Another Big Mess on Friday

Attention turns to the storm on Thursday Night into Friday. An area of low pressure will be sliding across southern portions of West Virginia. Then the storm is expected move across Maryland and Delaware into New Jersey, before sliding offshore. This would bring the heaviest axis of precipitation right over the region. Two to three inches of rain are certainly possible on Friday where it is all rain except at the ending. The snow in North Jersey and South Jersey also has to be taken into consideration. The creeks and streams are already running at or above normal from the recent melting snowfall. All of this suggests possible flooding of at least the smaller creeks and streams on Friday Night into Saturday as the rain water runs off.

Another concern I have is in Northwestern New Jersey, where we could have some potential freezing rain, wet snow, and sleet. With a lot of available liquid, even six hours of freezing rain could quickly result in one-quarter to one-half inch of ice. The snow on the ground in this location could also aid in holding colder air, in addition to the higher terrain benefits. If the 12z GFS is correct, the temperatures may never get above freezing before the ice or wintry mix changes to snow in the final stages of the storm.
But there is more. The 12z NAM and the 12z GFS shows a transition to sleet and wet snow as the storm pulls away (for most of New Jersey) and rapidly intensifies off the Massachusetts coastline, with possible accumulations. The temperatures drop quickly behind the storm, suggesting some potential flash freezing. We have forty-eight hours to see if this storm is actually going to end with several inches of snow or if this is just a false suggestion. The 12z NAM gives us about 0.25” to 0.50” of liquid to work with when the “540 Line” drops through to Cape May County. Without ground temperatures or transitions taken into consideration, this would equate to 3 to 6 inches of snow. The 12z GFS shows this transition happening even faster during the course of the storm, with heavy rain changing to heavy, wet snow in Central New Jersey and then eventually in Southern New Jersey.

There will be a lot to iron out here.

The blue line before the orange line is the “540 Line”.