Archive for extreme

Finally! El Nino is Bringing Extreme Weather to the U.S.

Posted in Severe weather, Winter weather with tags , , , , , , , , , , , , , , , , , on January 24, 2010 by stormstream

It’s taken half the winter to get here, but finally the low end strong El Nino weather pattern is bearing some major fruit in the U.S. in the form of extreme weather, and this active pattern looks to continue at least through the month of February, and very likely into the spring as well. Get ready for a continued wild ride on the Extreme Weather Express!

The jet stream is powerful and infused with moisture. This has led to many feet of snow across the mountains of California and the Southwest, and severe thunderstorms and tornadoes across the South. Now, we are once again heading into a period where the AO is severely negative, the NAO is negative and PNA is positive. This all equals major DOO DOO for much of the U.S. as we head into late January and through the month of February, but the most extreme weather will likely shift from the western U.S. into the central and eastern U.S. More severe thunderstorms and tornadoes will be possible in the Deep South, with major snow storms north of the heavy rain and severe storms. Also, serious intrusions of bitterly cold arctic air will be dropping into the lower 48 on a regular basis.

Anyone hoping for an early spring with an extended period of sunshine and mild to warm temperatures can kiss those hopes goodbye through at least mid-March, and I don’t care what that glorified rodent The Groundhog says in early February.

An Wild Weather Weekend for the Southeast with Severe Weather and Significant Snow Likely!

Posted in Extreme Weather Video, Severe weather, Winter weather with tags , , , , , , , , , , , , , , , , , , , , , , , on February 27, 2009 by stormstream

All systems are still go for severe thunderstorms, then snow across parts of the Southeast this weekend, and we are now getting into a range where I can throw out some more specific forecasts with some measure of confidence.

First, I’ll discuss the severe weather prospects for Saturday and my plans to chase the storms and do a live internet broadcast of my storm chase.

It is hard at this point to say exactly where the greatest threat for severe storms will be on Saturday.  The models are pretty much showing the area in Georgia and eastern Alabama along and south of I-20 as being in the threat zone.  However, I’m not sure the models are handling the effects of the large convective system over central AL and GA very well.  Surely this will reinforce the boundary farther south than the models indicate.  Right now, I’m thinking along and south of  line from Macon, GA to Troy, AL will be my target for severe weather on Saturday.

Steep lapse rates, rather low freezing levels, and the potential for rotating updrafts will lead to very real possibilities of large hail.  Also, the shear, divergence aloft and strong 250mb winds will lead to the chance for long-tracked supercells with a chance for a few tornadoes.

The plan right now is for me and my chase partner, Greg Zamarripa, to depart Atlanta at 11:30am and head for either Columbus, GA or Macon, GA as a base.  We will then head out in any direction from there to intercept storms.  We hope to be in our target by 2pm EST.  Storm chaser Mark Aubin will be targeting the Florida panhandle for any severe storm activity that erupts farther south.

I will be broadcasting my storm chase live on the internet on Ustream.tv and Severestudios.com.  Between 11:30am and 3pm I will be streaming live at http://www.ustream.tv/channel/mike-phelps-mobile-weather-stream.  Then, from roughly 3pm EST onward I will be streaming live at http://www.severestudios.com/livechase as Mike Phelps.  On the ustream.tv broadcast the viewer will have the ability to not only view the live video, but also hear audio from within the chase vehicle.  You’ll be able to listen in on critical nowcasting conversations and storm chase strategies, so you’ll actually feel like you are riding along with us on the chase.  There is also a chat feature where you can interact with me via instant message, and I can talk to you live.  The severestudios.com broadcast will not feature audio, but the video could be spectacular at times since we will be streaming at that location during the height of the storm chase.  I will be available to the media for live phone interviews any time at 404-202-6317.

Now onto the snow prospects for Sunday.

This looks to be a classic late winter/early spring upper level snow events for parts of the Southeast.  The upper low drops in from the northwest bringing with it a supply of moisture, cold air and strong dymamics.  These events are notoriously difficult to forecast and the area of heavy snow that falls will be dictated very much by the exact path the upper level low takes.  Right now, I’d say a general trace to 3 inch snowfall looks like a good bet across TN, northern and central AL and GA, much of SC and much of NC.  1 to 3 inches for Memphis, Birmingham, Huntsville and Chattanooga.  1-2 inches for the west Atlanta metro area, and 2 to 4 inches for the east and northeast ATL metro.  3 to 6 inches for Athens, GA.  4 to 7 inches for Greenville, SC.  I won’t venture to throw out a snowfall forecast for Columbia, Charlotte or Raleigh just yet, but they could also make out very well.  I also believe someone in the Southeast is going to see some “jackpot snow”of a foot or more, but it is impossible to pin down who that will be at this juncture.  I hope it is my backyard!  🙂  Now having said all that, I do need to caution that the bust potential with upper level snow systems in the Southeast is very high.  Honestly, we are not going to have a fully confident handle on this thing until it is happening.  The cities I listed above could just as easily end up seeing a lot less, or a lot more.  Definitely a system to monitor closely as there are sure to be several changes in the forecast over the next 24 to 36 hours.

I will also be streaming live video of the snow storm, and I will have more details on that in my blog entry Saturday evening or Sunday morning.

Significant Upslope Snow Event for the Central and Northern Mountains of North Carolina and Tennessee

Posted in Severe weather, Winter weather with tags , , , , , , , , , , , , , , , , , , , , , on February 2, 2009 by stormstream

There’s not too much to say about today’s non-system that hasn’t already been said, so I won’t waste any more time talking about it.  I will say that I would not be surprised to see an inch of gloppy, wet snow on the Cumberland Plateau this morning. I’ve driven up to the rest stop on I-24 in Monteagle, TN several times in situations like this, and been rewarded with some nice snowball-making snow.  And as for the second short wave, the clipper, that earlier looked like it could possibly provide parts of the Southeast with a dusting of snow on Tuesday night, well that now looks to provide only some light rain and snow flurries Tuesday afternoon, but will be a major factor in fueling the system that the majority of this blog post will concentrate on.

The cold front moves across the region today.  Light snow will overspread the mountains of eastern Tennessee and western North Carolina, and provide an inch or two of snow for locations above 2,800 feet.  Not a big deal.  The big deal comes Tuesday afternoon and night.

A winter storm watch is in effect for the following counties in the mountains of western North Carolina from Tuesday afternoon through Wednesday afternoon:  Avery, Madison, Mitchell, Madison, Yancey, Haywood, Swain, Buncombe, Graham, Ashe, Watauga, Grayson, northern Jackson, Caldwell mountains, Burke mountains and McDowell mountains.

During the day on Tuesday the upslope flow becomes firmly established across the mountains, and snow shower activity will steadily increase through the morning and early afternoon.  As the afternoon wears on an upper level disturbance will swing through the region and enhance the snow, as well as produce some wind.  That is when things get really interesting for especially the central and northern mountains of TN and NC, and especially west and northwest facing higher slopes.  Snow showers will increase to intense snow squalls and the wind will increase, producing low visibilities and blowing and drifting snow.  This will all generally be after about 2pm, and lasting through Tuesday night.  After that, the disturbance passes, and just general light to moderate snow shower activity will continue through the afternoon on Wednesday before coming to an end around sunset on Wednesday.  When all is said and done, elevations above 2,800 feet in the central and northern mountains of NC, and TN mountains along the border with NC, will have a general 3 to 6 inches of snow on the ground, and the ski resort elevations above 4,000 feet could see up to 8 inches, and possibly more than that in the most favored upslope regions.   Beech mountain, Sugar mountain and Wolf Laurel should make out very well with this event, so skiing will be back in full swing for the TN and NC ski resorts through the upcoming weekend.

Just a quick mention about the cold weather, then the warm up and severe weather chances that I mentioned in my blog yesterday.  We are definitely still on track to see some cold weather Tuesdsay and especially Wednesday.  Lows in the ATL area could drop into the 20’s with teens outside the city, with highs only in the 40’s on Tuesday, and possibly not making out of the 30’s on Wednesday.  Then starting Thursday the warm-up begins, and we are into the 60’s by the weekend.  In fact, this looks to be an awesome weekend coming up for any outdoor activities.  Heading into next week there are still some indications that a pattern that could favor some intense thunderstorm activity for parts of the eastern half of the nation could evolve by the middle or end of next week.  There is no way to be any more detailed than this right now.  This will be something that I’ll be monitoring, and as details come into better focus, I will certainly pass along my thoughts on this, but that probably won’t be until early next week.

Major Southeastern Winter Storm Still on Track, but Many Questions Remain

Posted in Severe weather, Winter weather with tags , , , , , , , , , , , , , , , , on January 30, 2009 by stormstream

As has been the case since about the middle of December, it is model madness today in regards to the major winter storm that will affect the Southeast next Sunday night through Wednesday.

The GFS is trending faster and weaker with the system. If this model were to verify then most areas between I-40 and I-20/85 would see a minor to modest snow event, with the southern Appalachian mountains making out pretty good, and areas north of I-40 doing ok. Nothing rip snortin’ as my friends in Texas would say, but still a nice little winter event.

Meanwhile, the 0z run of the ECMWF (European model) shows a classic Southeast snowstorm track with plenty of cold air in place to create a heavy swath of snow from Birmingham to just north of Atlanta to Raleigh. With a heavy dumping of snow in the southern Appalachian mountains.

Then you have the NAM, our high-resolution short range model that is showing the low pressure system also taking a favorable route for significant Southeast snow, but without the cold air that the GFS and ECMWF show. Thus, you end up with rain for much of the duration of the storm south of I-40, with a changeover to flurries and snow showers on the back side as colder air dumps in. Again, the southern Appalachians get a heavy dump of snow.

So, based on what the “Big Three” are showing today, one can conclude that there is a pretty good chance for a nice dumping of snow in the mountains of TN and NC, with potentially a foot or more adding up between Monday night and Wednesday evening. Monday night and Tuesday being synoptic snow, meaning snow with the system itself, then Tuesday afternoon through Wednesday being a prolonged period of northwest flow snow and snow showers behind the system that adds yet another 3 to 6 inches on top of the 4 to 8 inches that has already fallen. The ski resorts will be lovin’ it! This part of the forecast one can feel somewhat confident about. However….

For most of us in the Southeast who do not live in them thar hills, the snow forecast for Monday and Tuesday is still a very difficult one. Now it would be a lot easier if the forecast models had been performing consistently well this winter, but that is not the case. All of the big three, the GFS, NAM and even the ECMWF (statistically the most reliable medium range model) have been performing consistently poorly since about the middle of December. So, what we have to do is look at the performance of each one over the past 50 days or so, and try to draw some conclusions on which one is going to do the best based on past performance.

The GFS has tended to be too fast with moving systems in the 1 to 5 day range. This was very much the case with the last system – the ice storm. I feel that it is again too fast with the movement of the current system.

The ECMWF has been inconsistent this winter in the 6 and 7 day period, but it has performed much better than the GFS in the 1 to 5 day range. Therefore, I would tend to lean more toward following the ECMWF solution with this particular storm.

Finally, the NAM had not performed well at all as a short range forecast model up until this past storm. It did pretty well with the ice storm west of the Appalachians, and I regained some faith in this model again. However, with the system that will be developing this Sunday I feel it is under-forecasting the cold air. There is a decent snow and ice pack north of the Southeast region, and this is going to help with the southward penetration of cold air into the Southeast. Also, the NAM does not show much of a surface high pressure reflection across the northern Plains, the source of the cold air for our early next week storm. It has a 1034mb high over Idaho. Meanwhile, the GFS and ECMWF both snow a nice over 1030mb high pressure system seeding the cold air for the Southeast. I’d tend to buy the colder models over the warmer NAM at this point.

So, with all this said, my forecast for this system at this time follows closely what the ECMWF is showing in terms of surface low track and cold air, although I do feel the track of the low will be a bit more north and west of where the 0z ECMWF is forecasting it. I am also using the NAM as my forecast model of choice in regards to the speed of the system. This all translates into the potential for a swath of significant snow stretching from northwest MS middle TN, northern AL and north GA, and into western and central NC. The mountains of NC and TN will also see a heavy snowfall of a foot or more in some locations. By “northern AL and north GA” I’m talking about a line from Tupelo, MS to Cartersville, GA to Taccoa, GA. Still too early to pin down amounts in the potential swath of significant snow, but amounts could be over three inches. South of that more significant snow, I’d say accumulating snow will be possible along I-20/85 for cities like Birmingham, Atlanta and Raleigh. Again, it is too early to pin down a specific amount forecast so I’ll give a range of anywhere from a trace to 3 inches.

Finally, we cannot forget there will be a severe thunderstorm component to this storm. First for southeast TX and southern LA on Sunday, then along the Gulf coast of MS, AL and the Florida panhandle on Monday. Parts of extreme south GA and the Florida peninsula on Monday night. Then the eastern Carolina’s on Tuesday. Main threats will be damaging winds and some hail.

I just took a look at the 12z NAM, and here are some quick thoughts on that. First off, the NAM continues to show a slower speed with this system. I am even more confident now that the faster solutions shown by the GFS and ECMWF are less likely to verify than the slower NAM. So, I think the NAM is definitely onto something in regards to speed. Next, the 12z NAM is snowing the surface low tracking across the Gulf of Mexico, well south of the coast. This has resulted in a deeper southward penetration of the cold air, so the 12z NAM is definitely colder than its predecessor. Based on what I am seeing, I’d still say a swath of significant snow is possible for much of central and southern AR, northern MS, northern AL, much of TN and western and central NC. Maybe not so much of a dumping for the mountains of TN and NC if the low tracks that far south. I still buy the ECMWF track of the surface low more than I buy into the southern track depicted by the NAM. It’ll be interesting to see what the 12z ECMWF shows.

Bottom line: Still more questions than answers, but we are definitely starting to get some answers now, and more will come into focus later today and especially tomorrow, so stay tuned!!