Don’t look now, but the HRRR/GFS/RGEM just came in and they all have increased the precipitation that we can expect in the region. At this point in time, 8 inches of snow is looking more possible. Therefore, I am now increasing the forecast for Nassau to 4-8 with an outside chance of may even 10 though I doubt it at this time, and NYC to 3-6.
As of this morning Nassau and Suffolk are under a Winter Storm Warning, NYC is under a Winter Weather Advisory. Models overnight were fairly consistent in regards to the expected precipitation amounts, and therefore my snowfall forecast from last night remains as is. That being 2-4 for NYC, 3-6 for Nassau and Western Suffolk, and 4-8 for Eastern Suffolk. As I mentioned last night due to ratios and minor track differences it is possible some areas may exceed the expected totals.
Snow should begin soon or has begun throughout the area. The snow will become heavy as the morning goes on and taper off by early this evening.
Tonights model runs continue the theme of a moderate snowfall for the region tomorrow. The snow will overspread the region between 8 and 10 am tomorrow. It will continue throughout the day, heavy at times. Snow should begin to taper off sometime between 5 and 7PM tomorrow evening. Most models have come into agreement that snowfall will be somewhere in the 3-6″ range. However, I caution that we could see up to 8″ depending on ratios. (Usually we calculate 10:1, 10 inches for every inch of liquid, but when it becomes extra cold in the atmosphere this can go up to 15:1 or 20:1).
The further East on Long Island you are, the more snow you will see. The East End may every well see a foot of snow by the time the storm pulls away. For NYC you can expect about 2-4″, but the ratio comment above applies to NYC as well.
Here’s a current summary of liquid amounts that models are showing in NYC (Remember multiple these by 10/12/15/20 to get actual snowfall amounts). These liquid amounts increase as you go further East:
SREF: 0.45
NAM (regular): 0.35- 0.45
NAM (Hi-Res): 0.4-0.5
GFS: 0.10 – 0.15
RGEM: 0.40 – 0.45
GGEM: 0.30 – 0.35
The most recent model runs continue to trend towards more snow. The RGEM which is considered decent in the short range placed our region solidly in the 3-6/4-8 range. This aligns fairly well with the HiRes NAM model. The GFS continues to show less than both these models but has also trended towards a more significant storm.
Overall, we can expect snow to start mid morning and continue throughout the day. I will provide a late night update tonight and early morning update tomorrow. This is truly a nowcast type storm.
Total snowfall expectations:
This update will be short since more models are still coming out. A more detailed post will come a bit later.
Models continue to disagree on exact snow totals for tomorrow, and therefore it is very difficult to issue a definitive forecast (Yes I know I sound like a typical weather hack). While the no-snow models are gone, there is still a question of the actual totals. For now, the general expectation is for 2-5/3-6 area wide. If you live out in Suffolk you can expect more than Western Nassau and NYC. This storm will feature a tight gradient with significantly more snow the further East on Long Island you go.
There are two storms that we are tracking over the next few days. The first is for Friday morning: Snow will overspread the region overnight tonight and end by Friday morning between 9 and 11am. Total snowfall for the Friday storm will be 1-3 inches throughout the area. While not a significant event, it will be enough to cause headaches during the morning commute.
The more significant potential storm for our area comes mid-day on Saturday. As of now some models have it skirting just offshore, but the NAM has it impacting our region. The models that have it offshore continue to trend closer to the coast. At this time, I am leaning towards a minor event, but the NAM did get one of our surprise storms last winter correct. If the NAM is correct, we could see over 6″ of snow by the end of the storm.
The big wild card with this storm is the strength of an area of energy dropping in from the North Pole. As of now there is limited data on this energy since it is in a data sparse region. If the energy comes in stronger than modeled, the storm will track closer to the coast and be stronger than modeled. By this time tomorrow the energy will be much better sampled and we’ll have a good idea of what to expect during the day Saturday.
As of now here is a model roundup for Saturday:
NAM: 6″ Plus
GFS: Just off the coast
RGEM: Skirting the area with a few inches
EURO: Comes close to the area and a few possible inches
