Good evening from Southern Connecticut Weather. 

Let's get right to it. Today was a record breaking day in parts of CT, as BDL reported a 99 degree high temperature, breaking the daily record from 1934. In addition, HFD reported 99 and Bridgeport reported 94 degrees. It was a "big heat" day, with widespread highs above 95 and heat indices over 100. 

Some guidance continues to show tomorrow being another big heat day, with the favored areas of the Hartford metro area and northern CT River Valley seeing highs in the upper 90s to near 100 tomorrow while the rest of the state sees highs in the 90s. The combination of heat and oppressive humidity will bring heat indices over 100 again tomorrow. The impact of heat on the body gets worse as a heat wave progresses, so take precautions tomorrow and be sure to check on the vulnerable. 

Compounding the heat, is the increased risk of severe weather tomorrow. Today's storms were a bit more organized today than expected, and took advantage of the high instability environment to produce significant lightning and strong winds in northern CT. Tomorrow has the potential to be active, as the heat wave breaks in the wake of thunderstorms tomorrow. There are indications that more severe thunderstorm ingredients will be in place tomorrow, particularly in northern CT.

​The Storm Prediction Center has issued an enhanced risk for part of northern CT and a slight risk for much of the rest of the state tomorrow. 

Let's look at the heat and severe potential in more detail. 

Above: the latest SPC outlook for tomorrow's severe weather potential. 

The Heat
As I said above, we're probably looking at another day with highs in the mid to upper 90s. Despite the storms tonight, we will see very warm temperatures overnight, providing a springboard for temperatures to rise fast tomorrow. We should see full sunshine early, followed by increasing clouds in the early afternoon as we start to see instability reach its peak. 

We will need to watch the wind direction, which will determine whether we see higher end temperatures or temps a few degrees cooler. Hartford or BDL reaching 100 degrees isn't totally out of the question. Regardless of the air temperature, humidity is expected to be oppressive statewide once again, meaning it's important to take the heat seriously and stay hydrated. Heat indices will be over 100 again. 

Above, the Euro depiction of temperatures tomorrow afternoon. Below, the GFS temperature depiction. Both show highs in the upper 90s for central CT and 90s virtually statewide. This will set the stage for our severe weather potential. 

Severe Weather Potential
At the start of the day, the SPC put most of CT in a slight risk for tomorrow, but this afternoon they also added parts of northern CT and points north in an enhanced risk. The ingredients are there for an active day, with strong to severe thunderstorms tomorrow afternoon and evening.

First, we are expecting a moderately to strongly unstable atmosphere. This is measured by CAPE, and the ones I care about most here are MLCAPE (mixed-layer CAPE), and DCAPE (downdraft CAPE). Let's look at an averaged sounding in central CT before storms arrive tomorrow afternoon. 

Now there's a lot happening in this chart, which includes a sounding. Look at the MLCAPE. Seeing that number over 3100 is impressive to say the least. DCAPE over 1000 J/Kg is also impressive and suggests that strong winds are possible. Although not seen here, we also see a lifting mechanism as a mid level system dives in from the west and provides the shear and lift. We also see plenty of moisture with downright tropical dew points. 

For northern CT, that means we need to watch tomorrow closely as we may see a multi-hazard severe weather threat. Right now, the biggest potential is with strong winds, but there will also be a potential for some hail, heavy rain, and significant lightning. Although the tornado risk is low, it is nonzero in northern CT. 

For southern CT, wind, lightning, and heavy rain look to be the potential hazards. 

Now, let's be clear: severe weather is inherently localized. Not everyone will see severe weather, but this is the strongest severe weather signal we've seen thus far this season. I do think we see an unstable environment tomorrow and sufficient shear to organize things, but a limiting factor could be timing. The later the storms the less likely they are to maximize potential, though some could still be strong to severe. 

Like I said earlier, let's see what the environment looks like tomorrow, but with the combination of heat and severe potential tomorrow is a day where everyone needs to be weather aware. I would not be surprised to see more of northern CT in the enhanced risk zone tomorrow. 

To tie it all together, here's the high resolution NAM depiction below. This is between 4-11pm tomorrow, and is not a forecast, but it shows the general idea of what I think will happen. Storms will develop to our northwest during the afternoon and are likely to congeal into a strong line that produces damaging winds and significant rain/lightning. 

Key Takeaways

• Tomorrow is the last day of the heat wave, with highs in the 90s and maximized in central CT with potential highs nearing 100. 
  
  
• Heat indices will be over 100 again statewide, meaning heat related illnesses are possible. Stay hydrated and check in on the vulnerable. 
  
  
• There is potential for strong to severe thunderstorms tomorrow afternoon and evening, with the highest severe potential in northern and western CT. Strong to severe thunderstorms are possible across CT.  
  
  
• Strong winds are the biggest potential hazard, but other hazards such as heavy rain, lightning, hail, and an isolated tornado are possible (especially in northern CT).
  
  
• Outdoor activities are possible tomorrow, but keep a close eye to the radar during the afternoon and evening hours.  

A​s always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.

Thank you for reading. 
​
-DB​ ​

Good morning from Southern Connecticut Weather. 

We have been discussing it in our forecasts for a while now, and the second heat wave of the year has arrived. Although inland areas are most likely to verify a technical heat wave of three consecutive days of 90+, this heat wave will be felt across CT, as an expansive upper level ridge brings not just hot air temperatures, but oppressive humidity and high overnight temperatures. For this reason, this heat wave to end June is expected to be more widespread and stronger than the first one we saw. Let's jump right in. 

Above: European Model depiction of the upper level ridge over New England on Tuesday, which should be the hottest day of the heat wave. While the Pacific Northwest bakes under an all-time extreme heat regime, we have a very strong heat influence from a separate ridge over our region. That means hot and humid conditions and the potential for "big heat" i.e. temperatures over 95 degrees or heat indices over 105 degrees. 

Below: The current advisories in effect. Note that even New London County is under a Heat Advisory. It's possible we see some Excessive Heat Warnings this week, which are our highest level of heat-related weather warnings. 

Sunday (Today)
It is already warm and very humid outside, with dew points in the upper 60s to low 70s. Anything over a 70 dew point tends to be oppressive in my book. Although it is cloudy currently, that is expected to change and sunny conditions should lead to high temperatures this afternoon reaching the mid to upper 80s at the shore and upper 80s to low 90s inland.

Even if the temperatures don't hit 90, it'll feel like it with the heat index--a measure of how it actually feels based on air temperature and humidity level. If you are outside today, stay hydrated, and never leave children or pets in your vehicle. Temperatures climb rapidly in a car without adequate air conditioning.

​Monday-Tuesday
Each day should bring some of the hottest temperatures of the year, with Tuesday likely being the hottest of the heat wave. Humidity will be oppressive statewide, with heat indices above 100 in many spots. Tuesday could be the excessive heat day, with possible inland temperatures in the upper 90s and heat indices nearing 105. Keep in mind that we could see more westerly flow on these days, meaning that the shoreline, which tends to be cooler during these heat events, may not escape as much as they normally would. Below is the European Model depiction of the heat index tomorrow just before peak heating of the day. It'll be a hot one statewide! 

With regard to precipitation chances, each day has the potential for some pop up showers or thunderstorms, typical of summer, but the odds for any relief are low. Heat is nothing to play around with, and what's particularly problematic with this heat wave is the fact that overnight temperatures will be well above normal too. Know the signs of heat illness and check on your neighbors, family, and the vulnerable as heat illness can hit anyone and hit them quickly. 

Wednesday
The middle of the week should continue the heat wave, as we are likely to see high temperatures in the 90s again. Wednesday, however, looks to be the end of the heat wave. Depending on the timing of the front, we could see showers and storms break the heat later in the day on Wednesday, as depicted by the GFS image below. At this time, we're not expecting any severe thunderstorms, but it's something we'll be watching as some of our heat waves tend to get broken by big storms. 

Thursday-Friday
Although the oppressive heat will be a thing of the past by Thursday and Friday, it is still likely to be warm, especially Thursday. This period, unfortunately, is much more uncertain, as it is unclear how quickly the front will clear the area, and how active the trough will be in producing rain chances. That said, right now the guidance from both the Euro and GFS show an unsettled period, with rain likely. Whether it is washout rain remains to be seen, but it leans that way. Below is a GFS depiction of the period but the Euro is not too far behind in terms of rain chances increasing with at least one area of low pressure developing in the region. 

Saturday-Sunday
That brings us to the holiday weekend. It's uncertain at this range but it looks unsettled. The GFS wants to bring near washout conditions and much colder than normal temperatures. I'm not buying that right now.

The Euro isn't too far behind with rainfall, but it does have more seasonable temperatures. I will blend the guidance here and just call for seasonable temperatures and a chance of rain each day, but nothing at this time that would make me change my holiday weekend plans. Stay tuned however for future forecasts as things could go south if the model trend continues toward a wetter and cooler weekend. 

The Dailies
Monday: Hazy, Hot, and Humid. Highs in the low to mid 90s with the exception of the immediate shoreline. Heat Index above 100, especially inland. Chance of showers/thunderstorms 10%.  

Tuesday: Hazy, Hot, and Humid. Highs in the mid to upper 90s inland, and upper 80s to low 90s at the shoreline. Heat Index above 100 and possibly near 105 inland. Chance of showers/thunderstorms 20%. 

Wednesday: Hazy, Hot, and Humid early, followed by showers and thunderstorms during the afternoon. Highs in the mid to upper 90s inland and upper 80s to low 90s at the shore. Chance of showers/thunderstorms 50%. 

Thursday: Mostly cloudy and warm, with showers and thunderstorms. Highs in the low to mid 80s. Chance of rain 70%. 

Friday: Mostly cloudy with rain showers. Highs in the low 80s. Chance of rain 60%. 

Saturday: Partly cloudy with a chance of rain showers. Highs in the mid to upper 70s. Chance of rain 50%. 

Sunday: ​Partly cloudy with a chance of rain showers. Highs in the mid to upper 70s. Chance of rain 50%.

A​s always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.

Thank you for reading. 
​
-DB​ 

It appears cohort DB and I are on the same page.  A strong heat wave is on the way and this one may have staying power, as there are no real cool-downs foreseen.  Now there are technicalities with heat waves.  Technically, the definition is three straight days over 90.  Some locales may technically not make it, as there could be an 88 or 89 in between 90s, but it will be humid to very humid, so it's not like we're going to get cool or anything like that.

Currently: Not much going on.  High pressure basically overhead, stretching from Nova Scotia to the Delmarva.  A warm front stretched from Atlanta to off the Delmarva out to Kansas City.  That warm front will be the focal point for widely isolated t-storms the next couple of days.

Tonight: At first glance, looks like a good radiative night, but you don't usually radiate very well on Southerly winds.  So we'll go very close to guidance temps.  Look for lows 55-60, except low 50s in the NW hills and sheltered valleys.

Tomorrow: We begin the transition to warmer and more humid wx, but tomorrow is generally still not too bad.  I have gone 3-5 deg below guidance on temps, as I don't think the warm front gets as far N as guidance does.  They usually come thru slower than progged.  Highs should be 75-80, with a few low 80s possible along the I 91 corridor.  There is a very slight chance of a t-storm as the warm front approaches, but probabilities are too low to even include in the fcst.

Tomorrow night/Sat: Temps and humidity continue to increase.  There will continue to be a slight chance of a t-storm.  This time, I will include in the fcst.  Warm fronts do tend to produce.  But we have timing against us.  Fropa is slated for the morn.  However, morning warm fronts sometimes surprise, so for that reason I have included slight chances of t-storms.  As for temps, I've gone 5-7 deg cooler than guidance, because I think we'll struggle to clear out.  This may be the last day I do this for quite a while.

Long Term: The key points in the long term are increasing heat and humidity, and gradually, keyword gradually, increasing t-storm chances.

I still went a few deg below guidance on Sunday, because ENS guidance is cooler.  Plus we have time to adjust upward, always rather do that than flip-flop.  But it definitely begins to get genuinely hot! It is not impossible for t-storms to pop up along any local boundaries, but overall coverage and probability is too low to include in the fcst.  High temperatures generally in the mid 80s, except upper 80s along I 91.

For Mon, the chance of t-storms could be a touch higher.  Timing is way up in the air.  So I'll just broadbrush slight chances thru the entire area.  Although coverage will be low, any storms will be capable of being quite strong, given how hot we'll get.  In addition, steering currents are very weak, so flash flooding could be  real concern- but again, overall coverage will be very low.  I have gone close to guidance.  By Mon, we're fully entrenched in the hot air mass.  Highs should be near 90 statewide.   Sea breezes won't do much good to cool the air, since they'll increase humidity.

For Tue, I went close to guidance on temps, maybe just a smidge lower to compensate for potential cloud cover.  Highs once again generally near 90, maybe low 90s along I 91.  Regarding t-storms, I left them out of the fcst for the daytime, but ramped them up to scattered coverage at night.  Usually storms die at night, but they can sustain themselves when we have a very hot day.

For Wed, I followed the same general temp rule as Tue. I think we cool a few notches, because clouds will increase.  I think showers and storms become likely, and we very well could have svr wx this day.  It's hard to even try to talk about that this far out, but right now, Wed looks like the best day for that.  Highs should generally be in the mid to upper 80s, w/plenty of humidity!

Finally, for Thu, I went 3-5 deg below guidance.  Numerous t-storms should limit temp rise, although the air mass is super warm and humid.  So obviously, if there is more sun, it would be warmer than what I have here.  For now, I have highs of 80-85.  

Strong to severe storms could linger for much of the 4th of Jul weekend.  It seems nature wants to provide its own fireworks show this yr! We may even have to watch the tropics, as an anomalously strong tropical wave plows thru the Atlantic.  The same type of pattern that is conducive to HHH wx and t-storm chances here is also conducive to recurving tropical systems up the coast... stay tuned!

No time for graphics today.. See u next week!

-GP!