Synopsis
The premise for this week's weather in PA will be the progression of a slowly moving upper level low that will churn up some storms along a front that will be moving throughout tonight and daytime tomorrow. This system will have the potential to produce thunderstorms within the ridges and valleys, but over the course of the next 24 hours, this front will govern the state's weather, and then the vortmax will takeover until high pressure nestled inside a ridge aloft will round out the weekend.
Short Term (This Afternoon through Saturday)
A front currently draped across Ohio, Michigan, and Kentucky will progress into the state later today, but the showers ahead of the front will startup in Pittsburgh around 3pm (19z) this afternoon. These showers will trudge across the state, turning into storms producing heavy rainfall by 8pm (0z). As long as the strip of positive vorticity that is feeding this front holds true, Central PA will see heavy rain throughout the early parts of tonight, eventually dissipating as the vort max shifts north within the next 3 hours. Both the 12z NAM and GFS agree on this, and topography will definitely force the lift necessary for these storms to intensify. As this progress and reaches the lee side of the most eastern ridge, the system flattens out into more moderate persistent rain throughout the eastern half of PA, leaving its final drops up by Scranton around 21z Friday. Behind this lies and area of modest cold advection, but the upper level flow will remain zonal, and the clouds and present moisture will prevent any drastic drops in temperature overnight Friday . Lingering clouds in the west will remain in place as the trough begins to take control of weather in the west, with clouds being churned up and showers being resolved by both the 12z NAM and GFS, but within the south and east portions of the state, a surface ridge will start to help dry the lower troposphere and keep the vortmax energy from affecting the east. The vortmax will sweep across the stzte Saturday afternoon, but only clouds will make it though with a limited potential for a spotty shower east of the Appalachians.
Long Term (Sunday and beyond)
Once this trough passes through, the surface ridge will start to squeeze through the mountains. Its center will nestle itself over southern WV, western VA, and eastern KY and TN, and by Monday, a ridge aloft will move into the state, holding strong for Monday, at least until Wednesday. The upper level low will stick around for Sunday, but leaving little influence on the state as clouds remain scattered throughout the underlying areas, and by Monday it will be completely out of our area.
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