Feb 7: What to Expect Monday-Wednesday
As I sit here trying to make a final snow accumulations map, I’m realizing that there’s too much variance in what could possibly happen. Therefore, any snow map issued would have a tremendous likelihood of busting. I would rather be honest with you than lead you to believe in any specific solution only to find that it was far from reality.
We know the upper level pattern looks favorable with a strong W. US ridge and a E. US trough. We know that several waves of energy are moving through this pattern between Monday and Wednesday. We basically have two main systems to worry about:
The Coastal Low: This “thing” is rapidly deepening off the coast of South Carolina as we speak. It’s at 1002mb right now and modeled to drop into the 970s (millibars) by this time tomorrow. That’s bombogenesis! The significance of this coastal low is that is could provide a period of light-to-heavy snow for New Jersey as well as coastal flooding. In addition to wind field-related storm surge, we have a new moon today. The variance between a slight miss out to sea and a hard coastal thumping is too wide. Therefore, this has to be now-casted which I plan to do in great detail. The potential coastal flooding forecast has higher confidence because no matter what, we’ve got a very powerful storm out there in the Atlantic. The timing of potential impact from this coastal low is late tonight through tomorrow afternoon.
The Inverted Trough: Once the coastal moves out by tomorrow afternoon-evening, low pressure will transfer from the Great Lakes region and jump to the coast. It will then swing to the NE as set up an inverted trough across the Mid-Atlantic US. At the very least, this should bring at least a widespread prolonged period of light snow between Monday evening and early Wednesday morning. For those who fall victim to the heavier snow bands of the inverted trough, you could easily see significant to double-digit accumulations. As with heavier/convective snowfall, areas just outside of the heavier snow bands could see sinking air which would substantially limit accumulations. The high uncertainty exists in where the inverted trough will set up. It will run horizontally anywhere from Eastern PA through NYC all the way down to DC through the northern Delmarva Peninsula. The latest guidance is targeting the Mason Dixon line through parts of central and southern New Jersey but there is just THAT much uncertainty with this. Like the coastal, this will have to be now-casted which I plan to do in great detail.
In English: We know in general what periods to focus on:
First is the coastal snow possibility: Rain to snow is possible overnight into tomorrow. It could miss out to sea. It could puke snow. ENJ is favored over WNJ for snowfall, especially Ocean and Monmouth Counties. Coastal flooding is possible during this time from storm surge and new moon tides. Everyone from Cape May to Long Island should be aware of this, including the NYC metro area.
Then we have the inverted trough possibility: More snow is possible Monday night into early Wednesday morning. Light snow for most. Heavy snow for some. It all depends on where the inverted trough sets up from west to east.
Any and all other details will have to be now-casted as they unfold. This is the most honest forecast I can possibly make given the difficulty in forecasting such a high variance and volatile setup. Basically hope for the best and prepare for the worst. I’ll start now-casting later this evening as precipitation begins approaching from the S/SE. I thank you for your patience and understanding. Have a great day, enjoy the big game and be safe! JC