Saturday, May 17, 2014

What Are The Models Saying This Winter? - NASA Model

This is a series of posts that I have made in previous years, in which I display a specific long range model and its prediction for the upcoming winter. Based on its success in past years, I have decided to kick off the multi-month series early, to give you an early heads up on the upcoming winter.

Today's model will be the NASA model.

The above image shows the NASA model's forecast of 200mb wind speed anomalies across the world, with 200mb pressure contour lines superimposed. We want to mainly pay attention to the contour lines for today's analysis, since it seems to be the easiest for many to decipher over the anomalies. If we look at North America, we see the contour lines arching up across the West Coast, likely indicative of the presence of high pressure/ridging. This ridging over the western portion of North America then leads to a depression in the contour lines, where cold air would funnel southward into the central and eastern portions of the continent. This cold air would be helped along south by that troughing/depression in the contour lines. In other words, going solely by this image from this single model, we would be looking at a very similar set-up as last winter, with warmth over the West and cold over the East.

If we look at the North American temperature forecast for December 2014, the same timeframe as the image above, we see a similar story to my analog package which I posted about earlier this week. We see cold weather present across the South US, with warmth prevailing over Canada and the North US. This temperature forecast looks very similar to a textbook El Nino event, which is expected to form this summer and result, possibly, in a temperature pattern similar to the one above for this winter.

Lastly, the temperature forecast from the NASA model, valid December 2014, confirms the idea of a textbook El Nino pattern. We can recognize this El Nino pattern by viewing the below-normal precipitation across the Great Lakes and Ohio Valley, with a very wet precipitation pattern swallowing the Southeast and East Coast. These two features are common during an El Nino winter, and may very well appear this winter. On the West Coast, in accordance with the ongoing drought, we see well-below-normal precipitation values extending from California to Washington. All in all, even though this is a long range forecast, this solution is indeed a plausible one from this model.

To summarize, the NASA model is predicting the following conditions to begin the winter of 2014-2015:
• Cool South US
• Warm North US
• Wet & Stormy East Coast, Dry West Coast
• Very similar to a typical El Nino pattern