Excellent weather conditions for February are in place with temperatures rising through the mid to upper 40′s over the northern interior and much of Connecticut and lower to mid 50′s elsewhere! Indeed, this afternoon features the type of weather where you don’t need a coat or gloves!
A cold front is on the way though as you can see with the observations. Periods of showers are approaching from central Pennsylvania with temperatures falling through the 40′s, 30′s, and upper 20′s from central Pennsylvania through Ohio. As the cold front moves through tonight, most locations can expected showers at times although they will be widely scattered and light. As the cold air filters in tonight, the rain showers will mix and then change over to snow showers. However, accumulations will be limited due to a warm boundary layer with accumulations of a trace to as much as 2 inches.
So the cold air will be building into the Philadelphia and New York City metropolitan areas without much of a problem. The question is of course a major winter storm is on the way or just a few scattered snow showers and windy conditions?
All of our answers can be found with the water vapor satellite image here. As I was telling Premium Members this morning, the key to the forecast is that trough just off the West coast. THIS trough is why the storm is likely to stay east and the phase is going to happen too later in the forecast period.
The trough approaching the West coast is expected, and is on track, to push into the West coast tonight. As a result, the trough forces the ridge over the Rockies to the east which in turns pushes the trough axis over the eastern United States too far east. As a result, the storm track of the developing coastal low pressure system is, you guested it, too far east.
In order to change the forecast for this weekend, that trough over the West coast has to significantly slow down to keep the trough axis far enough west to allow for the phase of the Sub Tropical and Polar disturbances to interact and phase with the Arctic disturbance, thus leading to a powerful winter storm for the region. At this time, I have no indication of that happening at all.
What I do expect is a cold weekend for the northern Mid Atlantic with the threat for more scattered showers showers capable of producing one to three inches of accumulation from Saturday afternoon through Sunday. With temperatures colder, accumulation of snow will not be a problem and the snow ratios will likely be around 15:1 to maybe even 20:1. Temperatures will be in the mid to upper 30′s for highs on Saturday, mid 10′s to lower 20′s on Sunday morning, and upper 20′s to lower 30′s on Sunday afternoon.
I will of course keep an eye on the developments of this weather pattern and if that trough over the West coast ends up slower per 00Z observations (7 PM), I will of course send updates out. However, I don’t expect to.