The warm front moving through the region has been advancing northeastward much slower than what computer models have suggested so it took longer to get the hot/humid airmass to work into that region. Also, a morning MCS, which actually also tracked further southwest than what models suggested, which actually is not uncommon, and left a great deal of cloud debris across that region. While by mid to late afternoon, the atmosphere recovered across the mentioned areas of New York and the airmass became violently unstable, the air was capped thanks to height rises and subsidence in wake of the MCS. While the atmosphere became very prime for severe weather including the possibility of tornadoes, a capped atmosphere prevented any development from occurring.
As we move into Wednesday get ready for a mid-July type airmass across New England. Temperatures will be ranging from the mid-80's across central/northern New England to mid-90's across much of CT/RI and including the Boston metro area. Combine this with dewpoints into the lower 70's and it will feel absolutely miserable outside, and in fact very dangerous for anyone working outdoors. It's extremely important to drink lots, and lots of water! Remember to check on the elderly and the young as well.
(Image from today's 18z NAM showing 2M temps for 2 PM Wednesday)
Over the past few days I've also mentioned the elevated mixed-layer, a plume of very warm and dry air situation between 800-550mb or so in the atmosphere. The core of this elevated mixed-layer will arrive overhead tomorrow. This will be associated with extremely steep mid-level lapse rates on order of 7-7.5, perhaps even 8C/KM. This means the temperature will be dropping that many degrees in C per KM of the atmosphere between the mentioned levels! This combined with the extremely hot surface temperatures and very high dewpoints will lead to an extremely unstable airmass across our region. The atmosphere will be very prime for severe thunderstorms.
(Image from today's 18z NAM showing surfaced-based Capes for 2 PM Wednesday)
Also, yesterday I had discussed how our atmosphere would remain capped tomorrow and we would likely not see any activity except across central/northern NY/VT/NH/ME as these areas would be closer to the cold front and source of lift. Throughout the day on Tuesday as new computer model data would become available, several computer models have been indicating that this cap may weaken very late in the afternoon as mid-level temperatures actually cool as the core of the warmest mid-level temperatures at 700mb begin to slide east. Computer models are also showing some height falls later in the day as well along with a very weak piece of shortwave energy lifting northeast from PA.
So, what can we take from all this?
At this point it's very difficult to say whether or not we will see thunderstorms. In fact, it's probably more unlikely we see nothing as the cap may be just too strong to overcome. However, the atmosphere will be very prime for explosive t'storms so if t'storms are able to develop or move into the area they will be quite strong to severe with damaging winds and large hail definite possibilities. This is just a situation we will have to watch as the day unfolds.
Meanwhile, across central/upstate NY/VT/NH/ME, where strong lift/forcing will be available, we could be looking at a highly active severe weather day across these parts with damaging winds, large hail, and isolated tornadoes all a distinct possibility.
The threat for strong to severe t'storms will also be a possibility on Thursday as the cold front continues to work east through the region and once passing ushering a more fall-like airmass.
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