We have been in the second heat wave of the year and it will continue throughout the week and into the weekend. The problem with heat is that possibility of severe weather development.

Thunderstorms are extremely hard to predict, especially location and timing. When there is an approaching holiday, like Independence Day, weather forecasting becomes crucial.

Today:

The atmosphere in our area will become relatively unstable as a large mid-latitude system moves eastward in Canada, bringing us a warm front during the evening hours. 

Associated with this warm front is rain showers and possible embedded thunderstorms for the evening and overnight hours.

Independence Day:

Now the question is: Will rain cause headaches for the outside barbeques and firework shows?

The answer is yes and no.

The only reason is because thunderstorms are so small in comparison to the massive spread of our area. 

For example, a thunderstorm traveling southeastward will effect Reading, PA, over Norristown, PA, and eventually into Philadelphia. Areas like Doylestown, PA or even Lansdale, PA will be untouched.

After the warm front passes tonight, some rain may linger into the early morning hours, then there will be some clearing with high temperatures in the low-to-mid 90s.

That is the good news, but the bad news is that the mid-latitude system will pass just north of Maine, causing its cold front to push southward into our area by Wednesday night.

Cold fronts cause serious instability and depending on the speed and temperature difference, severe weather can be probable.

In conclusion, thunderstorm development is likely, but there is some uncertainty to take into account. By the evening hours, I would say there is a 35 to 45 percent chance to see rain or thunderstorms. 

Some areas may get lucky, where some others may not.

Follow @phillyburbswx on twitter for more updates on this fourth of July's weather. Any questions? Email the writer mld5202@psu.edu if you have any concerns on whether your area will be affected.