ACCUWEATHER: Blizzard warning in effect

  

NEW YORK (WABC) -- A Blizzard warning is in effect for the five boroughs of New York City, Long Island and central, southern New Jersey.

The warning is in effect for New York City until Thursday morning.

What the blizzard warning means is there will be winds in excess of 35 to 40 mph.

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As a low pressure system located over Lake Erie continues to weaken early this morning, a secondary wave is beginning to intensify rapidly.

This, of course, is the increasingly powerful COASTAL STORM that we've been talking about the past few days.

And, it'll be the source of some heavy snowfall and increasingly windy conditions here during the next 12-16 hours.

In the heaviest bands of precipitation, developing around daybreak and mostly oriented 50 miles east and west of I-95 between 8 a.m. and 8 p.m. -- snow will fall the rate of 1-2 inches per hour at times between Philadelphia and New York City.

Based on the 00z UTC model guidance, the core of low pressure ALOFT will be sliding eastward along the Mason-Dixon Line before drifting out to sea via South Jersey shortly before midnight.

This type of track (for the upper-level low pressure system) will put areas east of the Appalachians from northern Delaware to southern New England under a pool of exceptionally cold air -- with a fairly deep layer between 2,000 and 4,500 feet averaging between 20 and 28 degrees Fahrenheit.

Recent 700-millibar charts (the pressure level located near 10,000 feet) indicate that vertical motion fields will feature strong ascent through the day into this evening before this, too pivots into southeastern New England and then off shore.

So, 'all of the players have arrived on the field', and now its really a matter of monitoring radars and doing what we call "nowcasting" for the duration of this storm.

As of 2 a.m. -- the lowest central pressure on the coastal storm (not far from Norfolk, Virginia) was 998 millibars, or 29.48 inches of mercury.

By 2 p.m. this afternoon, when its position will be roughly 100 miles east-southeast of Atlantic City, its lowest central pressure is forecasted to be between 976 and 982 millibars (or between 28.82 and 29.00 inches of mercury).

Between 2 p.m. and 8 p.m. there should be more deepening, but it won't happen as abruptly as it will during the previous 6-hours.

Blizzard conditions will occur in parts of the region later today, especially those which located near and east of I-95, when the snow should be quite heavy and the winds will be the strongest.

While very poor visibility is a contributing factor, the reason it won't occur any earlier is that wind velocity criteria won't be met until late this morning or this afternoon.

We'll be watching many of the coastal communities today and tonight for not only snow, but also some sleet and just plain rain.

Much of Ocean, Atlantic and Cape May counties in New Jersey and Delaware will see most of this mixed precipitation, which will cut down on the total snow accumulation.

At Atlantic City's airport (located in Pomona), the precipitation changed over to mostly freezing rain as of 2:30 a.m. -- but for most of Long Island and in southeastern New England, while there could be some sleet, rain IS NOT expected at this time.

However, the "twin forks" region of Suffolk County could be the exception.

Please consult our snowfall accumulation maps for more details for any adjustments.

With the upper-level low moving into South Jersey this afternoon, any sleet or rain probably will be changing back over to heavy snow for a few hours before the storm comes to an end this evening.

Let's talk "end times" now >> the steadiest snow will be tapering off tonight, probably between 8 and 11 p.m. south and west of central New Jersey, but probably between 11 p.m. and 2 a.m. in areas farther north and east, including the New York City Metro Area.

Even though road crews will be working hard to clear streets and highways in time for tomorrow morning's rush, as the powerful storm departs, winds with a northerly component averaging a sustained 15-30 mph with gusts of up to 40 or 45 mph are anticipated.

That will cause extensive blowing and drifting snow, hindering clean-up efforts.

Tomorrow will be windy and cold, with most afternoon temperatures in the 30s (except the 20s in some of typically colder spots).

Some sunshine will be returning tomorrow, and both Friday and Saturday are also going to be dry days.

A wave of low pressure located in the Gulf of Mexico is destined to bring rain to Florida, and WILL NOT MOVE UP THE EAST COAST this weekend.

A broad, northwesterly flow will continue to supply the Northeast and mid-Atlantic states with cold air, and a "clipper-like" disturbance moving into the region on Presidents' Day -- bringing with it a chance for a bit of snow or some flurries.

Have a good day !!!

Here are bullet points for the storm.