Tuesday Rain

Thunderstorms tomorrow across the Delta. Another round of heavy rainfall is in store. I'm a bit concerned with the threat of severe weather seeing the forecasted wind profile, but the main thing to watch out for is heavy rainfall during the night time hours if you are on the road. I'll update tomorrow morning with some more details. We've got some clear and cool nights ahead of us.

The past few days have served to remind us Spring is not in full swing. Climatologically, the last freeze in most areas of Mississippi is mid-April, which is definitely something to keep in mind with planting season right at the doorstep.

So when will Spring get here? And how long will the cold air behind the front linger? These questions are answered using a variety of tools and experience. One widely used tool for long range forecasting is the teleconnection. Most of you are probably familiar with SOI (Southern Oscillation Index). The positive phase of SOI is associated with La Nina, while the negative phase is associated with El Nino.

At the top of the graphic below you can see that the NAO (North Atlantic Oscillation) is in the positive phase (above the baseline) and is forecast to go slightly negative (below the baseline.) The NAO serves as a proxy for blocking (High Pressure) to the North of the United States. When the NAO is negative, the blocking is in place, so weather systems tend to linger. When the NAO is positive, we see a more progressive pattern. We are currently in the positive phase, so we should see this cold air modify quickly with things warming up until another shot of cold air.



Graphic Below is from the Climate Prediction Center, which forecasts that we will see a warm up within the next month. Those of you with Spring Fever should like this graphic. The reds represent temperatures "above normal" for that time period. This forecast makes sense with the breakdown of the jet stream pattern typically observed during the winter months.