January 28-30 Potentially Historic Southeast Snowstorm Update

UPDATED POST HERE: http://theweathercentre.blogspot.com/2014/01/january-28-30-historic-southeast.html

This is an update to the earlier post on the January 28-30 Potentially Historic Southeast Snowstorm event.

We'll begin with the NAM model, which has actually beefed up its snowstorm amounts since its previous run. The NAM model now brings snow amounts near 2 FEET in the hardest hit areas, namely eastern South Carolina into eastern North Carolina. We see widespread amounts in excess of 12 inches slathered across the Southeast from Pensacola, Florida to southern Georgia and into the Carolinas. Accumulating snow also hits far southern Mississippi and Alabama, even extending into Louisiana. The NAM indicates the maximum amount possible in its solution is 21.2 inches, which would most likely hit somewhere in the Carolinas. I maintain my position on the idea that the NAM is too high with snow amounts, which would leave the Southeast paralyzed for not days, but possibly over a week or two.

The 18z GFS model really beefed up its snowfall amounts, bringing amounts as high as 22 inches to eastern South Carolina into eastern North Carolina. The model wants to begin a swath of accumulating snow in eastern Texas, including the city of Houston, before blowing up totals to near 12" amounts in southern Mississippi and Alabama. From then, significant snowfall pummels the states of Georgia, the Carolinas and even Virginia. Once again, I'm a little skeptical of the high snowfall amounts. Since models have been having trouble handling the energy responsible for this snowstorm potential since the get-go, confidence in these extreme snowfall totals is not that high.

We now go to the Canadian GGEM model's projection, which is far less bullish than the NAM or GFS models. The GGEM begins with a bit of snow in southern Mississippi and southern Alabama, only beginning to bring up snow totals in far eastern South Carolina and really getting going in extreme eastern North Carolina. I don't think we'll see amounts this low- while I'm not buying the extreme snow totals forecasted by the already-discussed GFS + NAM, I don't think we'll see these low totals either.

Lastly, we take a look at the European ECMWF model. The ECMWF starts out with accumulating snow in eastern Texas before weakening, only dropping dustings of snow throughout southern parts of Louisiana, Mississippi, and Alabama. We then see 2-4" totals popping up in Georgia, before 6" amounts form in far eastern South Carolina. The bullseye here hits the far eastern areas of North Carolina, where the ECMWF lays down 13.3". I'd like to see this model beef up amounts across the board and draw the higher totals back to the northwest, like the GFS and NAM do. I expect we will see 6" totals in Georgia, with totals near a foot (possibly just over that benchmark) in the Carolinas.

To sum up, I expect we see a swath of 1-3" snows from eastern Texas to southern Louisiana, and into southern Mississippi. From there, accumulations of 4-8" look to pop up in southern Alabama and the panhandle of Florida, before accumulations really ramp up in Georgia, South Carolina and North Carolina, where I expect 8-12"+ to fall.

Andrew

January 28-30 Potentially Historic Southeast Snowstorm

UPDATED POST HERE: http://theweathercentre.blogspot.com/2014/01/january-28-30-potentially-historic_26.html

Things appear to be setting up for a potentially historic snowstorm in the Southeast over the January 28-30 period.

The NAM model is the most aggressive with this storm system, dropping as much as 18.1" inches on the Southeast. As the legend on the right shows, we would be seeing accumulations over 6 inches in far southern Mississippi, and snow amounts over 1 foot slamming southern Alabama, much of Georgia, much of South Carolina, and eastern North Carolina. There is also 12"+ being forecasted in the panhandle of Florida, near Pensacola. Now, the NAM is notorious for over-doing snowfall, and I've got a feeling this situation applies here. If the storm does end up happening, you could probably cut these totals in half or so and end up with what we will see. Regardless, you get the picture: considering any snowfall in the South is a big deal, this much accumulating snow could be not only historic, but disastrous for those not used to snow falling in states like Georgia or Alabama.

The GFS model shows its forecast for all four types of precipitation for this event: ice pellets (top left), freezing rain (top right), rain (bottom left), and snow on the bottom right. The snow panel shows liquid equivalent snow amounts, meaning 0.5" on that bottom right panel would typically equate to 5" of snow. We see the GFS puts down all types of precipitation for this event, with freezing rain and ice pellets targeting southern Louisiana, southern MS/AL, central Georgia and eastern South Carolina. The snowfall hits areas immediately north of those two precipitation types. It looks like the GFS wants to lay down nearly 10" of snow in the Carolinas, though I'd put that at closer to 8 or 9 inches, considering the snow should be more or less heavier than your standard 10:1 ratio snow, where 10 inches of snow equals 1 inch of water. The GFS, while lighter in snow amounts than the NAM, still shows a pretty intense snow event for the South, with all forms of precipitation hitting the southern states.

The final model to look at here is the ECMWF model, which shows a much less significant snow event. We see the heaviest snow hits the coastal regions of South and North Carolina, where 6"+ of snow would be expected. The states of Georgia, Florida, Mississippi, Alabama, Louisiana and even Texas receive only a couple of inches of snow in this scenario. Based on the ECMWF Ensembles, I think the model is a little light on snow amounts across the board, and the more conservative estimates would probably range around the 2-5" range for the states previously mentioned.

This does look like a significant, and possibly historic snowstorm for the Southeast. My thoughts on the system side with the GFS model right now, which shows snow amounts decently as shown below. It would be wise to take off a couple inches here and there, specifically in the hardest hit areas, just to account for likely mixing of precipitation during the event.

Andrew

February 1-5 Potential Winter Storm

There is increasing potential for a winter storm in the February 1-5 period.

Shown above is the 500mb anomaly forecast off the ECMWF model, valid on the morning of January 26th. If you've followed this blog for a while, you know that we can use that area of negative height anomalies over Japan to forecast a storm in the United States. As Joe Renken states, we can extrapolate a storm over East Asia out 6-10 days to arrive at the timeframe for a storm here in the United States. Going that length past January 26th gives us a storm timeframe of February 1-5. That's not the only thing we can take away from this predictor, however. Looping the ECMWF forecast tells me that the storm system will be moving essentially due east as it passes through central Japan. This tells me that we could (keyword here is could) see our February 1-5 storm system also moving on a west-to-east track, not really curving north or dropping south too much. The 12z and 18z GFS models caught on to that idea of a west-to-east storm, but had the storm hitting the US on January 31st to February 1st, which is just outside the timeframe presented here. We'll discuss the models a bit later on in this post.

Adding to the evidence of a possible storm in the early February timeframe is what we saw happen in the Bering Sea on January 18th. The image above shows contoured 500mb height anomalies over the north Pacific on January 18th. We see a storm system moving east from far northeast Russia, which is the westernmost 'X' on the image above. The next day, we saw the storm move nearly due east to the second 'X' in the image, only moving just a bit north in the process. Going back to that link I posted above, there is also something called the Bering Sea Rule, developed by Joe Renken. The Bering Sea Rule states that a storm in the Bering Sea can result in a storm over the United States 17-21 days later. If we extrapolate the January 16th date out using the 17-21 day timeframe, we arrive at a potential storm in the February 2-6 timeframe. This fits well in the February 1-5 timeframe we got from the East Asian correlation, and the nearly west-to-east movement in the Bering Sea tells us the storm in the US may be west-to-east as well, like we saw in the ECMWF forecast.

Now, model guidance is pretty iffy on the timing of this storm, and that is to be expected. The GFS model wants to bring a zonal (west to east) track storm through the US, but on the January 31-February 1 timeframe rather than the early February time periods established by the East Asian correlation and the Bering Sea Rule. The ECMWF model brings a west-to-east track storm system through the US on February 2-3, which fits right into the two time periods we established above. However, the ECMWF is much less robust on snow totals; the GFS allows significant snow in the January 31 forecast above, while the ECMWF only lays down a handful of inches from the Plains to the Great Lakes.

I think we'll end up seeing a compromise, where the GFS slows down the storm to the ECMWF's timeframe of the first days of February, but we see increased precipitation amounts like the 0z ECMWF and 12z + 18z GFS put down, rather than the weak amounts put down by the 12z ECMWF model.

Andrew

Intense Cold Arrives Monday, Tuesday and Wednesday

Arctic air not seen since the early January outbreak is set to arrive on Monday in the Plains before flooding the northern US into Tuesday and Wednesday. Let's break down who will get the cold weather, and when.

WeatherBell

The ECMWF indicates we will see the core of the cold start out in states like Minnesota, North Dakota and Iowa on Monday, as this temperature forecast image for Monday morning shows. Below zero temperatures are expected from central Indiana back northwest, with temperatures below -20 degrees F anticipated in the aforementioned northern Plains states. We are likely to see school closings throughout the upper Plains on Monday as this cold filters in, with widespread cancellations possible.

Tuesday morning is when the Arctic air really flexes its muscles. We see the ECMWF model taking temperatures as low as -30 degrees F to Minnesota and Wisconsin, while giving cities like Indianapolis, Madison and Chicago severe cold that could easily flirt with -20 degrees F. The Northeast will begin to encounter these frigid conditions, as below-zero temperatures are forecasted to hit the entire region, except for areas immediately near the coast. I expect widespread school cancellations across Minnesota, Wisconsin, North Dakota, Illinois, Michigan, Indiana, Ohio, West Virginia, and additional closures throughout nearly each state in the Northeast. The Great Lakes will work to warm up those to the east of the bodies of water, as you can see in western Michigan and western New York.

The cold weather will begin moving out of the Plains on Wednesday, but not before another frigid morning brings well below-zero temperatures to Wisconsin, with other negative temperature values found in Minnesota, Iowa, Michigan, Illinois, Indiana, Ohio, and across New England. School cancellations should be considered a possibility in Wisconsin, Minnesota and western Pennsylvania. Cancellation prospects are a bit more iffy in the other states I mentioned.

A few tips for the upcoming cold blast:

If you absolutely have to go outside, make sure to follow these tips:

-Minimize time spent outdoors. Even if you have heavy winter clothing on, this weather means you must be indoors as much as possible.

-Load up on clothing. Any and all coats, jackets, hats, gloves, mittens... this is extremely dangerous cold weather that is not to be taken lightly. This isn't your average winter cold spell- this is the kind of weather that is more typical of the Arctic tundra.

-Protect your pets. Fur isn't going to suffice this time around- keep your pets indoors at all times. This is just as dangerous to them (if not more dangerous) as it is to you. If you have to take them outside for a walk, put some clothes on them. As silly as it sounds, it might just save their life.

-Stay indoors. As obvious as this tip may seem, some people need that extra reminder that they aren't invincible to all cold weather, even with heavy coats and jackets.

Andrew

Chicago, Detroit, New York City Targeted for Biggest February Snows

It looks like the end of winter will go out like a lion for a good chunk of the north-central and northeast US, with cities like Chicago, Detroit and New York City in the mix for the biggest snow events.

We're going to start with 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 (non-changing) 40-60 day interval for the next ~10 months before it dissipates over the following summer.

This season's LRC cycle is on a 57 day cycle length, meaning the weather we saw in December can be expected to "come back" as we enter February. The image above shows the surface condition map on the left and 500mb map on the right from December 14, 2013. If w extrapolate that date out 57 days, we come to the February 7th mark. To make up for natural shifts that occur in the weather pattern, we can reasonably stretch the timeframe out to February 6-8 if we want to. As the 500mb map above shows, we have high pressure over the West Coast, with only slight ridging in the Southeast and the storm system easily working its way across the Plains. Based on the pattern I'm seeing to start February, I'm thinking a storm track similar to the one this system took in mid-December could very well be in the cards, or possibly suppressed a bit to the south (not by much). Regardless of where this storm ends up tracking, we should be watching out for a wintry system to impact the Plains, Midwest and eventually the Northeast in the February 5-10 period (I put February 5-10 instead of 6-8 to cover the timeframe the storm will affect all regions of the US, not just for the image shown here).

The second snow potential to watch would fall around the February 11-15 period, as this December 20th disturbance brought precipitation to the central Great Lakes and northern Ohio Valley, with additional precipitation extended into Kansas and Nebraska. The pattern here had a nearly-closed low in the Southwest, with high pressure in the Southeast. I'm a little cautious of saying that this storm track may repeat exactly as shown- I'm thinking we'll see a slightly different track this time around. If it is to deviate from the December 20th track, I expect it would be more to the south as of right now. Again, we would want to watch February 11-15 for this potential storm.

The ECMWF model then has an intense storm moving north in the far western Bering Sea, and by using the Bering Sea Rule (which states a storm in the Bering Sea results in a storm in the United States 17-21 days later), we can find that this January 27th storm would equate to roughly a February 13-17 period for a storm in the US. By seeing how the storm is in the far western Bering Sea, we can guess that the February 13-17 storm potential would then be based in the Central US. Time will tell, as always, but the evidence is mounting for a storm system in this mid-February timeframe. The storm could also be significant if the projections of a rather strong storm in the western Bering Sea are correct.

Just two days later, on December 22nd, surface and 500mb observation charts show precipitation associated with a disturbance stretching from the Plains to the Northeast. I wouldn't be too surprised to see a similar storm track play out on the expected February 14-16 period based on the LRC's 57 day timeframe, mainly because the pattern I think we'll see in mid-February will continue to resemble the pattern showing up in early February.

The ECMWF model zoomed on the Bering Sea then sees a storm system enter the far western waters of its domain on January 30th, meaning we would then be eyeing the February 16-20 period after extrapolating out 17-21 days using the Bering Sea Rule. Again, since the storm is in the western Bering Sea, we might anticipate a storm in the Central or near-Eastern US in roughly this timeframe.

These LRC and Bering Sea images do seem to favor the Plains, Midwest, Great Lakes and Northeast regions for snow events, especially if the storms are able to transfer offshore (which I believe we may see in February). I'm cautiously optimistic that those in the north-central and northeast may see a full three month winter of not only cold, but snowy weather.

Andrew