Pattern Update–Persistence Continues to be the KEY!

The above is the first 19 days of Feb ..just shy of being 3 weeks into the month. As you can see…the look of this map and the departures looks no different from November, December or January…

The moral of the story is that every single time a pattern change was signaled to occur by long range guidance it simply has not occurred..

Snowfall is well below normal ..in locations such as ABE without counting October towards the winter snowfall we are approximately 18 inches below normal.

Our original winter forecast we have already admitted that it was going to bust and bust horribly but we were in good company as the majority of winter forecasts busted just as badly.

When we did revise the winter forecast at the end of December and released on January 1st we did indeed nail it from that point on with the warmer then normal and less snowfall then normal. The original however…failed and failed bad but we will still do a actual verification at the end of March…

So where are we going from here? There are some main weather media outlets that are still talking about cold and snow and the pattern changing in March etc..Is this true? Or are these folks just holding out hope because there has been a lack of snow and a lack of cold and they just want this to occur? Or is there a chance that March will come out cold and snowier?

Well…if one has been following the GFS it was suggesting that things could indeed get snowier and colder. However…caution must be advised because we have seen the GFS do this ALL winter long and it has failed to materialize.

So lets look at the teleconnections to see where we are heading..

From the images above we see three things:

1. A positive Arctic oscillation

2. A negative Pacific North American Oscillation (PNA)

3. A positive North Atlantic Oscillation (NAO)

If you are a cold and a snow lover these signals are the complete opposite of what you want to see for cold and snow in the east.

These signals indicate at the very least a continuation of the pattern that we have had all winter along which is times of cooler then normal to seasonal weather in an over all above normal temperature regime.

When we look at the guidance we see that the ECM fits the teleconnections the best by showing an over all warmer pattern with the shots of cooler weather.

And then more into the longer range..

In the first set of images we would not be shocked to see temperatures near or into the 60s…and in the second set of images we would not be shocked to see temperatures in or around the 70 degree mark if the day 9 scenario were to verify as depicted..

Of course some may cling on to the GFS and what it shows as of 12 Z ..

However…if one were to look at the teleconnections above what we see indicated would be closer to the ECM in reality then the GFS. When looking at the GFS one has to remember in the long range it has a KNOWN cold bias.

The moral of the story is essentially spring has sprung but there will still be shots of cooler weather. For those in PA ..snow chances are dwindling down and we here think that the chances of seeing any significant east coast snowstorm in PA the rest of this winter is at around 10%.

There is a high likely hood that the rest of the winter season will continue to produce warmer then normal temperatures overall & continue with the below normal snowfall.

Latest Thoughts on the System for the 19-20th ..Feb 2012

Starting yesterday at 12 Z basically all the guidance started to trend south with the system around the 19-20th. The 18 Z GFS continued with the south trend and the 00z guidance also continued the south trend with one exception to the guidance being the 00z NAM.

However…as we look at all the models at hour 72 you will notice that they are all in fairly good agreement with the position of this system. The difference with the NAM and to a lesser extent the GFS is the north extent of the QPF shield which gets into southern PA..

Lets look at the guidance…

Now in the above images we have all the guidance from the 00z GFS/GGEM/UKMET/ECM/NOGAPS. You can see that they generally agree on the low position at 72 hrs. with probably the ECM being the most south of the solutions.

Now this image above is the 00z ECM ensemble means and it basically supports the operational run . It can be argued that the system on the means is just a touch NE of the op at the same time ..However..for this system to effect PA and Northeast ..you do not want the means to show a touch NE but more N then anything.

We are going to attempt to show WHY this is not going to make it any further to the north then what we are seeing on the guidance and we are going to use the ECM @ 48 hrs. to show this…

First thing we notice is the 50/50 low and this is part of the problem in that the 50/50 low is to strong which causes a NW flow behind the Northern stream system (that all the guidance trended faster with) which causes the NW flow or confluence to NOT allow the heights to rise on the east coast. Which leaves us with..

Black lines indicate the flow which is ENE…

Another problem is lack of a + PNA ridge that goes across the west into Canada as the white line represents. If this would have occurred we would be looking at a sizeable storm coming up the coast. However ..we do not have this happening…

Third the lack of blocking. Even if we had a full phase between the northern stream and the southern stream..with a positive NAO in place there really would be nothing to stop this from cutting west.

So instead of having the heights rise along the east coast…we are left with lower heights due to the NW flow or confluence from the 50/50 low and this system has no choice but to follow the steering flow ENE and off the coast around Hatteras and bring the Mid Atlantic region a decent snowfall…

As of 6 Z the NAM ..while still bringing some light QPF north of the PA/MD border has really backed off and gone more south and east as well coming into harmony with the rest of the 00z models.

One thing is certain as you can see by the radar image above that this system is not going to have a lack of moisture. And I would not be surprised if we see a very expansive moisture shield with this system..

So with over whelming guidance support to suggest this system has little fanfare to the north of the PA/MD border …taking a blend of the guidance with less emphasis on the ECM but more emphasis instead on the ECM means this would be the most likely area that has the potential to see a heavy wet snowfall…

At this time we think that around 4-8 inches of snow could fall across the area that is in blue..

We will continue to monitor this system for any changes but with the NAM as of 6 Z now coming in more suppressed we pretty much feel that the models are coming into agreement on the ultimate track and resulting location of the storm…

Potential Exists For A Moderate To Perhaps Major Snowstorm Feb 19-20th- But Where?

We feel the above title is most fitting that for the end of the weekend that a moderate to perhaps Major Snowstorm could occur but the question that needs to be answered is what region is going to benefit from this system. Will it be the Mid Atlantic and Northern Mid Atlantic or will it be the Northern Mid Atlantic and the Northeast…or will this simply go off the coast of Hatteras and out to sea. All these have been shown on model solutions over the past few days.

The exact track of this system is still up in there air on the latest guidance and we are going to take a look at that in operational model form as well as ensemble model form..However before we do that lets take a look at the teleconnections that are in place..

For starters lets look at the MJO or the Madden Julian Oscillation.

The above images tell us that we are in phase 1 of the MJO and the bottom image is the 500 mb temp anomalies and you can see that across the east it represents more in the way of seasonal weather.

The above is the Arctic Oscillation and normally you want to see this teleconnection with showing in a negative direction . However, what this shows is a positive AO …but around the time of the storm this dips to neutral. What this means is that there should be seasonably cold air around at the time of the storm. However..nothing that would be considered arctic cold and that should not be too surprising considering how mild this winter has been.

The PNA or Pacific North American Oscillation looks to be positive and looks to stay positive thru the duration of the time frame in discussion. So this is a favorable teleconnection for trying to get a storm up the eastern seaboard..

Generally what a + PNA will do is set up ridging into the west coast , sometimes into western Canada and then form a trough along the east. So what this teleconnection suggests is that we will have a trough along the east in this time frame.

Now, here is the North Atlantic Oscillation or the NAO and interestingly enough this teleconnection more or less supports a system that would be further north and west.

Generally when storms end up being suppressed it is due to two main reasons teleconnection wise:

A. The NAO is strongly negative which creates very strong confluence over the east/ northeast

B, In tandem with this the AO is strongly negative which tends to help shear or dampen and crush the systems to the south of the Mid Atlantic Northeast region.

Notice we do not have either of those occurring at the present time with the upcoming system.

So in summary of the teleconnections we have the following:

A. MJO Phase 1 favorable

B. PNA positive which is favorable

C. AO which is positive dropping to neutral which is not the greatest but not the worse it just means that this will be a stale air mass over the region instead of fresh arctic supply..

D. The NAO . The NAO being positive argues for more of a NW track closer to the coast…not necessarily to the benchmark but indeed a further NW track .

So now lets look at the guidance and the ensemble guidance and see what solutions if any hold up to what the teleconnections suggest..

This is the 00z GGEM. While this has made a shift to the NW over all…this model is mainly a brush to the northern Mid Atlantic area..with the main storm occurring south of the Mason Dixon line. However..you will notice that this model also is about 12 hrs. slower then the rest of guidance so we will consider this a unlikely solution due to timing issue compared to other guidance.

The above is the 00z UKMET and this is similar in its depiction at least where it ends up at 96 hrs. as the GGEM but it is 12 hrs. faster then the GGEM. This also lines up fairly well with the ensemble means of both the GFS and ECM as you will see.

This is the GFS..this is the operational run and as you can see thus far it is pretty much the furthest NW of any model and the reason why is because it phases in the northern het stream disturbance with the southern stream SW over the southeast. This run is also colder then previous runs because it is not as AMPED up compared to other solutions..

00z ECM is very similar to the GFS in low position ( a little south) however the 00z ECM has taken a major trend with the northern stream disturbance towards the GFS which can be seen in the first 24-30 hrs. of the 00z ECM.

Verbatim about .37 gets to KPHL and only .07 at ABE and NYC..However this is greater QPF then the 12 Z run. Also important to keep in mind is the 12 Z means were more amped and north of the op yesterday afternoon.

So now we are going to look at the three models GGEM/GFS /ECM in the form of the ensembles at 96 hrs..

Now the last image is the GGEM means and you will notice that the means are Southeast..however you will also notice that they are about 12 hrs. faster then the OP GGEM. We are considering these means of the GGEM as lower probability because the model is clearly struggling with timing issues as evident in the difference between the OP and means.

Now the top image is the GFS and the middle is the ECM ensemble means and you can see that they are in fairly well agreement. The main difference is that the ECM is more AMPED then the GFS ..Which is kind of interesting considering the ECM means is a smoothed version of 51 members versus the GFS 12 members. The means of the ECM are also slightly more North as well compared to 12 Z ECM means.

In Summary the teleconnections would support more of a NW track up along the coast with the NAO positive and the PNA positive ..

We do not think the teleonnections are supportive of a system that would be south and east and miss the region..but the ultimate outcome will depend on Phase or no phase of the two streams..If there is no phase then it is very possible that this ends up being a Mid Atlantic storm with nothing but clouds north of the Mason Dixon line.. as it would slide ENE from the Hatteras Area..

If we have a full phase then we could be looking at more of an inland solution because of the positive NAO. With no blocking in place (other then temp block from the 50/50 low) this would then become a primarily rain maker for the big cities along the coast with heavier snows inland..

So there are a lot of questions to be answered yet ..but right now we are leaning towards the following scenario based on the ensemble means and teleconnections..

This much we will say…if this storm does come up the coast in a more northerly fashion that the surface temperatures will be in the low to mid 30s but the 850s supportive of snow. What this means is this would be a heavy wet low liquid to ratio snow and if this does come to fruition then it could become not only travel problems but also problems with trees and wires down due to the snow being heavy and wet..

So the potential is on the table but the exact track is in the air yet and whether we phase or partial or no phase at all.

Stay tuned we will continue to monitor and follow this potential winter weather event!

Light Snow Event Feb 11 ,2012

We decided to go ahead an issue the final map tonight figuring that since we are less then 24 hrs. away ..that there is not going to be too many significant changes. Also this way if I do receive any bad news tomorrow this way the final call is already out. This is basically a blend of the GFS and the ECM ..leaving the NAM completely out of the equation.
The winter mix is because we think those locations are going to have Boundary Layer issues. Otherwise will be to warm at the surface..
Overall generally a light snowfall.. Pretty self explanatory ..the storm should essentially come together to late...which means this could have been a bigger event but the players just are not aligning themselves properly in time. We would essentially need this low pressure to be a more consolidated low and bombing out around the Delmarva region. This is not being shown to happen until it is well north of our latitude..
However..in a winter that has been literally lacking winter weather..we will take what we can get!

Light Snowfall February 8th 2012

There is a mid level shortwave that will be moving towards the east. This mid level shortwave will be moving to the south of the PA/ MD border and really has limited moisture to work with... This mid level shortwave will cause precipitation to overspread the area. Temperatures in the afternoon will be in the mid to upper 30s across the areas anticipating some light snow.. With the ground temperatures relatively warm and this moving into the area in the afternoon we are not anticipating to many problems. Accumulations will be on the light side with a T-2 inch range but most locations probably in the 1 inch range. Locations such as KPHL may start off as rain but they should still see some snow as well.
There are two things that I want to mention as far as what can go wrong..
1. At the present time there is very dry air in place ..So we may experience some virga.
2. This is just a very weak system that will be moving thru so there is also the possibility that the MTNS may cause the precipitation to break up.
All and all a light snowfall is likely across the region ..there after temperatures will warm up again before getting colder again..

Pattern Update as of Feb 6th 2012

Below  is a map showing the first 5 days of the month of February. When we did the last update we mentioned that persistence to the pattern was the key for that next ten day period. This indeed turned out to be the case as we had mentioned that the MJO was in unfavorable phases.

So lets look at the MJO so we can see where we are and then we can make a determination to where we are heading..

Latest current Observation shows us that the MJO is for the first time this season in Phase 7. However..phase 7 is still NOT a colder then normal weather pattern across the area as this chart below will show..

So it is no surprise that the pattern has been an above normal pattern so far. This pattern should continue for a couple days but THEN ..guidance is beginning to indicate another first for this winter season..

MJO guidance for the first time this season from the ECM & the GFES is suggesting that the MJO is going to go thru Phase 7 and propagate into Phase 8 & 1 & 2.

This is what the 500 mb level looks like in each of these phases for the month of February.

As the charts show above Phase 8 thru 2 would indicate below normal heights across the region. So the MJO looks as though it would be supportive of colder weather into the Mid Atlantic & the Northeast.

And we do see the models such as the ECM showing this happening today at 12 Z..

The ECM today drops the Polar Vortex into the Northeast and if this were to verify conditions would indeed end up getting colder..

However, we see by the end of the run the model starts to try and bring the Southeast Ridge back into the picture. Last run of the ECM (00z last night) showed warmer air in the extended..

So it seems as though there could be mixed signals occurring for the longer range. So this leads us to look at the teleconnections and see what is happening.

There is no question that the Pacific North American Oscillation is positive and basically looks to stay positive. This would be supportive of a trough across the east with ridging out west.

The North Atlantic Oscillation however..is positive and looks to stay positive thru out the forecasted time frame above , all but one member of the ensembles.

This is where things begin to get a little interesting because as noted above a Positive PNA indicates ridging along the west with a trough in the east but a positive NAO indicates that the coldest air would not be able to penetrate to the south..

So here comes the wild card..and this wildcard looks to be the deciding factor in whether the pattern can switch to a colder pattern and perhaps sustained or if it continues to me more or less + PNA transient shots of colder air in between over all warmer temperatures and that wild card is the Arctic Oscillation..

Why is it the wild card?

Well you can see there is two clusters in the ensembles or two groups of clusters. One group is taking the AO back to the positive side while the other group is keeping it negative..You can see this on the image below which is the exact same image but I drew two circles on the two clusters..

So the wildcard would be the AO and what happens with the AO. If the AO goes back positive ..then without a doubt with a + NAO , any cold shots would be transient in nature. If the AO stays negative then there is a higher chance of colder air becoming more sustained.. So that leaves us with one other teleconnection to look at and that is the EPO..

Eastern Pacific Oscillation is currently negative and looks to remain negative for about the next week. There after it goes positive and then later in the forecast period goes neutral positive.

Putting the pieces of the puzzle together it appears as though the next few days we should continue the above normal category in temperatures and then with the MJO heading into favorable phases we should take a step down in temperature category to a more seasonal temperature regime. This would cover the next week. Beyond that the signals become a bit murky but we can see a warm up again before perhaps stepping back down..So over all we think that persistence to the pattern is going to be key!

One final thought is that unless we get some WELL below normal temperatures to occur..the positive anomalies you see at the beginning of this month are going to be very hard to over come which gives the month of Feb a good shot at another month of winter coming in at above normal.

There also could be a shot at some snow in the 5 day period ahead…this shot right now does not look to be all that impressive.. but this would be around Saturday the 11th of the month..

We will continue to monitor and follow the latest and you can follow us on Facebook as well..

Severe Weather Feb 2nd 2012

First of all there is a new look to the severe weather map that we are using. Hope you like the look. Now ..this forecast is based on the NAM/SREF a blend of the two models.
Severe Weather Parameters
The NAM is showing as much as 500-2000 CAPE across the area..
Lift index any where from 0 to -6 across the region
SWEAT Index is between 400-500 across western TX and Western OK
These regions also have EHI up to 1.00 or lower..
Shear is 35 knots to as much as 55 knots..
Mid Level Lapse Rates are 6.0-6.5
More then likely this severe threat will not occur until the late evening hours across the region.. as it is really not until after 11 PM where moisture flow from the GOM becomes involved and this is when the greatest warm air advection will also begin to filter into the region.
While the SPC does not see much of a tornado potential with their outlook if the NAM SWEAT index is any indication there could indeed be some isolated tornados across Western TX into Western Ok.. We do not agree with stretching the severe weather as far north as what they have indicated because the greatest parameters are further south.
The greatest severe risks will be damaging winds and hail..
Essentially a low pressure will be moving out of New Mexico towards the east with a warm front attached to it and this warm front will serve as the trigger for severe weather and rain across the area. This warm front will be followed by a cold front but this will be slow moving and not cross the region till Friday evening..So we could have two days to deal with severe weather across the region..