Sunday morning in Western Pennsylvania starts with dense fog, more rain expected this week
PITTSBURGH (KDKA) - After a very warm Saturday with temperatures exceeding our forecasted expectations, Sunday morning begins slightly cooler but with areas of dense fog. A Dense Fog Advisory is in effect for most counties east and south of Pittsburgh until 10 a.m. where visibilities are anticipated to be under a quarter of a mile in spots.
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Fog will start to clear out by midday thanks to daytime heating and mixing. This will lead to a partly cloudy afternoon with temperatures once again reaching a week above normal levels, especially for late September and the first day of fall. Highs will reach the low to upper 80s areawide. Expect an increase in clouds on Sunday evening and overnight.
Looking ahead into the upcoming week, broad southwesterly flow in the middle to the upper atmosphere will send several disturbances our way beginning Sunday night through Wednesday leading to periodic chances for showers and storms. There will also be above-normal amounts of moisture in the air to support rain, so confidence is high in decent precipitation chances to start the week.
The first initial trough or disturbance aloft in the atmosphere will likely bring a decaying complex of showers and storms our way on Monday morning. Some of our northern counties, especially along I-80 could see partial clearing Monday afternoon while isolated showers and storms continuing from Pittsburgh and points southeast toward the Laurel Highlands and northern West Virginia.
On Tuesday, a stronger disturbance with a more defined area of low pressure will move into Central Ohio by mid to late afternoon. There will likely be several bands of showers and storms ahead of this, which will move into Western Pennsylvania and Northern West Virginia as early as midday to early afternoon. However, more widespread rain and storms are expected by afternoon and evening.
Given the enhanced cloud cover, this should limit our severe weather potential Tuesday evening, but higher amounts of instability and some wind shear will be present across the border in Ohio where some storms could turn severe.
The trough of low pressure will continue to slowly move through the region on Wednesday with a continuation of scattered showers and storms. Through Wednesday night, models and model ensembles are in good agreement of a widespread 1-1.5" of rain across our region, which would be the most we've seen all month!
Toward the end of the week, model guidance begins to diverge leading to more uncertainty in the forecast. Things are trending less cool as of Sunday morning and we may end up with showers possibly returning next weekend as an area of low pressure that gets left behind to our southwest slowly starts to lift back through our area.
