Christmas Day Severe Weather Outbreak Could Repeat on Valentine's Day

The atmosphere could very well shape up into a situation that mimics the set-up that occurred on Christmas Day, 2012. The 500 millibar map from that day is shown above. We can see the storm system pushing down well into the Southern Plains, as depicted by the word 'Low' on the map. The national atmospheric flow appears not too disturbed in the East, with the exception of a weak ridge of high pressure in the Southeast. Stronger high pressure stands its ground on the West Coast, and this is the factor that typically allows storms to move east-northeast to affect the Midwest and Plains. The Southeast ridge also supports this.

We all know how that day turned out. Many Christmas celebrations were interrupted by wailing tornado sirens as a tornado outbreak hit. It started in Houston, and ended the day in far eastern Alabama. Along the way, 175 severe weather reports were submitted to the Storm Prediction Center, 60 of which were tornado reports.

I find it plausible that such a situation could indeed happen again, on Valentine's Day. The Lezak Recurring Cycle, which is a repeating weather pattern that occurs through the fall into spring, has a repetition length, or cycle length, of 53 days. This means that 53 days in the future from Christmas is when this atmospheric set-up could come back. And when we tally up the dates, we find that the 53 day mark lines up with Valentine's Day. Not a good thing to see.

I will publish more on this developing situation, and will always let you in on the latest in breaking weather, especially with this system.

Andrew

February 10-12 Potential Winter Storm

There does appear to be potential for a winter storm from the 10th of February to the 12th. Let's dive right in.

Model guidance is in fair agreement that a strong low pressure system will move into the Southwest US ahead of a massive high pressure system in the northeast Pacific, just off the West Coast of the US. This storm system will drop further south into northern Baja California in the days after this forecast image, which is valid for the evening of February 8th. The different shades of colors show confidence levels of the NCEP Ensembles as shown on the blue numbers on the legend at the bottom of the image. You can see that the center of this low pressure system has deep oranges, which correlates to 54% probability of the system ending up there- a fair chance this far out. Notice that there is a very zonal pattern across the central and east US. These zonal wind flows (zonal means west-to-east wind flow) typically result in relatively dry and warm weather across much of the nation. I can already see that this type of pattern could result in a very similar set-up as we enter this storm potential period. If you look back towards the West Coast, you will see that storm system pressing down on the pressure contours, as well as another area in the Pacific pushing up on the pressure contours. These are opposing low and high pressure centers, respectively. If we see the low pressure system drop further south and that high pressure system try to bleed east into the Pacific Northwest, it is very plausible we could see the infamous Rex Block formation emerge.

As illustrated in the above image (made by theweatherprediction.com), the Rex Block involves high pressure and low pressure essentially sitting on top of each other. This can happen anywhere, but for all intents and purposes, it has been shown on the West Coast. If you look downstream towards the central and east US, we again see that zonal flow pattern emerging in the East as a result of this Rex Block.

This is the latest European model forecast for the 11th of February. We can see our winter storm is actually in the Plains and shown as the tight gradient of pressure contours just south of the green-ish color in the region. This comes as a result of not the Rex Block (which is present in this image), but an amazingly-strong high pressure system in the Southeast. While many areas would see rain changing to snow in this event, should this storm even happen, the Southeast Ridge could really get in the way.

To be honest, I don't see this Southeast ridge happening. The only way we could see it would be in an extreme negative Pacific-North American index phase. When that index is negative, low pressure dominates the West Coast, and high pressure forms in the Southeast as a result. However, a glance at this and the previous run of the European model shows actually a positive PNA, which supports storm systems hitting the Midwest and Ohio Valley, rather than the Northern Plains. So I do not support the European model at the moment.

The American GFS model has been showing a pretty consistent solution of having a storm system moving out of the Front Range before sliding northeast and impacting the Upper Midwest, portions of the Central and Northern Plains as well as the Great Lakes. While this is nowhere near as extreme as the European model, this American model still does have a Southeast Ridge, although it is weaker than the European's. This is indeed a much more plausible solution in my opinion, with no unreasonably-strong ridge of high pressure in the East, when the atmospheric pattern does not support it.

I will continue updating this situation as the date draws closer.

Andrew

Long Range Lookout: Winter Slipping Away

Preword: Recently, I have been caught up in the swing of the stratosphere and investing all of my confidence in just a few factors. Starting today, I will present the good and bad sides of the forecasted weather, even though you may not find it as exciting as my other posts.

In a disastrous recurrence of last winter, the winter of 2012-2013 has so far brought little snow and only modestly increased cold in comparison to last winter. Don't get me wrong, this winter has had many more advantages than last, but still remains dismal. The long range will be a classic, painstaking case of some factors looking good while other factors ruin the party. We start with the current 500 millibar anomalies over the Northern Hemisphere. Blues indicate low pressure areas and reds show high pressure regions. Deeper shades of each color indicate stronger modes of their respective pressure systems. We can see a deep blue positioned over the Great Lakes in the wake of a very powerful storm system that impacted much of the nation's population. This area of cold will move on out of the region later on as we head towards the weekend. I want to turn your attention to eastern Asia in the upper right-hand corner of the image. See that massive high pressure system there? That will provoke high pressure in the United States as we enter next week and into the following weekend, and we could see another bout of above normal temperatures. Snow cover that was received in the past couple of days could be eradicated. This comes at a time when high pressure finally emerges into the West Coast, a good sign for cold and snow in the Midwest and East US. But, as a result of the forecasted high pressure system, it will be Alberta clippers that bring the best chances for snow.

We now move ahead to Mid-February. There is no longer high pressure over East Asia, but persistant low pressure anomalies. These low pressure anomalies would then inspire a stormy period to round out the month of February. Could these storms hit the Northeast? I'll discuss that a bit later down this article. Something that certainly is not good is that persistant low pressure in the Bering Sea. This goes with my 'some good, some bad' forecast, as this persistant low pressure in the Bering Sea can lead to above normal temperatures in south-central Canada and much of the northern United States. Even more depressing is the lack of Greenland blocking. Greenland blocking is the phrase that is used to reference persistant high pressure over Greenland. When that set-up happens, the atmospheric pattern is more inclined to introduce more wintry weather into parts of the US. A lack of this blocking leads to a more zonal, west-to-east jet stream that allows for warm temperatures and not many storms. It is very possible some of that high latitude blocking in eastern Europe (shown in deep reds) could migrate over to Europe, but that remains to be seen. Frankly, I'm not that optimistic on the idea. This dismal explanation is verified by slight high pressure in the New England area, likely as a byproduct of the low pressure in the Bering Sea, and in response to a lack of Greenland Blocking. One bit of good news is the forecasted high pressure over the Pacific Northwest. If you get high pressure in that area, the jet stream can be persuaded to dip south and let out some cold into the Northern US. Storms tend to follow a jet stream that favors wintry weather for those same regions, the Midwest and Ohio Valley for example.

Lastly, looking ahead to the heart of February just a few days after the above image, we find that the atmosphere has changed. That high pressure that was in the Pacific Northwest has now migrated into the Gulf of Alaska. This situation can then go one of two ways. The first option is for high pressure to then spread back on land into the Pacific Northwest, or the high pressure pushes west into the Bering Sea. Both moves would support a cooler pattern in the North US, but I'm not betting on it at the moment, as the consensus is not overwhelming and we are over 2 weeks away from this forecast image. We still see persistant low pressure in East Asia, adding to my theory of a stormy end to February. Also, we then see the forecast emerging for some spotty patches of high pressure in and around Greenland. Such an action could provoke a better pattern for the Northeast (notice the high pressure in New England is gone), but it's too far out for me to think about accepting or rejecting this idea.

So we could see some storms in late February, but the big story will be warmth in mid-February, with Alberta Clippers dominating that scene. Early February will be when the effects from the sudden stratospheric warming dies off, so that will add to the troubles the cold may face in the coming month.

Andrew

February 18-19 Potential Winter Storm

I am watching the timeframe of mid to late February for some wintry weather across parts of the nation.

The reason I post about this long range potential is because of a repeating pattern called the Lezak Recurring Cycle. Every fall, this pattern sets up and repeats itself every 40-60 days. That cycle length varies from year to year. This year's length is 53 days. If we go back from February 18-19, we find ourselves at the very last days of December. Looking at the 500mb map for December 29 (top image), we see a couple bumps in the contour lines, displaying low pressure systems. This could indeed produce some wintry weather within the Midwest and Great Lakes. A day later, on December 30th (bottom image), we see that the storm has shot offshore and is now impacting the Northeast.

This storm will depend on the atmospheric pattern that is in place when the system comes through. Looking at some very long range indicators, I see that this storm would indeed favor the Midwest and Ohio Valley for wintry weather. However, a lack of high pressure over Greenland could make for a more inland track that may promote more wintry weather for the Upper Midwest rather than the lower Midwest, but that is all TBD.

Andrew

February 14-16 Potential Winter Storm

If you're not into repeating patterns, this post is not for you. If you want snow, read on.

I am watching closely for the potential of a winter storm from the 14th of February to the 16th; these dates are very fluid.

The reason I post about this long range potential is because of a repeating pattern called the Lezak Recurring Cycle. Every fall, this pattern sets up and repeats itself every 40-60 days. That cycle length varies from year to year. This year's length if 53 days. If we go back from February 14-16, we arrive around the December 25-26 timeframe. If we take a look at the 500mb chart from December 26th (pictured above), we can see a storm system impacting the southern Midwest, spreading precipitation throughout the region. The Midwest and Ohio Valley would be impacted by this storm if it follows the same track as the December 25 storm did. Looking ahead to the last days of December, this storm then progressed to the Northeast. Could we see that region impacted by this system? That's not clear right now. The reason is that February may not feature as much high latitude blocking as previously thought. If this blocking does not appear near Greenland, the atmospheric pattern would not be favorable for coastal storms, and then this storm track may take a more inland pattern.

But again, this is based off the LRC pattern and does have bust (failure) potential. I post about it because this pattern has fared well this winter, and should perform well as the winter progresses.

Andrew