Currently: Sprawling strong high pressure covered most of the Northeast and mid-Atlantic states. This high is responsible for the cold weather across the area today. However, this cold spell will be very short-lived.
Tonight: With increasing clouds and rapidly increasing warm air advection, temperatures will not fall much tonight. In fact, low temperatures may be early at night. Since for record-keeping purposes, low temperatures are recorded from midnight on, and temperatures will already be rising by then, I went a couple degrees above all guidance tonight. Expect temperatures to be steady then slowly rise overnight around 30 south, but fall into the mid to upper teens in the far north early in the morning before rising. Up north, the cold air will take a bit longer to scour out.
Tomorrow: Not that straightforward of a forecast for tomorrow. First off, you have stubborn cold air at the surface. We have zero cold air damming. However, cold air is never that easy to scour it, simply because of physics: Cold air is more dense than warm air. Then we have cloud algorithms all over the place. I'll word it as interludes of clouds and sun. Lastly, the NAM tries to spit out light rain. I'll ignore this. Sfc humidity does creep up, but soundings show plenty of dry air aloft, and not nearly the amount of lift you would want to see to produce measurable precipitation. With all these factors in mind, I'll go just a shade cooler than guidance. Expect highs in the mid to upper 40s. Interestingly enough, with a SW flow, a sea breeze-like feature could develop during the afternoon along the south coast and keep temps a few degrees cooler there.
Tomorrow Night/Sat: It is rare this time of year that a storm tracks so far to the west that the actual precipitation associated with the storm misses your area, but that's exactly what's going to happen. Low pressure will track over the Western Great Lakes. Therefore, all the precipitation associated with this should stay west of our state. Temperatures will soar with a deep layered southerly flow ahead of the storm. Guidance is in pretty good agreement, and will use a guidance split for temps. Highs should reach the mid to upper 50s. Once again, a sea-breeze like feature should keep the coolest temps along the south coast.
Long Term (Sunday to Thursday): On Sunday, we will see a few hours of rain, in association with the cold front. This will be a morning event with rain falling from early morning to late morning. I'll cut a couple degrees off temperature guidance, only out of caution. Current guidance is suggesting record highs. The air mass is warm enough, but it generally takes a perfect setup for this to happen. Given we're still 3 days out, I won't go quite that high yet. It should also be noted that high temperatures should occur early Sunday morning, with falling temperatures for much of the day thereafter, with a NW breeze developing. Generally expect high temperatures within a few degrees of 60! There is even a slight chance of thunderstorms. But once again, given that it's day 3, and the chance is low, I kept it out of the forecast for now.
Mon-Tue: Generally fair weather. Tuesday will be much cooler than Monday. Temperature guidance does not look too bad, but I did go a bit lower than guidance on Monday, due to the GFS' typical bias of not recognizing cold air advection. Expect high temperatures in the 40s Monday, dropping to near 40 Tuesday.
The next storm system approaches the area Wednesday. Right now, models are pretty disorganized with this threat, showing a "coastal scraper" early Wednesday and then a strong cold frontal passage early Thursday. Each one of those has light precipitation with it. As you should expect, the coastal scraper would produce more precipitation east of I 91. With marginal temperatures, it looks like the coastal storm would start as snow or sleet, then transition to rain or sleet. Then the cold front would start as rain and transition to snow or sleet. This evolution needs to be watched, because if the front would speed up and/or the coastal slow down, they could phase and produce a bigger system closer to the coast. But for now, will go with the modeled scenario. I'll go several degrees below guidance Wednesday, due to my expectation that it will be cloudier than modeled. I don't like the idea of a lot of sun between systems, given the very low sun angle this time of year. I'll go close to guidance on Thursday, with minor adjustments here and there. For Wednesday's highs, expect temps to be around 40. Thursday should actually see temperatures falling through the 30s, as much colder air moves in.
Looking out into the longer range, the cold frontal passage on Thursday starts the major pattern change the area will be undergoing which should make winter weather lovers much happier. Beyond that cold frontal passage, a much colder pattern looks to be setting in as far as the eye can see! In addition, there is really no reason to believe the storminess will not continue. Stay tuned!
Now, let's look at some of the systems slated to affect the area in graphical format. Let's start with Sunday morning's frontal rains. You can see on this map that heavier thunderstorms make it to about the Delaware River or a little east of there. It is not inconceivable that a bolt or two of lightning makes it this far east.