Thursday, February 9, 2012

Feb 9, 2012: Light Snow For Saturday


With yesterday's storm clearing the region after producing up to 1/2 inch of snow, locally higher, across parts of the area, today brought mostly sunny skies with high temperatures rising back into the 40s, melting the leftover snow from last night. Temperatures will stay mild through tomorrow, reaching the mid to upper 40s across most of the area, but the biggest development in the forecast is for a light snow event on Saturday which will likely end up as one of the only snowstorms of the winter to produce over 1 inch of snow for the area.


Friday Night - Weekend: Light Snow, Then Cold


Yesterday's update mentioned how a storm will affect the area on Saturday with light snow, but since the last update, this afternoon's models trended further west and stronger, with the NAM and SREF showing the potential for nearly 5 inches of snow in NYC and more significant amounts northeast of NYC. The models backed away further southeast this evening, however, with the 18z GFS again showing a light snow event, although the NAM still showed at least 3-5 inches of snow north and northeast of NYC. The latest 0z GFS run complicated the situation even more, suddenly trending towards a solution close to what the NAM had earlier today with a stronger and snowier storm.


The models are still having issues with handling the storm even though it's less than 2 days away, which is resulting in lower than average confidence in the forecast. Although huge changes will not take place with the storm, minor changes are still causing uncertainty with the forecast, especially regarding where the main low pressure develops. To the left, I posted an image from the 00z NAM from the NCEP model website (direct link to 0z NAM), showing two low pressures; one is due east of the North Carolina and Virginia border, and the second low pressure is southeast of the first one, directly over the heavy precipitation marked with blue and purple colors. The question is which low pressure becomes the dominant one; the latest GFS run and the NAM runs which showed a bigger snowstorm focused on developing the western low pressure, which then moved up the coast to bring moderate snow accumulations to the I-95 corridor. The CMC and UKMET, along with the 0z NAM which is posted above, develop the further east low pressure, resulting in light rain/snow for the area with at least 1 to 4 inches of snow north and northeast of NYC, but the main storm stays offshore, preventing the entire region from seeing moderate to heavy snow accumulations.

Although there are still about 36 hours left until the strongest part of the storm affects the area, slight changes are still expected with the models. There are two main possibilities for the storm at this time; one is where light snow affect places north, NE and west of NYC, with light rain/snow in NYC and Long Island, with accumulations between 1 and 3 inches, locally higher in southern CT. The second scenario is where a stronger storm develops, bringing at least 2 to 5 inches of snow in the immediate NYC area with 3 to 6 inches towards southern Connecticut and northeast of there. For now, I am going in between, leaning a bit towards the less snowy solution due to lower than average confidence, but the potential is there for a snowier outcome than currently expected.

Despite the uncertainty with the overall set up, snow will still fall across the area. Light snow is expected to develop after at least 12 AM with the storm ending around noon Saturday. The intensity of the precipitation is the main uncertainty, and should the storm end up weaker, more rain would fall in Long Island and NYC, with lower snow accumulations and warmer temperatures, reaching the upper 30s to lower 40s, while a stronger storm would bring more snow than rain to these areas while keeping temperatures lower. The storm will end by the early afternoon hours, with isolated snow showers lasting overnight along with windy conditions developing, with gusts up to 40 mph possible resulting in wind chills dropping into the single digits by Sunday morning for parts of, if not most of the area. Stay tuned for more information on the storm, the weekend cold and any updates that may change the forecast.


Next Week Overview: Temperatures will stay chilly through Monday and Tuesday, although the latest models are signaling that another light snow event may be possible around Tuesday night into Wednesday. Should this potential verify, it will not be a big storm but rather a light snow event similar to yesterday's storm.

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