We are fully engaged in a summer-like pattern as temperatures the past few days have been in the upper 80's to lower 90's across the region and with dewpoints into the upper 60's to lower 70's it has felt very uncomfortable outside and of course, we've had our daily t'storms, although not everyone has seen rain or storms. This pattern of heat/humidity and storms will continue through the week and into the first part of the weekend and each day there will be a threat for strong to severe storms. However, on this post we will just focus on Wednesday and what tomorrow may bring.
We are looking at yet another hot and humid day across the region tomorrow as temperatures away from the immediate coastline will once again get well into the mid to upper 80's to perhaps even 90F, in fact, places like Windsor Locks and Hartford could be looking at a 4th consecutive of 90F+ temperatures! Dewpoints will once again remain in the mid to upper 60's so it will feel very humid outside.
The big difference between tomorrow and the past two days is we are looking at more of a widespread threat for showers/t'storms, along with an elevated risk for stronger to severe t'storms. Remember, when talking about strong t'storms, we are referring to t'storms which are capable of producing winds 40 mph or greater and/or small hail and when talking about severe t'storms, we are referring to t'storms capable of producing winds of 58 mph or greater, and/or hail 1'' in diameter or greater. Also, not every thunderstorm becomes severe and the majority of people don't usually experience "severe" t'storms.
With that said, tomorrow, computer forecast models are showing a fairly strong piece of shortwave energy, embedded in the mid-level wind flow moving east-northeast from PA to NY right through southern New England during the afternoon hours. As this shortwave energy approaches the region, winds well up in the atmosphere will begin to increase and provide us with sufficient wind shear, something we have lacked the past few days. This wind shear will really help for storm to become better organized and sustain themselves much longer. The shortwave energy will provide a focus for strong lift, something we've also lacked and that will allow for t'storms to be more widespread than they have been the past few days.
With very little in the way of a cap tomorrow we should begin to see cumulus clouds beginning during the mid to late morning hours and this will really prevent temperatures from reaching into the lower 90's and may prevent anyone from seeing 90F tomorrow. The combination of heat/humidity will once again provide us with quite an unstable airmass tomorrow, although probably not as unstable as the past few days b/c we will be looking at weaker mid-level lapse rates tomorrow. This instability will provide the fuel storms will need to develop and strengthen.
The combination of stronger wind shear and an unstable airmass will lead to the development of scattered t'storms during the early afternoon hours and we should see storms last well into the evening hours as the energy will be slow to move through. The increased wind shear, along with instability will also increase the threat for stronger to severe t'storms tomorrow across the state. Some of the storms that develop tomorrow will have the potential to produce winds of 40-50 mph and possibly as high as 60 mph. While hail may not be a huge threat due to weaker lapse rates, the strong wind shear, along with some directional wind shear (change of wind direction with height), we could see some isolated supercell t'storms tomorrow, storms which have stronger rotation. If any supercells do form, the threat for hail would locally increase and we could be looking at the potential for hail up to 1.5'' in diameter.
While confidence in the threat for t'storms is very high, confidence in how strong/severe the storms become or how many of these storms become strong to severe is lower. This is due to the fact that the lapse rates will be so weak. When mid-level lapse rates are weak, below 6 C/KM, (this means that for every km you rise in the atmosphere, the temperature on average decreases by 6C), air parcels aren't really rising all that rapidly. Steeper mid-level lapse rates (higher rate of temperature change) allow for much more vigorous upward parcel acceleration and this translates to a much greater severe weather risk and t'storms have the ability to grow very tall, tapping into the much colder air in the mid/upper troposphere and stronger winds.
All in all, we will once again see t'storms tomorrow afternoon/evening with activity being more widespread than the past two days. The threat for stronger/severe storms will also be a bit more elevated than the past few days. If outdoors, keep a close eye to the sky and up to the minute weather forecasts and prepare to seek shelter inside to avoid lightning.
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