So You Thought This Was Going To Be Simple –Part 4!

Alright there still seems to be alot of confusion going around the internet and this is because of two American Models. Now..before we get to looking at the guidance..the very first thing I want to do is to look at the pattern.

MJO or Madden Julian Oscillation is currently in phase 7 and looks to be headed towards Phase 8. By the time of this storm which is still 72-96 hrs away we will probably be borderline 7/8. These phases, especially phase 8 are very favorable for east coast winter storms.

The arctic Oscillation is actually negative but expected to rise towards neutral in the next 7 days. So with a negative AO we do have a supply of cold air available to tap into.

NAO is negative and expected to go towards neutral negative over the next 7 days. This is a change from before which was more a neutral positive. So this too would be more supportive of colder air available.

Next is the Pacific North America Oscillation or the PNA. Clearly the PNA is positive & a positive PNA argues for a trough across the east and a ridge across the west. So as you can see all teleconnections are favorable for an east coast storm.

Now lets look at the guidance and we are going to start with the 12 Z Nogaps followed by the 18 Z Nogaps..

Keep in mind the SE bias of this model and notice where it ends up at 12 Z at 96 hrs.

Notice how a model with a very progressive SE bias is very close to the coast? With the models bias this should be more south and east.

So lets see what the models have done at 12 Z & 18 Z.

Well as you can see the GFS is still taking this system off the coast and out over the gulf stream. This is the models first error. The system is going to want to develop and track along the greatest thermal gradient which is on the western side of the gulf stream. Secondly we can see that the GFS at 12 Z is no more closer to the coast then the NOGAPS. So this is certainly a flag to the GFS/and its ensemble means. What about 18z?

As you can see it stays on its same track and if you now compare it to 18 Z Nogaps it is well out there beyond the Nogaps. So again we will consider this model as an outlier at this point and time.

GGEM..its kind of funny when one looks at the GGEM because it is actually showing what the Nogaps was showing at its most western extreme model run. The GGEM essentially goes across C Pa. This was what the NOGAPS had done as well at one point and time. The GGEM is too far west & while a track that west could happen..the chances of it happening are slim less then 2 %. The GGEM would be rain for alot of folks and alot of it. Exception being western PA and NY.

Now people are bringing up the GGEM ensembles and how they are further to the east. This is indeed true but with what was just said above you would think the means would be further east. However, at the same time what these people fail to mention is that the means are trending west. Of course you will hear that the western members of the means are skewing the means. That is only true if you do not know that the means are a smoothed down average of all the solutions & in order to get a means further to the west..it means more members are west then there are east members.

00z GGEM means

12 Z means

One can clearly once again see that the 12 Z indeed is more west then the 00z.

Many have claimed the UKMET is out to sea. This simply is once again misinformation as at 84 hrs the UKMET is actually snug to the coast of Hatteras. From there it moves ENE and ends up in a position about where the GFS is at 96 hrs. Once again using the NOGAPS bias and how its more west..one would expect the UKMET to come back west as we get closer to the event.

All that remains to discuss is the 12 Z ECM…

Now as you can see above the ECM has actually trended more west with the area of low pressure & this is very evident when you look at the QPF image. I am not going to do the normal breakdown of the hours like I normally would do ..but basically from East Central PA to NW NJ and 40 miles Inland from the coast to the NE would be cold enough to support all snow. To the West of KPHL in PA and then in MD from about WC MD on all are cold enough to support snow. The temperatures are in the lower to mid 30s at the surface with the exception of Central Jersey and South they are 35-40 and then along the coast into SNE they are 35-40. Basically if you are inland..you are looking good for a heavy wet snowfall.

The means are above and as you can see the means are pretty much more organized and amped up ..There are about 30% of the members that are more west then the op.

Current thinking has not changed from what we have set out with from the beginning of tracking this event. If you are N & W of the cities you will be a snow to wintery mix..far N & W mainly a heavy wet snow. In the cities themselves more rain then anything else with the potential of some snowfall at the start and at the end.

Track of the storm would be along the eastern side of the appalachians (inland ) to just west of Hatteras and then NNE from there within 50 miles or less from the coast.

We are upgrading to a level 3 alert for the interior regions from Md on NE . Potential in the interior regions exists for a significant winter storm with a heavy wet snow accumulation.

As you can see the ECM QPF outlook below…

(removed cause accuweather complained)

One thing to consider is the airmass that is in place before this storm arrives is extremely cold. This cold air at the surface will be very hard to dislodge and could be stubborn to leave the area in the areas where rain is expected. So this could result in ZR. This is something we will have to keep an eye on.

Stay tuned for more information on this winter storm!

So You Thought This Was Going To Be Simple-Part 3

Let me start off by saying that there is a lot more to look at besides where the low pressure is on a weather chart. So many people have been asking lately..well why is this low going off the coast and the temperatures are so warm? Can a storm create its own cold air? All kinds of questions going around out there and yet no one is answering them. So we are going to attempt to answer some questions that you may have in this discussion.

First of all..the track of a storm system is only one aspect of a thermal or temperature profile. Is there high pressure to the north? Is that high sliding east? Which direction are the winds from? You can have a low pressure track off the east coast at 75 miles out and if you have an east wind with a high pressure sliding off to the east…then what that spells is easterly fetch off the atlantic ocean & warm air making inroads along the coast…

So lets look at the guidance tonight. Keep in mind from the beginning of tracking this event we have been using the NOGAPS as a flag towards the other models. That is another aspect people can not grasp. They cry the NOGAPS is not being consistent it went east..You expect and want the NOGAPS to be east because of its bias but when it is east ..if you take notice the global guidance then goes in the direction the NOGAPS was showing which was to the west. That is how the bias works. If it would keep moving west…then this storm would be going thru central PA and the snow would be well west. So with that in mind here we go…

First up is the GFS and we notice now it is actually seen the light of the rest of the guidance and now shows a low developing in the GOM. It started doing this at its 12 Z run and since then each run of the model has been trending west. GFS however..has no QPF on the western side of the storm , even though temperatures are cold enough to support snow. However..its also a more amplified system on its 00z run then any of its more prior runs.

GGEM..for the most part has always been west with this system and has also been one of the better performing models with it remaining towards the west. At 96 hrs though it is east of its former location but people are making it sound on the internet like its still not a coastal hugger when the truth of the matter is that it actually is.

If that is not a coastal hugger I do not know what you would call a coastal hugger. Furthermore there is talk that the system is not an inland system. This is all false to as this system travels to the east side of the Appalachians all across land.

Next up is the UKMET ..as you can see the UKMET is also a coastal hugger as well and also is an inland runner on the east side of the Appalachians.

The only model left to analyze is the 00z ECM. If you remember the 12 Z ECM was more east and as I been saying all day long yesterday..it was a hiccup run and would come back west. I was told i was wrong…Interesting thing was I was correct.

Here on the ECM you can also see this takes a very similar track as the rest of the guidance and is also what would be considered a coastal hugger.

So pretty much you can see that basically all guidance is in agreement on a western track close to the coast, the one different though is the GFS with no precipitation on its western side. However..this model is just playing catch up to the rest of the guidance and its means tell you that its going to be coming further west still.

So, I fully expect the GFS to keep trending towards its means.

However..i want to go back to the ECM model and break down the model for you in a PBP fashion.

At 84 hrs out the 850s on the ECM are from 0 to –5 from just to the N of KPHL extending east across C NJ..anywhere above that line you are below freezing in the 850 level.

Surface at 84..temperatures from KPHL south and east are 35-40 into CNJ. Anywhere north of there..as well as west is below 30 degrees.

At 90 hrs..from about ABE on south and east and into all but extreme NW NJ and then west into Central W Md the 850s are 0 to +5. Also those 850s extend across Long island. Anywhere west of that line or north of that line the 850s are 0 to –5.

Surface at 90 temperatures from KPHL south and east & into central NJ are 35-40 . Anywhere north of there..as well as west is below 30 degrees.

96 hrs ..850s are below freezing virtually everywhere with the exception of along the coast from NJ to Southern New England.

96 hrs surface..are in the 30s virtually all over between 30-35 with some pockets of 20s as well.

102 hrs 850s are below freezing every where with the exception of Cape Cod

102 hrs Surface temps are below freezing everywhere with the exception of 35-40 in Southern New Jersey!

That is the operational ECM 850s and surface temperatures. So basically supporting snow if you are inland and if you are along the coast you are looking at a more snow to rain type scenario IF and only if the ECM operational verifies as is.

The ensemble mean while AMPED has a different conclusion and it appear as if it would be cold enough to keep most places as snow..

Total QPF on the ECM is also below..as you can see it definitely has come more west..

(Edited cause Accuweather complained)

We will continue to keep the Level 2 Alert in effect but if guidance continues to go to what we are thinking then we will be upgrading to a level 3 later today with the 12 Z update or after the 00z update.

Our thoughts at this point have not changed with the original scenario map that was made a few days ago and we still think this could come as far west as over SNJ (alot of the spaghetti plots of the GFS were hinting and showing this) .however..if that occurs then we could also be talking about a dynamical situation where the storm is amplified and colder above and would pull that cold air down to the surface thru evaporational cooling. That my friends is how storms create there own cold air.

So to sum up anywhere from 50 miles or less to the coast with snow to rain along the coast (immediate) snow to a wintery mix..(30-50 miles inland) and then snow/sleet far N & W (60 miles)..with the potential of a significant accumulation of heavy wet snow and coastal flooding along the coast..beach erosion and strong winds.

Stay tuned for more updates on this system!

So you thought this was going to be SIMPLE? Part 2

Take a deep breath and a ride with me thru the analysis of the 12 Z guidance…For this update i am simply going to transfer a post I made at American Weather Forums to here cause it hones down on the message of the hour..

Here is the problem that i have with some of the 12 Z guidance..

 

Now....I am not sure how I can make anyone understand this any clearer then what i am going to this go around.
GFS we know has a progressive bias. Can we agree here? So arguing a progressive bias would argue that it would be south and east in a coastal storm situation and could be that way up until 72 and under. And we potentially see that bias in place today as we seen the GFS actually come in more amped then its previous runs and digging the trough deeper.

 

Here is the GFS at 102 and as i said one could easily argue that it is showing its south and east bias. Or one could easily argue that since its going back more amplified it could actually be going back towards the solution that was easily wrapped up? Agree?
Now when we look at the rest of the guidance ...we see the GGEM is west ...and has a bomb , on the warm side..but then the GGEM can have a warm bias as well...
12 Z UKMET also has a strong storm and is a flag to the ECM because it is further to the west then the ECM appears to be from the play by play that I have written.
So basically without even talking about the NOGAPS yet we have a stronger..slower solution on two of the models (GGEM & UKMET) and another model (GFS) that is becoming slower & stronger & much further SW compared to its previous run. Compare 6 Z 108 versus 12 Z 102 and you get the comparison to what i said above.
Now lets suppose that blocking is in place ..because that is the seasonal trend.. which it has been but does not mean that because it has been that it will be in every particular instance of a storm. For sake of discussion lets suppose blocking is in place and we have a stronger high pressure over and north of Maine...

Which looking at this image above we see a high to the west and we see a high pressure to the east with some semblance of a connection to each other. If that high pressure is stronger then what most models have it...could that or would that not argue for a slower & stronger & more amplified system?
Now...lets finally turn attention to the Nogaps...
We see at 108 hrs that the low pressure is alot further to the SW then say for example the ECM which by 96 hrs has it all the way up off the MD coastline....
We seen with this most recent past system that the low pressure actually went up into C PA before reforming off the coast along the coast of SNJ. The only model that showed that NW track was indeed the NOGAPS until the 00z runs of the night while the storm was already in progress and it was snowing outside.
If the GFS progressive bias is leading to a South and East solution (though i believe its still catching up) ...& we know that the NOGAPS definitely has a south and east and even more progressive bias then the GFS...then one has to ask themselves :
Why is this very progressive southeast biased model actually slower then for example the GFS/ECM?
I guess that gives you something to think on

So You Thought It Was Going To Be Simple?

The very first image I am going to start with is actually going to just blow your mind away. And the very last sentence that i end this discussion with could leave you flabbergasted! And the in between discussion we hope answers your questions you may be having.

So what is going on with January 25-26? So many twists & turns in the guidance..not changes per say that reflect in the surface as much as changes at H5 level. Almost every model last night had some changes at H5 (500 mb level)

So lets put that first image up so you can get in a proper perspective state of mind.

(Edited Accuweather complained of use of them)

Now…what you are looking at above there is the ECM QPF map for the storm that we are talking about! Blown away?

Before we look at the ECM though lets look at the rest of the guidance tonight…Tonight first on the order of agenda is the GGEM…

Now as you can see the GGEM is in the same location as its 12 Z run was when it is south of Pennsylvania. You might have heard that the GGEM went east! Well let me put that untruth to rest as you can see looking at the 12 Z image before when the GGEM was at that latitude ..it actually went a slight tick west..

However..even though it went a slight tick west it managed to become colder aloft then the 12 Z was. Now what the GGEM did do is it became a slight bit faster. But notice that we are still developing what would be a Miller A solution on the GGEM.

Next up is the UKMET…

Now the UKMET did indeed trend more to the east. There is no qualms about that..however it is also not Out To Sea. So again some misinformation going on across the internet. The other thing to consider is that its 12 Z run yesterday was also a slow outlier. It was slower then the ECM and it was slower then the GGEM which put it really far inland! So it was only natural for it to trend more east because it was to far west..However..IMO it over compensated for its adjustment. Will show why then we think this shortly!

Next up on the list of guidance is the GFS.

These are hrs 90 & 108. Faster then a speeding bullet, faster then even superman is the GFS as it just literally flies thru time with this system. So fast that by 120 hrs its GONE! Now wait a second…did i mention the fact that the UK/GGEM all have a low coming out of the GOM or a Miller A? Did i mention the fact that the GFS is a Miller B with a norlun type trough depiction? Ok moving on as we toss this model into the recycling bin because its a fast outlier compared to the rest of guidance & its evolution of the storm is not accurate either.

Now lets move on to the Nogaps! Ahh the valuable tool that so many do not understand & the reason they do not understand it is because they do not incorporate it into there thinking process. So they are not familiar with how the bias works.

So what do we know about the Nogaps? Well we know that it has a very progressive bias and we know it has a SE bias when it comes to coastals. This is why the images above do not spread the QPF more westwards like the GGEM and the ECM. However…here is a thought to ponder…

1. With the progressive bias of the NOGAPS..does it make sense that it is also a slower moving system? After all its bias should be moving much quicker.

2. Notice though as well that the GFS is east of where the NOGAPS is? So this is just one more reason to discard the GFS into that recycling bin.

However, could the fact that the NOGAPS is slower (and its bias is progressive) be a hint that this storm will be slower then what the latest guidance tonight is suggesting? In other words..the guidance has trended quicker with the storms progression (not as quick as the GFS though) ..but could it be hinting it will be slower?

Now lets look at the only model left and it belongs with the image that started this discussion.

Now..we see here at 96 hrs that the 850s are certainly cold enough and supportive of snow if there was any QPF falling at that time. And we see at 120 hrs that the 850s are alos cold enough for snow. However, what we do not see is the in between hours…but I do have access to them and verbatim what the ECM is suggesting is the big cities are mainly rain. However…again there is some false information going around on the internet in reference to what the ECM shows in between hours and this is because the people giving the information are in the region that is rain on the ECM. From I-78 North on the 00z ECM the temperatures at 850 never get above freezing. Thats right they never get above freezing. What about the surface temps ?

1. At hour 108 the surface temps from I 78 N and west are 30-35 degrees. SE of there 35-40 and in southern NJ 40-45.

2. 114 hrs.. 35-40 has crashed back into SW southern NJ but the big cities are still in that range. North and west of from 78 they are once again 30-35.

3. 120 hrs the 30-35 line has gone back thru the big cities and SNJ is now 35-40

4. 126 hrs the temps are in the 20s inland and 30s to the NJ coast…

So you can clearly see that the ECM is not all rain….it is rain for the big cities ..but with 850s at or below freezing i 78 & points N & W and into NW NJ ..this would be a heavy wet snow!

So, we see no reason to change our thinking at this point and present time from what it has been. We still think that this should track about 50 miles or less of the east coast. There is a possibility that this could trend colder yet…and cold enough for all snow even in the big cities. We are keeping the level 2 Alert in place with the models offering up a large amount of QPF (look above) ..

Now , remember i said I would leave you flabbergasted with the last sentence of this discussion?

ECM means…

Words from Pro Met Will…

Just SE of ACK at 120h. Definitely some bagginess in the isobars to the SW suggesting that there are def some amped up members that look closer tot he op run.
If the ensemble mean verified though, everyone would stay snow.

Now look at the very first image above and think about what the means suggest!