4:

NBC 4 shows 3-5 inches of snow for the whole county, with higher totals possible. Everything will be out by 2-3 PM. 

They also show a timeline of how bad conditions will be outside. On Sunday morning, they think that there will be heavy snow with low visibility, plus untreated surfaces will be slushy. By the afternoon hours, they think that surfaces will be wet/slushy, and by night, untreated wet roads(also includes snow-covered and slushy roads) will be frozen over and will be slick.

Overall, what do I think, in terms of totals? 3-5 inches for the whole county, with higher amounts possible if bands set up just right(so 3-5+ inches). This will be wet, heavy snow. Temps will be hovering at the freezing mark, so some accumulation will be canceled, but heavy rates will make up for it. And, as reassurance for us snow lovers, temps right now are 5-8 degrees colder than expected, which means surface temps aren't as warm, which means that it will be easier to support accumulating snow. Models don't do a good job at forecasting dynamic cooling as well, so during those heavy bands, temps could drop a couple of degrees colder than the freezing point(below 32 F). As it is looking right now, MoCo, and the general DC metro area, seems to be a sweet spot for this storm. The snow will come in the early morning hours. The heaviest snow should be between 6-10 AM. The snow should be out by the afternoon hours. We should be getting some of the heavier bands, and that's why a lot of forecasts have us in the higher amounts possible area. The NWS says that we should expect 1-2 inches per hour rates in heavier snow bands. We have a good chance of starting as rain, and then turning back to snow. However, we could easily end as rain too, but I think the chances of that happening are low. Take note that temperatures will rapidly fall below freezing after the storm, causing a flash freeze. Temps will not go above freezing on Monday, and will be in the teens; and may even go into the single digits! This storm won't have much of an impact on schools, because I don't think that this event will be able to close offices, which is needed to close schools. This snowstorm, on my snowstorm rating system, will be a moderate storm. Even with that being said, you should be taking this storm seriously. Please avoid any travel, unless needed. Stay safe everyone, and I hope you enjoy the snow! We have many more storm threats coming up soon...