Saturday, February 11, 2012

Forecast for Sunday, February 12, 2012

Snow squalls and snow showers this evening will create hazardous travel across most portions of the region this evening and into late tonight. These snow showers and snow squalls will be associated with an arctic cold front moving through. A half inch to two inches of snow may accumulate in a number of locations from Philly on west and south, while a coating of snow is possible north and east of the city.

The inverted trough that we note for this evening could pose a slight problem for this forecast of snowfall. In the past, they have been able to locally enhance a band of snowfall and produce amounts of four to six inches in a very narrow corridor. A few years ago, this happened from Philadelphia International Airport down through the Atlantic City Expressway corridor. Computer models handle such scenarios very poorly, even hours from the actual occurrence of the event. It seems as though some of our modeling throughout the day has suggested some sort of snow burst moving through this same area, although it isn’t indicating that much snow. Still, the concept of a localized spot receiving in excess of three inches of snow cannot be completely ruled out, especially with the convective look of some of the soundings and the arrival of colder air during darkness.

Nevertheless, the wind will pick up with the front and snow bursts. This will likely reduce visibility to below a mile for a time. If the snow rates are on the heavy side, brief visibility reductions of ¼ of a mile are possible. Wind gusts of 40 to 50 MPH are possible behind the front, particularly with any snow showers and squalls. The strongest winds will be around Midnight. Any wet spots will turn to black ice overnight.

Sunday is blustery with intervals of clouds and sunshine. A secondary front should come through on Sunday Evening and Sunday Night with the possibility of snow flurries and snow showers, especially north. This may also provide a second round of wind gusts of around 45 MPH.

A weak disturbance may impact the area Tuesday into Wednesday. Very little moisture is associated with this system, although models may increase the precipitation amounts closer to the event. It may have some lingering cold air to work with to bring a light mix of rain and snow across the area. There could even be some freezing drizzle in our northern counties. Thursday Night into Friday may be an active period of weather as well, although this could be more of a liquid event with the moderating temperatures. One concern I have is that the models trend colder for these late week events.