Some Snow Likely Saturday

A light dusting on Christmas Eve and a sloppy mix on Boxing Day were a good reminder that yes, it actually does snow in DC, despite seeing few flakes last year.  However, neither of these events delivered solid, accumulating snow, but by Saturday, that may change.

Two of the snowier possibilities

An area of low pressure is expected to bring precipitation to the area on Saturday, but exactly how much and what type has not yet been pinned down.  It is not a particularly strong system, and the temperatures will be right on the border, so anything from a light rain/snow mix to a nice fluffy 4 inches is possible.  

A more northerly track would lead to a very weak storm that would be mostly light rain throughout the day Sunday, with some flakes mixed in early.  However, a more southerly track and a stronger low pressure system would lead to a sustained light to moderate snowfall starting late Friday night and tapering off Sunday evening.  

At this point, the middle ground seems most likely:  a light snowfall of an inch or two with a bit of rain mixed in towards the end, especially south and in the District. That said, it's always colder up north near Damascus, and the cows there could see three or four inches of snow.

By no means a significant storm, this should be a nice snow to brighten up the break, and bigger things may be in store for next week, when a system makes its way up the coast.

Sandy Departing Area; Storm Recap

Sandy is leaving the area and the worst of the storm is over.  While the effects in the D.C. area are moderate, they are nowhere near the destruction in New York City.  There, gusts of up to 80 mph combined with a record storm surge lead to effects far greater than those seen in DC.  The subway flooded,  Lower Manhattan lost power, and FDR drive was inundated.

What was different here?  Mainly the storm surge.  Most of the damage in NYC was widespread flooding caused by the rising levels of the East River.  Manhattan is an island, DC isn't.  While the winds were stronger in NYC, the DC winds were only slightly overestimated, as widespread gusts were reported to reach or exceed 60 mph, including a 76 mph gust in Laytonsville, Montgomery County. The rains here were more significant than NYC, with 4-7 inches of rain being the norm throughout the area.  That said, the flooding from a 13 FOOT storm surge is much greater than that from 7 inches of rain.

So, where was all the destruction? Why wasn't this like the derecho? A combination of factors.  Firstly, the worst of the storm happened at around midnight, when most people were asleep. But, the main reason was actually because of the derecho. The summer storm already knocked down any loose limbs and weak trees, leaving few easy targets for Sandy.  In addition, the massive repairs after the derecho strengthened the power grid.  With this storm happening in late fall, there were fewer leaves on trees to pick up the gusts.  Just as a windmill with one small blade wouldn't spin as much, trees with fewer leaves will be less likely to fall due to wind.
While many in the DC area will view this storm as underperforming and forgettable, I'll chalk it up as a victory for PEPCO here, and in the Tri-State New York area, it will take time to heal from this disaster.

Sandy's Effects Starting to Ramp Up

Despite some premature calls that Sandy is merely a "breezy rainstorm", things are going to get serious overnight.  Winds that have been sustained at around 30 mph will almost double to around 55 mph, and gusts around 45 mph will approach 75.  Rains will intensify and be blown sideways by the wind Sandy is still over the sea, and will soon make landfall near Cape May, NJ, or the Delaware coast.  At this point, the location landfall doesn't matter, as the storm will trek west and park itself over the Mason-Dixon line, whipping us with intense winds all night.

The strong winds and rains will slowly decrease in the morning and could change to wet flurries as they depart.  However, the strong winds tonight are not something to be trifled with.  Stay inside; trees WILL fall, branches WILL turn into projectiles; and power lines WILL  snap.  I doubt that there will be school on Wednesday, and possibly even Thursday,  however, this will be largely dependent on power outages and other damage. I will try to post tomorrow with a recap of the storm, but that seems unlikely due to PEPCO.

Hurricane Sandy on Track to Bring Severe Winds and Rains to Area

Sandy is churning up the East Coast, and starting to interact with the coming cold front to create a huge storm, with tropical storm force winds expanding up to 500 miles from the center.

I am standing with my last forecast, as Sandy will likely take the track I called for earlier, except a tad north, making landfall in southern New Jersey, rather than the Delaware Bay.  This will lead to sustained winds of around 50 mph, with gusts up to 70.  The damage will be massive, with winds on the scale of our summer derecho, lasting from Sunday afternoon until things finally start to clear out midday Tuesday. At the end of this, we could see anywhere from 5-10 inches of rain, enough for some major flooding.

The most significant effects of the storm will be felt in NYC, where a significant storm surge could lead to major flooding downtown, worse than Irene last year.

Even though we seem to have avoided the track up the Delmarva, which would have lead to all hell breaking loose, this will still be a huge storm, enough to shut down schools and power for days.

Hurricane Sandy Taking Aim At DC

A storm's a'brewing.  A category 2 hurricane over the Bahamas, Sandy will make landfall on the East Coast of the United States.  The last time a tropical cyclone phased with a Nor'easter like this, it was "The Perfect Storm" of 1991.  Call Sandy the Perfect-er Storm then, as she has the potential to make history.

At this point major impacts for the DC area are highly likely, as Sandy is a huge storm, with tropical storm force winds (39+) extending hundreds of miles from the center.   At this point, Sandy seems likely to head north until making landfall near the Delaware Bay and jogging west from there.  This will lead to extended periods of heavy rain and high sustained winds of 50-60 mph with gusts up to 80.  While our last two major tropical encounters, Irene and Isabel, were relatively quick,  Sandy will affect the area for about two days, starting with the outer bands reaching us during the day Sunday.  The storm will ramp up and be at its worst Sunday night into Monday, with winds howling, leading to widespread power outages. The intensity will start to lessen into the night, and the storm should largely depart Tuesday, with massive destruction it its wake.  With winds comparable to if not exceeding Isabel, for a longer period of time, the destruction could potentially eclipse the summer derecho, and lead to school cancellations.  To exit on a more peaceful note, Sandy will bring an extremely cold pocket of arctic air and leave a few departing flurries Tuesday night.

However, this storm is still three days away, and has the potential to go in two directions. Sandy could stay further out to sea and make landfall in Long Island, leading to much less intense of  a storm here, as the winds would peak at around 35-40 mph, and last much shorter.  This would lead to effects on the scale of Irene, with significant but not devastating power outages, and a quick return to normalcy.
On the other hand, the storm could go further west than expected, tracking up the Chesapeake.  This would be a disastrous scenario for the area, as we would experience sustained hurricane force winds with gusts approaching and potentially exceeding 100 mph, the likes of which this area has never experienced.

As the storm approaches, the track will become less fuzzy, and I'll be better able to asses the potential impact on the area and school closings.  As of now, I would say there's about a 70% chance that school is canceled Monday, but don't start cheering because you'll have more time to work on your college apps- your power will probably be out.

Presidents Day Disappointment

While a storm seemed likely earlier in the week, the storm is taking a much more southerly track than expected, likely leaving us with some sparse drizzle and flurries. While this storm seemed promising at first, the southerly track will lead to a lack of moisture and cold air needed for a decent snow. In addition, no snow is in the forecast for the near future, and winter is starting to wrap up, so the chances for a major snowstorm this year are decreasing with every day that passes.

Wintry Mix Inbound

National Weather Service loop of the precipitation coming our way.


The first potentially significant winter storm of the year is coming, and while it won't be "the big one", it definitely will be disruptive. Like lots of DC area storms, there is going to be a sharp cutoff in terms of who will get rain and who will get snow, as temperatures will be borderline throughout the storm. As usual, the horses and cows in Damascus will get more snow than the people living in Silver Spring and Bethesda.


Most of the county looks to get an inch or so of snow/sleet tonight before the switch over to freezing rain. A glazing of freezing rain on trees and cars is possible when you wake up in the morning, however, this will begin to melt away during the day as the temparatures slowly climb above freezing. However, the finer details of temperature climb are still murky and could result in anything from a transient burst of freezing rain that is quickly washed away to a significant glazing that could lead to major travel disruptions throughout the day.

The computer models tend to under forecast the ability of cold air to remain in place in our area (cold air damming), which leads me to think that we could get a good coating of ice over the snow before it is washed away by the rain. Right now I would predict an inch of snow and sleet overnight with a glaze of about .1-.2" of ice overnight that is slowly washed away during the day as the temperature climbs above freezing. This will lead to traffic and other delays in the morning that will subside as the day moves on.

While in no means a major storm, this could be the first storm of the year with some tangible snowfall, and considering that it's already January 20th, it's better late than never.