3/20 All Zones AM Update: Spring & Winter Weather Take Turns This Week

Happy Monday! Spring has arrived officially on astronomical calendar. More pleasant weather with temperatures closer to seasonal levels are coming in just in time for it, over the next couple days. Some ridging over the region will support high temperatures in the lower to middle 50s this afternoon. There will be plenty of sunshine for much of the day, and winds remain light of the northwest.

Then more clouds will be increasing later this afternoon and evening, as weak cold front approaches. This system could produce some scattered showers overnight. But moisture with this front will be limited over the region. These showers will likely stay mainly southwest of NYC, with a weak wave of low pressure along this front. More cloud cover tonight will keep temperatures from dropping out the middle 30s to lower 40s over much of the area.

Tuesday clouds will skies will clear for more sunshine later in morning and afternoon as deeper, drier northwest flow develops. Temperatures will rise into lower to middle 50s again during the afternoon. But a stronger cold front associated with a deeper trough, will move through the region by the evening hours. Temperatures behind this front, will be colder than normal once again by Wednesday and Thursday. Highs will only be middle to upper 30s on Wednesday and perhaps closer to 40 on Thursday over the region.

Then as the trough lifts out, temperatures may rebound again closer to normal by Friday and the weekend. However, another storm system will be approaching from the southwest. This will evolving out some pacific energy phasing into larger cut-off low. At the same time, some ridging over Western Canada will cause more confluence with high pressure and much colder airmass over Southeast Canada.

The main question is how far south high pressure over Southeast noses into Northeast. This could allow for some cold air damming over the region, for the the cut-off low to remain  further south or transfer to secondary low off the Mid-Atlantic coast. Therefore the chances for more wintry precipitation increases for much of the region, assuming the secondary low also tracks far enough north. But if high pressure remains further north, it will more likely remain warm enough for some rainfall, sometime between Friday and Sunday. Latest GFS and ECMWF ensemble guidance appears to support the colder solution with some snow/ice accumulation mainly over the Interior.

A couple of cavets to watch here is that there appears to be some residual high-latitude blocking over Atlantic side. This will support more confluence with high pressure to positioned further south with colder air, than models suggest. On the other hand, the southern stream is also appears to becoming more active with a pacific jet extension by next weekend. The result is a more progressive pattern with more mid-level ridging building the Northeast and Mid-Atlantic, allow the storm to track further northwest. If this happens, it may be even warmer and drier for much of this weekend.

So we will continue to monitor this system this week. But at this time, we don’t feel there is a lot of support for more significant wintry precipitation this weekend, especially closer to the coast. Stay tuned for zone forecast updates this week, on more cold air  returning for Wednesday and Thursday and on the potential storm system by this weekend.