Author: Alex G

Don’t look now but Winter may be coming back very soon. The long range models are showing something brewing for the end of this week. Stay tuned for more as the week progresses…

So many of you are probably asking what the heck happened with all the forecasts busting? Well, the answer is mother nature will do what she wants to do. In this case, the low tracked further West than anyone expected. The low was about 25-50 miles further West than was expected, which in the case of today was the difference between a 12-18″ blizzard and a snow/sleet fest. There were some hints of this potential last night on the NAM, but it had little support from other models. The RGEM lent it some credence but not enough to believe that the storm would unfold like it has today.

At this point, we can expect Sleet/Snow and possibly Rain for the rest of the morning. The precipitation should begin to end around 1 or 2PM this afternoon. While the snow-depth will not be what we expected, the sleet that has been falling for hours will make conditions just as if not more treacherous. Also, be careful while shoveling, the depth of the snow/sleet will be deceiving compared to the weight.

This GIF says it all for how I’m feeling right now, and how I bet all weather forecasters are feeling…This is by far the most difficult forecast in a LONG time.

As of this afternoon, we’re experiencing model mayhem…Essentially what is going on is that several models have started to trend subtly West with the upper level low pressures (NAM, RGEM, RPM), while others have held the course (EURO, UKIE, 3K NAM). What this means is that there is significant uncertainty at this time in regards to the total snowfall to expect tomorrow.

Here are my thoughts at the moment, and subject to wild change (This is a very low confidence forecast):

Eastern Suffolk: 0-6 inches
Western Suffolk: 6-12 inches
Nassau: 10-15 inches
Queens: 12-18 inches
Brooklyn and Manhattan: 12-20 inches

For all the above, shave off a few inches or more along the South shore, especially in Suffolk.

In terms of timing, snow will start overnight sometime after midnight. Depending on the model snow COULD end as early as 7-9am or continue through mid-day. The other significant part of this storm will be the wind. All the models are showing wind gusts exceeding 40-50mph. This will create whiteout conditions during the heavy snowfall and have the potential to cause power outages as well.

As I alluded to yesterday, this forecast is becoming VERY tricky. We’re at the point where a 25 mile shift East or West will make a significant difference in snowfall totals. At this time frame the margin of error on models can be 50-75 miles under normal circumstances. The key here is where the Rain/Snow/Sleet line sets up and the models are struggling with this forecast. Some have the warm wedge reaching no further West than the middle of Suffolk county, while other’s have the warm wedge reaching as far West as Brooklyn/Manhattan. It’s possible we may not know how far West the warm wedge reaches until the storm is well underway.

I have very low confidence in the following snowfall forecasts, and will likely have to change them several times today and possibly even adjust while the storm is ongoing:

Manhattan and Brooklyn: 14-20 inches
Queens and Nassau: 12-18 inches
Western Suffolk North of Sunrise: 10-15 inches
Eastern Suffolk: 6-12 inches

Areas South of either the Southern State or Sunrise Highway can expect lower totals. Areas to the North, especially North of the LIE can expect totals on the higher end. This is due to the Rain/Sleet line making it on shore and cutting down on totals.

Timing: Snow should start sometime around or just after Midnight tonight. Some models have the snow starting as late as 1-3am (3K NAM actually starts as late as 5am but this is probably too late). In terms of end time, this also varies widely depending on the model and the track. My best guess is somewhere between 1 and 4pm for the snow to stop.

I’m posting multiple snow total maps so you can get an idea of what we’re looking at. Keep in mind that on ALL the maps, sleet is counted as snow. So in the areas that I highlighted above that could warm, several inches can be taken off the snow totals.

As of this morning, models continue to come into agreement in terms of the track of the Pi Day Storm. We are still a ways off from locking in totals, but it is becoming clear that in general we can expect a 12-18″ snowfall area wide. However, there are a few models showing us going over 18″ and approaching the 20-24″ range. Two keys and wildcards amongst many variables are:

1. The track of the low. How far East or West does it end up tracking?
2. Do the low pressures centers do something called closing off? Some models are beginning to show them close off, which would mean a slower and stronger storm. It’s possible we may not know this until tomorrow or possibly while the storm is under way. This requires close watching.

Overall, temperatures will remain cold through Tuesday. We can expect snow to begin sometime late Monday night or early Tuesday morning. Depending on the factors I mentioned above snow may not end until late Tuesday night. The hope is that by either tonight or tomorrow the models will agree on the track and the closing off of lows. If not, we will be in a true nowcast situation.