Currently: A stationary front extended from Northern VA to the Southern edge of the Delmarva Peninsula. A weak wave of low pressure had developed on the front over the mountains of WV. Cold high pressure stretched from the Great Lakes to Northern ME. This frontal boundary will serve as the focal point of unsettled weather across our area.
Tonight: We need to watch for the potential for some light wintry precipitaiton across interior portions of the state. The first question, of whether or not it will be cold enough, has already been answered (it will be). The other questions are how much precipitation will fall and what type it will be. Fortunately, it looks like sleet should predominate rather than freezing rain, and that is a good thing. There could even be a burst of snow across the northern and central parts of the state... it wouldn't be totally inconceivable for snow to make it all the way to the coast. A coating to 2" is possible across the north- generally I 84 and north, with most accumulations restricted to the cold surfaces, and the closer to 2" readings restricted to higher terrain.
As the core of the cold air moves in, it will also allow drier air to slip into the state, which means precipiation should shut off this evening and it should stay dry until tomorrow afternoon. By then, the thermal profiles aloft clearly support rain, although it wouldn't be a total shock if some sheltered location starts off as a little freezing rain.
As for tonight's temperatures, they will be cold, and it will be rather a shock to the system. Lows should be 25 to 30 up north and 30 to 35 in the south, with most of the state, except the far SE, getting to or below freezing.
Tomorrow: The first half of the day should be dry, albeit cloudy, then precipitaiton should return by the 2nd half of the afternoon, as the aforementioned frontal system starts moving back north as a warm front. For now, based on model temperatures, I'll keep all precipitation as rain. Thermal profiles aloft definitely support rain. However, it is not out of the realm of possibility, as I mentioned, to see some freezing rain at the start in the usually coldest spots. We'll have to keep an eye on that! As for temperatures, most of the state will stay in the 30s, which is why we need to watch for areas of freezing rain.
Tomorrow Night/Sat: As the warm front approaches, we'll see a period of rain tomorrow evening. Temperatures should then stay steady or slowly rise tomorrow night. Saturday's temperatures should rise to 50-55, with the warm front by then very close to the region. Most of the time later tomorrow night and Saturday should not see rain, although there will be areas of drizzle and fog. Rain should develop later in the day Saturday and Saturday night as the front sags back south into New Jersey. A wave of low pressure will move along the front, as well, enhancing lift across the state.
Long Term: To start the long term, Sunday is basically a wash out. With a stationary front stalled south of the state and waves of low pressure moving along it, that is a good recipe for overunning rains to continue all day. In addition, temperatures should be a good 5 degrees (or maybe more) cooler than on Saturday. So look for a chilly, raw, rainy Sunday.
Then Monday through Wednesday will feature much nicer weather. Monday is most likely the pick of the week, but that isn't saying that Tuesday or Wednesday will be bad. Highs should be generally 50-55 through the period, with the coolest day possibly being Tuesday.
Models then hint at a cold high building back in over Canada for Thursday and Friday, while a coastal storm forms offshore along an old frontal boundary. That would likely spell a rain changing to a wind driven snow event for much of the state, with colder air building in behind the storm- although by then we're way far out, so details have yet to be ironed out.
In the long range, the overall pattern will shift dramatically to one that features a very strong -NAO. We have not seen a truly negative NAO of that magnitude in quite some time. While details as to when and what types of storms we get are too far out to say much about, these types of scenarios generally spell cold and stormy weather across our area.
Now, let's take a look at our weather in graphical form. We'll highlight the storm for Sunday, because I really want to post the GFS Ensemble map regarding our coming negative NAO.
Anyway, I'll leave it at that for now, and we'll see where that goes... see you next week!