Updated Winter Forecast

Before the winter season began all the teleconnection signals were there to suggest that this Winter would be a colder then normal winter and a snowier then normal winter.
Majority of the region had gotten off to a above normal snowfall thanks to a October 29th Pre Winter Historical East Coast snowstorm.
Since that time period snowfall has been hard to come by in the Mid Atlantic into the Northeast and this can be blamed on three things:
1. The polar vortex which has been centered over Alaska. We need this to be centered more to the east in south central Canada or North Central Canada.
2. Lack of blocking. There has thus far been no positive height anomalies over Greenland. This is again something needed for a cold and snowier winter.
3. Finally the Southeast ridge. This has been a permanent feature of the winter season of 2011-2012 so far.
Looking ahead we see nothing to suggest that this pattern that we have been in is going to change. Yes the GFS suggests its going to change but even that model which was bringing positive height anomalies into Greenland of + 4-+8 now shows negative height anomalies.
So lets look at the teleconnections to see if we can see any semblance of hope:




AO remains positive with no indication of going negative. The NAO remains positive with no indication of going negative. The EPO remains positive and does go negative at the very end of the ensembles. However..the PNA goes negative at the end as well.
In a nutshell the teleconnections suggest that there could be transient shots of colder air with the EPO going negative but with the PNA going negative majority of that colder air will be centered in the PNW..
So…with all the above said this is the outlook for the rest of the winter . For a different viewpoint read what Bobby Martrich from Lehigh Valley Weather Patrol sees for late winter ,but we have to go with what the overall pattern is suggesting and the teleconnections are showing! We hope this is a forecast we bust on!

Where is Winter?

This is the question that is on the minds of every weather hobbyist, every Pro Weather forecaster & every individual who has an interest in weather.

We are going to attempt to answer this question and hopefully by the time we are finished …we will have a clearer picture of what has been happening and where we are heading.

Before we do this though lets look at where we have been..

With looking at the above images you can see exactly WHY the winter weather lovers and pro mets are asking the question..Where is winter? November was warm and December was warmer yet!

What has been the cause of this happening? There are several reasons and we are going to take a look at them now:

First lets look at the Madden Julian Oscillation.

This clearly shows that we are in Octant 5 or phase 5 of the MJO and the resultant look at 500 mb level in that phase is as follows:

As you can see this leads to higher heights across the region which results in warmer weather.

Lets look at the AO and the NAO in the current observations..

Both the Artic Oscillation and the North Atlantic Oscillation have been very positive. Matter of fact the AO has only dropped to neutral territories for a 2-3 day time span since Mid November. Usually the time span for a weather pattern to last before it breaks is 45-60 days. So if you figure this started in Mid November then 60 days would come around Mid January..

Now..before we get into some evidence pointing to this pattern change we want to talk about the upcoming short term time frame..

Now as you can see despite having a very positive AO and a very positive NAO the models above ..ECM & GFS are showing a full  trough with a cold front blasting thru the region with the first true arctic air into the east. European computer model at this time frame and thru 144 hrs. are showing temperatures in the teens- 20’s for highs and lows subzero to teens depending where you reside.

Folks this is some serious cold air. With North Northwest winds this will make the air even colder yet…

Now you also notice that there is a low pretty far off the east coast at 120 hours as well. We have been monitoring this time frame for some time and we still are not 100% convinced the models have this resolved yet. Could this low end up closer to the coast?

The answer to that really depends on whether or not the cold front blasts thru the area and ends up setting the axis of the trough to far to the east. Right now that is what the models are suggesting..However..we are taking the more cautious approach which is thinking that there is still the potential on the table.

First..we have never seen amplification as great as what is being modeled without something happening..and the models are hinting that something could happen but off the coast..but this is what we find interesting..

You can see that the two main models further up the GFS & ECM are as progressive as the most biased progressive model. Generally when we see something like this it factors as a red flag.

Another thing that we want to point out is the AO..which is the reason for the cold air showing up on the guidance ..

Now what we notice here is the extremely positive AO at +4.5 falling during that time frame to – 1.5-2.0. Generally when you see a decline in a teleconnection such as the AO & NAO ..this can indicate a potential storm along the east coast. So ..factoring that into the equation along with the amplification being shown we think that right now it more or less is riding on the timing of the shortwave that will be riding over the top of the ridge. This period needs to be monitored closely.

Now…lets get back to the pattern change around mid month with the 60 days running out. Do we see anything that hints to this occurring ?

As you can see the GFS is for the first time that we have noticed indicating a Negative AO & positive PNA along with a negative NAO in its long range at or towards the period we are anticipating.

The ensembles of the GFS do not quite get the NAO negative ..they do keep it positive but the AO is more negative on the ensembles..

So the signs are there indicating a pattern change is just around the corner. We think by the 22nd of the month of January we will be looking at the pattern change in complete transition to a colder pattern with potential storms resulting in Winter Weather!

Stay tuned as we follow this pattern change along with the possible potential in the next 5 days!

December 27-28th Update & Final Scenario map!

This may be being to generous with the snow on this map. Let me explain why..Latest ECM has the low at 36 hrs. over Hawley, PA. 540 line at this point is in west central PA..and between 30-36 hrs. over the area in snow on the map  only up to .50 occurs. Here is where the problem lies at 30 hrs..the 540 line is back in central Ohio along the Canadian border so the precipitation that falls between 24-30 hrs. would be mainly rain. so by 36 hrs. the .25-.50 that falls is falling during the time frame when the 540 line is starting west of the region and moving to that position by 36 hrs. By 42 hrs. the 540 line is in Eastern PA and into Eastern NY but on the southern end into PA (central and west) majority of the precipitation has already ended. Further NW into the part of NY in the snow map you have .50-.75 falling but again we are starting off with some of that precipitation being rain because of that 540 line being west. Looking at the wunderground maps for snowfall they are not all that generous with the snow either.  So do to the track of the low which basically all guidance now agrees on this looks to be a mainly rain event with some snow possible but unless the colder air comes in quicker the air mass ahead warms up and then where it is colder it is only antecedent cold air at best...

December 27-28th Storm Track

With all guidance now in agreement this is the expected storm track. We will update scenario map later today with rainfall and snow totals!

Post Christmas Storm Wed Dec 28 into Thurs. Dec 29-2012

As everyone is quite well aware the models had given up on the ideal of a White Christmas because they were ejecting the energy from the cut off low over the SW too soon and the storm has become delayed now till the time frame of the 28th-29th. Post x mas storm!

However, before we look at the guidance we are going to take a look at the teleconnections that are in place..

First up is the Madden Julian Oscillation and you can see as of the 23rd we were in Phase 5 of the MJO. Phase 5 is a warm phase for the eastern USA and much of the USA in general as the below image will show you..

These are your 500 mb anomalies and as you can see blue is no where to be seen in the USA but rather green which indicates a warmer then normal pattern.

This should come as no surprise as we see that both the GFS and the ECM are both showing a very positive Arctic Oscillation

Whenever you have a positive AO it means all the cold air is locked up to the north and the USA is generally above normal and this has been the case since at least November 1st..

The next is the North Atlantic Oscillation and you can also see that we are looking at a very positive NAO which is forecasted to go negative but not in time for this upcoming storm system. When the NAO is positive it is very hard for storm systems to slip off the coast to the South and east and inland runners become more common.

Finally the PNA is neutral at best right now but as you can see it is expected to rise. When we have a positive PNA this correlates to troughing in the east or central part of North America and a ridge to the west.

So what we are looking at is a + AO +NAO neutral PNA and a very positive EPO. Along with the MJO in an unfavorable phase.

So the reality of the scenario is that we are having warm signals and it should be no surprise when we see the CPC issue this type of map for the 6-10 day time frame..

Now, that is a pretty clear picture of what the teleconnections in place indicate. This would be the over all theme but it does not mean that some cold air intrusion can not happen it just will not be sustained and that leads us to the storm system for the 29th and 30th.

With a rising PNA this would indicate a trough digging into the east. However..with the other teleconnections unfavorable for any real “arctic air” we are looking at some colder air or more seasonable air incoming . The question is whether or not this colder air can make inroads before the storm system comes out of the Southwest.

The other piece of the puzzle is all season long we have had a SE ridge in place and the models have been generally under doing this ridge in the medium and the long range. Matter of fact if you believed the GFS about two weeks ago we should be in a very cold pattern right now and for the next couple weeks. They been under doing the SE ridge and trying to rush in the pattern change..

Now lets look at the guidance for the upcoming storm..

Now as you can see the ridge is pumping out ahead of the system and this system becomes an inland runner. Matter of fact it travels thru central PA into Central NY.. Below is the ECM verbatim off the accu pro images:

At 72 hrs. the 540 line runs essentially right at KPIT in a north to south fashion then bends towards the NE along the US/Canadian border..Temps at 72 are as follows: 30-35 from about central PA west Into the NE.. from north of ABE SW into SC PA 40-50 degrees and these go into New Jersey and SNE ..At 78 hrs. low pressure is over SC NY almost on the PA/NY border..540 line is into East Central PA.. then the 540 line runs NORTH to touching the eastern side of Lake Ontario so the only part of NY that is behind the 540 line is the part that is SW of Lake Ontario it then runs right along the Canada US border so all of NEW ENGLAND or the NE is on the warm sector side...temps are now 35-50 depending where you are Located from NE PA SW into South Central PA ..North central PA (SC PA and NC PA are 35-40) so the temps rise from 72 hours in these regions..these 35-50 temps then go into the NE into SE NY/Central New England and into Southern Maine where they are in the 40 degree range! At 84 hrs. the 540 line has now crashed thru all but VT/NH and NE into Maine which is still warm sectored and the low is over VT/NH temps at this hour are now 30-45 across the region with the warmest NE of the center of low pressure! 1 inch to as much as 2.5 liquid total equiv...

Now as you can see the ECM verbatim would be too warm for much of the area to see any snowfall with the exception of western PA and parts of Western NY..

The image above is the 00z UKMET along with the 00z ECM and you can see that the two models are in pretty good agreement with the track of the low at 72 hours and the UKMET also is a warm model run for this system.

GGEM not quite as far west as the UK/ECM but again you can see that it is showing an inland runner and also the 540 line is pretty far to the west.

Then we have the GFS..

Now as you can see the GFS is SE of all the other guidance and it is also slower then the rest of the guidance. You also notice that the cold air is a touch stronger on the GFS but when you look at the surface temps you see that they are the warmest underneath the heaviest precipitation where the 850s are above 0 and so is the surface..

This would indicate rain along the east coast with some lighter snows in the lighter precipitation to the west of the blue 850 line.

However we also see that the GFS is an outlier when it comes to the rest of the guidance.

So we have essentially four models that are showing far western areas with the potential for snowfall , and these areas may start as rain..and for the rest of the region they are indicating heavy rain.

With the teleconnections that are in place we feel that the best chances of snow are going to be in the areas to the west. This would be west central PA into western NY and into Western New England.

This would be taking a blend of the 00z UKMET/ECM/GGEM and about 10 % of the GFS since it appears to be to SE which would make it to cold at the surface in some locations. 

The teleconnections in place would point more to a coastal hugger or an inland runner.

It is way to early to speculate about accumulations. This would not be a 10:1 ratio for places that do get snow because the 850s are not all that cold in locations that will be cold enough to change to snow.

So this is our current thinking at this point and time..

If we were to take the ECM verbatim the rain line would be further west. The GGEM would also be further west. And the UKMET would also be further west but the above is a “blend” of those three models.

Its also important that people realize when we analyze a model it is verbatim to what the model run is showing but does NOT mean that that is what we are thinking. The ECM would suggest ALL RAIN for pretty much all of New England and you can see that we do not have ALL of New England in rain! The GGEM would be pretty much the same story as well as the UKMET. And this STILL could end up being to cold above..

If the ECM track verbatim ends up being correct along with the UKMET then the snow area will decrease but for NOW we are using a blend..

Stay tuned …

Christmas Eve and Christmas Day Potential

It seems like we have been talking about this system for about 2 weeks..Well not on this blog but on the Facebook page.

So lets take a quick trip back into memory lane to the month of November when we seen temperatures that were in the 60s-70s..

Quite a warm month was on tap across the region. This continued thru about the first week of December but then something happened. The pattern stepped down.

Lets use ABE for this example..

 8  44  29  37   3  28   0 0.02    T    0  9.4 25 310   M    M   4 1      37 290
 9  48  27  38   4  27   0 0.00  0.0    0  3.4 13 190   M    M   2 18     17 210
10  42  23  33  -1  32   0 0.00  0.0    0  6.3 17 330   M    M   2 1      22 310
11  39  20  30  -4  35   0 0.00  0.0    0  1.1  8 270   M    M   0        14 280
12  40  18  29  -4  36   0 0.00  0.0    0  0.6  7 240   M    M   0 1      10 210
13  48  19  34   1  31   0 0.00  0.0    0  4.8 13 320   M    M   0 18     16 290
14  51  27  39   7  26   0    T  0.0    0  2.6  9 170   M    M   9        13 170
15  56  43  50  18  15   0    T  0.0    0  7.3 18 210   M    M   7        23 180
16  54  35  45  13  20   0 0.00  0.0    0 10.5 29 290   M    M   1        51 280
17  39  25  32   0  33   0 0.01    T    0  5.5 14 340   M    M   6 8      17 340
18  35  19  27  -4  38   0 0.00  0.0    0  4.1 14 320   M    M   1        17 340
19  48  19  34   3  31   0    T  0.0    0  6.0 16 240   M    M   4        21 240

Now what we see is the first days of December that were well above normal but then we notice that we started seeing temperatures that were now in the seasonal to slightly above normal and some days even below normal. This is something that we did NOT see in the month of November as it was pretty much an all out blow torch. So the pattern has indeed stepped back down as we were talking about prior.

Now was there a reason for this warm weather? Yes there indeed was..

Just take a look at how positive the Arctic Oscillation was. Not really a surprise with the warmer then normal weather. However now look what has happened! These are the observations and NOT the forecast models AO predictions. The Arctic Oscillation has taken a slide into the negative territory.

Now you can see the reason why the weather has become more colder then previous because that Artic Oscillation has taken on a negative outlook.

The next part of the picture we want to look at is the MJO.

You have to look at this very carefully but you can see that the MJO is still in the COD in which it looked like it would come out into phase 4 or 5 but looks like its lost the progression. Essentially when the MJO is in the COD it has less of an influence on the pattern and makes the other teleconnections more in play.

So presently as shown above we have a – Artic Oscillation a + PNA (on the CPC charts) and a positive NAO.

So what this means is that with a + NAO we really have no support for a storm to go southeast and out to sea AKA the GFS model camp. However with a positive PNA and a – AO we do have support for a trough to form in the east and ridging to arise in the west.

So lets take a look at the models. For the purpose of this discussion we are not going to look at the GFS because we like to look for consistency in the models and then go from their.

So here is the 12 Z GGEM. As is the bias of this model when it comes to the phasing of storms it tends to over phase and over amplify. Northern stream and southern stream phase together and bring an inland runner.

UKMET shows a storm developing in the GOM and then it essentially takes a track very similar to the ECM and blows up a storm .

So we have two models that are showing amplification of the weather pattern and one model not posted (GFS) which simply slides south and east and never really even develops the storm.

Lets move on to the European Computer Model which has shown consistently a solution very similar with very little alteration in evolving and track. Timing has changed on the ejection of the shortwave energy but other wise its been consistent..

And the result of that run is as below:

As you can see the ECM is showing a solution cold enough to produce snow across the vast majority of the region delivering a White X mas to the vast majority of the region.

Does the ensemble means back up the model ? Well 120 hrs. never updated but we will rely on Pro Met Bobby Martrich from Lehigh Valley Weather Patrol and his response to the question is as follows:

“Lehigh Valley Weather Patrol with Bobby & Suzy Hour 120 and 132 also support it. Looks to be a tad colder at 120 and 132 than the operational.”

And we can basically confirm this at 144 hours on the ENSEMBLE means as well:

So with all the above shown and discussed we like to go with a solution that has shown consistency. This solution has been the European Computer models which even has the backing from its own ensembles…

What can go wrong? The low pressure can end up being more amplified while in the GOM region and cause a stronger height rise along the east coast which would result in a shift west ward with the zones as shown above.

This is only a scenario map based on the most consistent model and its ensemble means which fits the teleconnections discussed above.

Stay tuned for more information as this gets closer!