From the US National Weather Service
One thing we are monitoring is a “warm nose” or layer of warmer air that could change snow characteristics or even precipitation-type near or south of Pittsburgh. The first image highlights that uncertainty and how the forecast changes if it advances farther northward than expected.
At this time, areas near and south of Morgantown are likely to see warm air create a period of sleet and/or freezing rain during the day Sunday. Even with lower amounts of snow, this mix of snow + ice + sleet can still impact road conditions and result in power outages.
There remain scenarios that this warm layer works farther northward. What does that mean? If this does occur (a lower probability to do so), these areas may see slightly lower but still impactful amounts of heavier/wetter snow that is harder to deal with.
The second graphic highlights how this event may change with time for a place like Pittsburgh: dry, fluffy snow to start becoming wet/heavy during the day Sunday before transitioning to dry/fluffy Monday morning.
This is why simple temperature changes can create more nuance to a forecast that a “storm total snow” may not fully describe. Our office works hard to communicate all these aspects with regional partners so they can best navigate the challenges winter storms create.
