Mar 18-19, 2013 Storm Updates

Occasional updates will be posted below on the late season rain, snow and ice event currently affecting the region. Yesterday’s forecast discussion for this storm can be found here.

Blog Updates:

12:40 AM: Since the last update, the sleet/rain line gradually moved north, with NYC, then parts of Long Island and northern NJ changing over to sleet and then rain. The end of the precipitation shield is moving much faster than expected as noted earlier, especially with no precipitation over parts of Pennsylvania where the models originally had moderate-heavy rain that would have resulted in steady moderate rain overnight for the area. While the radar is filling in over New Jersey, it’s not doing so to the extent that was originally modeled, and steady precipitation is expected to continue through at least 2-4 AM before becoming lighter, mixing with sleet and freezing rain inland where ice may be a concern for the morning commute. Temperatures will continue to warm on Tuesday afternoon into the low to mid 40s for most of the area with showers ending.

While the timing of the changeover to sleet and rain was generally close to the forecast, a little slower than expected for some locations, the snow that fell was heavier than expected, and while it was expected to be more of a wet snowfall that would struggle to accumulate,  the snow began to accumulate not long after falling and continued to steadily add up unlike typical late March snow events which are typically marginal for snow accumulations, more like a January than a late March snow event. Snow rates of near to locally over 1 inch per hour were observed, which exceeded the forecast. Based on preliminary storm reports from the National Weather Service, snow totals as of 12 AM were anywhere from 1/2 to 5 inches in southern CT, up to 2 inches in Long Island and 3″ in Nassau county, 1-4 inches in NYC, 2-5 inches in the north/west suburbs, and 3-6 inches for NW NJ and SE NY.

9:50 PM: Snow, heavy at times, continues to fall across most of the area, although southern areas near NYC are seeing mixing with sleet and some rain. Totals are already reaching 3-5 inches across parts of northern NJ, with just under 2 inches reported in Central Park. Over the next few hours, the mixing line will continue to shift north, with the immediate NYC area changing to rain and interior areas to freezing rain and rain, with precipitation gradually becoming lighter. Snow totals of 1-4 inches are expected in NYC and western LI, 2-5 inches for the north/west suburbs, and 4-7 inches for the interior parts of the area.

8:30 PM: Over the last hour, heavy snow fell over the immediate NYC area, with snow rates of over 1 inch per hour reported in some locations. With these rates of accumulations, the snow is already exceeding the forecast across most of the area. The latest revised snow forecast is for 1-3 inches in NYC, 2-4 inches for the north/west suburbs, and 3-6 inches for interior parts of the area. The snow is expected to gradually mix with and change over to sleet and rain over the next few hours as temperatures begin to gradually climb, but with less rain than initially expected for the overnight hours.

7:15 PM: Currently, widespread moderate snow is falling from NYC and further west, mixing with sleet near NYC and parts of NE NJ. Meanwhile, steadier precipitation is starting to spread into Long Island and Connecticut. Accumulations reported so far are generally under an inch, with another 2-4 hours of moderate snow expected over northern NJ before precipitation gradually continues to change over to sleet and then rain. A development in the forecast is for an earlier than expected ending; based on latest trends, the steady precipitation may end before the early morning hours, with only showers persisting through Tuesday afternoon.

4:30 PM: Throughout the early-mid afternoon hours, snow began developing over western Pennsylvania, gradually spreading east and NE into the rest of the state. As of 4:30 PM, light snow/sleet has started to spread into western parts of the area. The arrival of precipitation so far is slightly slower than expected, while another trend to note is that western Pennsylvania is not seeing any precipitation currently, while most of the 12z models had heavy precipitation falling there at this time. This trend will continue to be monitored tonight in case the forecast snow and precipitation amounts need to be lowered.

The expectation at this time is for snow to continue to spread in and intensify, with moderate snow west of NYC late this evening. Towards 9 PM, NYC and Long Island are expected to change over to rain, with the rain/snow line gradually moving north, reaching the rest of northern NJ towards 11 PM, while NW NJ, interior SE NY and southern CT away from the coast change over to a mix of snow, sleet and freezing rain, later on changing to plain rain towards 2 AM. Forecast snow totals are for little to no accumulations in NYC and Long Island, up to an inch for the immediate N/W suburbs, 1-3 inches for the interior suburbs and 2-5 inches for interior parts of the area.

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