Date: Saturday-Monday, July 22-24 2017
Action Day? No
The heat wave will drag into the weekend before a cold front arriving late on Monday will bring a return to seasonable weather on Tuesday.
Mostly sunny skies through the early afternoon on Saturday will allow temperatures to reach the low 90s F. The combination of a storm system
approaching the state from the west and a warm front lifting from the south will increase cloud cover in the late afternoon on Saturday,
with scattered thunderstorms possible by the early evening. There should be sufficient cloud cover and thunderstorms to limit ozone to the top of the
Moderate range. If thunderstorms do not move through the state as expected, conditions will be favorable for ozone to rise into Code Orange range at
isolated locations. Particles will remain in the Moderate range. Temperatures on Sunday will remain in the low 90s F despite scattered thunderstorms
throughout the day. Breezy and northerly surface winds in the morning will shift to southeasterly by evening. Precipitation is most likely to begin
in the afternoon and carry into the evening. Mostly cloudy skies and rain showers will push ozone and particles lower into the Moderate range for
Sunday. A cold front will arrive on Monday. Showers and thunderstorms ahead of the front should once again limit ozone to the Moderate range,
with particles dropping into the upper Good range.
High pressure building over Pennsylvania will bring mostly sunny skies to the state on Tuesday. A seasonable and much less humid air mass will build in
behind Monday’s frontal passage. These conditions along with northwesterly flow aloft will bring ozone and particles well into the Good range.