Friday Soaking In Store?

We need the rain...there is no question about it.  Looking back at the past 90-days we can see, region wide there is quite the rain deficit.  In fact, if we extend this period to the past 6-months we can see the rain deficit is even greater:

With the month of July yielding summer in full-fledged beast mode with temperatures exceeding the 90F mark numerous times and very little (in fact hardly any) widespread rainfall the ground is bone dry yielding a substantial brush fire risk.  With this we really need this rain and it looks like we'll get our wish on Friday as a developing area of low pressure is expected to track northeastward along an advancing cold front providing ample moisture and lift to generate widespread precipitation.

Both the NAM and GFS computer forecast models are indicating the potential for a quite a bit of precipitation to fall, beginning late overnight Thursday and lasting through the first half of Friday.  In fact, both forecast models are indicating as much as 1-2'' of rainfall could fall across a large portion of the region with even potential for isolated higher amounts, especially in any embedded thunderstorms:

As the cold front approaches from the west, a warm front will be surging northward at the surface.  With the area of low pressure expected to track right over southern New England or just south so the warm front will likely not make much progress into southern New England and actually may stall just north of Long Island Sound across coastal CT.  South of the warm front the airmass is expected to become exceptionally moist with dewpoint temperatures rising well into the 70's and precipital water values (PWATS) rising well above 2''...and indication of an exceptionally moist airmass:

One interesting aspect with this system will be the strengthening of the lowe-level jet and winds within the lowest 5,000ft of the atmosphere.  Both the NAM and GFS indicate that winds will strengthen to as much as 30-40 knots and be coming from the southeast.  This flow will not only work to transport copious moisture in off the Atlantic but will actually also work to enhance the degree of directional shear in place.  This will be very important for anyone south of the warm front as if any thunderstorms develop and tap into this shear they could begin to acquire rotation and pose a threat for a brief/weak tornado.  The highest likelihood for this is across NW CJ into the NYC metro area and onto Long Island.  In fact, many of the tornadoes which have occurred in the NYC area and on Long Island have occurred in similar setups to tomorrow.  With the degree of instability isn't expected to be all that great, with the surge of low-level moisture (dewpoints near or above 70f), and rich presence of low-level moisture in the low-levels thanks to the southeasterly winds will create a very buoyant low-level airmass and an unstable layer here.  While 500-800 J/KG of mixed-layer cape is not usually sufficient for severe weather, given how this setup would yield low-topped thunderstorms (thunderstorms which don't grow very tall) and they feed off of the low-level airmass and utilize those conditions.  This combination of shear/cape would be sufficient to enhance storm rotation:

This point-and-click forecast sounding for a location on Long Island shows very good low-level directional shear along with strong winds (encircled area on bottom left) and looking at the hodograph you can see a curved looked indicating the good directional shear present (encircled on top right):

For those been asking for rain it appears Friday will finally deliver the goods and for a widespread across across southern New England where region wide as much as 1'' of rain could fall.  Some localized areas could also see up to 2'' of rainfall with perhaps even a few locally higher amounts!  This would certainly do wonders for the long-term rain deficit we're facing.

As for any severe weather potential, we have to watch where the warm front stalls as just south of the warm front atmospheric conditions could favor some of the thunderstorms becoming strong and posing a threat for strong to damaging wind gusts and even a brief/weak tornado.

Assessing Today/Tonight's Thunderstorm/Severe Weather Potential

The potential exists for numerous shower and thunderstorm activity to develop region wide later this afternoon with the activity lasting well into the overnight hours.  Some ingredients will be in place for a few of these thunderstorms to become strong to severe and have the potential to produce strong to damaging wind gusts and perhaps even some large hail, especially in any rotating thunderstorms.  The next big question is, do these ingredients (which we will look at below) all come together at the right time to produce a bigger severe weather event?  This is a question in which we will slowly begin to answer as the afternoon progresses.  The reason for this is due to the mesoscale (small-scale) factor of the setup.  Often times with convective events, the severity and extent of them all comes down to very small-scale features and it is very, very difficult to forecast/pinpoint these features more than several hours in advance.  

Instability

When dealing with the potential for convection, one of the questions we always face is how unstable will the atmosphere be.  For the past several days, computer forecast guidance has hinted that with the combination of heat/humidity the airmass could become quite unstable...the question was whether or not cloud debris from previous day's convection over the Great Lakes would allow for less in the way of surface heating.  Given the satellite trends this morning, this is not the case.  While we do have some cloud debris moving over the region, strong surface heating is occurring across many places and away from the coast temperatures should soar well into the lower to middle 90's.  With dewpoints in the mid to upper 60's this will yield quite an unstable airmass.  

While typically we see the airmass become more stable as the sun begins to set (with the sun setting and surface temperatures lowering this allows for a stabilizing atmosphere), there are certain ingredients which could keep us quite unstable well into the overnight hours.  These ingredients include; the potential steepening of mid-level (700-500mb lapse rates) thanks to cooling temperatures in the mid-levels of the atmosphere and/or the advection of an elevated mixed-layer plume, and a further moistening of the low-level airmass.  The latest NAM computer forecast models show mixed-layer cape values as high as 1500-2000+ J/KG indicating the airmass will remain quite unstable well into the evening and into the overnight hours:

Wind Shear

As the shortwave energy approaches winds throughout the troposphere are expected to increase and this would help any thunderstorms that develop organize and also enhance the potential for strong to damaging wind gusts.  By early evening we see the nose of a rather modest 35-45 knot 500mb jet punching into southern New England.  While the 500mb winds over southern New England alone aren't that strong, the core of the stronger winds just off to the west can actually help to intensify convection if the thunderstorms are just to the east of this axis.  

We also see an increase in 700mb which should approach/exceed 30-35 knots.  This will help yield vertical shear values of around 35 knots which is supportive for thunderstorms to become organized and also may help with the enhancement of storm updraft rotation.  

850mb winds are expected to approach 30 knots as well which will help with stronger low-level shear values and also enhance some potential for updraft rotation.  The combination of these strong winds aloft will yield a threat for strong to damaging wind gusts with the strongest thunderstorms:

While the shear still looks to remain adequate, latest trends have decreased the degree of wind shear over southern New England for later on.  If this trend does continue the threat for severe weather would be diminished and we would only be looking at a few isolated reports of wind damage and maybe some hail.  Something to keep an eye on as the afternoon continues to progress.

Dry Mid-Levels

While some dry air is good to have in the middle levels of the troposphere, too much dry air is no good as this eats away at storms updraft strength...at the same time it can enhance the potential for stronger winds to mix  down.  Forecast soundings do indicate a quite a bit of dry air in the mid-levels, however, some indications are they could moisten up somewhat.  This is something to keep a close eye on.  If the degree of dry air is too much, this would limit thunderstorm coverage and could decrease the potential for severe weather.  This is a rather difficult signal, however, as one model shows a great deal of dry air and the other model not nearly as much.  Too illustrate we will look at a bufkit sounding for Windsor Locks, CT for around 5:00 PM this evening:

Forcing

Perhaps one of the biggest questions is the degree of forcing.  Latest data has continued to slow down with the eastward progression of the shortwave energy moving through Quebec Provence in Canada.  Forcing is huge as it provides the lift necessary for parcels to rise and generate showers and thunderstorms.  While there are hints at some localized areas of enhanced forcing across the region, it's unclear as to whether that would be enough to spark any activity.  Looking below we see the main piece of energy still well west at 8:00 PM this evening.  in fact, it is entirely possible we see this energy push through tomorrow sparking a threat for thunderstorms, including a few strong to severe thunderstorms:

  

What to Expect:

At the least it looks like we'll see some shower and thunderstorm activity develop later on, however, the coverage and extent of this activity is still not all that clear.  As the afternoon unfolds the situation will become more clear.  At this time it appears the potential foe widespread severe weather may be lowering, however, if a cluster of thunderstorms does develop it could produce a swath of damaging winds and perhaps even some hail.  

Given the slowing down of the shortwave energy, this may be opening up a window for the possibility of thunderstorms tomorrow.  The atmosphere does look to be unstable and with steep lapse rates and strong wind shear, thunderstorms could become strong to severe and pose the threat for strong to damaging wind gusts and large hail.  

There is lots to work out over the next several hours but if today doesn't work out that could just mean increased potential tomorrow.  

Thunderstorm/Severe Weather Potential Friday, July 22nd, 2016 Across New England

A rather intriguing setup looks to take place across New England on Friday as a potent shortwave trough and attendant cold front plow into a very hot and humid airmass.  While there may be some questions regarding how high temperatures climb (we will touch more on this later on), the potential exists for temperatures to climb into the lower to even mid-90's.  With dewpoints expected to soar into the upper 60's to perhaps lower 70's (although they could drop...again we'll touch upon this more later on) the combination of heat and humidity will make it feel quite uncomfortable.  The combination of heat and humidity would also yield quite an unstable airmass and that would be the fuel necessary to spark off some thunderstorms and some of which could become strong to severe.  

Looking at the 500mb pattern in place Friday morning we see substantial ridging across the central and southern portion of the United States placing the northern-tier of the United States and a good chunk of the northeast on the crest of the ridge allowing for a northwesterly flow in the mid and upper-levels of the troposphere:

While not all northwesterly flow events produce severe weather or widespread severe weather across New England, some of our biggest events gave occurred with northwesterly flows in the mid and upper levels of the troposphere.  

Embedded within this northwesterly flow will be two features which will be very big potential focal points towards the development of thunderstorms along with the potential for some severe thunderstorms.  These two features are; a shortwave trough which is expected to push into northern New England along with a subsequent piece of shortwave energy and attendant cold front and the other feature being a potential elevated mixed-layer plume.  The potential for an elevated mixed-layer (EML) plume to traverse over the region would vastly increase the potential for not only thunderstorms and a few thunderstorms but would increase the potential for a severe weather outbreak.  Too save time to further read and understand EML's please refer to my blog post devoted to them:

http://weatherwiz.blogspot.com/2015/06/what-is-elevated-mixed-layer.html

For Friday we are tracking two potential pieces of shortwave energy.  One is expected to push through northern New England during the morning hours.  With increasing dewpoints, low-level moisture, and shear, this feature could be associated with showers and thunderstorms which move through the Great Lakes the night before.  It is this potential which yields questions with how much heating we see later on in the day.  If this feature is associated with a quite a bit of cloud debris and shower/thunderstorm activity, it could take quite a while to clear things out meaning we don't achieve maximum heating.  This would yield lower temperatures and subsequently lower instability values.  However, this could be more important for northern New England and areas north of the MA Pike as the timing of the second shortwave would favor thunderstorm activity during the daylight hours.  Further south across southern New England, the timing may favor thunderstorms after dark, thus the degree of heating is not as important.  While typically, especially across this region, thunderstorms lose their strength as the sun begins to set and instability begins to fade, steepening lapse rates (faster decrease of temperature with height through the troposphere) could help to keep the airmass quite unstable well into the overnight and this would yield the threat for thunderstorms (both strong to severe) to persist well into the overnight for southern New England.

The second shortwave feature is the main player and would be the focal point for afternoon/evening thunderstorms.  This is expected to approach northern New England during the late afternoon hours and be accompanied by modest height falls.  

The next feature is the potential plume of EML air which may traverse over New England.  This feature would be key into yielding the moderately to perhaps extremely unstable airmass and would provide sufficient fuel for thunderstorms to not only become quite strong but reach severe limits:

     

As far as wind shear is concerned, winds throughout the troposphere should be more than adequate to not only help generate thunderstorms but keep updrafts maintained, and also perhaps help with updraft rotation.  The best wind shear appears to be located across northern New England where they will be closest to the stronger 500mb and 250mb winds:

What can we expect for Friday?  Well in the very least, we won't really have a full idea until Friday progresses as as are then able to pin-down the mesoscale (small features which play major roles in these type of events) aspects.  However, right now this is some of the potential that exists...

Some morning shower and thunderstorm activity is expected to push through portions of New England Friday morning.  After this activity passes the question becomes how quickly do we clear out?  Multiple computer forecast guidance indicates we will clear and do so quickly allowing for temperatures to soar into the 90's with dewpoints near 70F.  This combination along with steep lapse rates would yield a strong to extremely unstable airmass for much of New England.  The focus now would be across northern New England where they will be closer to the approaching second shortwave and strongest shear.  Here we will be on the lookout for the development of more showers and thunderstorms and on a widespread level.  Given the potential for strong to extreme instability and strong wind shear several of these thunderstorms could become strong to severe and produce strong to damaging winds, large hail, and given the degree of shear, supercells would be possible yielding the potential for an isolated tornado.  The extent of this potential all depends on degree of instability and timing of the features (does the shortwave time perfectly with the arrivial of steep lapse rates and strong shear?).  If everything times together we could be looking at a major severe weather event with numerous reports of several weather.  If the timing is not perfect than we would be looking at widespread thunderstorms with only a few becoming strong to severe and isolated pockets of damage.  

For southern New England...the watch will be on the activity to the north as this activity could come together to form what is known as a mesoscale comvective complex (MCS) and push through portions of southern New England overnight.  If the airmass remains quite unstable, this complex could produce a swatch of strong to damaging winds and even large hail.  Again this depends on the degree of instability and how the activity to the north evolves.  

Too summarize some of the things to watch;

1) EML/lapse rates...There is not 100% confidence or agreement that we do see an EML-plume/associated steep lapse rates traverse into New England.  Some computer guidance suggests this while others do not.  If we don't see this feature occur the threat for a severe weather outbreak would vastly diminish and the overnight severe threat for southern New England would be very, very slim.  

2) Morning cloud debris associated with shower/t'storm activity...again, this is more of a concern for northern New England but if it takes a while to clear out and surface temperatures do not realize their potential, the degree of instability will be vastly less and the threat for a widespread severe weather outbreak would be lessened.  

3) Surface dewpoints...This is something else to watch.  Some forecast soundings indicate surface and boundary layer winds may become more westerly in nature.  If the degree of low-level moisture isn't very high, or if the high dewpoints only exist up to a couple thousand feet or so, westerly winds would work to mix down some of this drier air aloft and that would drop the surface dewpoints and vastly decrease instability and subsequently severe weather potential.  

All in all Friday has the potential to be quite an active day for a good chunk of New England and we are just coming off of the region's biggest severe weather event this summer (Monday, July 18th, 2016).  While this potential exists, there are certainly alot of questions still to be answered with regards to how the key features evolve and we should get a better idea as new data continues to roll in.  As Friday morning progresses, we will develop a very good idea of what to expect as the mesoscale features are pinned down.  

Monday, July 18th, 2016 Thunderstorm Potential.

Another hot and steamy day is in store for Monday as temperatures ahead of an approaching cold front are expected to soar into the upper 80's to lower 90's with dewpoint temperatures in the 60's and perhaps rising into the lower 70's as the front approaches (thanks to increasing theta-e and theta-e pooling).  The combination of heat and humidity will lead to a quite unstable airmass tomorrow across southern New England.  While mid-level lapse rates may be modest at best (~6 C/KM), dewpoints climbing up to around 70F (or perhaps a little higher) could help to offset the weaker lapse rates and yield as much as 1500-2000+ J/KG of mixed-layer cape tomorrow afternoon:

With such an unstable airmass in place and an approaching weather system, the question becomes do we see showers and thunderstorms tomorrow and if so, what are the chances for strong to severe thunderstorms?  With the main cold front pushing through western and central New York during the late morning hours, a line of showers and thunderstorms is expected to develop back across central New York state during the late morning and early afternoon hours and push southeast  with the storm motion from southeast to northeast.  This line would approach southern New England during the early evening hours.  This would result in some unfavorable timing for our region, however, what we will have to watch for is a pre-frontral trough setting up across eastern New York and sliding through southern New England during the early to mid afternoon hours.  It is this feature along with modest height falls which could provide the focus for the develop of showers and thunderstorms across southern New England during the afternoon hours.  

Severe Weather Potential:  

While a widespread severe weather outbreak is not anticipated, the possibility does exist for several thunderstorms to become strong with a few reaching severe limits.  The degree of instability is certainly not a question tomorrow nor is the degree of wind shear aloft, however, there are some uncertainties with regards to where the best mid-to-upper level forcing is located.  By late afternoon, we see as much as 35-45 knots of wind at 500mb (~18,000ft AGL) overspreading southern New England which is more than sufficient for thunderstorms to become organized.  However, we see the strongest winds back further to the west and subsequently the strongest mid-level forcing as well:

One thing to watch tomorrow is perhaps the degree of low-level directional shear that a few of the computer forecast models are showing.  Computer forecast models are showing southerly winds at the surface, then turning to southwesterly in the lower-levels of the atmosphere and then more westerly in the mid-levels of the atmosphere.  This is indicative of good directional shear and with good speed shear (increase of winds with height through the troposphere), this can allow for strong thunderstorms with have strong and mature updrafts to actually begin rotating which can increase the potential for both larger hail and even a tornado...just something that needs to be watched.  The best potential for this possibility would be the CT River Valley where the surface winds could remain more southerly to even southeasterly:

While the more widespread thunderstorm activity may be confined back across much of New York into PA and into VT along/just ahead of the cold front and closer to the best mid and upper level forcing, the pre-frontal trough sliding through southern New England during the afternoon should provide a focus for showers and thunderstorm development as well.  While the setup really doesn't favor a big severe weather event right now, some of these thunderstorms across southern New England may become strong with a few reaching severe limits.  These thunderstorms will be capable of producing strong to damaging wind gusts, some hail, and while a low potential, an isolated tornado can't be ruled out given the degree of directional shear being advertised.  All storms will produce cloud-to-ground lightning and with precipitable water values approaching 2'' torrential downpours are likely.  The best threat for strong to severe thunderstorms may be confined to NY, PA, VT, western MA, and northwestern CT.  However, if the better forcing pushes east faster than modeled and overlaps the strongest instability and wind shear, then a bigger severe weather threat may materialize.

Anniversary of the July 10th, 1989 Tornado Outbreak

One of the more infamous tornado outbreaks to occur across southern New England happened on July 10th, 1989.  On this day 10-tornadoes were confirmed across the states of MA (7) and CT (3) and if you expand to include the states of NY and NJ, a total of 17-tornadoes were confirmed (4-in NY and 3-in NJ).  Of the 17-confirmed tornadoes across the four states, two of them were rated as F4 tornadoes, one in NY and the other in CT.  (While this tornado was rated as an F4 during its peak intensity, there are some questions to whether the tornado was really that strong but that's a story for another time).

Atmospheric conditions on Monday, July 10th, 1989 were prime not only for the development of severe weather in the afternoon but for the development of tornadoes as well.  In fact, the airmass across a chunk of NY and into southern New England was something more typical for the southern Plains than for the Northeast or New England.  The biggest contributor to the tornado outbreak was the presence of an elevated mixed-layer (EML) which advected into the region.  EML's develop/originate across the inter-mountain states across the southwestern United States and are a very critical player in major severe weather/tornado outbreaks and are one of the primary reasons as to why the southern Plains sees the severe weather they do.  For a little more info on EML's check out a previous blog post here:

http://weatherwiz.blogspot.com/2015/06/what-is-elevated-mixed-layer.html

Looking at an observed skew-t forecast sounding from Albany, NY  from 8:00 AM on the 10th we see several eye opening features present:

1) EML:  You can see the presence of the EML as clear as day on the sounding.  This is a critical feature as it is associated with very steep lapse rates (change of temperature with height) and when placed over a warm/hot and humid airmass will help contribute to an extremely unstable airmass and with the passage of a morning warm front that's exactly the type of environment that would develop during the late morning and afternoon hours.

2) Winds:  Notice how towards the surface you have winds from the SE but just above the surface winds shift to the SW...this is an indicator that the warm front was in this vicinity and this also yields some degree of directional wind shear (change of wind direction with height).  This is another ingredient for the development of supercell thunderstorms and tornadoes.  Also, as you increase with altitude through the troposphere notice how the winds even back more towards the west and northwest.  This showed that there was a great deal of directional shear throughout the entire atmosphere.  Winds aloft too were strong and would actually even strengthen as the morning and afternoon progressed which provided some great speed shear (change of wind speed with height) as well.  This is key for storm organization and to further enhance the effect of the directional shear.
If we actually looked at the sounding for Buffalo, NY for the same time, you can actually see shear just off to the west much much stronger and this is what would work in for the afternoon hours:

Looking at the 500mb and 700mb patterns on that day, we see a very favorable pattern for the advection of an EML right into the Northeast and southern New England.  Established ridging across the southeastern United States places New England on the prosperity of the ridge (provides the more westerly flow in the mid-levels of the troposphere) and with a digging trough in the west coast of the United States, this allows for some EML air to get entrained in the wind flow around the ridge and this pattern configuration favors the advection of the EML right into portions of the Northeast and southern New England.  What we also see is a vigorous piece of shortwave energy right near the United States/Canadian border associated with a shortwave trough pushing a strong cold front southeast.  This would be the focus for the lift needed in order to develop the severe thunderstorms:

 The result...

As the shortwave trough continued to dig and the vigorous piece of shortwave energy continued moving east through northern New England, this allowed for a strong cold front to advance southeastward into an extremely unstable airmass.  As the cold front approached, and heights began to rapidly fall in response to the approaching shortwave trough and the atmospheric cap associated with the EML began to erode, explosive thunderstorm development occurred across New York state and then this activity progressed towards MA/CT/NJ where further activity would develop as well.  Given the atmospheric conditions of extreme instability and very strong speed and directional shear, the thunderstorms quickly became supercell thunderstorms (thunderstorms which have strong rotation known as a mesocyclone) with several spawning tornadoes, including the two violent tornadoes in NY and CT.  Another aspect which helped the development of tornadoes were the very low lifted condensation levels (LCL's) thanks to the strong presence of low-level moisture present with high dewpoints.

Major severe weather and especially tornado outbreaks are quite rare in this portion of the country, however, they do happen.  In order for them to happen you need a special combination of atmospheric ingredients such as; high instability, presence of an elevated mixed-layer, and strong directional/speed shear all to coincide with the passage of a weather system such as a cold front.  On this day in 1989, we saw this perfect combination of ingredients to coincide with the passage of a cold front.

Thursday, July 7th, 2016 high heat/humidity induced thunderstorm possibilities.

As we push through the first week of July real sultry summer weather has bestowed upon us with temperatures climbing well into the 90's with dewpoint temperatures well into the 60's to even lower 70's.  While the duration of the high heat/humidity will be on the brief side (only a few days), its presence will certainly be felt.  Also, as typical with this time of year when we run into bouts of high heat/humidity, we also run into the potential for afternoon showers and thunderstorms and as we move through the next couple of days we will deal with that potential.  For right now, however, we will take a look at Thursday.

While widespread showers and thunderstorms and widespread severe weather is not expected tomorrow, a few isolated thunderstorms are expected to develop.  Not every town is going to experience a thunderstorms (in fact only a handful of towns may be so lucky) but for the towns that do the storms could be on the strong side.

For Thursday, we are expecting to see numerous locations (especially away from the immediate coastline) experience their second consecutive day of 90+ degree temperatures.  This, combined with dewpoint temperatures into the 60' to perhaps lower 70's will yield a moderately unstable airmass and this will provide the fuel necessary for the development of thunderstorms.  In fact computer forecast models are indicating as much as 2000-3000 J/KG of surface-based cape across the region with as much as 200-2500 J/KG of mixed-layer cape.  Typically it is difficult to get mixed-layer cape values these high without the presence of 6.5 C/KM or higher 700-500mb lapse rates (they will only be on order of about 5.5 C/KM tomorrow), however, given the presence of upper 60's to lower 70's dewpoints this will help compensate a bit for weaker lapse rates:

   The question is will we have any source of lift to generate showers or thunderstorms..the answer to this question is it appears so:

Now with such high instability values and a lifting mechanism moving overhead, you would perhaps expect more in the way of widespread thunderstorms or even a bigger threat for severe weather, however, we are lacking a few key ingredients.  Below is a forecast sounding for Windsor Locks, CT tomorrow afternoon.  I have highlighted a few different features:

white:  weak wind shear:  The winds throughout the troposphere tomorrow will be very, very weak.  In fact, up through 20,000+ feet winds will only be around 5-15 knots.  That is very weak.  Winds this weak will make for storm organization quite difficult and also prevent sustained updrafts.  This will mean anything that gets going will quickly collapse and weaken.

blue:  drier air:  Notice the spread between the dewpoint temperature (solid green line) and the temperature (red solid line).  This indicates the presence of some very dry air.  Now, dry air in this level of the atmosphere is a good thing, so long it doesn't mix to the levels below it.  In tomorrow's case, conditions will allow for some of this drier air to mix down into the lower levels which could also end up dropping dew points a little bit, thus lowering instability values.

Purple:  warming:  There are two areas here, the solid purple line next to the temperature line and then circled below on the bottom left with "700-500mb lapse rates".  This warming in this level yields a temperature change between about 10,000ft and 18,000ft of only 5.5 C/KM.  This is very weak.  What this means is as rising air parcels encounter this level, this will rise rather slowly and with weak shear storms will struggle to really penetrate this level and when they do it will only last very briefly which also indicates short-lived (or pulse storms).

Putting all this together what can we expect?  Most towns stay dry tomorrow, however, given the presence of high heat/humidity and an approaching system, atmospheric ingredients will be in place for the development of a few thunderstorms, especially along the east sides of the Berkshire/Worcester Hills.  With weak shear in place and high instability, any storm could quickly become quite strong, however, with the weak shear will be short-lived.  The presence of the drier air aloft and dewpoint depression at the surface (surface temperatures in the 90's minus the dewpoints in the upper 60's to lower 70's yielding a depression ~20F) will result in the potential for some strong wind gusts.  With high moisture content this could yield a wet microburst (heavy rain/strong winds) which could result in some wind damage.  Not everyone sees a storm tomorrow but whoever does could see a nasty thunderstorm.  Thunderstorms will also be slow movers so they could drop a lot of rain in a short timeframe resulting in some flash flooding, even despite the dry ground.