Zonal Pattern Gives Way to More Extremes Across the Country

Good Evening! 

A weak area of mid level energy moved quickly through the Northeast last evening and into the early morning hours today, which had just enough kick left to it to bring  some isolated and relatively light areas of precipitation. Depending on your location, this precipitation varied from plain rain, freezing rain, or even some light snow. Any frozen precipitation accumulations were extremely light, but still made for a slick morning commute today. The quick-moving west to east flow that has become established over the majority of the country will be responsible for bringing some more weak mid-level energy over the region through the rest of the day, which has led to a rather dreary and  warmer day than the past couple of days. West/southwesterly flow has allowed mid level temperatures to rise over much of the Mid-Atlantic and Northeast, which has allowed surface temperatures to respond accordingly throughout the day. We have seen highs across much of the Northeast rise into the lower to middle 40’s across the majority of the area, with higher readings around the 50’s observed in portions of southern New Jersey. These mostly cloudy and slightly-above normal temperatures should continue into the evening hours, with a chance of some patchy fog across the area as some moisture may become trapped within a low level inversion.

Expect temperatures this evening to fall back into the upper 30’s and lower 40’s across the immediate NYC metro area, with cooler temperatures likely well to the north and west.

This evenings latest regional radar mosaic, GOES 13 visible satellite imagery, and surface observations showing a more mile and dreary end to the day across much of the Northeast

Tuesday Into Thursday 

A deep cyclone moving through portions of central and eastern Canada will continue to drag a rather stout southwesterly flow over the Northeast tomorrow afternoon, which should also bring in more dry air to clear out the low-mid levels of the atmosphere. This should allow for a vast majority of the clouds to dissipate as the day goes on tomorrow. This deep southwesterly flow and relatively clear skies across the area should allow temperatures to rise into the “well-above normal” territory as highs will likely get into the middle-upper 40’s-with some 50-degree readings possible. Thankfully, moisture will be quite limited across the east, so we expect a generally calm and mild day tomorrow for much of the Northeast. Later in the day, a cold front associated with the same cyclone in Canada will begin to creep into the Northeast. This front will work east through the area throughout the overnight hours, but will likely bring lows down into the upper 20’s to low 30’s just in time for the morning commute on Wednesday.

Wednesday  should be a much cooler day by contrast as northwesterly flow behind the cold front ushers in fresh, Canadian air. A vigorous little area of mid level energy will be opening up from its time as a closed upper level low and will begin to quickly head east across the southern half of the country. This strong west to east flow across the nation will ensure that this area of energy becomes sheared out, with all of its rain staying well to the south of the Northeast. In fact, conditions will remain very dry across the Northeast, and there may be a couple of strong post-frontal wind gusts in the early part of the day. The renewed northwesterly flow, clear skies, and dry air should allow temperatures to stay relatively cool across the majority of the region, with highs in the middle to upper 30’s likely. Locations to the north and west may in fact see highs stuck in the lower to middle 30’s as some deeper Canadian air becomes trapped. These calm and cooler conditions will last into the evening hours on Wednesday before another weak cold front begins to move into the east. This front will be severely moisture starved, but will be capable of reinforcing the cold air already in place. With dry low/mid levels, cold air aloft, and light northerly winds, conditions should be supportive of some radiational cooling to take place. This should bump lows down into the middle to upper 20’s , with upper teens to middle 20’s likely off to the north and west.

Thursday morning will see the reinforcement of colder air over the Northeast, with the morning commute likely starting off quite crisp in the 20’s. A mid-level ridge will begin to build over the Ohio Valley in response to an area of Pacific energy digging into the west coast, but conditions over much of the Northeast will likely remain quite cool and clear as high pressure begins to build and expand over southeastern Canada. This should lead to another pleasant day with highs mainly in the upper 30’s to lower 40’s. Mid level flow will begin to shift to the southwest during the evenings hours on Thursday, which will begin to set the stage for another above-normal period of temperatures.

Loop of this evenings NAM model showing a brief period of cooler temperatures over the Northeast, followed by another warm surge by the end of the week.

Uncertainties Arise for Christmas Weekend 

If you’re on social media and follow some of the various weather pages out there, you’ve likely seen the numerous maps and forecasts that show a massive area of Arctic air dropping into the west, while a large area of warmth rises over the east. While the exact details of how this weekend will play out are still a couple days from being hashed out, what we know about this setup is that there will be a substantial amount of Pacific energy dumping into the west by Friday. All this energy injected into the flow will begin to carve out a large trough over the western/central US, while the downstream response will likely result in a ridge forming over or just off the southeast coast. This pattern will be supportive of increased heavy precipitation over the Southeastern to Northeast US as the gradient between the cooler airmass over the central US clashes with the relatively warmer airamss over the east on Friday and Saturday. Shortly after, the models begin to diverge on just how much the trough and accompanying cold is able to move east by Sunday/Monday. The other major question here will be where exactly does the ridge over the southeast set up? A ridge over the southeast will almost certainly guarantee an above-normal Christmas day, while a ridge off the eastern seaboard may allow cold to creep into the picture just in time for Christmas. These details will take a couple more days to flesh out, and we will certainly be monitoring them over the course of the week.

This afternoons European Ensembles showing a rather significant amount of spread in the overall 500mb pattern for Christmas day, showing nothing is set in stone yet.

Stay tuned for further public updates! . Also join us at 33andrain forums for free discussion on everything weather-related.

Have a great night!