1/25/2011 Extended Forecast: Snow Map Forecast

A major winter storm is about to impact New Jersey on Wednesday. A winter storm watch remains in effect for the entire state with the exception of Coastal Atlantic and Cape May County.

At this point, it looks like initially we will have enough mild air in place for sleet to begin this storm in many places in the interior of Central and Southern New Jersey. This sleet may mix with rain at times, especially the closer one lives to the coastline. A changeover to rain is possible in Southeastern New Jersey. In Central and Western New Jersey, the question continues to be raised about the potential of freezing rain if in fact the rain mixes with sleet. Overall, there is a possibility of a coating of ice in some areas and this is going to be difficult to pinpoint down. The liquid amounts we have to work with the initial part of the storm from dawn to dusk looks to be around or below 0.25”. I could even see a lull in the precipitation happening or just some drizzle during this period. This may lead to the perception that this storm is a bust. This leaves me with the concerns that many will not postpone their travel plans in the evening.

The interesting period begins during the evening rush hour as the coastal storm intensifies rapidly as a piece of energy approaches from Maryland. The intensification will wrap around colder air into the storm changing any mixture or rain over to snow. This transition will happen very suddenly from west to east. The “540 Line” pushes well off the coast by the early evening hours. This is also when we have potentially more than 0.75” of liquid to work with in some areas. This means a good thumping of accumulation snow can be expected across the entire state with the least amounts around the Cape May area where the warmer air holds the longest. Any areas that see rain during the day will likely experience a rapid drop in temperature once the snowfall begins. This would likely be a flash freeze in these areas.

There is going to be some banding with this system. The North American Model is very good at picking up such convective features. On the future radar above from the 18z run, you can clearly see a band developing right over New Jersey during the height of the storm. This band will contain snowfall rates of two to four inches per hour. This band will occur, but on the modeling it will likely shift run to run. There could be some rare thunderstorms with snow in the band as well.

As the low rapidly deepens, the winds will become stronger across the area. This may coincide with the heavy snow raising the possibility of at least near-blizzard conditions. The winds would be strongest along the coastline. Wind gusts of at least 40 MPH could transpire across the region, particularly coastal regions.

Any sleet or icing during the day or a flash freeze of water on trees will coat the trees with ice. This will already give some extra weight. The snow is expected to be a wet snow the further and further away you are from the Delaware River. This suggests the potential for some downed trees and wires and power outages. If there is icing on the trees, it is like applying glue to poster board and then sprinkling glitter on it. Even a three to six inch snowstorm, if it is wet snow, can bring wires and trees down.

Snowfall totals across the region are on the accumulating snowfall map. I will tell you that for the moment I am putting a cap on the amounts. There are some models still showing the potential for 12 to 16 inches of snow for portions of the region. I am using a lower snow ratio because of the possibility of snowflakes with more moisture content and the air temperature could take an hour to get primed for accumulation…dependent on that flash freeze. Be prepared for an additional increase in snowfall should models continue to indicate more than 1.00” of available liquid.