Today was day two of what will be an extended heat wave in Connecticut. Inland areas saw temperatures in the mid to upper 90s and even the shoreline saw highs in the low to mid 90s with heat indices touching 100 at times. Bradley Airport (BDL) had a high of 97. Hartford (HFD) had a high of 97. Bridgeport (BDR) had a high of 94.
The active weather week continues tomorrow with even higher heat indices and a threat of severe thunderstorms during the afternoon.
I alluded to it on Sunday, but now I have enough confidence to declare tomorrow a SCW Period of Interest.
First, the heat. A heat advisory will be in effect for all of CT through the day. Tomorrow will almost certainly be the third consecutive day of 90+ in inland CT, making our first heat wave of the year official. It'll actually be a few degrees cooler with additional cloud cover, but the tradeoff will be higher humidity. Dew points should be in the upper 60s to low 70s, with most having dew points in the 70s. It'll be hot and oppressively humid, and heat indices will be over 100 for many tomorrow. Use heat safe practices tomorrow regardless of whether you are outside or inside.
Second, the storms. The Storm Prediction Center (SPC) has kept most of CT in a slight risk for tomorrow. Beginning late morning we should see activity pop up in the region as a front moves through during the day. There will be instability, ample moisture, and sufficient shear. The hangup may be lapse rates and the relative lack of height falls per the NWS, but the ingredients are there otherwise, and the high resolution guidance has activity in CT tomorrow afternoon.
I still think the greatest severe weather threat is to our north, but we can't rule out strong to severe thunderstorms tomorrow afternoon centered between about 3-8pm. Wind would be the greatest threat, but an isolated tornado and hail are possible too. We'll be watching, and we encourage you to keep an eye to the sky and radar.
In the wake of the front, it'll still be hot, but the humidity should come down briefly as we get northwest flow advecting in drier air. That said, highs are expected to be in the low to mid 90s on Friday and back to the mid to upper 90s on Saturday. There may be some thunderstorms on Friday afternoon, but we're not expecting any widespread severe weather threat at this time. Saturday should be clear.
Originally, it looked like the peak of the heat would be centered Wednesday and Thursday, but the guidance has continued to extend and increase the big heat (95+) signal for the weekend as the ridging that is baking much of the US expands and and Atlantic ridge allows for favorable advection of heat and humidity. As a result, the hottest day of the entire period looks like Sunday now. Expect more heat advisories if not an excessive heat watch/warning.
Ensemble guidance has inland temperatures in the upper 90s on Sunday, and operational guidance has been flirting with 100 degree temperatures inland. I'm a little skeptical of 100 being possible with dew points in the upper 60s to low 70s. That would produce a rare extreme heat day. Usually, the higher the air temperature the lower the dew point. It is difficult to achieve 100 degrees in this region, and like inefficient mixing of humidity, cloud cover, cooler morning temperatures, and wind direction could keep highs 98-99 rather than 100-101 again. We'll keep watching the trend for Sunday. It's going to be hot no matter what.
Another front is expected to be in the area Sunday, with big heat, moisture, and shear present again, a severe weather threat is possible. It's far out and we don't know the timing of the front yet, which will be critical. It is something to watch, however. This is another potential period of interest, but let's wait a little longer before declaring it.
The heat wave is likely to break after this front, with temperatures next week looking seasonably warm.
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