The Luck Of Irish Could Mean Snow On St. Patrick's Day
By Steven Strouss
PHILADELPHIA (CBS) -- The Eyewitness Weather Team is monitoring a developing storm that could affect us Sunday night into Monday with another round of wintry weather. This storm is tough to forecast because it comes on the heels of very mild temperatures (forecast near 60 degrees Saturday) and the placement of the Arctic high, which will provide the cold air, is hard to pinpoint at this time. Models are in agreement that a large storm will sweep across the Central US this weekend, tap into Gulf moisture and strengthen along the East Coast. The exact timing, path, and intensity are still uncertain and these are important for forecasting how much and what type precipitation will fall.
Less than two weeks ago (on Monday morning March 3), in a similar situation, the Arctic high pressure won the battle and pushed the heaviest snow bands south of Philadelphia. The city ended up with 3.4" of snow while parts of southern DE and southern NJ measured over half a foot of the white stuff. As mentioned earlier, the key ingredient for snow is the location of the Arctic high. Just because it won earlier this month, doesn't mean it will do so again so we will have to see where it sets up once the players come onto the stage. The placement of the high is important because as we approach mid-March, cold air is necessary to counter the higher sun angle, and the strength of the high will also determine how far north the precipitation shield is able to climb.
Here is what we can say with confidence now.
- A large storm system with lots of moisture (rain and snow) will impact the Central and Eastern US this weekend.
- It gets cold Sunday night with temperatures dipping down below freezing in Philadelphia.
- Models are trending farther north which means more precipitation is likely for the Delaware Valley
- Precipitation – probably in the form of snow begins by midnight Sunday and ends by Monday evening; exact timing will fluctuate as new information comes in.
- The best chance for accumulating snow (as it looks now) is south of Philadelphia from Central DE through Southern NJ
- Monday morning's commute will most likely be impacted by this storm.
- If the trend continues north, the surface low (currently tracking south) could bring enough warm air to change snow over to rain or a mix in our southern zones.
It is not out of the question that the storm misses us completely but that is looking less likely. Although it is too early to provide accumulations, there is enough snow potential here for school delays or closures in parts of the region. We only need 2.6" of snow in Philadelphia to tie us with the #2 Snowiest winter ever (65.5" in 1995-1996) and this storm may just send us over the top.
Although the calendar says Spring is less than a week away (March 20th), this exhausting winter just won't quit. Some models are hinting at additional snow chances before the end of the month.
Stay tuned over the next few days as we will provide new information on this storm. You can also follow the Eyewitness Weather Team on Facebook and Twitter.
Steven
