March 16-20 Potentially Significant Storm System

I'm watching for a potentially strong storm system in the March 16-20 timeframe.

WeatherBell

The image above shows 500mb height anomalies over the North Pacific, valid on the morning of March 10. If we look at Japan, we see deep purples over the island nation, indicating the presence of anomalously low heights. This tells us there is a storm system afoot; the purples indicate the storm is of the stronger variety when compared to other systems. How can weather in Japan relate to weather here in the US? If we use the 6-10 day correlation, explained by Joe Renken, which states that a storm system in Japan can affect the United States 6-10 days later, we find that this storm system would be expected to create a storm in the United States during a March 16-20 time period. Even more interesting is how models bring two strong storm systems through Japan during this March 10 time period, meaning we could be in for a significantly stormier and cooler than normal mid to late March.

We can actually figure out the projected track for this storm as well, by using a tool titled the Lezak Recurring Cycle. The Lezak Recurring Cycle, or LRC, is a tool developed by meteorologist Gary Lezak that, in essence, can enable forecasters to predict the overall weather pattern months in advance. The gist of the LRC involves a cycling weather pattern that develops in October and November of each year; no pattern is the same from year to year. Around mid November, the LRC begins to repeat, meaning we start to see a similar weather pattern in mid November that we saw in early October. This means that the cycling pattern has begun, and it will continue to cycle on a regular, unchanging 40-60 day interval for the next ~10 months before it dissipates over the following summer. Since this season's cycle has been holding at around 57 days, we can go back from the March 12-17 period and arrive around the  January 16-20 time period. The image above shows observed 500mb height anomalies from the January 16-20 timeframe, where North America is located on the upper right portion of the image. If we look at what the atmosphere was like in that mid-January period, we find a defined northwest flow scenario, with strong ridging over the West Coast leading to deep negative height anomalies across the East Coast. The jet stream below for the same January 16-20 period reflects this northwest flow.

If you're a weather buff, you probably know where I'm going with this. If not, pay close attention. The northwest flow scenario involves the jet stream shooting north into Alaska due to that massive ridge of high pressure, before plummeting south into the Southeast and then north again across the East Coast. In the January 16-20 period, we also saw support from the subtropical jet stream, which helped to enhance wind speeds and phase the two jet streams. If a storm were to come along during this northwest flow scenario, it would most likely become enveloped in the jet stream, and become a coastal storm. To sum up, if the LRC cycles again to be even somewhat close to what we saw in mid-January, it's possible this ends up being an East Coast storm. However, because we're so far out, we don't even know if this storm will even happen. This is just a heads-up for a part of what could be a very stormy mid-March.

Also see: March 12-16 Potentially Significant Storm System

Andrew

March 12-16 Potentially Significant Storm System

I'm eyeing a potentially significant storm system around the March 12-16 timeframe.

Shown above are ECMWF model projected 500mb height anomalies over the North Pacific, valid on March 6th. We want to take a look at Japan in this image, which is on the left-hand side of this graphic. If we look at Japan, we see deep purples over the island nation, indicating the presence of anomalously low heights. This tells us there is a storm system afoot; the purples indicate the storm is of the stronger variety when compared to other systems. How can weather in Japan relate to weather here in the US? If we use the 6-10 day correlation, explained by Joe Renken, which states that a storm system in Japan can affect the United States 6-10 days later, we find that this storm system would be expected to create a storm in the United States during a March 12-16 time period. 

There is something I'm watching in this time period and on model forecasts. If you were to animate the maps over the North Pacific, you would find that it almost seems like two separate systems impacting Japan over the March 6th time period, but the proximity to one another makes it seem like one big storm. It might take a little while to determine if this really is one strong system or two moderate systems, but until then, it's better to err on the side of caution and discuss how a single, strong storm system could impact us.

We can actually figure out the projected track for this storm as well, by using a tool titled the Lezak Recurring Cycle. The Lezak Recurring Cycle, or LRC, is a tool developed by meteorologist Gary Lezak that, in essence, can enable forecasters to predict the overall weather pattern months in advance. The gist of the LRC involves a cycling weather pattern that develops in October and November of each year; no pattern is the same from year to year. Around mid November, the LRC begins to repeat, meaning we start to see a similar weather pattern in mid November that we saw in early October. This means that the cycling pattern has begun, and it will continue to cycle on a regular, unchanging 40-60 day interval for the next ~10 months before it dissipates over the following summer. Since this season's cycle has been holding at around 57 days, we can go back from the March 12-17 period and arrive around the  January 16-20 time period. The image above shows observed 500mb height anomalies from the January 16-20 timeframe, where North America is located on the upper right portion of the image. If we look at what the atmosphere was like in that mid-January period, we find a defined northwest flow scenario, with strong ridging over the West Coast leading to deep negative height anomalies across the East Coast. The jet stream below for the same January 16-20 period reflects this northwest flow.

If you're a weather buff, you probably know where I'm going with this. If not, pay close attention. The northwest flow scenario involves the jet stream shooting north into Alaska due to that massive ridge of high pressure, before plummeting south into the Southeast and then north again across the East Coast. In the January 16-20 period, we also saw support from the subtropical jet stream, which helped to enhance wind speeds and phase the two jet streams. If a storm were to come along during this northwest flow scenario, it would most likely become enveloped in the jet stream, and become a coastal storm. To sum up, if the LRC cycles again to be even somewhat close to what we saw in mid-January, I would anticipate a Nor'easter or some sort of coastal storm for this March 12-16 period. Lots of time for this to play out, but historically, the East Asian correlation and LRC have been doing very well, and I see no reason to discount them now.

It's also worth noting that with this system we could see a rather pronounced severe weather threat. As we enter spring, storm systems can become more 'dynamic', for lack of a better term, and pull up more moisture to enhance the severe weather threat. The jet stream, which naturally strengthens as we enter spring and summer, could only add fuel to this potential severe weather fire. I'll have more on this aspect a little later down the road.

To sum up:

• A storm system will impact Japan in the March 6th period, leading to a storm threat in the US over March 12-16.
• Cold weather is also anticipated during this timeframe.
• Based on two reputable indices, we could be looking at a Nor'easter for this time period.
• If there are two storms instead of one, like we discussed at the top of this post, there could be two coastal storms (but that will need more investigation).
• There could be a severe weather risk with this event.

Andrew

Weekend Snowstorm Targets Midwest, Ohio Valley

I'm expecting a snowstorm to impact the Midwest, Ohio Valley and East Coast this weekend.

As the graphic above shows, I anticipate the heaviest snow to extend from northern Missouri through Illinois, Indiana, Ohio and into Pennsylvania and New Jersey. West Virginia and Virginia will also be impacted by heavy snow. I anticipate we see amounts somewhere in the 6-8" range over the Midwestern states I just mentioned, while areas along the East Coast have a higher upside, possibly near 12". With this storm comes the threat for freezing rain, and I expect this threat to reside from Arkansas into Kentucky, eastward through the Virginias. Pinpointing the location of freezing rain is difficult, and with model guidance still having numerous issues handling this event, do not be surprised if my forecast chances later today. I based this map off of the 12z GFS, seeing as the system has finally made it ashore and a general forecast with this layout appears to be the consensus at this time.

A look at enhanced water vapor imagery shows the storm system making its way onshore, throwing out massive amounts of moisture ahead of it, as the warmer colors show. The circulation of the storm remains just offshore of California, a bit east of that swath of dry air depicted in dark blues. As the system makes its way onshore, we should see model guidance improve and (hopefully) settle on a solution, as the weather balloons sent up by each National Weather Service office at 6 AM and 6 PM (central time) each day will be able to ingest data from the storm, which then feeds into the models to make a more accurate forecast.

There is some talk about model guidance underdoing precipitation in this storm, and also being too far south. The jet stream is predicted to be aligned in such a way that the storm would normally push further north than it is currently projected to go, and we would typically see the heaviest snow shifted to the north as well. However, with models standing their ground on the storm staying south, and both the northern and southern jet streams now "sampled" by those weather balloons, having been onshore for some time, tells me that the storm will most likely stay on its southern track. The under-doing precipitation claim is a bit more difficult to decipher. On one hand, model guidance is notorious for over-doing precipitation when you compare observed precipitation to forecasted precipitation, but in this scenario, we will have a strong jet stream and Gulf of Mexico moisture feeding into the environment, which would usually help enhance precipitation totals. I want to wait for a bit before making a call on that issue, because it'll most likely take a close analysis of radar trends to determine how model guidance has been handling that aspect of the storm.

Andrew

March 12-17 Potentially Significant Storm System

I'm seeing the potential for a significant storm system in the March 12-17 period.

Shown above is an ECMWF forecast for the evening of March 5th, depicting 500mb height anomalies over the North Pacific. If we look on the left half of the image, we see a deep trough over Japan, one with strength we haven't seen in some time.If we use the 6-10 day correlation, explained by Joe Renken, to tell us when these two systems may 're-appear' in the US, we find ourselves at a March 12-16 potentially significant storm. If this solution were to verify, we could see the strength of the trough translate over to that March 12-16 storm as well. This could mean a significant storm system, potentially accompanied by significant cold weather. It's too far out to tell if this could be a big snow maker, but judging on how the climate is shaping up for mid-March, I would certainly keep an eye out for some snowy impacts.

The GFS model shifts the timeframe a little further down the road to the afternoon of March 7th, but agrees on the idea of a strong storm system over Japan. Again, it'll take a while before we get into details, but it's clear that there is a chance for a significant storm system over the March 12-17 period. I'll have more details on potential tracks in coming days.

Andrew

March 1-4 Potentially Significant Snowstorm

There is a rising possibility of potentially significant snowfall over the March 1-4 period.

The first wave of this snow event will come along on March 1st, roughly around this Saturday. Latest model projections take this system as a rather disorganized system, with lobes of vorticity scattered about the general storm. The jet stream around this system has a jet streak just to the southwest, meaning the storm would be expected to strengthen and dig a bit further south in the process. However, seeing as this system never really develops itself, and with a lobe of the polar vortex to the north in Canada, the best bet would be to maintain the storm where it is. Barring any significant model changes in the future, this first wave looks close to being correct.

The second wave is a bit trickier. We have an elongated band of vorticity, which is able to trace its roots back to Baja California. We also see a large system in Montana, which will have quite an influence on the system. The jet stream looks to have this system in its grips, as the band of air is depressed in the Southwest and rises northward as a result. This is also reflected here on the 500mb chart, as you can see the northeast progression of contour lines from the Southwest to the Northeast. On one hand, we could argue that the jet stream may eventually push this storm further north than projected. However, on the other hand, the lobe of the polar vortex to the north could end up pushing the storm back to the south. If there is to be a shift, I would be more inclined to side with a northward shift, but everything remains up in the air until we get these two waves sampled.

The general idea here is that we are likely to see a snow event in the March 1-4 period. How can I be so sure? Take a look at the graphic above. If you look closely you'll see a bump over Japan in the upper left hand corner, and if you were to loop through the 500mb anomaly charts for Japan over the past few days, you'll see that there have actually been two systems moving through Japan. If we use the 6-10 day correlation, explained by Joe Renken, to tell us when these two systems may 're-appear' in the US, we end up with a rough March 2-6 timeframe, and that really boosts confidence in this snowstorm idea. In the past, this 6-10 day correlation has verified with a high success rate, and I expect a similar story to unfold over the next several days.

Continuing to look outside the models, the jet stream in the Pacific is absolutely roaring right now. Wind speeds are in excess of 150 knots at maximum intensity, and if this event takes advantage of the jet stream (which does look probable), we could be seeing not only an increase in storm intensity, but an increase in the severe weather threat.

Just for a little eye candy, here's what this morning's 6z GFS showed for the snow events. Don't buy into this, the GFS gave out some strange solutions in this run that I don't really agree with. The thing to take away here is that two storm systems are likely in the first week of March, and we could see some significant snowfall as a result.

Andrew