Monday Afternoon Technical Discussion

Synopsis:

A few showers (mostly of the "rain" variety) will cross the state overnight, most of them remaining west of I-99. Skies will clear out on Tuesday, setting up a rather pleasant week, weather wise, with the exception of a system that may or may not drop some rain on the state on Friday.

Short-Term:

Some scattered showers are likely to pass through the area as we go through the overnight hours. The current satellite imagery shows rather thick cloud cover across the state, while radar images show a few showers already working across the western half of PA. These showers are likely to only remain in that part of the state, as the moisture will likely diminish as the piece of energy moves farther east overnight. Thus, the greatest chance for showers (likely rain showers in most locations, though a few of the higher ridges could drop off enough to see a few snow flurries) will be west of I-99.

Conditions should improve by Tuesday morning, with the state primarily under the influence of high pressure off to the east. Clouds will be on the decrease as we go throughout the day.

Long-Term:

The pleasant weather conditions will continue on Wednesday, as high pressure continues to hang around the Northeast. Most models are in agreement that skies will be clear through Thursday morning at the earliest. These clear skies should also allow temperatures to moderate to near-normal or slightly above-normal ranges. Disagreement between the WRF and some of the longer-range models, specifically the GFS and ECMWF, begins on Thursday and last into the weekend (or at least the end of the WRF's forecast period) over a vort. max setting up off to the west beginning on Thursday. The GFS and European models both show the vort. max diving to the south and keeping Pennsylvania dry on Friday, but do bring a few clouds in along a diagonal line on Thursday. The WRF, on the other hand, keeps Pennsylvania more clear on Thursday, but does look likely to drop rainfall across the state on Friday. Analysis of future runs will be necessary to make a more confident decision, but at this point, we sided with the longer-term models. The weekend appears to be shaping up nicely, with mostly clear skies as we avoid a trough which will cross New England early Saturday.

-Devin Boyer