Weather blog
W/Trey blog
Key Points:
-Isolated shower chance through sunset mainly west of I-79 and NW PA.
-Mid to upper atmosphere smoke lingers through Tuesday leading to hazy skies.
-Isolated to scattered storms with wind possible Monday afternoon and early evening.
-Best chance of rain and storms late Monday night through midday Tuesday with passing system.
-Overall severe risk low, but gusty winds are possible.
-Seasonable mid week before late week warming trend.
Forecast Discussion:
A smoky haze plus some low and mid-altitude clouds have played a role in keeping temperatures muted by a couple of degrees across Western PA this afternoon. This has also led to slower than anticipated isolated shower and thunderstorm development, but we're now seeing signs of some pop up activity downwind a lake-breeze across Northeast OH and along the OH/WV border. These isolated showers will continue through sunset with most of the activity diminishing by sunset.
While an isolated shower cannot be ruled out overnight, skies in general will be partly cloudy with temperatures falling into the mid 60s. For Monday, west/southwest winds will slowly advect warm moist air into the region, but more wildfire smoke and haze aloft will play a role in keeping temperatures from getting as hot as they otherwise would with the low level warm air advection. We still anticipate low to mid 80s areawide. A disturbance accompanied by the subtle warm/moist air advection will trigger some isolated to scattered storms around 2pm—first along the I-80 corridor to Lake Erie in Northeast OH and Northwest PA. These cells will gradually build southeast with some storms possible even as far south as the Pittsburgh metro and I-70 corridor through sunset. The setup will be favorable for downburst winds with gusts reaching as high 60mph in the strongest cells. I do not anticipate a tornado threat tomorrow because of a lack of low level wind shear. Low level wind shear will improve Monday night into Tuesday morning ahead of an approaching surface low and stronger push of mid/upper level winds. However, a temperature inversion settling in after sunset will prevent much in the way of surface based storm development. Still, scattered storms are anticipated Monday night into Tuesday morning across most of our forecast area. Gusty winds, torrential rain and frequent lightning may accompany some of the strongest cells.
The cold front will pass through between 10am-4pm Tuesday across our area resulting in a shift in wind shift to the northwest (some winds will be gusty) along with additional showers and storms. The highest coverage of rain and storms for Tuesday will generally be from the Pittsburgh area and especially east into the Laurels and south into Northern WV. Storms may gradually intensify upon moving southeast into more unstable air through the day, so a severe risk may materialize south of I-70 and especially south of I-68 through the afternoon on Tuesday.
Lingering showers are expected Tuesday night into the Wednesday as the surface low occludes to our east. These will not be terribly widespread, but the cloud cover and northerly flow will keep temperatures below normal, especially on Wednesday with highs generally in the mid 70s for most. A slow, but steady climb in temperatures is expected for the end of the week with highs returning to seasonal norms by the weekend. Our next system is poised to arrive Saturday into Sunday with at least a chance of isolated storms by that point.
