The week ahead: It’s almost April, and we’re still talking about snow

Another snow discussion? It’s almost April! If you’re a snow fan, don’t get your hopes up too much.

March 23, 2013; 12:02 AM • by Weather Dan

Believe me, I’m just as fed up as you are.

Keep this stat in mind as you read the forecast: the average high temperature for March 22 – 30 runs from 62 degrees at the beginning to 65 at the end of the period.

The best two days of the upcoming week? Today (Friday) and tomorrow (Saturday). Cherish them. Relish in the fact that the daily high temperature will have a ‘5’ in the tens place. Based on current projections, we may not see 50 degrees again until late next week.

In the meantime…we’re still worried about snow. As I’ve mentioned in the past, snow in late March isn’t unheard of. Neither is snow in April.

THE COLD AIR

The source for all this cold air we’ve been experiencing is linked to a phenomenon called the Arctic Oscillation (AO). The oscillation is evaluated by measuring the difference in pressure values between the polar regions and the mid-latitudes (where we are). This manifests as a strong presences of one pressure value – either high or low – over the poles and one of the opposite intensity (low vs. high) closer to the tropics. It is then all condensed down into a numeric value that typically ranges between 2 and -2, but can stray outside those ranges when the pressure centers are particularly intense.

When the pressure center over the arctic is high, the index is said to be in the negative phase. When the pressure center over the Arctic is low pressure, it’s in the positive phase.

To give you some context, the current AO value is near -5. That mean’s we have a rather strong area of high pressure over the poles, blocking the typical polar placement of very cold air. It (in this case) gets forced toward North America, and storm systems that would typically take a more northerly track get forced southward was well. And that’s how we get to where we are now.

The Climate Prediction Center outlooks for the next 6-10 days and next 8-14 days show the cold lingering around for most of the next two weeks. While these forecasts won’t give us exact temperatures, they do give a strong sense of confidence that our temperatures are going to remain below normal for the near future.

SNOW

It’s been much talked-about for a few days now, but I really don’t see a lot happening with this storm – it’s just a little too warm.

Don’t be surprised to see some snow mixed in with rain beginning Sunday afternoon and lasting through the overnight hours. Accumulations, however, should remain minimal. Temperatures are going to have a hard time getting cold enough to support much snow – or any accumulating snow at all. I just can’t see anyone in the Richmond metro getting more than about half an inch to an inch of snow. Absolute worst case, two inches.

Unfortunately it’s going to be pretty lousy for just about everybody.

March 23, 2013 12:02 AM 5