Could this December be a brown one with temperatures in the 50’s maybe even the 60’s leading up to Christmas? The models continue to show temperatures will be above average through at least mid December. The graphic above is the 18z GFS temperature anomaly. It continues to show temperatures 10 to 20 degrees above average on Wednesday December 10th.
Some of you may say, “well the GFS is never that accurate that far out, usually the ECMWF handles long term better.” That may be true, but comparing the ECMWF to the GFS, the ECMWF is slightly warmer than the GFS. The above image is of the ECMWF valid on Saturday December 13th. Taking a closer look at the statewide view of the ECMWF, you can see the upper 50’s will be working into southwest Iowa with the mid to lower 40’s across northeast Iowa on Saturday December 13th. Would not be surprised to see temperatures in the lower 60’s across southwest Iowa late next week.
So what is causing this warmer weather trend? Taking a look at the GFS 300mb level wind speeds, or also where the jet stream resides during the winter, you can see that most of the country is in a big ridging pattern. However, if you notice off to the west, a deep trough is just off the west coast. This may be what provides our cool down.
Yesterday we showed you the MJO forecast, and not much as changed since yesterday. It is still forecasting cooler weather building into the forecast by later in the month, and this would explain the big trough that is just off the west coast late next week. It would be hard to image that temperatures in the 50’s would make it though Christmas, but anything is possible when it comes to weather. We will have to see what the models continue to throw our way, otherwise, plan on above seasonal temperatures through next week!