Currently: A cold front extended from near Toronto down through Central Ohio. There was a little bit of cold air damming over the area, which extended across the Northeast US down into C PA. Beyond that, temperatures were much warmer.
Tonight: With warm air advection continuing, don’t expect much of a dropoff in temperatures. In addition, showers are possible at any time, but should become more numerous toward morning, as the cold front approaches. There should not be any thunderstorms or severe weather, since the low pressure associated with this frontal system is all the way up by James Bay! Low temperatures will generally be in the mid 40s. Expect generally steady temperatures, and a fairly uniform temperature range tonight, since coastal areas will be under the influence of an onshore southerly flow blowing off the Long Island Sound.
Tomorrow: Rain clears out from west to east, from about rush hour to lunch hour, SW to NE. It will be warmer than normal. This cold front is mainly of Pacific Origin and doesn’t have very cold air behind it. High temperatures tomorrow should be generally in the low 50s SE coast and NW hills, to as warm as near 60 in a few of the warmer spots in the CT Valley!
Tomorrow Night/Thursday: Expect continued warmer than normal weather for this period, since we’ll still be under the influence of a Pacific high pressure system. Late in the day Thursday, a cold front will go through that will usher in much colder air. There won’t be any precipitation associated with this cold front, but we will notice westerly winds gusting to 30-35 MPH ahead of the front, then switching to a more northerly direction behind the front. Temperatures Thursday will literally be a carbon copy of those of Wednesday- ranging from the low 50s in the NW Hills and SE coast, to near 60 in the CT Valley.
Long Term (the weekend and beyond): This is where it gets much more interesting. The first system to affect the area will be an Alberta Clipper system for Friday. With cold air seeping into the area from the Northwest, and the clipper passing nearly over Dulles Airport, a little rain or sleet at the beginning should quickly change to snow. However, since the clipper low is passing well to the south, the south coast would be the most favorable area to get accumulations. Most accumulations should be in the light range- at least that is the current thinking. This map, from the latest GFS, is a pretty good “middle of the road solution” in terms of placement and key features with this clipper.
What was originally expected to be a snowstorm over the weekend is now going to slide harmlessly out to sea. What will be left behind is a very cold weekend (seems like that is becoming a theme this month)! Saturday and Sunday’s low temperatures will be in the teens across the state and maybe even some single digits in the normally colder locations. Along with wind gusts to 35 MPH on Saturday, it will feel even colder! Temperatures statewide this weekend may not make it above the freezing mark.
As mentioned, the potential weekend snowstorm now looks to slide out to sea. However, that opens the door for a potential larger event centered around Tuesday of next week. What’s ominous to me is that different models show different ways for this to happen, such as leaving the weekend storm close enough to phase energy into the new storm, having the weekend low move into the 50/50 region (I’ll explain what that means in a minute), and creating its own block, or having the Tuesday low blow up all by itself and becoming a monster. Normally, when you see three different ideas all creating a large storm, there probably will be a large storm. Now, 50/50 simply means 50 degrees north latitude, 50 degrees west longitude. A large storm in this area slows down the flow over and near the United States East Coast, so that a storm would get turned up the east coast and slow down. Now, obviously, at this juncture, it is way too early to pin down specifics such as storm track and timing, and way too early to even think about potential amounts. But needless to say, this is definitely a system to watch. The image you are about to see is a depiction from the GFS Ensembles. I’ll explain it after I post it.
As you can imagine, if there are so many ensemble members, there usually are one or two, for lack of a better word, “wacky” ensemble members. These members may not even know a storm exists, or have a track that’s 500 miles different from anything else. There could also be one that makes a monster storm out of nothing and then affects the rest of the run further down the line. Anyone who knows about statistics can understand that a mean, which this map is, is generally “smoothed”. In other words, you may have a few ensemble members that show no storm at all, and a few more that have the storm very weak. Therefore, an ensemble mean tends to be weaker than an operational model. However, because there are so many ensemble members, they are also subject to less run-to-run variance than a single operational model. The map I posted shows the GFS ensemble mean valid next Tuesday evening. From my experience using ensemble models, this is a very strong signal, especially that far out in time! (Ensembles tend to get more smoothed out with overall features the further out in time you go.)
Moving beyond that potential, an active, stormy, and probably colder than normal regime is expected to continue. Operational and ensemble guidance shows several more potential snow events as we move further into meteorological (and even astronomical) Spring! Then again, I wrote discussions 2-3 weeks ago that were more typical of May, so why not have winter in spring now?
That’s all for now! Have a great rest of your week!