White Christmas

11:55 am in Winter Weather by Ted Keller

Various Snow Projections

Odds are against us getting Christmas to be white with snow most of the time but this year we should should see it!

The storm first highlighted last week has actually held together and the timing puts it into the Ozarks on Christmas Eve.  As with most storms, the track is in disagreement among the computer forecast models.  This has not been much of a timing issue however as Friday still looks like the day with some precipitation breaking out Thursday night.

While the precipitation is expected to be primarily snow Friday afternoon, it night start as a bit of sleet Thursday night.

The graph is valid as of about noon Wednesday.  The plot is meant for Springfield. The reddish lines are one computer model, the blueish are another.  The red model favors more snow with totals right around 2″  The blue model is not nearly as enthusiastic about the white stuff.

Now here are some Ozarks maps.  The first is the red model (NAM), the second is the blue (GFS). The NAM has more snow in general and more to the south.  The GFS has snow largely missing the Ozarks except for areas east of Springfield.

NAM snow

GFS Snow

I’m always a bit torn on snow around Christmas because I know folks want to travel to to see friends and family or to do last minute shopping and even a light snow can snarl things up a bit.  On the other hand, if the actual snow ends up in-between these two models. it won’t be too bad and only an over night snow into Christmas Day could be timed out better! 

What we don’t want is a repeat of 2002, which for those of you who don’t recalled dumped a huge snow on the Ozarks on the 23rd, slowing Springfield down to a crawl!  It took me nearly two hours to get from near Battlefield Road to the studio that day!

Tom and Jill will have the latest!  I’m watching this one from home.  Be safe!

White Christmas?

9:09 am in Winter Weather by Ted Keller

I think our chances for seeing a white Christmas in the Ozarks are slightly higher than average…

This weekend weather system won’t do it even if it does manage to lay down some measureable snow as it will melt pretty quickly.

The basis for my observation comes from just casually glancing at the long-long range models, those that run out 10 days (or more).  Now, no one should ever believe the exact output of any of these models of course.  But I do think you can pick up on some trends if you watch them long enough.

The overall trend for the next several weeks is a progressive pattern of  cold air invasions with storm systems coming out of the northwest and “making the turn” so to speak over the central U.S.  Simply put: there is cold air and storm potential!

As an example, this morning there is a hint at something around the 15th, another near the 18th and perhaps even a third right before Christmas. 

Now, the dates are not nearly as important as number of systems.  While there is no guarantee that any of these will contain the right mixture of cold air for snow or track in a favorable way for the Ozarks, well, how does it go, half the battle is just showing up?  Something like that…

FYI: this is all  in line with what is expected during a La Nina pattern of weather over the U.S.  which puts a precipitation maximum just to our east.

When all is said and done, our ground may end up bare this holiday but hey, this is the season for faith and believe, right?  I’m a believer!

Video Clips of the Dallas/Seagoville, TX Tornadoes, 9/8/2010

7:45 pm in Extreme Weather, Severe Storms by Ted Keller

Footage of a tornado passing through west Dallas, TX late this afternoon.

Severe Storm Front

5:55 pm in Did You Know?, The Ozarks, Weather Education by Ted Keller

Me and the Rapid Scan DOW Radar

The Severe Local Storms (SLS) Conference is held once every two years.  It’s sponsored by the American Meteorological Society (AMS) and its purpose is to bring together scientists, researchers, forecasters and anyone else involved in severe local storms. 

This meeting, held in Denver this time around, comes on the heels of a huge tornado research project.  Vortex 2 was a multimillion dollar data collection extravaganza covering two storm seasons (2009/2010) and involving hundreds of people. 

I traveled here in hopes of learning some preliminary findings from Vortex 2 and also to get a sense for how the project went and whether the goal of a better understanding of tornadoes was realized, at least at this early stage.   There are other topics of research going on as well and I wanted to learn more about these too.

The conference is made up of of sessions in which presenters are given 12 minutes to talk about their subject using Power Point and sometimes video. There are also poster sessions where the information is printed and hung up along with all the other posters.  Attendees can then just walk up to the poster that interests them and at certain times have access to the author(s) of the poster to ask questions.  Finally, there are invited speakers and special sessions to round out the conference.

As is typical when I attend these conferences, there are papers presented which are FAR beyond my understanding.  But what does make it through helps me to understand severe storms just a bit more. It’s also just fascinating!  Researchers are doing some really exciting things in the areas of remote sensing and instrumentation, computer modeling and forecasting techniques.

I’ll blog in more detail here over the next few days as I collect my thoughts and notes and as time permits.

Record Low Pressure!

4:00 pm in Did You Know?, Extreme Weather, In the News by Ted Keller

Very Deep Low 10/26/10 18z

Not since the Superstorm of 1993 has a low pressure system over the United States achieved such a low central barometric pressure!

From the National Weather Service:

“New record set today for the lowest pressure in a non-tropical storm in the mainland U.S. The massive storm system barreling across the central U.S. had a minimum central pressure of 28.24″ or 956 mb (equivalent to the minimum pressure of a Category 3 hurricane). This breaks the old record of 28.28″ (958 mb), set on …Jan. 26, 1978, during the Blizzard of 1978 (aka the Cleveland Superbomb). This is also lower than the March 1993 Superstorm (aka “The Storm of the Century”), or the “Witch of November” storm that sank the Edmund Fitzgerald in 1975, or even the Columbus Day Storm of Oct. 1962.”

Editors note: it looks like 28.21″ is the official lowest pressure of this storm.

Development of "bomb" low! Thanks NSSL!

Such intense lows at the surface of the earth are brought about in this case by a powerful jet stream wind pattern.  For lows at the surface of the earth to deepen, air must be evacuated out of the top of the low faster than it can be replaced from below.  When this is true, air molecules are removed from the column of air leading to less air pressure as measured by a barometer.  This is called hydrostatic pressure or the total weight of the air on the barometer.

Strong jet stream winds high in the atmosphere can set up a path for air to take away from the deepening low leading to a drop in pressure.

Wind at the Jet Stream Level (300mb) 12z 10/26/10

Wind and pressure are intimately related.  The deeper the low, the larger the difference in pressure or pressure gradient observed.  The stronger the pressure gradient, the faster the wind will blow.

This storm had widespread 40-50 mph wind gusts connected to it over areas of Iowa, Illinois, Minnesota and Wisconsin eariler today.  Some of the gusts near shower and thunderstorm bands reached 60-70+ mph.

Also, the storm system has spawed many tornadoes in parts of Illinois (EF2 near Peotone), Indiana and Kentucky.  At  this writing, many tornado warnings were in effect for counties in Tennesee, Kentucky and Alabama.

Link to a great write-up by the Duluth National Weather Service.

Tornadic Supercell Near Richmond, VA!

3:42 pm in Extreme Weather, Severe Storms by Ted Keller

Tornadic supercell with a hook echo passes over the northern Richmond, VA area. Tornado report at Mechanicsville, VA.

Multiple Tornadic Supercells on Wednesday

10:53 am in Extreme Weather, Storm Summaries by Ted Keller

Hail near Brighton

A pre-Thanksgiving outbreak of supercell thunderstorms occurred on Wednesday the 24th in the Ozarks.  Some produced tornadoes.

It would be a challenge for me to count them from memory!  I know that several passed over the same corridor affecting portions of Vernon, Cedar, St Clair, Hickory, Polk, Dallas and Camden counties.  This was the earlier portion of the outbreak from mid afternoon through early evening. 

Damage was reported near Wheatland and Cross Timbers in Hickory County from this early round.  This was confirmed as two tornadoes today by the National Weather Service. 

Later in the evening, the supercells started shifting more to the south.  One cell starting ramping up significantly as it crossed into northwestern Greene county.  This storm continued east-northeast into southern and southeastern Polk.  This storm was responsible for multiple reports of damage near Brighton on the Greene/Polk county line. This too was confirmed as an EF1 tornado by the National Weather Service today.

Looking North from Hermitage. Photo by Ron Gamble.

A supercell started showing signs of rotation in Jasper and Newton county shortly before 8 pm.  This storm remained tornado-warned as it traveled into Lawrence county.  This was of course a concern for Greene county as it approached.  As it crossed the county and city of Springfield, multiple reports of hail from quarter to as high as ping-pong ball sized were reported.  There was also some minor wind damage.  The tornado warning picked up again as it was just leaving Greene and continued through Webster and Wright counties!

Dent county went tornado-warned for a time late in the evening followed by the final warning in Barry county just before 11 pm and into the 11 o’clock hour.

The National Weather Service has a full report on this storm.

Welcome “Weather and Climate” Students

8:35 pm in MSU Classes by Ted Keller

It’s a new semester and there is lots to cover!

This week, we’ll get right on the topic of Hurricane Irene and do a “crash course” lecture on tropical weather systems.

I’ll also cover the basics of atmospheric composition and structure, talk about weather maps and charts and give an assessment test.

Be sure to check out a disscussion board on “Irene” too.

Winter Systems

8:42 pm in Winter Weather by Ted Keller

There are two weather systems which will tap into the abundance of cold air in place over the central U.S. this week.  At this writing, neither seems to be a huge threat.

The first slides in Wednesday.  It’s main threat is to produce light showers and drizzle which will fall into sub-freezing morning air on Wednesday.  This then is a potential for some light freezing precipitation.  It may cause somewhat of a hassle if it happens to occur during the morning off-to-work and/or school time.  It is expected to “warm” on Wednesday afternoon to above freezing in the middle thirties which should eliminate the freezing threat for all but the extreme eastern and northeastern portion of the Ozarks.  The light freezing precipitation may make a comeback late Wednesday when cold air comes back around the other side of this system.

Then on Friday, a weak little weather system is shown crossing the southern Great Plains.  If this finds some strength or changes track slightly, it could deliver some snow to the Ozarks, perhaps leaning south?

Both of these threats are in line with the higher index of weather system count I talked about in my White Christmas thread last week.  In the fantasy-land world of computer models, there are still a few weather “systems” between now and Christmas (which by the way looks cold at this point), perhaps 19-20 and again around the 23rd?  As I indicated earlier, the exact dates are not as important as the fact that thet show up and there is cold enough air in supply.

Weekend Cold (and snow?)

12:09 pm in The Ozarks, Winter Weather by Ted Keller

Another arctic front will slam through our area on Saturday.  

While Minneapolis and parts of the upper Midwest are under a blizzard watch, our portion of the system consists of a cold front and very strong winds in the wake of the front.

Snow chances come in two forms: a brief changeover late Saturday as the front comes through and then some snow that may wrap around the upper Midwest storm which would affect central and eastern Missouri implying flurries in the Lake of the Ozarks area Saturday night.

Some computer models are outputing minor snow accumulations in the same areas I discussed earlier in the week to the northeast of Springfield and those chances remain as they were, outside the mainstream output.

The winds Saturday night and Sunday will be gusting over 25 mph!  This combined with temperatures in the teens will produce wind chill readings in near zero or even slightly below during this time!  Sunday’s high will only reach into the twenties.

Snow and Cold

7:44 am in Forecast Discussion, Winter Weather by Ted Keller

Get ready for more arctic air, led in by some snow this weekend.

The overall picture hasn’t changed too much since yesterday.  There is still a disturbance diving into the central U.S. this weekend from the northwest.  It still looks like it will rev up a storm which gets stronger as it moves east of us.  There is enough cold air to produce snow on its backside in the Ozarks late Saturday. 

There seems to be an accumulation track setting up from just northeast of Springfield, east-north eastward to around St. Louis and on into Illinois and points east.  As is always the case, storms at this distance need to be monitored carefully.  My feeling is that accumulating snow will track through the Ozarks late Saturday.

Then, cold air slams in!  This is easily the coldest air so far this season.  There are hints at single-digit low temperatures Monday morning with highs barely clearing twenty.  Brrrr!

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