Thursday, February 27, 2020

Update - February 27, 2020

This past week has seen another couple of decent precipitation events for much of the area.  Even parts of the moderate drought area did get at least some precipitation.  The following map shows where the precipitation occurred and how much fell (rain and snow):

With the latest events, the amount of precipitation (rain and melted snow) has been rather impressive for the cold season!  Since January 1st, many areas have had more than 3 times what is normal!  This has also occurred where it has been "wet" for 5 to 6 years!  Here is a map of the percent of normal for the period January 1 through today (Feb 27):

In the previous post I did on the 21st (you can read it by clicking  here), I had mentioned "hints on perhaps another system around the 3rd of March, give or take a day or two".  How does that look?  Well, let's look at the satellite image for today:

The Jetstream continues to be a configuration to "bottle up" the REALLY cold air well to the north.  But it continues energetic enough to keep it active.  There is a pretty wet storm off the California coast.  But, it is not moving much at all, unfortunately.  It appears that it will spin down before making much progress east or before it is able to impact the mainland.  The potential March 3 system based on the pattern cycling is present!   But as of today, it is merely a minor disturbed area of the atmosphere across the northeast Pacific and is denoted by the red circle on the image above.  That is almost 3,500 miles from Kansas! 

There is a really good chance that it will amplify and dive south by the weekend, and into a decent storm!  However, almost every computer forecast model takes it way south and then east across Texas and into the lower Mississippi Valley by next Tuesday (the 3rd).  There is still at least a very small chance that the eventual storm comes out farther north and west which would impact at least the eastern High Plains!  The Canadian Forecast Model has actually had that solution several times in it's model runs of bringing widespread rains back into much of Kansas.  Confidence of this happening though is very low.  We'll see.

Yesterday at a meeting I mentioned the 10th as a potential date for another system.  There continues to be a hint at that also by some of the long range models.  

As far as temperatures - more of the same of ups-and-downs.  But, nothing Arctic in nature is showing up nor is it expected for a while - if at all.

Finally, you probably have seen this image floating around...

That white stripe is only a 8 to 12 mile wide band of snow that fell a couple of days ago.  That was 8 to 13 inches of snow that fell in just 3 or 4 hours!  Either side of it - NOTHING!  That can be attributed to mesoscale forcing that is extremely difficult if not impossible to forecast it's existence or location even 6 hours from occurring!  

A satellite view (green is snow cover in this image)

No photo description available.

Finally....April 21-22, 2020.  Some of you know what that date represents.  More on that in the next post or two.

Friday, February 21, 2020

Update - February 21, 2020

After quite a few weather and climate presentations over the past 2 weeks, I'll share some of those highlights in this posting.

This seasons (since October) forecasting has been particularly challenging (more so than what would be typical) for the central U.S..  Computer forecast models, and not just the American model, have failed miserably many times on type, intensity and location of upcoming weather systems.  For me, I've got some longer range outlooks pretty spot on but have not done so well with others.  

One particular contributor to the weather pattern (at least on a seasonal scale) has been the Arctic Oscillation (AO). In that previous post I did last week on the 14th (you can read that one by clicking here) I mentioned the positive phase of the AO was possibly, and partly, responsible for the relatively mild winter so far.  Lately, the phase has been extremely positive!  My initial outlook back in early November I said "this Winter outlook = very changeable   Averaging out the very cold to rapid warm-ups should yield temperatures near normal for the winter."  Well, there certainly have been many cold fronts but followed with rapid warmups!  But the warmups have lasted longer and the cold has (for the winter) not been overall cold.  The winter (DJF) will end up being anomaly mild (but not a record as many have said).  I did have a cautionary statement since it was early in the new pattern: If the pattern locks into place during the warm phase then it would be warmer than normal.  That's exactly what happened.

As for precipitation in that post: AS far as precipitation - these numerous intrusions of cold and the way the jetstream configuration has been does not bode well for precipitation.  Based on what has happened so far, I would lean towards the dry side.  But, again the pattern has not fully developed so there is still a bit of hope.

For much of the high plains that worked out pretty good.  But other areas have had a pretty good amount of precipitation!  The forcing for more precipitation than expected can be tied to several active Madden Julian Oscillations - and that continues!  But that excessive dry area of especially far western Kansas into eastern Colorado continues to be a concern.

Going forward....

First, here is a map of precipitation that was observed this past 7 days...

That precipitation you see there on the map was primarily snowfall.  That was not well forecast a week in advance.  So, I consider that a "bonus" event which is always good this time of year!

In that previous post I did on the 14th, I discussed the MJO and it's phase and if (emphasized IF) it was one of the strong contributors to the current pattern, then weather systems would get very active at the end of February and into March.  As of this writing, that appears pretty likely.  Here is the current phase of the MJO:

Based on historic MJO events in the current phase space, it gives me more confidence in that increase storm chances going well into March.

Looking at this mornings satellite image:

There was a strong system approaching California and was directly tied to a response in the southern branch of westerlies from that MJO.  This system approaching California will bring widespread precipitation to the central part of the county this weekend.  In fact, I can tie this particular hemispheric upper flow to what happened in late December, producing widespread rain on the 27th and 28th of December! 

Back to the satellite image, the big red X near the top is a disturbance in the strong Jetstream of wind poised to slam into the Pacific NW.  But, the million dollar question is what type of development and eventual path will that take early next week.  There is a small chance that it could strengthen soon enough and dive south where it could provide additional precipitation about Tuesday (for the high plains).  That, IF it happens, would be snow and not rain - along with a lot of wind and much colder temperatures.  Stay tuned with your favorite weather source with that system as we get closer.

Then, based on cycling of the weather pattern, there should be another one of the rapid warmups later in the week.  But, I'm seeing hints on perhaps another system around the 3rd of March, give or take a day or two.  

Going onto March, I think it may stay active with quite a few opportunities for precipitation producing systems.  I'm leaning towards at least normal precipitation.

As I mentioned the past few weeks at the meetings I presented at,  if March ends up near normal in temperatures, then April is almost assuredly going to be "cold".   In fact, lumping March, April and May together I would not be surprised to see that 3 month period average out below normal on temperatures (but as is typical with wild swings of temperatures - especially early).  As far as precipitation, I would lean on those areas that have been wet to continue to be wet.  However, that excessively dry area where the drought developed since fall may have an increased opportunity to get several shots of significant precipitation during that time.  Fingers crossed.   More on that later.

For the next 7 days, here is the outlook for precipitation from the Weather Precipitation Center:

I'll try and update later next week.

Friday, February 14, 2020

Updated - February 14, 2020

Sorry it's been a while since I updated this blog.   Those that have followed this for a while - you know my "excuse"...  Very little free time to get 'er done.

Over the past 30 days, here is a look at how much precipitation has fallen across the central U.S....

The trend of the past few months has continued, not only for temperatures but for precipitation. The Heavy wet snow that fell on the 28th of January made a huge impact on soil moisture.  You can see that impact with the bullseye of precipitation from near Liberal through near Greensburg.  Also, the excessively wet conditions continue across the eastern plains into Mississippi Valley.  The wetness has now shown up across much of Texas!

As far as temperatures, the really cold air this winter has only made brief appearances (such as the current episode).  I really believe the Arctic Oscillation and North Atlantic Oscillation have been mostly responsible for the "mild" winter.  Will that continue?  I have a gut feeling it may not last entirely through late winter.  Based on some cycling of weather patterns, it would appear to me that occasional shots of cold will continue into early March (but also mitigated by brief "mild" periods).  If March doesn't end up that cold, then I bet April will!  More on that later.

What is next?

There is a pretty robust Madden Julian Oscillation and you can see that with the bright colors on the bottom left side of the following satellite image...

There has been a pretty good response to upper flow into North America.  Based on one projection....

IF,, and that is a BIG IF, the MJO carries into phase space 2 on the projection above at a significant standard deviation, then it would appear that storm systems may get really active across the central U.S. at the end of February and into the first week of March.  But, that might impact Nebraska and the upper Midwest, but there is also a distinct possibility the impacts would be farther south into much of Kansas, Oklahoma and Texas.  There is a lot of uncertainty!

In phase space 1 and 2 (getting into March), here is what is strongly possible for temperatures and precipitation....

As far as the next 7 days....cold-mild-cold with very little opportunity for significant precipitation.  From the Weather Prediction Center through the end of next week (21st)...

I'll see if I can get an update in later next week....