All eyes turn towards this weekend’s Nor’easter which will bring us the most snow we’ve seen since last winter. Confidence is growing that NYC and points south could receive over a foot of snow by Sunday. In addition, forecasters anticipate that this storm will bring sustained winds of 30mph to coastal areas with gusts as high as 40-60mph leading to whiteout blizzard conditions. However, it is important to not, even at this point, 48 hours from the start of this event, that a good deal of uncertainty remains about these forecast snow totals.

Rest of today – mostly clear with high temperatures reaching into the mid-30s but a northwest wind in the 15mph range making it feel colder.

Friday – slightly cooler with highs in the low-mid 30s, clouds I increasing through the day as the headline storm for the weekend approaches.

Saturday – snow should begin falling from southwest to northeast overnight Friday and continue throughout the day Saturday. Sustained northeast winds 25mph-30mph could lead to drifting and blowing snow, making for hazardous teavel conditions. Some potential exists that enough warmer air wraps into the storm off the Atlantic that some areas see a changeover to a rain/sleet/snow mix in the afternoon before transitioning back to all snow Saturday night. Total daytime accumulations are currently forecast between 3-7″. Overnight accumulations could be in the 4-8″ range.

Sunday – some lingering snow showers are possible Sunday morning but conditions should improve rapidly as cloud cover decreases with the storm exiting to our east. High temperatures are expected to be in the mid-30s.

Monday – warmer with high temperatures in the mid-30s and sunny skies.

Complicating Factors for Forecasting the Nor’easter

• Model divergence – European models favor a solution that has the storm moving quicker and further south than US based models. This scenario would result in minimal snow for NYC, hence why the minimum snow forecast is only 2″.
• Unpredictable snow bands – as we are all too aware from last year’s fiasco of subway shutdowns in anticipation for a blizzard that didn’t materialize, when it comes to Nor’easter type storms, where, when, and for how long deformation banding features (heavy bands of snow) set up will make or break a snowfall total forecast in either direction. However, these types of mesoscale banding features are not easy to predict with confidence before they actually start forming. Should parts of our region fall under one of these banding features where snow could be falling at rates of 1″+ per hour, you could easily see total snowfall forecasts be shattered.
• Intrusion of warm air – if enough warm air works its way into this storm off the warm waters of the Atlantic (where above normal temperatures thus far this winter have kept the sea surface temperatures abnormally warm), then some areas could see a rain/sleet mix for periods of time. Forecasters are overall confident the window for this mixing is small enough that overall totals won’t be dented too much, though.