The National Weather Service in Pittsburgh has issued a forecast for the coming days that suggests residents enjoy the dry weather while it lasts. According to the Area Forecast Discussion, today will remain dry with above-normal temperatures under the influence of a high-pressure system and rising heights at 500mbs, but change is on the horizon as a low-pressure system is set to bring showers and potential storms starting Friday.
Starting Friday, weather patterns take a turn as an upper-level low from the west heads toward the Great Lakes, challenging the serene status quo with increasing cloud cover and rainfall probabilities—however, the quantifiable details of these showers and potential storms are still up in the air. "The first wave in the morning will use up most of its energy breaking down the ridge axis which will be located over western PA," the National Weather Service Pittsburgh detailed, noting that the anticipated cloud cover may "limit the rainfall" and a following stronger wave due in the afternoon could stir more widespread shower activity despite a "lack of instability and strong shear."
As per the forecast, the wet weather is expected to persist into Saturday owing to the cold front that pushes through, heightening the risk for showers and storms once more. The NWS Pittsburgh analysis mentions increasing sheer to around 30kts on Saturday, offering a potentially more buoyant atmosphere and hence an opportunity for stronger storm development, depending on whether these storms can be initiated.
The long-term outlook for the area doesn't promise a quick respite, as troughing over the Great Lakes could sustain chances for "low probability, diurnally driven convection" through early next week. With model confidence diminishing over time due to the complexities of short-wave dynamics, the National Weather Service offers only low rain chances with a hint of uncertainty lingering that could see dry days dominating northwest flows.
Aviation impacts will be minimal initially, as high pressure ensures VFR conditions and only an increase in mid to high clouds later in the day, though MVFR fog is a potential in some locations near dawn. Approaching the weekend, VFR conditions give way to possible rain showers and thunderstorms, bringing with them a greater likelihood of MVFR or even IFR restrictions due to lowering ceilings and visibility. Coupled with the continuous slow movement of the upper-level trough through Monday, aviation stakeholders should remain alert for periodic disruptions.
