After a chilly wakeup this morning, temperatures should for the most part rebound nicely across of the area, as a high pressure system remains in-place. It will keep our skies sunny throughout the day, with temperatures generally in the mid 60s. However, coastal regions will experience yet another slightly chillier day, as easterly winds off the cold ocean will prevent temperatures from exceeding 60 degrees.
The gradually departing high pressure system, and the low pressure system offshore are combining to generate easterly winds for this afternoon, as shown above. The pressure systems are relatively weak and are departing, which means the winds will be light — this will allow the cold, marine influence to not penetrate as far inland as they did on Easter Sunday. The lighter winds will allow temperatures to be about 5 degrees warmer than yesterday along the coast (upper 50s to around 60 as opposed to low to mid 50s), yet up to 10 degrees warmer than yesterday in areas west of the city, where temperatures in the mid 60s to upper 60s will be common. If those winds lighten up even more, we would not be at all surprised if some spots touched 70 degrees, since 850mb temperatures are a few degrees above freezing.
As that high pressure system continues to move eastward, it will give way to a low pressure system that will pass to our north on Tuesday. This will increase our high clouds a bit for Monday night, which will keep temperatures a bit warmer than they have been the past several nights.
Although most of the storm’s associated precipitation will stay to our north, it will be dragging a cold front to its south, and potentially give us some showers or even a rumble of thunder sometime late Tuesday afternoon, through Tuesday night.
With the low pressure tracking to our northwest, and a cold front forming to our west, our winds will turn southerly — as they typically do ahead of a cold front, as counterclockwise flow from the low to our northwest yields southerly winds. This will increase our humidity a bit, and also warm up the airmass as a whole significantly, as 850mb temperatures are expected to be +10C. When enough sunshine occurs and there is no colder air layer at the surface, you can often add 15C to your 850mb temp — yielding a +25C temperature, or a high of 77 degrees F, theoretically, on Tuesday. This allows us to have some confidence in an early-afternoon high in the low to mid 70s on Tuesday for places west of the city, where they may initially be enough sunshine to somewhat take advantage of those warm 850mb temperatures, but perhaps not enough sunshine for upper 70s. If the clouds hold off a little while longer, upper 70s are certainly possible! If the clouds move in a bit earlier, then upper 60s would generally be the rule.
Even the city itself could reach the low 70s on Tuesday, but coastal areas may once again miss out on the warmth, since strong southerly winds ahead of the cold front will create a cold layer at the surface, due to the ocean influence. This may be yet another day where temperatures are stuck in the low 60s with plenty of wind on most of Long Island, but with temperatures 1o-15 degrees warmer and lighter winds inland.
Regardless, clouds and showers will move in as Tuesday afternoon progresses, thanks to the cold front, and may linger through the night as more energy forms behind the front. Fortunately, skies will gradually be clearing on Wednesday morning, leading to partly cloudy skies by the time we hit Wednesday afternoon. Although we will be on the cold side of the cold front, northwesterly winds downsloping off of the Appalachian Mountains will allow the initial chillier air to compress as it sinks (the northwest winds push the air up and then back down the mountains, leading to sinking air), and thus warm a bit more than the chillier airmass would indicate, and also keep any ocean influence at bay. Thus, temperatures can still be expected to rebound into the low to mid 60s, even along the coast.
Thursday should have similar weather to Wednesday, but then uncertainty in the forecast increases, as a storm system could be approaching for Friday. As of now, it is expected to weaken as it approaches, which would only lead to a few scattered showers for Friday, and perhaps still a nice Saturday. We will keep you updated on the weekend’s forecast as this week goes along.
Overall: A pretty typical spring week. I like to say that there are three categories of “nice” weather: one where it’s perfect for exercise (60s), one where it’s perfect for more leisurely outdoor activities, such as a picnic or reading a book (70s and 80s), and one where it’s perfect for a dip in the pool or the beach (80s and 90s). Monday, Wednesday, and Thursday all look like great days to head out for a run/walk or play some pick-up basketball, whereas Tuesday has lots of potential for warmth, but uncertainty in cloud-cover and rainfall still remains.
Have a great day, everyone!