Pittsburgh Weather: The first day of summer brings the heat
PITTSBURGH (KDKA) - Hello, summer.
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Today: Hot! Turning humid. A passing shower is possible this morning for the Laurels mainly. There is an Air Quality Alert in place for today due to poor air quality.
Alert: Potential for a FAWD on Wednesday with storm chances on the rise and high temperatures.
Aware: The heat is the biggest concern right now.
Summer begins today and here comes the heat. You may be taken by surprise by just how hot it is going to get today with highs near 90 all of a sudden. I am fairly confident that Pittsburgh will be shy of 90 degrees today, but there is a chance that we will see one or two places across our forecast area that hits 90 today. My bets are places on somewhere in Beaver county and Morgantown for places that have a solid chance to hit the 90-degree mark. I have Pittsburgh hitting 88 for today's high.
The reason for the rapid warm-up is a powerful ridge of high pressure that is set to develop on top of us today. The ridge will bring compressional heating. A sinking of air that through pressure causes heating. It's the same principle as what occurs when you squeeze some silly putty tightly in your hands. You can then feel the residual heat that compressing the putty causes. We are basically going to be living that today on a much larger scale.
While today is going to be hot, I still have Wednesday as the hottest day of the week even with the afternoon to evening storm chance. I have Pittsburgh hitting 90 degrees on Wednesday. Our 850mb temperatures (what I generally call our core temperatures) go from 17c to 19c in early morning GFS model runs. The EURO goes from 20c to 21c tomorrow. Generally for us to hit 90 degrees I prefer to see 850mb temperatures in the 20c or greater range for Pittsburgh. I generally find the GFS more accurate with 850mb temperatures and the EURO as more of an outlier for my own calculations.
The other big story is something that happens here when we see sinking air and that's poor air quality. When it comes to air quality, there are five levels. Those levels are good, moderate, unhealthy for some, unhealthy, and finally very unhealthy. We are in the 'unhealthy for some' orange level today. Western Pennsylvania has several built-in factors that make our air quality so poor on days like today. While we are not in a bowl, we do have mountains and high hills to our west and south. This does act as a bowl of sorts for us when winds are blowing in from the northwest and blowing to the southeast.
Finally looking ahead, Wednesday will probably be the hottest day of the week. I am forecasting a high in Pittsburgh of 90 degrees. We also have a storm chance for Wednesday beginning at 3 PM. Wednesday will be hotter than today unless rain arrives earlier than expected. The rest of the week will see highs in the mid to upper 80s.
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