The Rest Of 12 Z Guidance- ECM adds confusion!

The rest of the 12 Z Guidance is in from the last update…and with the ECM just in now it becomes a question of whether or not this is going to be two systems or one system and when?  Before we get to the ECM however..lets look at the 12 Z UKMET/NOGAPS/GGEM.

You can see the 12 Z UKMET is still supporting a powerhouse type of system which would still probably rival 1993. This would result in some very heavy rains with some flooding issues thruout a good part of the region.

The 12 Z NOGAPS sticks to a similar track as its 00z run..however at the 850 level it is colder then last nights run. This would still be a pretty large QPF system and powerful storm.

The GGEM which last night was missing the party has now joined closer to the majority of the guidance with a 994 MB low just off the coast of NNJ at 132 hrs out.

Now here is where the model madness and mayhem lies …the 12 Z ECM which just came out is alot faster which results in a weaker Northern stream energy..which causes things to not be as amplified ..which does not allow the baroclinic zone to pull back closer to the coast..so it scoots OTS. This is generally more in line with the GFS. Red flag? Could be..time will tell we will continue to monitor.

However…what this results in is the following:

More emphasis becomes placed on the system for wed/thursday…and using the same place as we used last night ABE as an example..

THU 00Z 31-MAR   3.7    -2.6    1017      80      93    0.03     556     543    
THU 06Z 31-MAR   0.9    -3.3    1012      98      98    0.25     552     542    
THU 12Z 31-MAR   0.3    -2.5    1010      95      99    0.27     548     540    
THU 18Z 31-MAR   1.8    -3.0    1008      87      71    0.05     545     538    
FRI 00Z 01-APR   0.7    -4.3    1008      98      63    0.04     541     534    
FRI 06Z 01-APR   0.1    -4.8    1007      99      34    0.01     539     533

Would still lead to a storm that would probably provide parts of the region with a wet snow storm but now we are talking about an earlier system and not as powerful of a system.

So with the 12 Z guidance it seems as though we have the ECM/GFS focusing on the wed/thursday time period.. which the rest of the guidance such as the GGEM also have… (UKMET has this further south not effecting the region) ..but these two models (GFS/ECM) have no focus on the second system between 120-132 hrs.

At this point and time we are not going to change any thinking from what we have previously talked about. We have already mentioned that there could be two threats in this period with the wed thur threat and then another one for friday. The thinking still remains the same but it will have to be watched to see if it is indeed going to be two separate systems or one larger system that effects the region.

Perhaps 00z model runs will clear things up a little later tonight.

Stay tuned for further information!

Potential for a Powerful Nor’ester on Some Guidance.

It seems like we have been talking about the Heather A signal for some time. To refresh the memory a Heather A signal is when the teleconnectors are showing a rise from a very negative NAO to a positive NAO and how this usually signals a large storm along the east coast. For more information do a google search on Heather Archambault.

Some of the guidance last night was indeed picking up on the signal and showing the signal ..while some of the guidance almost seemed as if it was lost to what the other guidance was showing.

We are going to start with the guidance that seems to be on one side of the camp..That would be the 00z GFS/GGEM

You can see the GFS above at 144 hrs. While it does show a storm system along the east coast..it completely fails to phase and so we continue to end up with a disorganized and weak storm system that would bring some moderate rains across vast majority of the region.

At 12 Z today the GFS does still have a low pressure off the coast but again the way it gets to this location is completely different from the guidance from last night. This does not mean it can not be correct it just means that right now it would be a low probability scenario outcome.

The GGEM last night stood out in even more contrast as it does not even have a system on or near the coast.

The system it has is well out to sea. Again, this does not mean it could not be correct but with the Heather A signal it would also be very low probability.

Lets move on to the more interesting of the 00z guidance and the next two would suggest a Massive Flooding rain event across a good portion of the region. That would be the UKMET/NOGAPS

Now that storm on the UKMET one could say is indeed impressive. This storm on the UKMET could possibly rival the Superstorm of 1993. Needless to say the UKMET is probably on the deepest side of the solution envelope. This would like mentioned cause some Massive Flooding issues and I am pretty positive some severe weather outbreak as well across the region.

00z Nogaps also shows another system that would lead to some very heavy rains with flooding potential as it is quite warm with the solution it is showing. Remember we are dealing with a coastal system here so seeing the NOGAPS in this position becomes important when looking at other guidance like the GGEM for example with it being OTS.

Now what the UK/NOGAPS have in common is they are both showing a very powerful Nor”easter type storm system that one would generally expect when there is a Heather A signal. So one has to lean more towards that camp at this present time.

Now what about the ECM? Where does this model fall as of 00z? Well the ECM is probably the most impressive of all the guidance if you are looking for snowfall.

980 MB just off the coast of NYC. The ECM actually develops this storm over the GOM & SE and then moves it up along the coast as it is deepening.

The ECM for some parts of the region , even down towards but not quite in PHL would more then likely be a heavy wet snow.

For example the soundings look like this at ABE:

FRI 12Z 01-APR 1.4 -0.5 1003 94 100 0.42 543 541
FRI 18Z 01-APR 0.9 -3.2 990 90 91 0.81 533 542
SAT 00Z 02-APR 0.7 -4.8 988 90 95 0.33 526 535
SAT 06Z 02-APR 0.4 -5.0 991 84 91 0.11 527 534
The above is for ABE
Total QPF 1.67
Surface temps 32-34.5

So, as of 00z last night we can place the ECM in the same camp as the UK/Nogaps.

These three models suggest a Potent and powerful storm will effect the east coast. We will monitor the rest of the 12 Z guidance and update this later this afternoon.

We still feel the potential exists for a powerful storm system to effect the east coast in this time range. Potentially heavy rains in the warm sector and heavy snows in the cold sector.

Stay tuned for more updates.

Threat #2 This Is Where It Gets Interesting!

As we have been discussing for a couple days now..the teleconnections that are in place reflect and represent the potential for a heather A signal storm system to effect the east coast.

The details on such a system are not known at this time but its interesting to see that basically all guidance , at least in the ensemble means show the potential of this system. Operational models also have the system, some alot weaker and disorganized AKA GFS and some missing to the east AKA ECM. Lets look at the guidance on this system..

The GFS as stated above falls into the disorganized and weak system which is off to the south and the east.

Not to much change when looking at the 18 Z GFS..it still has a really disorganized system and still generally off to the east and not effecting anyone outside of New England.

However, when one looks at the means we get a completely different story..

You can see on the means for the time range out we are talking about a pretty strong signal for a coastal storm to effect the region. Really not that much difference with the 18 Z means either.

The operational GGEM has a pretty potent system and it is actually an inside runner. As modeled the heaviest snows from this system would be over far interior or western regions..

12 Z UKMET which only goes out to 144 hrs shows what would be a potent storm coming up the east coast as well..

European Computer model has this at 144- 168 hrs out..

However, in its means we get this ..

As you can see the means of the models are showing a very strong signal for a coastal storm in this time period..even though the operational models are shifting around the details. This can generally be expected at this point and time.

This storm could if it indeed does come about provide the region with heavy wet snows and heavy rains with coastal flooding. We would need this system to phase the southern stream energy together with the northern stream and we could then be talking about a potent spring Nor Easter on our hands in this time period. Certainly something we will continue to keep our eyes on and continue to update you with the latest information as it becomes available!

Threat #1 Update For March 30-31st

This is going to be the first of two updates this afternoon and this will cover event #1 that is on the near horizon. Considering we are only about 4 days away from this first system there is still a fair amount of disagreement with what is going to happen with this system.

Being that we are four days away you will NOT find us making any definitive statements . We are not going to say that this system will cause snow to fall..we are not going to say this system will cause rain to fall. Why? Because we like to deal with more certainty in forecasting then uncertainty and at 96 hours out there are still to many uncertainties , especially when models are not in agreement. If we are going to be wrong in a forecast it is because something did not go according to as planned not because we made absolute statements at 96 hrs out. Can it snow this time of the year? Yes it can. 3 days ago just proved that to be true. Does that mean it will snow again? No.

With that out of the way lets look at the latest guidance that 12 Z and 18 Z offered up to us today..

The GFS at 12 Z says the system is going to stay to the south of the area and not really provide the region with any precipitation. However, the latest GFS run would actually give parts of the region a snow to rain to snow type scenario or in some locations such as ABE it could give a minor all wet snow event..

12 Z GGEM brings the system from the south and moves it towards the NE and its temp profile is one that would suggest that a wintery mix of snow/ice is possible across parts of the region.

The UKMET appears to take a low towards and into Ohio and then redevelops this low off the southern New Jersey coast at around 108 hrs out and moves it NE from there. This is pretty consistent with its prior run for this system..

The European Computer model on other other hand tends to start this system pretty far off to the south at 96 hrs and then moves it towards the NE and redevelops another low more south of the rest of the guidance..

While 850s on the ECM are supportive of frozen temperatures ..the boundary layer is generally to warm for any frozen precipitation..(there could be some exceptions to this however).

At the present time we are not talking about a system that will have an abundant amount of QPF. The QPF with this system looks to be light to moderate at most with about .50 or less thru out the region. If this were to end up being an all snow event  for some locations (higher elevations)  at the present time it would only be about in the 2-4 inch range.

It does appear as though some locations could be dealing with wintery weather ..but the where..and how much and exact details are too far out.

There is a possibility that a bigger storm could follow this particular system. The next post will cover that time frame and its possibilities weather wise.

Threat # 2 On The Horizon

Well threat # 2 is the one that we started talking about yesterday & today the model runs have actually started to back off somewhat on this threat.

The GGEM actually has no threat in this time frame what so ever. Some are saying that last night the model did indeed have the threat on it but they would be sadly mistaken or getting the time frame confused with another system..

Here was last nights 00z GGEM

You can see there is high pressure in control across the region and that pretty much is in agreement with todays GGEM.

Again, you can see from the image above that there is high pressure that is in charge across the area so with the GGEM there has not been a storm threat. Another thing i want to point out on the GGEM is the lower right hand image if you look at the black line that is suggesting that the region would be quite cold in the 850 level.

The GFS however does have a system on its horizons ..however as you can see above it keeps this system off to the south and east and it also becomes a little on the warm side cause it completely misses the phase.

So thus far we have the GFS which is south and east & the GGEM which has no storm. The 18 Z GFS still has the system but it cuts it off over the Southeast off the coast of Florida.

The European Computer model..

Also has a system but it as well is off the coast and really is just a miss to the east of the region. Again on the ECM you can see that the 850s are pretty cold and a nice trough across the east with a ridge into the west.

So , at the present time ..there is little if any model agreement on what is going to happen with this system but at this point and time we would just like to remind you the readers of the teleconnections and what they are going to be doing at this point and time.

1. The NAO is going to be going from negative to positive. When this happens this is referred to as the Heather A signal and usually means a large storm is going to happen along the east coast.

2. The PNA is going from positive to negative.

Now, as a way of throwing caution with the guidance out at our readers we want to show you what the most progressive bias model does with this system. Keep in mind that this is a coastal system that we are talking about…

Interesting huh? Remember…the bias of the model generally implies that the rest of the guidance would be too far south and east with this system. Something to keep an eye on and see how this model trends along with the rest of the guidance..Perhaps a sign that the bigger threat still does exist and the teleconnectors are indeed correct…

Two Threats Looming On The Horizon! Threat #1- March 30-31

The first threat coming up is about 120 hrs out or less. The models are really not in agreement on this particular threat at this point and time. Essentially we have the GFS and the UKMET that are pretty much similar in thinking with the ECM trending towards the GFS. The GGEM appears to be out in left field with this system compared to the rest of the guidance.

So we are going to take a look at this first system and we will look at the 12 Z runs as well as the 18Z runs.

The above is the 12 Z GFS and as you can see it has a system effecting the area and at this point and time it appears as though some of the Northern Areas would start off as frozen..however..as warmer air starts to move in at the surface it appears as though this would change over to rain after the hours shown above.

As you can see the 18 Z GFS above is fairly similar in its depiction with overall the same outlook and solution.

The European Computer model also has this system but it appears to be a tad bit slower with the timing then the GFS.

Temperatures on the ECM are in the 30s and 40s and the QPF with the system is on the paltry side compared to the GFS.

The UKMET is overall pretty similar and redevelops the area of low pressure off the SNJ coast. All and all when looking at these three models the way the systems acts reminds me of the one that just moved thru the region with its snowfall. One main difference is this system is not going to be originating as far north and may work a bit more south as the time nears.

Now the GGEM on the other hand would be the southern outlier..

The GGEM as stated is on the southern edge of the guidance and would not have this system effecting the Northeast in any fashion.

So overall, within the next 4-5 day time period it looks like a system could provide parts of the region with some more wet snowfall as well as some rain across the region.