All indications continue to point to some wild weather along the I-95 corridor (DC-to-Philly-to-NYC) from late this afternoon through tonight as a powerful cold front with a wall of water heads towards the east coast. The threat for localized flooding and damaging wind gusts continues with the latest computer forecast model information.
Heavy rainfall between late this afternoon and early Thursday will produce a widespread 1-2 inches along the I-95 corridor and there will be local amounts of up to 3 inches. The likelihood for localized flooding (e.g. streams, streets) is increased because of the recent frigid spell experienced in the Mid-Atlantic region. The ground has thawed out in the top few inches due to the recent milder temperatures, but not too far below the surface, it is still quite frozen and this will force quite a bit of runoff in the overnight hours as the heavy rain falls in a short period of time. Furthermore, there is some snowmelt occurring upstream of the I-95 corridor that will likely contribute to rising water levels around here.
As far as winds are concerned, there has already been a report today of gusts to 67 mph in Westmoreland City, PA as a squall line passed through western PA. All computer models continue to feature a vigorous short wave at 500 mb that takes on a slight negative tilt (orientation from NW to SE) in the overnight hours as it crosses the Great Lakes and Ohio Valley and a widespread strong jet streak of 130+ knots at 250 mb approaching the southern Mid-Atlantic. Furthermore, there is a rapidly intensifying surface low pressure over the Great Lakes and a strong low level jet that has actually been increasing in strength on the latest computer models as the event draws near. All of this suggests that there is a good chance for damaging wind gusts in the period from late today through tonight with possible downed limbs and power outages.
Bottom line, prepare for a wild time in the Mid-Atlantic region with localized flooding and strong-to-damaging wind gusts. The action begins in the northern and western suburbs of DC and Philly during the late afternoon hours, and early this evening across NYC - it continues everywhere through much of the night. Cold air pours in on Thursday behind the frontal system after it clears the east coast.