Tuesday, November 24, 2015

Thanksgiving storm update - 11/24/15

On Saturday I had an extensive post about last weeks severe weather and an outlook for the "Thanksgiving" storm.  You can read that long post here.  At the end of that post I discussed the upcoming storm.

In that previous post I showed a satellite image with  three features that were going to impact the plains weather.  The first was a low pressure system aloft (labeled L on the previous satellite image) and talked about how it would weaken as it moved south and then east and eventually into the plains.  Today that system had reached the southern Rockies and as expected was contributing to bringing Gulf Of Mexico moisture northward.  This moisture will translate into low clouds, some fog and drizzle later Tuesday night and Wednesday across a large part of Texas, Oklahoma and eastern Kansas.

Here is the latest satellite image as of Tuesday afternoon...(edit on image below - Sandra, not Rick)

Referring back to the satellite image I showed on Saturday....The original "L" is now the "X" over southern Colorado.  The original X1 is now the strong Low off the NW Coast.  The original X2 has moved to north of Hawaii but will likely still be a play maker for the plains (more on that at the end of the post).

More importantly is the storm, the one off the NW coast.  Again, in the previous post I showed the X with the superscript 1 on the satellite image.  At the time it was just a disturbance but as advertised it has since amplified into a power upper storm just off the Washington coast.  It will continue to drop south and become a big upper low over the Great Basin.  The strong jest stream on the west side will eventually translate around and lift out across the plains Wednesday night and Thursday.  The result will be a strong cold front dropping south into the plains and copious amounts of precipitation developing across the region.

The six million dollar question is just in what form will the precipitation fall.  The upper low has not been fully sampled yet by the National Weather Service observation  program as the storm was still off the coast.  But it has become increasing apparent that there will be mixture of precipitation as there will likely be a warm layer aloft with the storm.  The best guess, keeping in mind the limited sampling in the upper parts of the atmosphere, is the following for Thanksgiving Day and Friday...

The freezing precipitation will likely transition from west to east and this map illustrates perhaps the farthest east.  In other words, it will start as rain in areas like Amarillo, Dodge City, Wichita, Topeka, KC, Lincoln (etc.) and then flip to freezing precipitation later Thanksgiving or Friday.  It should remain all liquid across SE KS and most of Oklahoma.

What's my confidence?  Not that high, at least initially.

Snow amounts?  You're going to here everything because the media likes to use computer forecasting models that sometimes just are not capable of modeling the true atmosphere.  I've already heard 6 to 8 inches for Dodge City, yet there is a strong possibility that it may not even flip to snow until late in the storm.  What I'm saying is that it is WAY TOO EARLY to discuss amounts of snow and exactly where the snow will fall.

Here's the kicker....what about the X2 out in the Pacific?  Chances are pretty high that the upper low that forms out west may sit there for a number of days.  Eventually the X2 system will be ingested into the Great Basin storm and will be "kicked out" across the plains.  The most likely time for this will be late in the weekend.  It too should bring additional precipitation and I'm guessing the frozen line will be a bit farther south and east, but details are highly uncertain, if not impossible to say for sure.

Finally, what about Tropical Storm Rick Sandra that is in the bottom of the satellite image?  It will likely become a hurricane as it turns north.  Eventually the remnants will track  northeast and perhaps into Texas and the lower Mississippi Valley.  That will definitely have to be watched as there is a scenario that it would bring extensive flooding rains to that part of the country.  It's not entirely out the question that those remnants could be even farther north!  It'll have to be watched!

The Weather Prediction Center has the following outlook for precipitation through Sunday.   Impressive for anytime of the year, let alone the last part of November!

Stay informed by monitoring NWS forecasts at weather.gov.  If you're going to be on the road later this week and weekend, you can go to each states road reports web page.  A quick map to each state's DOT can be found here.

In Kansas you can go to: http://kandrive.org/kandrive/roads/#conditions/-98.41/38.3957/7 

I will not be able to update this post until perhaps the weekend.

Saturday, November 21, 2015

Tornado Outbreak - Thanksgiving - Updated 11/21/15

The past seven days since I updated this blog were mind boggling for me, as a Meteorologist, and I'm sure for a lot of you.  I intended to update before now, but it's been a bit crazy.  If you missed the post I did a week ago, it can be found here.  In that post, I discussed the MAJOR storm that was going to impact the central part of the country.  Let me start with the tornado outbreak.

As far back as records go, the severe storms with numerous tornadoes was a historic event, especially for the area west of about 98 degrees west longitude.  Not all tornado tracks have been calculated yet, nor the number, but so far it looks like at least 3 dozen occurred!  Unreal for this late in the fall! 

But, let me just put this out there.  The tornado events were NOT the result of El Nino!  If you go back a few posts, you will understand why.  First, El Nino is not a "thing" or object that causes storms on a very small scale (such as tornadoes).  Second, the atmospheric flow aloft (jet stream) has NOT responded yet to the warm event in the Pacific (El Nino).  

The more important features could be the relatively warm waters of the North Pacific interacting with the MJO (have discussed this already), and the rapid cooling of the northern latitudes at the surface. The result caused the vigorous upper storm to dig into the southern Rockies (that is not a rare occurrence).  There was a leading "weak" upper system that came out of the southern branch of the westerlies that helped to draw moisture northward out of the Gulf but at the same time was weak enough that there was not a cold front behind it as it departed.  Then this vigorous upper system produced a tremendous jet stream that moved out across the plains (again, not a rare event). Everything came together just right to produce the supercell thunderstorms and resulting tornadoes. These specific type of setups have occurred before (not many), but this time all the necessary ingredients combined to produce the severe weather including the tornadoes.

The following are maps showing the tracks of most of the tornadoes that occurred...(click for a larger image)

I've been a professional Meteorologist for 32+ years and this is the first time in my career that I have been concerned for myself and my families safety once the tornadic supercell developed near Liberal, KS.  I was not at work but was able to interrogate the storm using radar software from home.  I knew the tornado that developed with that storm was large and potentially violent, especially considering it intensified after sunset (one reason is the nocturnal jet that forms after dark).  The track was consistent and it became increasingly apparent that Dodge City was in the potential path.  What made it worse, for me personally, is that the track was consistently right at my house!  Plus, the storm was showing absolutely NO change in intensity which was very concerning.  I got extremely nervous and actually a little sick to my stomach because I knew if the trend continued there would be tremendous destruction and a high potential for loss of life.  Visions were running through my mind of my personal belongings being scattered to other parts of Kansas.  I didn't feel a threat for my families safety though as I'm fortunate to have adequate shelter from these types of events. Wow, my cell phone about burnt up from the constant calls and text messages.  It was intense!

Here is a map showing the potential track (red line). 

BTW, this would have also been right across the Boothill Casino and the Dodge City High School.

Fortunately for Dodge City, the storm finally cycled and the original tornado weakened and turned north before dissipating, but not before travelling an astonishing 51 miles!  I might add that at it's largest size, the tornado was 1.1 miles wide with winds varying from 100 to 155 MPH!  Over a mile wide...think about that!

A second smaller and weaker tornado developed as the first was dissipating and fortunately (again for Dodge City) it turned immediately north.  

In addition, look at how fortunate Kismet and Plains were!  The two towns were blessed in a way. The original track would have taken the tornado right over both communities!

One final bit of information on these tornadoes.  The track and size of the tornadoes from Liberal were almost identical to what happened May 26 of this year!  The only difference was as the storm approached Dodge City in that event, the tornadoes turned to the right instead of the left and spared the city!

So, after the severe weather outbreak, the following day was greeted with a major snow storm!  The heaviest snow fell in a band from northwest Kansas into southeast Colorado.  The largest amount I saw was near Colby where around 20 inches fell!  This morning (Saturday the 21st), the band of snow still on the ground was very evident.

The storm that produced the severe thunderstorms and snow, also brought quite a bit of precipitation. Here is a map showing the estimated amounts for the past seven days.

Doing the damage assessment survey of the tornadoes, I saw a fair amount of milo that had not been harvested yet.  Unfortunately, most of it was sitting in standing water and likely will not be cut until the ground freezes later this winter.  I discussed this possibility in the previous post.

The earthquake on the third day?  I'm a Meteorologist, not a Geologist LOL.  It was the first time that I have been aware as it happened.  I was awoken by items rattling on the walls. 

In that post I did a week ago I mentioned the potential storm for Thanksgiving week.  Wouldn't you know, the potential is growing!  I won't go into too many details just yet (and I will do my best to update this Monday or Tuesday).

The latest satellite image from this morning...

This is a busy and very complicated satellite image showing numerous contributors for this weeks weather.  

First, the "L" off the west coast.  It is moving south and will eventually weaken and move across the central U.S. sometime Tuesday.  It may be just strong enough to bring some showers, but more importantly it will help to bring Gulf moisture back north.  

Second, look at the bottom right.  That is Tropical Storm Rick.  It, if it gets picked up by the jet stream, could potentially bring excessive rains to parts of Texas or lower Mississippi Valley.  

The most important feature is the X labeled with the 1 (Thanksgiving system).  It is really just a minor disturbance at this point but is expected to amplify and intensify into the first of the week.  The second X (labeled with 2) will also impact the pattern but at this point I'm not confident on it's interaction.  There are numerous possibilities at this point.  Once the X (#1) begins the amplification process I should have a better idea of all the developments.

At this point, the most likely solution, would be a major snow storm for the northern and central Rockies and out into the adjacent plains and perhaps as far as northwest Kansas.  Rain and thunderstorms will become increasing likely elsewhere.  All this would occur, most likely, up to Thanksgiving day.  The end of the week and into the weekend would be followed by MUCH colder temperatures with areas of the northern plains down into Nebraska potentially staying in the single digits for highs.   Details are highly uncertain so check back Monday or Tuesday.  Stay up-to-date by checking weather.gov.

A first guess at the amount of precipitation that "may" fall through the end of the week...

Again, details are highly uncertain so check back Monday or Tuesday.

Saturday, November 14, 2015

Update 11/14/15 - MAJOR storm

In the post I did on the 11th (click here) I discussed the vigorous storm lifting out of Kansas (which brought a "mini" blizzard and eventually severe weather including tornadoes to the midwest).  This system was the first intense development of the fall season.  Also in the post I talked about the Madden Julian Oscillation (MJO) and the impacts it was going to have and was having on the jetstream and a possible storm for the first of the week.

Updating that situation...indeed it looks as amplification is taking place in the winds aloft.  Looking at the satellite image from this Saturday afternoon....

The extended jetstream from the MJO is pointing towards southern California in the image.  Upstream, nearer the MJO, the Rosby wavetrain energy propagation was forcing strong riding of the flow across the Pacific basin.  This in turn is causing the significant deepening of the storm (#2 on the image) that will impact the plains this week.  Before I discuss that storm further, look at the "little" system (#1) on the image south of the Four Corners region.

This little storm, number 1, was helping to increase flow across Texas bringing increasing clouds and humidity.  Showers and thunderstorms will be increasing across Oklahoma and Texas, especially Sunday and some of this will move into Kansas (especially south central and eastern Kansas).

Back to the more important feature, #2.  There is still a tremendous amount of uncertainty of the magnitude and placement of this system as it drops into the Rockies and movement into the plains.  The possibilities are numerous.  There is no sense in getting specific at this point.  But, what is certain is that this storm will be intense with the likelihood of  severe thunderstorms, heavy rain, lots of wind and most likely heavy snow.  The "where" is just plain impossible to nail down, at this point in time.  But here are some educated "guesses"..

Severe weather early (Monday)...from the Storm Prediction Center

The severe risk for Tuesday will shift south and east.

As far as precipitation from this storm for Tuesday and Wednesday, here is an educated guess from my office...NWS Dodge City

Regardless of where everything sets up, I think there is a very high probability of precipitation that WILL impact harvesting of any residual crops across the plains. I hope those that need to get corn and milo out of the field are doing so this weekend.

I'll try and update this Monday to get more specific, hopefully.

Beyond this system, it looks like a much colder pattern is setting up towards next weekend and into Thanksgiving week.

Wednesday, November 11, 2015

Update - November 11, 2015

Just a quick update.  See the previous post here

The Fall pattern is getting cranked up, finally.  The first major "cyclone" to impact the central U.S. was lifting rapidly out of Kansas this Wednesday afternoon.  Blizzard conditions were observed for a time across northeast Colorado, far northwest Kansas and into Nebraska.  The visible satellite image was impressive this morning showing the typical comma shaped pattern associated with deepening mid latitude systems.  (click for a larger version).

In the "warm" sector ahead of the storm there had been a few reports of tornadoes, a couple of hail reports and a lot of wind damage reports from thunderstorm gusts.  This type of system will likely repeat again this winter and then again in the spring and early summer.  I should get an idea of a general time frame for this to happen in two to three weeks, so stay tuned.

The jet stream (strongest winds aloft) will continue strengthening and storm systems will begin to amplify more readily across the U.S..  Currently I'm watching a Madden Julian Oscillation (MJO) out over the Pacific.  I've talked about the MJO numerous times in this blog.  There is currently an awesome response from this MJO as it continues tracking very slowly east/east southeast.

Energy is being transported poleward (mirrored in both hemispheres) and it will eventually allow the Pacific jetstream to expand eastward into the western part of the country.  This should serve to help systems amplify across the west which will then impact the plains.

First up will be a potential precipitation maker late Monday into perhaps Wednesday.  There have been a few computer forecast models that have had this depicted to varying strengths.  If this does develop, then there will likely be another behind it toward the following weekend.  I'll try and update about these two systems and their developments sometime this weekend.

Thursday, November 5, 2015

Thunderstorms in November & CoCoRaHS - quick update 11/5/15

See the previous detailed post I did yesterday by clicking here.

In that post I gave an outlook into next week.

There was a narrow band of thunderstorms that swept across much of Kansas yesterday evening.  Here is a map showing the rainfall...(click for a larger version)

The rainfall was highly variable with some areas getting nothing or very little and others getting over an inch.    Rainfall maps like the one above can be made much more accurate if we had more observations.  One way is to ingest observations of rain gauge amounts through  a program that was started back in 1998.  That program is CoCoRaHS.

Events like last night, with the highly variable amounts that fell,  could be more easily verified if we had more reports.  Look, for instance at Ford County, KS.

Radar data was used heavily in generating the rainfall map but that radar data also ingested reports from CoCoRaHS to verify what the radar was calculating.  The CoCoRaHS program is an extremely important part of the observing program.  I talked with a few folks in Ford county that had 3/4 to 1 inch.  Please consider joining!

Wednesday, November 4, 2015

Update - 11/4/15

In the post I did on the 29th (read it here), much of the discussion was about the "Halloween" storm that had been discussed about in previous posts.  In that last entry, I showed a map of expected precipitation.  Here is that map..

and here is a map showing the precipitation that ended yesterday...(click for a larger version).

That was a pretty good forecast from WPC!

I also posted a map of the expected jet stream position for today (the 4th) and highlighted the unseasonably mild conditions with a chance for thunderstorms and where snow might fall this week.

Here is that forecast map from last week...

Here is the latest satellite image from this afternoon....
So far that forecast from last week is panning out perfectly!  There is currently heavy snow in the Rockies and the afternoon's temperatures are certainly mild for early November.

With the recent precipitation and with these mild temperatures it sure appears as if the Winter Wheat is making rapid Fall growth!  I'm only guessing, but is there now going to be a problem with green bugs?  A widespread hard freeze is still a ways off (although a freeze is likely soon - see below).

Looking back at the satellite image above, the upper system near Las Vegas will be progressing east and north during the next 24-48 hours.  Thunderstorms are going to be possible as this system moves out into the plains.  But the timing will prevent anything widespread until the system gets farther east.  The main risk of severe weather will be across the eastern half of Oklahoma and Texas.  

Here is the expected precipitation for the remainder of the week and into the first of next week....

Looking ahead...

The winds aloft are increasing with a lot of "energy" starting to build up across the Pacific.  As systems move off the Pacific into the U.S., there will be the opportunity for them to intensify into major storms during the next 1 to 3 weeks.  HOWEVER, not all signs are lining up, just yet.  One piece of this puzzle I look for is the blocking across the North Atlantic.  With blocking in this region, storms tend to slow up and amplify meridionally across the U.S.  One index I look at is the North Atlantic Oscillation index (NAO).  Currently it is positive (no blocking) and is expected to persist that way for a while with tends to allow storms to progress rapidly across the country.  But, it can change phases very quickly so close monitoring is essential.
Here is a plot of the phase of the NAO (historical and projection)...
Notice that by next week there is some suggestion that the index will go negative.  I'll be watching that closely as some of the aforementioned systems coming off the Pacific could amplify much more strongly than what is currently expected.

As far as a widespread freeze....

Once this current system moves out into the plains, there should be a "cool" shot of air behind it.  This time of year there does not have to be a really cold airmass to allow for freezing temperatures.  I suspect that temperatures will get to freezing Friday through Sunday, at least as far south as the Oklahoma/Kansas border.  Just how much below freezing will depend on sky conditions and surface winds.  For many areas of the plains, the first "vegetative killing freeze" has not occurred yet, but it is several weeks later than the climatalogical average. 

Again, any system that exists later next week will have to be watched for amplification.