In the NECN Weather Center, we're quite sure there will be one big weather story this midweek: an intense combination of heat and humidity moving in Wednesday and persisting into Thursday for Central and Southern New England that will produce the hottest "heat index" temperatures, or "feels like" temperatures, so far this season. As highs near 90 in Southern New England on Wednesday, and may cross into the 90s for Central and Southern areas on Thursday, dewpoint temperatures will climb well into the 60s and perhaps even to around 70 degrees, marking an oppressive amount of moisture in the air.
The second story that we're increasingly concerned may take the spotlight in the weather world is the way this heat and humidity breaks late Thursday. In an active weather pattern that's featured numerous strong jet stream disturbances racing across the country and sparking severe thunderstorms and tornadoes in the process - including here in New England - it appears we may come under the gun again Thursday afternoon. An intense and energetic upper level disturbance will race out of the Great Lakes and capitalize on available heat and humidity to create thunderstorms late Thursday. At present, I'm concerned about a few factors, specifically: 1) The storm center is still strengthening as it moves just north of the Canadian border with New England, 2) This creates a fast, strong wind across all of New England, 3) the available heat and humidity will fuel thunderstorm development as a cold front approaches, and 4) a prevailing south wind will become southwest during the day Thursday, leaving a favorable setup for very strong and damaging storms for most of the region.
Having said that, with another day to go, there are some factors that could diminish the severe weather threat: dry air aloft or clouds sliding in before the storms arrive (limiting heating). At this point, however, neither of those mitigating factors look likely. We'll keep you posted on NECN.
Interested in a technical analysis of the severe weather threat for Thursday. A streaming technical video discussion is available on Matt's website, by clicking here.