Dreary and complex weekend ahead

Good evening!

After the very light rain/snow mix yesterday, we’re now firmly entrenched within a much more mild and moist airmass thanks to the large upper-level system over the Southeastern US that we have been talking about since last week. This system has been quite challenging to nail down over the past few days, as key features that will determine the overall impacts from this system are constantly changing.

So what exactly has changed?

Well, the first major change that we’ve seen is that the system as a whole is quite a bit more disorganized than what the models originally projected, and this has led to the precipitation over the Southeast to also become quite disorganized and lackluster in nature. Another major change that we’ve seen is that a shortwave trough currently over eastern Canada has trended stronger and further south over the past couple of days, which is keeping the overall storm much further south than previously expected. Now if this sounds familiar to you, this is generally the same thing that happened with last weekends snowstorm that stayed well to the south of the Northeast but still managed to significantly impact portions of the Mid-Atlantic and Southeastern states.

With these two significant changes in mind, this means that the strong low-level jet that was supposed to overspread the Northeast will now be less impressive and much more suppressed to our south this evening and throughout the day on Saturday.

With the main mechanism for heavy rain potential now located our south, this evening and the majority of Saturday should really only be capable of light to locally moderate rain showers for much of the New York Metro area, with more steady rain likely over southern portions of New Jersey. Regardless, with warm air advection from the south increasing overnight and cloudy conditions remaining in place during the entire day on Saturday, we should see highs in the middle to upper 40’s over the entire area, with lower 50’s possible closer to the coast, making for quite the dreary day.

These temperatures will be running anywhere from 5-10 degrees above-average for this time of year, which is quite the change considering we were 10-15 degrees below-average earlier this week.

This afternoons high resolution NAM model showing the vast majority of the heavy rain staying to the south of the NYC area Fri/Sat

Unsettled conditions remain through Sunday night

As we head into the evening and overnight hours on Saturday, we should begin to see the upper-level low slowly begin to move into portions of the southern Mid-Atlantic states. As this systems pushes to our south late Saturday night and during the early morning hours of Sunday, the positioning of the upper-level system will allow for stronger areas of lift to develop from north to south, which should finally result in a batch of moderate to heavy rainfall pushing through the Mid-Atlantic and Northeastern states.

The complex part of this forecast really begins on Sunday afternoon when another shortwave trough will be quickly moving over southern Canada. Recent model trends have shown that this Canadian shortwave trough will have the potential to interact with the upper level low located to our south, which could help to spawn an area of low pressure off the New Jersey coast. While southerly flow and very marginal surface temperatures should keep precipitation limited to a dreary and cool rain throughout our area, we could see some colder temperatures begin to bleed in over the Northeast later Sunday afternoon. This will have some very important implications for locations well to the north and west of the New York city area as we head into the evening hours on Sunday when the surface low pressure system begins to strengthen off the New Jersey coast. With the colder air bleeding in from the north and the upper-level low to the south of Long Island providing sufficient lift for continued precipitation over PA/NY/NJ, there is the possibility that we could see rain gradually change to a wet snow/rain mix for locations over NE PA, SNY, and elevated portions of NW NJ. Again, temperature profiles are very mild and the best chance for a light mix of precipitation will come from “dynamic cooling” within heavier areas of precip to the NW of the city.

~Updated NYC Weekly Planner ~

Clear and cooler start to the work week 

As the shortwave trough moving through Canada gradually digs into the Northeast overnight on Sunday and into Monday morning, we should see the mild and dreary conditions gradually fade from northwest to southeast. A much cooler mid-level airmass will be moving into the area during the afternoon hours on Monday, which should also eliminate most of the residual clouds from this weekends storm system in addition to bringing high temps across the area back into the middle to lower 40’s. Relatively clear and calm conditions should persists through the middle of the week as an upper-level ridge and associated area of high pressure gradually builds in over the East. Highs will likely be limited to the upper 30’s to middle 40’s Tuesday to Thursday before our next potential storm system begins to build to our west. Unfortunately, it appears that we could be looking at yet another dreary weekend next weekend over much of the East as an area of low pressure develops well to our west, dragging mild/moist conditions  along the coast.

This afternoons ECMWF model showing much of the same late next week as another area of low pressure brings the potential for rain in the East

We’ll have updates on Sunday’s  wintry mix potential likely during the day tomorrow, so stay tuned for updates!

Have a great weekend! 

Steven Copertino