Saturday morning technical forecast

Synopsis:

 

Much cooler conditions across the Commonwealth today after the cold front passage yesterday afternoon. The sunshine will stick around today and tomorrow, so we should have a pretty nice weekend on tap. Clouds begin to move into Western PA by tomorrow afternoon, and showers move in tomorrow night. All areas of Pennsylvania will see rain showers by Monday morning. These showers should dissipate by Monday afternoon, and we can expect milder temperatures on Monday as a warm sector of air moves through. However, by Tuesday, it will be cooler again for most areas, but it will be dry. Expect showers to move in again Wednesday ahead of a cold front, which will sweep through on Thursday. Cold air is expected to move in behind the front, and temperatures will stay cold through the end of the week.

 

Short-term:

 

After yesterday's very balmy spring-like weather, we will see more seasonable temperatures this weekend. A cold front moved through yesterday with very little moisture along it - the reason why only a few areas of Pennsylvania saw any shower activity. Sunshine will prevail today and tomorrow, as an area of high pressure sets up over the Northeast for the weekend. This high pressure will be moving north and east, away from PA, by Sunday evening, allowing clouds and rain to move in late Sunday into Monday. The 540-mb. line will also come back up by the afternoon on Sunday, setting the stage for milder air. There is slight disagreement over when the showers will begin moving into PA, with the most recent models suggesting the rain will move in sooner (around 03Z on Monday for the 12Z WRF, and around 00Z on Monday for the 6Z GFS) rather than later (around 06Z on Monday for the other WRF runs, and around 03Z on Monday for the other GFS runs). Precipitation amounts from this first round of rain will be heaviest in the northwest part of PA, and in the mountains, with those areas possibly getting 0.5" to about 1" (according to the 00Z and 06Z GFS runs), or 1" to 1.5" (according to the 06Z and 12Z WRF runs). Other areas will see 0.5" or less, generally. So, it will not be a flood event or anything, but it will be something to be aware of. Once the showers move out Monday evening, expect a dry slot to move over PA for Tuesday, before the next weather maker comes on Wednesday.

 

Long-term:

 

Another storm system is expected to move in for Wednesday, spreading rain across the Commonwealth by Wednesday morning. There will be a warm sector of air with this storm as well, but it will likely stay to the south this time. The cold front will move through sometime Wednesday night, with the shot of cold air from Ontario coming for Thursday. There is a chance of a mix of rain and snow showers with the leftover moisture Wednesday night. A couple of rain or snow showers could linger through the day on Thursday, but then clear out for Friday. Sunshine and cold temperatures (highs only in the 30's and 40's) will dominate for Friday and into the first half of next weekend. The main thing to watch for long-term is how much of the moisture will turn to snow with Wednesday night's FROPA, and how cold it will get for Friday and Saturday.