A strong cool air mass for this time of the year remains in place over the region, with temperatures remaining cooler than average across the region. A gradual warming trend will continue slowly through the weekend with highs returning back into the low 80s, which will become more noticeable next week as a warmer and more humid air mass returns into the region with 90s likely to make a comeback for some after a month-long absence.
[notice]Starting on Friday, August 16, the blog updating schedule will be returned to the morning hours, and observations will be posted for the previous day; today’s observations will be posted with tomorrow’s update.[/notice]
Tonight – Weekend: Slowly Warming Up
A cold air mass gradually dropped southeast through Canada, and was advected into the region with a westerly flow aloft behind a strong shortwave trough on Tuesday night. The air mass entered the region in a moderated form, with temperatures aloft at the 850 millibar level originally as low as 0-2 degrees Celsius in Canada, warming up to 6-8C as the air mass entered the region, although this is still cooler than average for August, which resulted in colder than average temperatures in the surface as well. With a high pressure overhead, clear skies and relatively light winds were observed last night, allowing for temperatures to quickly fall with unseasonably cool overnight lows in the 50s for most and the 40s inland. Central Park had a low of 59 degrees, which is 9 degrees below average and 5 degrees warmer than the record low of 54 set in 1964. Temperatures fell as low as 46 degrees in Sussex, NJ.
Winds aloft will switch towards the southwest as a weak trough digs into the central US, slowly bringing a slightly warmer air mass into the region, which along with ridging in the Atlantic Ocean slowly expanding west into the region will result in the cool air mass weakening, although this will be a gradual process with a slow warming trend over the next few days. After high temperatures reached the mid to upper 70s across the area today, mostly clear skies are expected again tonight with lows falling into the upper 40s inland, low to mid 50s in the north/west suburbs, southern CT and eastern-central Long Island, and the upper 50s to low 60s in NYC and the immediate coast.
The high pressure will remain over the region through Friday and the weekend, keeping mostly sunny skies for Friday and Saturday with highs slowly warming into the upper 70s to low 80s on Friday and the low to mid 80s on Saturday. A frontal boundary will slowly crawl to the north in the Mid Atlantic states, but will remain suppressed south of the area due to the high pressure; some increase in cloud cover, however, is expected, with partly to mostly cloudy skies and highs in the upper 70s to low 80s, with cooler temperatures in the mid 70s towards eastern and coastal Long Island where a breezy SE wind is expected.