Where did Spring go?

Well. . .even though the calendar says Spring starts tomorrow, we won’t be enjoying Spring-like temperatures for a while yet. Today was rather nice in the DC-Baltimore area as temperatures approached 60. The funny part, this happened after the cold front went through this morning. . .thank you downslope winds! Ahead of the front, we didn’t get out of the 30s! It’s amazing living here sometimes. Since moving to this area I have experienced two hurricanes, an earthquake, a derecho, two relatively snow-less winters, and multiple 100+ degree days.

So what gives with this pattern?

12z GFS initial 500 mb heights and vorticity on 03/19/13.
12z GFS initial 500 mb heights and vorticity on 03/19/13.

The image above shows the main culprit of our cold pattern highlighted with the red circle. That area is a ridge or bubble of high pressure that is now blocking the flow. This forces colder air from Canada south towards the U.S., while storms have to go around. This block is expected to persist and may lead to more antics starting this weekend. As a reference, the 558 height line in Greenland is the same as it was over NJ this morning. Just a bit unusual. . . This means that “Spring” has literally gone to the Arctic!

The Arctic Oscillation forecast valid on 03/19/13.
The Arctic Oscillation forecast valid on 03/19/13.
The North Atlantic Oscillation forecast valid on 03/19/13.
The North Atlantic Oscillation forecast valid on 03/19/13.

The Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) forecasts above show that both indices are going to remain negative for the next few days. In fact, the AO is going to tank in the next 48 hours, which will drag the NAO with it as they are both calculated near each other. What does this mean for your forecast? It’s going to stay cold if not get colder as we head towards the weekend. The storm track will remain quite active and it’s possible that many areas will see one or two more snowstorms. On the warm side, there may be a couple opportunities for severe weather, but limited to the Gulf Coast.

The  Climate Prediction Center (CPC) 6-10 day temperature forecast probabilities.
The Climate Prediction Center (CPC) 6-10 day temperature forecast probabilities issued on 03/19/13.
The CPC 6-10 day precipitation forecast probability valid on 03/19/13.
The CPC 6-10 day precipitation forecast probabilities issued on 03/19/13.

To put these forecast ideas into perspective, I included the Climate Prediction Center’s 6-10 day temperature and precipitation probability forecasts above. It’s extremely rare to see 90% probabilities of below normal temperatures. Notice the increased chances of precipitation along the East Coast? With cold air and precipitation, even in late March or early April, one has to watch for surprise snow. Is it too late for DC-Baltimore-Philadelphia? Personally, I think I’m too jaded to get hopeful, but this pattern tells me to watch out!

Thanks for reading!

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