11:30 AM (Monday) | **Some accumulating snow early Wednesday in the I-95 corridor**
Paul Dorian
Upper-level energy will enhance the post-frontal precipitation early Wednesday all along the I-95 corridor; map courtesy NOAA, tropicaltidbits.com
Overview
A strong cold front is pushing across the Upper Midwest and it is the leading edge of some very cold air for this time of year (Minneapolis, for example, to drop to five degrees below zero later tonight). This frontal system will slow down in its advance to the south and east on Tuesday as it’ll become more aligned with an upper-level wind flow blowing from the southwest to the northeast. At the same time, upper-level energy will be moving to the northeast from the south-central US and it’ll ride up along the slowly advancing frontal boundary zone. As a result, precipitation will become enhanced behind the surface cold frontal system and this will lead to a rain-changing-to-snow scenario along the I-95 corridor from late Tuesday night into Wednesday morning. Accumulations are likely during this rain-to-snow event early Wednesday on the order of a coating to three inches and this should take place in the big cities as well.
“Frontogenesis” will be quite high early Wednesday as the slow-moving front crosses over the I-95 corridor and this should help to enhance precipitation; map courtesy Accu Weather, NOAA
Discussion
It is rather difficult to get accumulating snow around here on the back side of a cold frontal system as you need perfect timing between the advancing cold air and the usually departing frontal precipitation. On Tuesday, a strong cold front will be slowing down as it pushes into the eastern Great Lakes and Ohio Valley and upper-level energy is likely to enhance precipitation on the northwest (cold) side of the slowly advancing frontal system. Ahead of the front, temperatures in the DC-to-Philly-to-NYC corridor should actually well up in the 50’s for highs on Tuesday and there will be some more rainfall, but temperatures will then likely drop later in the day and tomorrow night with the arrival of the cold air mass.
Snow (in blue) is depicted in the I-95 corridor early Wednesday by the latest run of NOAA’s GFS computer forecast model; map courtesy NOAA, tropicatidbits.com
By the wee hours of Wednesday, enough cold air will have likely filtered into the immediate I-95 corridor for a changeover to snow in most areas including in the big cities of DC, Philly and NYC. The precipitation is likely to continue into Wednesday morning and accumulations of up to a few inches are possible – even in these urban areas. As the precipitation lightens up late Wednesday morning or at mid-day, rain may very well mix back in as the upper atmosphere warms up a bit and then the afternoon should feature dry conditions with partial sunshine, but quite cold conditions. Overnight lows on Wednesday night could bottom out in the upper teens in some suburban locations and Thursday will be well below-normal temperatures and likely a fresh snow cover in most areas of the I-95 corridor. Looking ahead, there may be a significant storm to deal with from late Friday into early Saturday which is likely to result in heavy rainfall for the I-95 corridor and then we’ll have to monitor the prospects for another storm by the middle of next week.
Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com
Video discussion: