Wintry Weather Or More of the Same?
Buckle up, this is going to be an extensive blog post. However, that's what the Arkansas Weather Blog has always been about. We have 2 systems to watch over the next 7-10 days. Will it bring wintry weather or more of the same? When I say more of the same, I mean snow (wintry weather) north, rain elsewhere with a flake or two mixed in for excitement.
The 1st system arrives Wednesday with a round of rain. It's an interesting situation as the upper level low will not zip to the north, but cut underneath ridging located to the north. I think we're going to have to put this one in the camp of "more of the same". On the backside, the rain may change to snow due to marginally cold air and moisture being thrown into it. I just don't see any true arctic air on the playing field for this one to work with at this time.
Storm system #2 late next weekend. As you can imagine, being in the long range the models show a variety of solutions with each run. They range from the system dropping so far south, it's dry. I've also seen runs with snowstorm written all over it. There are also indications it could be "more of the same".
At this time, I think it's the latter, but being in the long range there's a "?".
I have 2 reasons for this. First, the Euro and GFS ensembles lean towards a more northern track. Also, the pattern does not really change. There's really no true arctic air on the playing field this far south as these disturbances roll off the Pacific Ocean. HOWEVER, that may change and I have more on that below.
Alright, so now we're to the model data. I'm going to use the European Ensemble from Weatherbell.com.
This is the probability of 24 hour snowfall exceeding 1''. The purpose is not to make a snow forecast, but to show you where it thinks the track of the storm will end up and who has the greatest chance for wintry weather. This GIF will include the 2 systems, Wednesday/Thursday and the late weekend event. Watch the 2 individual purple blobs roll from west to east.
Yep, both systems appear to bring "MORE OF THE SAME". However, my usual disclaimer. Things can always change!
So what can happen to get out of this "More of the same" pattern?
For that, let's go to a view of the northern hemisphere using the Euro Ensemble 500 mb height anomalies. I love using this product. It really shows you where ridging and troughing should present itself.
Here's where we are now. Look at all the blues over the Pacific Ocean. That's a lot of storminess and it brings a mild flow off the ocean. The source region of our air is NOT from the arctic. It's a stormy pattern with rain and thunderstorms across the south with snows at the higher latitudes. We need this to change if you want really cold air.
Now, let's go towards the middle o the month. Those blues over the Pacific have backed into the Gulf of Alaska with a ridge over the eastern Pacific right up in the arctic. THAT'S A PATTERN WHICH COULD DELIVER COLD AIR! See the trough over the south and southeastern United States? Cold! I'll throw my word of caution out further along the post.
Temperature anomalies at about 5000 feet Monday through Monday Jan 11th. It's colder than average at that level as storms roll off the Pacific
North American temperatures Jan 10th through the 17th. Now, we're seeing the effects of ridging over the eastern Pacific and the colder air establishing itself over us. Is it possible?
There have been signals from time to time of much colder air moving south. The arctic oscillation index has been negative, the north Atlantic oscillation index has been negative, but the eastern Pacific Oscillation index (EPO) has been positive. The EPO needs to go negative with the other 2 to deliver the chill winter weather lovers want. If that eastern Pacific ridge builds in the long range, it will go negative and the forecast hints at that. Will it though? I'm skeptical. It seems like it's always more of the same around here, but we have to break that streak at some point, right? Will this be it? It will be fun to watch. Glad you are buckled up here on the blog and ready to ride!