Lets see if we can clear up the confusion!

The purpose of this post is to see if we can help clear up some of the confusion that is out there on the internet in regards to what is happening in the world of weather.

To do this the first thing we have to do is look at what pattern we have been in ..

What we derive from those two images is that it has been warm or above normal in the central and Eastern part of the USA and colder along the west. This is indicative of a pattern of a positive NAO..positive AO and a – PNA.

There is no doubt about November being a warm month. However, there is a lot of talk on the internet that because November is warm that this means that this pattern will continue thru the winter ahead of 2011-2012. Is there truth to these statements or are people basically suffering from what we refer to as short term memory when it comes to the weather?

So lets look back some shall we?

Now as you can see this was 2010 and it was also above normal but not as above normal as this year has been..

What about 2009?

Interestingly enough we see that 2009 was perhaps warmer then 2011..

Now lets look at the winters that followed ..

The winter of 2010

The winter of 2011

So as you can see the warm month of November in previous years did not result into a warmer then normal winter over all. In other years back further it has and it has not..The conclusion is that there really is no conclusion on November warmer then normal means warmer then normal for the winter ahead. However..most recently a warmer November has meant a COLDER winter.

So if you were to use the most recent times this has happened I would say that it is pretty apparent that a colder winter is most likely..to occur. 

However..is this warm pattern expected to continue or are things shifting? Well lets take a look at this now as well. We already covered the pattern we have been in..so now lets look at what the models are saying for just ahead..

The above is the 18 Z GFS ensemble means of the 850 mb temperature anomalies as we head into December and as one can tell this is not portraying a warm look. These images would NOT equal a temperature departure map like was shown for November. No..this would show at least the first half of December as below normal across the region.

However…lets look at the ECM ensemble means..

Interestingly enough we can see that the ECM ensemble means are also showing a colder pattern is forthcoming.

These images above would also not equal a warm pattern. So as one can plainly see the guidance is suggesting a “flip” to occur..but when does that “flip” start?

If you been following our Facebook page we have been talking about a step down pattern change..

You can see this occurring already at 48 hrs. out..

This will lead to a more seasonal if not below seasonal day and then moderation for a couple days occur and then we step back down again..

Then we moderate once more, and then we step down again and this time into a more sustained colder period…as the means above from the ECM show.

So the very fact that we are now getting these colder shots in between the moderating times is in itself a pattern change from the consistent above normal pattern that has been in place ALL month prior.

Now..we have covered the most recent pattern and we have covered the step down pattern and have covered the fact that December will not end up looking like the month of November…and we have also covered the fact that a warmer November does NOT indicate a warmer winter overall.. The next thing that we need to cover is the potential that lies in the 6th to 10th of December with the pattern changing..

This was the 18 Z GFS for the time period being discussed now and as you can see the 18 Z GFS has a cold front progressing towards the east and a wave of low pressure developing along the front and brings rain then that rain changing to snow..The air coming behind the front is much colder then the air ahead..

12 Z GFS was similar with this idea but did not really develop a wave on the front…

Now why is this so interesting? Well this is what makes this interesting:

Now what you are looking at is the 12 Z ensemble means members and they can be found at the following link: (click here)

What you essentially notice is that there is 7 out of the 12 members that show the cold front further east and thru the region compared to the operational member in the upper left corner. You also see three of the 12 showing energy or moisture left behind to the south or the southwest …

Now the above is the 18 Z members for 192 hours which can be found by clicking here ..

And interestingly enough you now see there is now seven members that show moisture being left behind compared to the operational in the upper left ..and you also see that the majority of the members have the cold front further east then the operational.

So this gives two potential implications..

1. The colder air is going to be in place faster and before the operational is suggesting and

2. That the development of a wave along this front is becoming more of a possibility…

and perhaps adding another one in here would be perhaps slightly more amplification is being detected now in the guidance.

In other words we have to watch to see if the cold air comes in place BEFORE the wave forms because if it does then we could be talking the potential for a SWFE or a Southwest flow event where warmer air rides over the top of colder air in place at the surface…which would result in a wintery scenario across the region..especially N & W of I-95.

Now the ECM also shows this same general idea with that potential during that same time period and if you look at the ensemble means you will indeed see that the temperatures would be supportive of what is just said above.

You need to be very careful of what you read out there on the internet. People have thrown in the towel for winter based on the month of November.. Pro Mets such as one named Kerry Dean are insisting that there is no pattern change in the making.Instead they say climate should be stepping down..However, what they are not seeing is the pattern that has been in place has been one of much above normal and the pattern that guidance is suggesting and showing is quite the opposite of that pattern that’s been in place.  However as this very lengthy post shows… the thinking a pattern change is not occurring is built on a false foundation.

Perhaps one other area should be addressed and that is the myth that you need a –NAO for the weather to turn cold…

January 1994 is above and that was a severely positive NAO and look at the results..The difference was in the Power of the Negative EPO..The EPO is below:

So when people are trying to determine where the cold air is coming from? Remember the power of the Negative EPO…

Enjoy the weather folks cause it’s the only weather that you got!

Severe Weather Outlook November 22nd

Once again we have decided to issue two zones with the yellow zone being the most likely zone for severe weather based on parameters off the 00z NAM and the SREF..

In the yellow zone we see this is the best location via the parameters of CAPE 500-2000.

EHI is 0.5-1.0 this would signify the potential for tornado’s.

Lift index –2 to – 6

Lapse rates are about 6.0-6.5

SHEAR about 25-50 knots…

Further to the north the parameters are either extremely low (such as Lift index, Lapse rates (less then 5.5) or they are essentially non existent like the CAPE. The only favorable ingredient for severe weather further north is the shear.

Another factor that may have a impeding on severe weather once again will be the cloud cover that is expected to be in place..

The greatest threats to the north should be wind and or hail with heavy rain..while the southern regions can expect the potential for Tornado’s in addition to the wind or hail and heavy rains!

Pre Thanksgiving Snow & Rain Storm

We started talking about this potential already back on October 29th as the next potential storm to bring snowfall to the region.

Currently we have a cold front to the south of the region off the Carolina coast and then back to the west and heading SW we have a stationary front with waves of low pressure along it.

By Tuesday 18 Z (afternoon) we will have one area of low pressure over Southern Illinois with a warm front pushing north of it, and a cold front trailing south/southwest from the area of low pressure. . Preceding this we will have high pressure stretched across the NE region. This will allow colder air to reside in that part of the country.

The high pressure will begin to lose its influence and move away from the region as the low pressure out of Southern Illinois moves ENE taking a track across Central PA. This puts the area of PA/NJ etc. in the warm sector of the storm as the warm front pushes thru the region.

This system will produce a moderate size snowstorm to far northern new England and bring some heavy rains along with the possibility of thunderstorms into the rest of the region.

General rainfall to be expected ranges from one to about two and a half inches with the possibility that locations in SNE localize out at three inches and generally a 4-8 inch snowstorm with the potential in Maine for lollipops of 10-12 inches.

It is possible that after the cold front passes thru the region in PA ..that some showers of rain may mix with or end as snow in NE PA but for the most part we are looking at a rainstorm in the local region of East central PA into NYC…

Severe Weather Potential for the 21st Of November!

The above is the most recent surface map and you can see the cold front is basically across Southeast TX and then rides NE from there.

It is along this front and to its south and east that we think the greatest chances of severe weather will be.

The areas further north will more or less be dependent on a warm front moving N towards the region.

So we have two areas highlighted..One area is where the greatest chance of severe exists and that would be tornado’s and wind or hail.

The other area would be mainly for isolated instances of wind and or hail.

Now the areas in yellow is where we think the greatest risk for tornados would be based on the Energy Helicity that is available that you can see on the images below as 1 or above which is in the color red..

SWEAT index is quite high on the most recent GFS across some of the region.. With an area as high as 500. Keep in mind that anything above 400 can mean Tornadic activity is possible.

Now, part of the area in high SWEAT is also in the red zone on our map. The red zone is more isolated severe. While we do not expect any tornado’s to occur in that area we can not rule out an isolated tornado in that area …especially in TX where the SWEAT is high. Now if the EHI in those areas was also projected to be high then a more tornadic threat would be possible ..however..that is not the case so we keep with Isolated Severe in that region.

CAPE is about 500-2000 across the region. This is another reason for only isolated severe in the red zone and that is because cape is generally less then 500. The greatest CAPE values is over the yellow zoned region.

Lift index is 0 to –6..

SHEAR is more then favorable for severe weather with shear values of 25-50 knots.

Now perhaps one limiting factor on the severe out look is this:

The NAM shows the same cloud cover. First image is 7 AM in the morning and the next is at 1 PM. So cloud cover may be a negative factor on the severe weather as it would cut down on the day time heating ahead of the cold front.

We disagree with SPC and there slight risk zone and there tornado highlighted area because as you can see there is a lack of EHI as far N into ARK as what they show.

Stay tuned for more info should it become necessary and as always follow the latest on the Real Wx Service Facebook fan page!

Severe Outlook For Sunday the 20th of November

By 12 Z this morning low pressure should be in the vicinity of Eastern OK . A cold front extends South and then southwest from this low and then also extends NE to a low over the Great Lakes. It is this cold front with colder air behind it that will be the focal point and trigger for severe weather.

We are a little concerned with the potential for tornados and this is more having to do with the Energy Helicity Index then any other parameter in place. Those images are below:

The areas that are in red are essentially the greatest areas for the Tornado possibilities as the EHI is above 1. SWEAT index is less then 400 though on the latest NAM.

Lift index across the area is 0 to –8

CAPE (convective potential energy) is also pretty impressive with 500-3000 across the region depending on where you are located.

Shear is more then favorable with 25-50 knots across the region . Mid level lapse rates of 5.5-6.5.

Dew points in the 60s..surface temperatures in the lower 80s (ahead of the colder air) all spell potential for a recipe of severe weather with the potential of Super Cells.

The threats that will exist as mentioned above are Tornado’s along with damaging winds in excess of 60 MPH and large hail.

We would not be surprised to see a tornado watch issued in that region by the Severe Prediction Center by later in the afternoon into the evening time if those EHI #’s become a reality.

Stay tuned for more information should it become necessary & as always you can follow on Facebook for all the latest information!

Pre Thanksgiving Storm Potential Via Teleconnections

If you have been following with us on our Facebook page we have been talking about having to watch the time frame of Thanksgiving for the next potential storm system that could bring snowfall to the Northeast region.. We first started talking about this on Oct 29th during the historical Northeast Snow Storm. We are going to take a look at the teleconnections first and then we will look at the guidance.

The first thing we are going to look at it the MJO or the Madden Julian Oscillation.

According to the image above we are currently in Phase 8. We mentioned before that if this was December Phase 8 is where you would want the MJO to be if you wanted a colder pattern and snow potential. However since it is in November instead this means that after this current transient cold shot we are going to moderate in temperatures once again but nothing like this last moderation we saw. Keep in mind this is November and keep in mind that we have been talking about a step down pattern. So lets look at phase 8 of the MJO.

As you can see we see higher height anomalies along the east into the Northeast.

Now this is the MJO forecast and you can see that the MJO is forecasted to go from Phase 8 to Phase 1 & 2. So let’s now look at those phases and see what they indicate..

So now we see that phase 1 and two represents that step down pattern into a colder weather pattern. Now we will look at the NAO.PNA & AO.

First is the North Atlantic Oscillation and you can see that it is starting to tank during this time period. This is in favor of colder air penetrating into the region..

The Arctic Oscillation is a bit more divided with some members tanking the AO while other members are keeping the AO positive. It is important to note at this time that there are presently more members showing the AO going negative then there were a couple days ago & we think the negative trend is correct based on what the PNA is projected to do.

As you can see the PNA is projected to be rising to positive during this time period. So this would argue that a trough should be building in the east with ridging building in the west. So as we can see the teleconnections are favoring a return to colder weather.

Now lets look at the guidance to see if they are showing any type of storm for this time frame.

We first look at the UKMET and we can see that the UKMET @ 12 Z today does indeed show a storm system across the southeast. This model only goes out to 144 hours.

We move on to the GFS and that is the image on the left. We want you to notice that the GFS is well NE at 144 hours. However the image on the right is the 12 Z Nogaps which is the most progressive biased model there is and it shows a more southwest and slower solution. This points to the GFS at being a too fast progressive outlier!

Next up is the ECM. The ECM shows a storm system developing over the Southwest and then moving to a position off the New Jersey coast at 150 hours.

Now. be very careful here because there are some “pro mets” claiming that the ECM is not showing snow in its solution but we beg to differ.

The image above is a “3” hr. total of snowfall that occurs from 147 hours out to 150 hours out based off the 12 Z ECM. So folks the model does INDEED show SNOW. In the big cities? No.

Another thing that it is important to note is that the ECM last night was showing a solution with the low pressure near Buffalo NY & even in that solution the same areas above seen snowfall.

The truth of the matter is the 12 Z ECM is actually south and east of its 00z run last night and is actually colder with temperatures basically in the 30s at 18 Z Wednesday!

Now lets look at the ensemble means of the ECM..

A couple things on the image here. First you see a slightly more progressive system & second you see a weaker system. This is to be expected because it is an ensemble means made up of about 50 members-so it smooth’s it down.

The other thing to note is if you look at the 850 MB level temperatures it is actually colder at the 850 mb level then the operational.

So…what you can see is that the models do indeed show a potential for a storm in this time frame. The teleconnection’s also support a return to a colder pattern.

At this present time the only thing we are suggesting is that this time period needs to be watched. It is possible that because the models are now beginning to recognize the change to occur that they could be under estimating the high pressure (cold air source) to the NW of the storm.

At this time there is the potential that some areas may indeed end up with a white thanksgiving..but the details as to what locations and amounts etc. are not going to be clear at a 7 day time lead. The key word here is potential!

Stay tuned as we continue to monitor this potential!

November 16th Daily Outlook

As of 6 Z low pressure is near the SNJ coastline. By 12 Z low pressure will be over or north of the Great Lakes and a cold front will be moving from western PA towards the east. This cold front will be responsible for more clouds and rainfall today.

Meanwhile another low pressure will be developing along the cold front in the south central states and and this will move to a position off the New Jersey coast by Thursday at 6 Z.

Once this cold front moves thru the region temperatures will begin to drop across the region and we will be experiencing more in the way of below normal temperatures.

As far as rainfall is concerned..generally we are looking for anywhere from .25 to about an inch to at the most 1.25 inches over majority of the region in the next 24-48 hrs.