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Heading Into A Cold Period With Light Snow / Snow Shower Chances

The groundhog said we would have an early spring and it looks like his forecast is not going to verify. There is a a blocking pattern that will set up over the north Atlantic that assures us of cold air next week and likely multiple chances at snow showers or light snow.


The Infamous Omega Blocking Pattern!


The NAO or North Atlantic Oscillation is basically the El Niño of the Atlantic Ocean. When the NAO goes negative it supports a large blocking pattern over the north Atlantic and normally leads to colder than normal weather in the eastern US. When the NAO goes positive, we normally see warmer than normal weather. Notice the latest NAO state and forecast shows a highly negative phase through early March.



Knowing the NAO phase allows us to evaluate the medium and long range data to see if it is picking up on this setup. When we look at the pattern late next week, we see an Omega (Rex) blocking weather pattern setting up over the north Atlantic. We call it an Omega block because it is shaped like the greek letter Omega Ω. Notice the flow appears to trace the greek letter Omega.


Gfs 500 mb 2


Lastly, you notice the low in this pattern with the bright colors positions itself near the Great Lakes meaning a persistent push of cold air into our area and frequent chances of snow showers / snow squalls.


The bottom line is this is exactly what we would expect to see during a highly negative NAO, so we know the computer model data is sound.



What Does This Mean For Next Week?


It is simple. There is a high probability of colder than normal temperatures dominating the next 10-14 days. The Climate Prediction Center is banking on that and you can see their 8 - 14 day forecast.


CPC 3 Month Temp Outlook


Looking at the GFS late next week, we see below normal temperatures dominating our area. Keep in mind, the blue colors are colder than normal temperatures.


Gfs temperature anomoly 2



How About Snow Shower / Light Snow Chances?


We know that colder air will be moving in later next week so it means any precipitation after about Wednesday has the chance to fall as light snow. Looking at the latest GFS and EURO, we see a consistent fetch of moisture into our area as that low gets stuck over the Great Lakes area. Noting the Omega Block will be in places means this is legit output from the computer models.


GFS Precipitation Late Thursday

Notice the GFS shows light snow  / snow showers widespread in our area Thursday.





GFS Precipitation Late Friday

Notice the GFS continues to show widespread snow showers on Friday.





GFS Precipitation Late Saturday

Notice the GFS shows another repeat performance on Saturday.




Notice the GFS clearly shows the precip type as snow late next week.

Gfs precip type 2

My Thoughts On Mid To Late Next Week


I love writing blogs like this! They are intiquing because there is a cascade effect that produces a number events that lead to the final forecast. We see a negative NAO trigger an Omega (Rex) block over the north Atlantic Ocean which causes the storm early next week to get stuck over the Great Lakes which triggers a cold spell in our area which allows snow showers. We are able to trace the forecast to an initial cause then follow the sequence of events and verify that they are accurate. The sequence of events lead to a sustained colder than normal spell late next week and the opportunity for light snow or snow showers.


It appears there will be a disturbance almost every single day next week. Notice the GFS has literally a train of disturbances in our region mid-late next week.




Each one of these disturbances will provide snow showers or snow squalls. We will need to watch each day closely and we will be able to dial in which has the best chance at any light accumulations. Nothing looks like a snow storm, but some light accumulations on the grassy surfaces are not out of the question in a setup like this.





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Well, hopefully when all done it is piled up past our door... I don't have to go anywhere though !

evan, that is not going to happen. :(

Marc, any chance of these snow showers/squalls being convective snows?

prelude, computer models this far out have terrible boundary layer resolution, so that would be only speculation at this point.

Marc, non weather question for ya. You plan on attending the Carl Casper auto show?

prelude, I am! I wish I could bring my car, but it is just too cold to bring it out.

I hear ya my man im wishing I could get the motorcycle's out but as you said its just way to cold. If I see you up there I will definitely introduce myself.

prelude, sounds good! I was always surprised they did the show so early since weather can really mess things up. Many of those show cars never have seen rain and this time of the year that can get salt on them. It just seems like an odd time.

Yeah I agree I never did quite understand that. Then again I dont understand why the official temp is taken at the airport e but thats a whole different story, one I will never quite get. Anyways, im pretty sure most cars are trailer in. However Louisville does makes up for it with the awesome Hot Rod show in the summer.

I hope to see you out there! :)

Marc, I know you hate long range models. However, Baseball tryouts, etc. etc. are around the corner in the next 2 weeks or so as we transition to the outside spring sports for my kids. Any chance we shake this below normal trend after the next 2 weeks or are we locked into a rather cold March on average?? Nothing more miserable than watching kid in temps in the upper 30's and low 40's for 2 hours

First time I've checked this blog out. Very well put together and detailed. Darn, now I have 3 blogs to look at now:)

Grant, thank you! :)

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