PITTSBURGH (KDKA) – Sunday morning will start with clear and cool air across the region, but several changes are expected from late morning into early afternoon.

Warmer and slightly more humid air will move northeast from the Ohio Valley ahead of a strong cold front that will lead to a quick but severe round of thunderstorms later Sunday evening.

Highs will likely reach in the upper 70s to lower 80s before a stronger storm system and associated cold front develops.

The air becomes humid as the day progresses, although there is some variation in the amount of moisture that penetrates. Areas west and north of Pittsburgh are likely to see the highest amounts of moisture, with dew points near 60 degrees, and this is where the highest amount of instability or storm fuel will be present.

The Storm Prediction Center currently has most of the Pittsburgh area southeast of Pittsburgh classified as Level 2 “Low Risk” and Level 1 “Low Risk.” Strong wind gusts and hail (quarter to half dollar size) would be the primary risks with any cell rotating.

There is a very low risk of tornadoes, particularly near I-80 in northwestern Pennsylvania and northeastern Ohio, where slightly higher, low-level shear will occur. However, limited amounts of moisture are expected to keep cloud bases fairly high, which should counteract this threat.

Storms would likely develop across Ohio in the early to mid afternoon around 3 to 4 p.m. and then move into western Pennsylvania around 5 to 6 p.m. Showers and storms will impact the greater Pittsburgh area between 7 and 9 p.m., so if you're traveling keep an eye on the radar during the Steelers game and bring rain gear as there will likely be a few storms at game time.

The intensity of the storms will decrease as the storms move into and east of Pittsburgh as the air becomes drier and less unstable. As the front advances, any showers and persistent storms will move out of the region between 10pm and after midnight, resulting in breezy north-westerly winds and cooler air moving in from the north-west.

Monday will see partly to mostly cloudy skies with high temperatures in the lower to mid 60s. A few lake effect showers may affect our northernmost counties, primarily along and north of I-80.

A more persistent cool weather pattern will settle into the Pittsburgh region this week as a low pressure area forms directly to the northeast. This will bring west to northwest winds for several days with highs in the low to mid 60s and lows in the 40s, giving a true taste of fall.

As high pressure winds ease next Thursday and Friday, patchy frost is expected in the early morning hours of both days, particularly in the Laurel Highlands and Ridge areas.