Saturday, January 28, 2012

February 2-4 Potential Snow Event (Issued 1-28-12)

This is hour 156 of today's 12z GFS Ensembles. This is the timeframe we are looking at for a potential snowstorm in the East US. As we can see, there are two camps: One that brings all precip north into the Midwest (North Camp) and one that has the most precipitation down south in this page (South Camp). For a simple reference, let's count out how many ensemble are in which camp.
(Out of 12 ensembles)

NORTH CAMP: 8 ensembles (67%)
SOUTH CAMP: 4 ensembles (33%)

Now, of course, many things will change- that was simply for just a glance at it.
Something that makes me think about this storm is checking out the teleconnections.
Here's the PNA forecast.
Most Recent PNA Forecasts
Positive PNA Phase
In a positive phase of the PNA, a ridge sets up over the West US, and the storm track is diverted into the Southwest and then either into the Midwest or Northeast. The forecasts for the PNA in this timeframe (Feb. 2-4) are a strong positive, meaning that the effects of the +PNA will be more pronounced. This is shown in many of the ensembles of the 12z GFS. You can see the +PNA by tracing the red rain/snow line through Canada in the West US then diving back south into the East US.

Something else we can use to check out the storm is the NAO and AO. In the positive phase of the NAO, we see warm temperatures across the East US. The big snowstorms usually fall during a negative NAO. In the ensembles, we have checked and see a -NAO developing on the forecasts. This would bring the biggest snows to the Northeast, theoretically.

The AO is forecast to be negative during this timeframe, which would supply the cold air as well as increase chances for snow for the East US.

But here's where the buck stops for the Northeast's big snow possibility: The MJO.
MJO Forecast
Basically, when the MJO is closest to the edge of the image, the effects of each phase are stronger. Right now, we are in Phase 6. The Green line is the GFS Ensemble forecasts for the MJO, enhanced by individual ensemble forecasts shown in the yellow lines. The current forecast by the GFS Ensembles and other models are to have the MJO go into a strong phase 7 around the time of the storm. Here are the temperature and precipitation effects of a Phase 7 MJO.
Temperature Anomaly

Precipitation Anomaly
The Northeast is typically dry during Phase 7 and phase 6 (in case the MJO ends up in Phase 6 during the storm). That would be a major blow to the forecast, seeing as the MJO would be at a strong level and therefore could deter the AO/PNA/NAO effects. For temperature, Phase 6 and 7 both involve the East US being warmer than usual.

My Thoughts
In my opinion, I think that while some indices are pointing toward a total Northeast Snowstorm, i'm going to have to go with a Midwest/Northeast shared snow event for now. Based on the strong MJO combined with a strong PNA and subsequent -NAO/-AO, it seems likely that the end result will be a shared snowstorm with these two regions. Another thing that enhances my shared snowstorm theory is how the ensembles are more unified with that idea than a pure northeast snowstorm. In this winter where the models are doing poorly, I find much more confidence in a group consensus rather than just one person's idea of a scenario.


mike paulocsak said...

Hello Andrew.I'm not going to post anymore quetions on here due to the fact people are starting to judge how i accidently mispelled a few words in the previous post you had.I didn't come here to be judged,just to talk about the weather.Again Andrew,thanks for answering the questions i asked you.I really regret doing this,but i'm not going to be run in the ground due to the fact that certain JERKS on here don't realize people make mistakes.

mike paulocsak said...

Hi Andrew.This goes with my previous post.They are also say i'm putting your forecasts down in the ground,i'm a bit lost on that one.You know i stuck up for you several times.

Jeremy Petrerson said...

How can we have a winter storm forcasted for the mid west when the local guys are calling for highs in the upper 40's all this week? I'm not saying I don't believe it, just saying its hard to with all the different opinions form the differnet forecasters.

I think we wil have a fairly good Feb, and I agree with your "Equaling out" theory, But I just can't see anything out of this 2/2-2/4 idea.

Andrew said...

Mike: You are one of the most loyal supporters of my blog thus far. I am furious at what has happened in recent days. I will let you decide for yourself, but if you decide to keep commenting and something arises, it will be dealt with swiftly.
Again, it's your decision as of if you want to keep commenting, but I am very sorry and very disappointed in the things that have happened to you.

Jeremy: I understand your point of view. The likely reason is that this storm is too far out and uncertain. Time will tell, i guess.

mike paulocsa said...

Hi Andrew.Don't worry i will.I just don't understand how people can judge someone for spelling something wrong here and there.I notice several people who post on here spell words wrong every now and then.But myself,i let it go.I figure,we are all only human.

Raymond said...

Andrew, when you say shared storm for midwest and northeast do you mean a storm will come in to the midwest,weaken, and then a new storm will form along the east coast?

Andrew said...

Mike: Some people are just that way, i guess. Misinterpretation is what I think has happened here.

Raymond: I mean a single storm will spread its snow/rain across both the Midwest and Northeast.

Andrew said...

EDIT to Raymond: Not in a weakening sort of way- it will affect both regions at once if this verifies.

Vlad said...

I surely hope it will be a snow event. Andrew, did you see the 12z GFS run? Holy cow, widespread 12 inches + in Missouri, where I live. Too bad it won't happen though. :( Curious to see how this storm plays out thought.

Wally said...

Yes the t.v. station's in Chicago are calling for the 40's and maybe 50 this coming week, come Saturday it drop's to the 30's and snow. No mention of Sunday yet.
Wally, Huntley, Ill

ERN WX said...

Why do some people have to go crazy over the simplest of things? Why are you being so harsh to Mike? If you want to discuss ages and spelling, make your own blog to dicuss those topics! Unless I am mistaken this blog is called The Weather Centre, not The Age/ Spelling blog. Please calm down. Thank you.

Andrew said...

Vlad: Yes- the end of the GFS is a storm that everyone in the weather world is closely watching right now for the Northeast, even though it may be long range.

Wally: Thanks for the report!

ERN WX said...

Hello Andrew. Have you been waching the Feb. 4/5 eastern snowstorm potential? I think that there is certainly some hope for a good ( 6+ inches) snowstorm for the I 95 corridor. I would certainly appreciate your thoughts on the matter. From what I have been seeing, with a fresh cold airmass in place precip type would be snow ( subject to change) for many people. The Nao looks to be neutral to negative at the time of the storm. I hope you get some good snow, and thanks for the great work you do!!!

ERN WX said...

Henry is completely thrilled by this storm. I think it may end up slightly further east than what the 12z euro has.