This is in reference to the time period around the 10th of the month and in reference to being called a wish caster. Majority of your storms this winter season have all trended NW within the short term at 48 hrs and under. We see this clearly with the last system where the professionals were calling for snow to begin and changing to ice …while we had stated from the beginning that this would start off as ice and any snow would come in on the backside if there was enough left over QPF. What was the result of this system? It came so far NW that it cut thru western PA and then moved to the ENE from there. No model actually showed this occurring and the closest one was the UKMET.
How about the monday and tuesday storm? I already showed how this was also modeled to be to far to the east in the medium range..
And now the 12 Z GFS at the same time period from today..
Another case of where the models have trended NW in the short term. Why is this? Because they recognized now that the trough was going to be sharper then what it once believed..
Matter of fact the 12 Z GFS is the exact same solution as the 12 Z Nogaps..
Pretty interesting huh? What about the system before this last one that dropped the ice? The one that dropped basically a foot of snow on the region? Was this also not modeled to far to the east in the medium term?
What happened as we got closer?
We came further west. Matter of fact this was the storm system that ABE was only suppose to get 4,3 inches from and we ended up with 11.6 inches and the professionals had to keep upping the totals and they still ended up well short with the final call. We could actually take this NW trend even further back but then we are talking about a completely different pattern…
The moral of the story is the pattern has been one in such that the models have not picked up on this west trend till the short term ranges..
Now what pattern are we in and when is this pattern expected to change?
The arctic oscillation is currently positive and is expected over the next seven days to drop towards neutral…This generally has been resulting in seasonal temperatures because you do not have a strong negative AO. When you have a strong – AO then you are looking at a stronger push of colder air.
NAO is positive and over the next seven days is going towards neutral. Once again ..there is not a strong negative NAO in place so …usually when you have a strong –AO + NAO in place you are looking at systems potentially suppressed to the south and the east because the cold air just crushes these systems in the southern stream.
What about the PNA?
PNA is neutral and over the next 7 days is trending towards the negative. Remember it is a positive PNA that is responsible for developing a trough along the east coast and ridging out west.
However..we can still get ridging to occur out west if we have a negative EPO. So do we ?
What happens with a negative EPO is two fold. One the stronger it is the more ridging to the west. As you can see when this system would be developing in the GOM ..we actually have a negative EPO of about –2.
The second thing that this does is it creates a SE ridge..
We see this in place at 78 hrs on the 18 Z GFS..
However..by 84 hrs the model literally pushes the SE ridge away with barely a surface reflection of a low at 1016 mbs.
Essentially all models are relatively in agreement that this system is going to stay off to the south and the east. The reasons why?
1. The trough never becomes sharp enough ..so this allows the system to slide south and east.
2. The pattern change AFTER this storm..
Why at this point and time am i staying consistent with my thoughts?
1. Models tend to under do the Southeast Ridge and break it down to soon. This recent time period is generally the first time we have seen an influence from the SE Ridge.
2. When you have a negative PNA this causes higher heights along the east coast. This could cause a further west track…
3. We have seen multiple times in past weather seasons where the Polar Vortex was modeled to be too strong and too far south or to elongated…in the shorter term this proved to be wrong in the medium term ..not always but often enough to make one think. This is the reason of why the push of cold air is so strong. What happens if that is wrong? Higher heights along the east coast.
4. A negative EPO with a Southeast Ridge would not be penetrated by a weak surface reflection of 1016 when the high pressure is stronger by 10 mbs.
5. Majority of the systems this season have trended back towards the NW when it came to short term range of 48 hrs and under.
Now, one can say that this is wishcasting ..however..the results are clearly documented and shown above and majority of us know what has occurred this season.
So lets see what the professionals are saying …
THE ECMWF SHIFTED IN THIS
DIRECTION LAST EVENING AND THE 12Z CYCLE MAINTAINS THIS SCENARIO.
THEREFORE, THE MODEL CONSENSUS IS FOR NO REAL STORM NOW FOR OUR
AREA THURSDAY. HOWEVER, WE HAVE SEEN SEVERAL TIMES THIS WINTER
THAT AS WE GET CLOSER TO THE EVENT, THE MODEL GUIDANCE COMES BACK
NORTHWESTWARD WITH THE STORM TRACK. WHILE THIS COULD HAPPEN AGAIN
WITH THIS SYSTEM, THERE ARE A FEW THINGS AGAINST IT. FIRST, THE
BROADNESS OF THE UPPER-LEVEL TROUGH AS WE WOULD LIKE TO SEE MORE
SHARPNESS TAKING PLACE AS IT NEARS THE EAST COAST. SECONDLY,
FOLLOWING THIS STORM THERE IS A PATTERN CHANGE FORECAST TO OCCUR.
The above is from MT Holly… It appears to me that they acknowledge what has happened prior and that this could happen again…however..they outline the reasons why the models “could” be on the right direction as well.
Lets see another agency which is HPC
CONSIDERING MODEL VARIABILITY
OVER SEVERAL SYSTEMS THIS WINTER...GUIDANCE TRENDS ARE NOT SET IN
STONE...BUT DO BECOME HARDER TO REVERSE AS LEAD TIME SHRINKS
TOWARD SHORT RANGE TIME FRAMES. ACCORDINGLY AND CONSIDERING
CONTINUITY...HPC PROGS REMAIN PRIMARILY DERIVED FROM THE 12Z/05
ECMWF ENSEMBLE MEAN WED/THU...AND A HINT OF THE GFS. THIS OLDER
ECMWF MEAN TRACKED SYSTEM SWATH SLIGHTLY MORE TO THE LEFT THAN THE
BULK OF NEWER 00/12 UTC MODEL AND ENSEMBLE GUIDANCE AND TRIES TO
INCORPORATE ANY LINGERING POSSIBLE EFFECTS FROM ANY SYSTEM
EJECTING OVER SERN US RIDGING ALOFT.
HPC also acknowledges that things are not set in stone and actually have the system tracking up the coast to the left of model guidance.
In other words these agencies are looking at the guidance and then taking weather history and climo into consideration and putting out a forecast. While doing this they are saying that a NW trend is indeed possible but not a certainty…
It seems to me that they are saying the same thing as i am as far as the potential for this to come back further to the NW in the short term. There reasoning boils down to past weather ..which some want to say is irrelevant..interestingly enough it has relevance with the professionals.
So..what we are going to do is we are going to continue to monitor the guidance over the next 24-36 hrs and see what changes take place.. In the mean time..we are not going to change our thinking that this could come further NW in the short term. To clarify short term is 36-48 hrs and under.
Its not like we have not seen this happen recently so its not out of the realms of possibilities of happening again.
Now..what is even more interesting is the same people that accuse me of wishcasting etc and constantly put down the Nogaps etc..do not realize that thus far the NOGAPS has been consistently showing this system to be further to the south and the east..So if this indeed does end up missing the region….well….I think where this is heading is clear .
We will continue to monitor this time period & continue to update this every 24 hrs..
Next up in the next hour is what about Monday and tuesday?
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