Sunday, December 28, 2014

Update - December 28, 2014

In the last post (click here) I discussed several things.  One was the opportunity for a little snow across the high plains (2 to 4 inches) for Friday into Saturday, but with a lot of uncertainty of the location.  Again, it's very difficult to impossible to pin point amounts or location when it's several days or more out.  In advance of the minor storm that produced the snow it warmed up considerably on Christmas Day with many locations reaching the 50s and 60s.  The snow that fell was concentrated in two locations across the plains. See the map below...(click for a larger version).

Attention now turns to a extreme Arctic outbreak, one that has been predicted for some time.  As of Sunday afternoon the leading edge was moving into the Dakotas.

Looking at the satellite, the polar jet stream was making a plunge into the U.S. and the cold has only one to go...SOUTH!  By Tuesday temperatures will have fallen into the single digits across most of the high plains (and perhaps below at a few spots).  Readings will stay primarily in the single digits during the day and with stiff north winds the wind chill index will be in the dangerous category.  There is even some evidence that temperatures may not get much above zero at a few spots.  Even with not much clearing Tuesday night it appears readings will fall below zero at many locations (see maps below). 

BTW, those temperatures you see on the above map?  That is NOT the wind chill index, it is the air temperature!

Snow will accompany this cold outbreak.  The liquid to snow ratio will be high so it should be a pretty fluffy snow.  I have high confidence of 1 to 4 inches across much of the high plains.  Details of course this far out are impossible so stay informed through the NWS website

Wednesday, December 24, 2014

Quick update - 12/24/14 - Get ready for an Arctic intrusion

Current Weather

As I discussed in the previous post (click here) I was anticipating a significant storm east of Kansas.  As far as snow, not so much.  But the current storm along the Mississippi Valley produced killer tornadoes yesterday (Tuesday) in the south and now extreme turbulence over the midwest. This is impacting travel by air with significant delays being experienced.  There will be snow across the Great Lakes though.

The other feature that I discussed in the last post was the system that at that time was northwest and west of Hawaii.  It was anticipated that it would cause some issues as it approached late in the week.


This feature that had been north and west of Hawii is now (as of Friday afternoon) diving into southern Oregon and extreme northern California, as seen in the satellite image.  Click for a larger version.

This X that is depicted on the map will intensify as it dives southeast into the Rockies.  There is still a lot of uncertainty in the track and amplitude.  However, just as expected in the previous post, the surface response will cause much warmer temperatures across the high plains on Christmas Day.  Enjoy those temperatures as that will be a distant memory very soon.

As the surface and upper systems organize it appears that precipitation will develop late Friday and into Saturday.  There should be a quick change over for much of the plains, with accumulating snow expected.  But as is typical, it's impossible to pin point where and how much.  Again, keep checking for the most up-to-date forecast.  I think it's reasonable to expect a 2 to 4 inch band with this system - but the where just can't be forecast this far in advance.

The Cold

As I've expected for some time (go back to the previous posts) the Arctic cold is still on schedule.  In the post I did Monday I threw out numbers of 20 to 30 degrees below normal. I'm gaining confidence on the cold and there is pretty good evidence that by the middle of next week we could be looking at some VERY cold temperatures!  Specifics will depend on snow cover, sky cover and wind.  But there is the potential for lows much below zero across a large part of the high plains.  There could even be daytime temperatures around zero or colder and with wind producing life threatening wind chill readings! Those with livestock interests should prepare for very harsh conditions.

The map below is just a guess, but depicts a strong possibility.

I'll try for an update on Sunday.

Merry Christmas!

Monday, December 22, 2014

Update 122214 - Get ready for the cold

I've been trying to figure out the cycle length and orientation of this years weather pattern and I "think" I have it figured out.  If I've got it right, then expect a pretty severe cold spell starting later this week and progressively getting worse into the first of the year.  Before I discuss that, I want to look back at what recently happened (and is currently on-going).

Past Weather

In the last post on the 16th (click here) I discussed the possibility of snow across much of Kansas.  Indeed it did materialize.  The heaviest amounts were in a stripe from northern Clark county to north central Kansas.  Local to the Dodge City area the most reported was 6 inches near Belpre.  Much of western Kansas only saw a dusting to nothing at all.  Click on the map for a larger version.

In addition to the forecast of snow, I discussed the likelihood of Arctic air returning for the last part of December, plus the hunch of a high impact storm around Christmas.   That is still on track.

Current Weather

As of today (Monday) there was an organizing storm just north of Kansas City.  Widespread rain was falling across northeast Kansas.  There were sprinkles across the western part of the state.

This storm was evolving and deepening with another shot of energy diving southeast across the western high plains which will develop into another storm, east of Kansas.  By Christmas Eve there should be a very strong storm impacting much of the eastern half of the country.  The combination of the two storms mentioned will bring travel headaches to the country.  If you're traveling by air on Christmas Eve or Christmas Day, expect major delays!

Behind these two storms there will likely be a dump of Arctic air into the country.  Looking at the current surface chart from Canada, there is very cold air building up and headed this way.

I've mentioned in several previous posts about trying to figure out the repeating pattern cycle length.  I think I've got a pretty good idea.  If my calculations are correct, then an extended cold period is likely, starting right after Christmas and continuing into the first of January.  The cold could be 20 to 30 degrees below normal. That would mean lows in the single digits to perhaps below zero, and highs in the teens and 20s.

What about moisture?

Looking at the satellite map below, there are several features to point out.

The first is the low that is currently north of Kansas City.  This won't have any impact on the high plains but has been bring the rain discussed above.  The second feature is really not depicted on the map but is essentially a very strong jet stream that will be diving into the deep south bringing the travel impacting storm by Christmas eve, but east of Kansas.  The third feature is the X north and west of Hawaii.  This will be our next weather maker as it will be approaching the plains late Christmas day and into Friday.  It's impossible to predict the strength or location (and track) but it should have an impact on travel across the plains.  In advance of the system, it will cause of surge of  mild air to head north with above normal temperatures possible across Kansas for Christmas Day.  But as the system moves out of the Rockies, it is likely that cold air to the north will be tapped so that there should be wintry precipitation with it.  I just can't say at this point if it will be Nebraska, Kansas or Oklahoma.  Stay tuned.

Another feature is the big blue H over the Pacific.  This is an upper level ridge that will intensify and build into western Canada over the next week.  Depending on the amplitude, a very cold airmass is likely to drop into the states.  This cold will be similar to what happened in November.  Anytime an Arctic airmass resides over the states, any minor disturbance in the flow aloft usually results in some sort of precipitation.    I think the end of the month and into the first of the year could get rather interesting.  I'll attempt to update this again soon.

Tuesday, December 16, 2014

Update - 12/16/14

Past event

In the last post I did on the 8th (click here) I discussed the potential for a storm a week away.  That storm did materialize and brought widespread precipitation and even at least 3 tornadoes to Kansas and Oklahoma.  If you didn't get a chance to see the tornado video in Harper county, it can be viewed here.  There was at least one other tornado in Harper county and also at least one in Oklahoma.  Tornadoes in December in Kansas are rather rare, occurring about every 10-15  years but usually east of I-35.

In the cold air of northeast Colorado there was up to 12 inches of snow.  Elsewhere in Kansas there was quite a bit of rain in some areas.  (click for a large version)

This was the second mainly rain event in Kansas this month.  For December that is just a bit unusual but also rather typical for an El Nino type winter.  The cold we saw in November WILL eventually make it back into the central U.S., it is just a matter of time.

The precipitation that has fallen this month is certainly good news but there are areas that are still missing out.  The U.S. drought monitor map shows areas that are still exceedingly dry (although the map does NOT take into account the precipitation that fell this past weekend).

For Dodge City in particular, even with above normal precipitation for 2014, the ongoing long term dryness can be seen in the graph below.  That graph shows the deficit of moisture that has been in place since October of 2011.

The current atmosphere

As of this Tuesday morning there was a fair amount of snow cover across Canada and parts of the northern plains.   The good news out of this is the snow accumulations across the drought stricken west.  There has also been copious amounts of rainfall in the lower elevations out west going a long way in reservoir storage and relieving much of the drought.  Back to the snow cover, it is about normal for this time of year.

Looking at the satellite image, there are several important features.  One is the anomalously strong jetstream across the Pacific, meaning wind speeds aloft area VERY fast. This type of setup is unstable and usually leads to downstream amplification of weather systems.  This is NOT the first time we've seen this during the this years fall and winter.  There are several upper level lows or disturbances denoted on the map.  The most important for the near term was the X that was approaching California and the other feature, an "L" just west of the Oregon/Northern California cost.  The X will be approaching the central plains late Wednesday and into Thursday.  The "L" will eventually drop southeast and affect southern Texas.  However, the X system will enhance the opportunity for freezing rain and snow across much of the central plains.  The track of the surface response is in question (as is the exact track the upper system takes).  Somewhere across Kansas there could be a stripe of 1 to 4 inches of snow with freezing drizzle or freezing rain across Oklahoma and perhaps south central and southeast Kansas.  The local updated forecast is the best bet to keep on top of that information.  Go to and click on the part of country you're interested in for the local NWS office forecast.

The future

I'm not real confident on the eventual evolution of the flow aloft with so much going on across the Pacific.  However, if you go back several posts, I've discussed the likelihood of Arctic air returning for the last part of December.  I need to analyze the repeating pattern and see if I can determine the cycle length.  I've got a pretty good hunch that there will be a high impact storm around Christmas with a dump of Arctic air about the same time.  If you're traveling by air across the county around that time, be prepared for unpleasantness.  I'll try and get additional details later this week so keep checking back.

Monday, December 8, 2014

Update - 12/8/14

This will have to be short due to time constraints...

See the previous post by clicking here.  In the outlook portion I gave reasoning for a precipitation event that was hammering California and some of that "wave train" energy would make into other parts of the country.  Indeed  many areas were fortunate to receive very welcome rains (thankfully not snow with wind) late last week.  The map below is a crude analysis of amounts, some very generous!

I also discussed the relatively "mild" weather expected through at least the 13th with any major changes waiting until mid-month.  That is still on track. There are some pretty decent signals of a significant storm developing this coming Sunday/Monday across much of the middle part of the country (Dakotas to Texas) with the most likely area centered on Oklahoma and Texas.  As the storm organizes I'll be able to pin point the details so I'll post again towards the end of the week.  Wintry precipitation is not out of the question on the cold side of the storm, but there are way too many uncertainties to guess where that might be at this time.  Check back later.

The Weather Prediction Center forecast of precipitation during the next 7 days....
Even though I can't give a lot of details on this potential developing storm, if you're traveling late in the weekend or early next week, you will want to keep checking forecasts (and they no doubt will change as we get closer).

Returning Arctic air for later in the month is still on track too.  More on that later.

Monday, December 1, 2014

Update - December 1, 2014

 **** the original post was accidentally deleted - so if you saw that, this post might be worded differently ****

Happy first day of Meteorological Winter!  BTW, unlike astronomical winter than runs from December 21 through March 21, Meteorologists define winter as December 1 through February 28, often referred to DJF.

A look back

Back on November 4th, I started mentioning the possibility of a high impact storm that could occur around Thanksgiving.  At that time (and in later posts) the location of such a storm was in doubt.  The storm finally did materialize but impacted the eastern states and up into New England.  If you traveled by air last week, did you experience issues?  The storm dumped large amounts of snow and did impact commerce and air travel nationwide (that had connections to one of the major hubs).

Forecasting a significant storm several weeks in the future (in this case about 3 weeks) is difficult at best.  But, the spatial accuracy is almost impossible, especially for the first few storms of the fall.  After a pattern is established and starts to repeat the accuracy of the location of such storms will improve.  But is this even usual information if the spatial accuracy is lacking?  In this case just knowing that there would be travel delays by air should of helped.

Behind the storm of last week a build-up of frigid air across Canada began to race south into the states.  The low temperatures for Monday morning were very cold behind the Arctic front.

This cold came on the heals of a ridiculous warm spell. Ahead of the Arctic front very warm air descended from the high terrain of the southern Rockies (called adiabatic warming) and spread across the plains.  At Dodge City the high temperature of 78 and 79 on Friday and Saturday (28th & 29th) was the third warmest two day period for late November since records have been kept.   This was the second time in less than a month that record warmth was followed by very cold temperatures.  I would bet this will occur again sometime this winter.

Looking ahead

The jet stream across the northern hemisphere is active, but changing.  There are three features that have caught my attention.  One feature is the "wave train" of energy that is propagating from the Asian continent in an arcing manor into the eastern Pacific west of California.  This downstream propagation of energy is referred to as a Rossby wave or a planetary wave train.

I've highlighted this occurrence on the following map showing the arcing nature.

This wave train is likely responsible for the storm that is bringing MUCH needed precipitation to drought ravaged state of California.   Some of the affects of this will be moving into other areas of the U.S. during the next 5 to 7 days.  The Weather Prediction Center (WPC) has the following possible outcome through December 8th.  Much of the precipitation will be liquid (except for the higher elevations).

Back to the Dec 2014 500hPa map above....another feature that is important is the big red L over the Hudson Bay area and the associated circular flow around it.  This feature has been rather persistent so far this fall and I fear that it may be dominant this winter.  The reason for the "fear" is that is will unleash Arctic air periodically.  The Arctic air will become quite intense due in part to the other big red L associated flow around it that has be parked over Siberia.  If the Hudson Bay feature becomes the dominant contributor to our weather, then a cold and dry winter can be expected for much of the eastern half of the country with the high plains on the western fringes.

However, the wild card in all this will be the flow across the Pacific. There is another feature currently that is contributing to this weather pattern.  This feature is referred to as a Madden Julian Oscillation (MJO).  I recommend that you take a minute and read a FAQ on the MJO by clicking here.  If you're bored and need something to read, take a look at detailed information on the MJO by clicking here.  

Often an MJO causes coherent changes in the jet stream from the tropics into the mid or high latitudes, across BOTH hemispheres.  Look a the map below.  This is a satellite image and I've highlighted the flow from the tropics.  Notice how the flow is mirrored across the equator into both hemispheres.

I believe the "wave train" I discussed earlier in this post and the coherent MJO signal could both be indications of an El Nino response.  If this is true, then the contributions from the Pacific will become more pronounced and continue into the deep of winter.  Combine this with the semi-permanant Hudson Bay circulation and suddenly we're back to the below normal temperatures and above normal precipitation that the previous winter outlook was indicating.

So, for the balance of this month, the weather pattern will be relatively "mild" through at least the 13th of December (with a few minor cold shots - but also mild periods).  Any major changes will likely wait until mid-month.  I'm seeing some indications of another significant shot of Arctic air, especially during the last 10 days of the month.  I'll be watching closely for the signal because if it does come to pass, there could be serious cold issues across much of the central part of the country, including the high plains.  Serious = lows 10 to 20 below and highs around zero to single digits.  That type of cold combined with any contributions from the Pacific could could result in a major storm.