Folks we need to be clear on something for those that do not understand how the bias of the NOGAPS works. In the longer range of the model if the system is more wrapped up and west of guidance then that flags the guidance that it is too far east or south. In the medium range you want to start seeing the model start to go south and east and the rest of the guidance trend to its more NW previous solution. Does not have to be as far west however..but you want to see it west. In the shorter range if the model is more NW then the rest of the guidance it is a flag again. This is how the bias works with a SE progressive model. Last nights 00z NOGAPS was thru Central Pa which would be a driving rainstorm for all. I mentioned this last night was already too far to the west..it was an extreme version. So you wanted it to come more east which it has but as you will see its not what would be called OTS…
Now, applying this models bias properly you would want and expect to see all guidance to the west of where that is. So lets look at the 12 Z guidance.
We are going to start with the model that has been discarded as an outlier by HPC.
Operational GFS looks good for a Major East Coast snowstorm. However..by the end of this you will see why its an outlier and why it was discarded.
Next up is the GGEM/UKMET
Couple things you notice about these solutions. First of all, they are all slower then the GFS. Second of all they are all west of the Nogaps and West of the GFS. Thirdly they are pretty much amped up solutions which makes sense as an amped up solution would be more west. If it was weaker ..it would be more east.
Next up is the ECM…ECM is relatively consistent with this storm from 00z last night.
850 freezing line never gets north of I78 on the ECM & QPF output of the ECM has increased from last night. Essentially N & west of I-78 is over 2 feet of snow..Along the coast would be heavy snow to heavy rain back to snow as the heights crash with the 850s. This could very well be a case where the coast sees heavy snow (wet with temps in the mid 30s) ..however..too early to know those details and just giving you the idea of what is potentially on tap.
Now why is the GFS op an outlier? This is something alot of people do not want to hear. However..first the GFS is a fast outlier to its own means. Second it is too far to the north compared to its own means. Third its too far east compared to its own means.
The GFS means actually track the low over Cape May NJ just like the 00z ECM from last night.
So you can see why the GFS OP run was discarded! Its timing is similar to the ECM/GGEM/UKMET in the means.
Here at R.W.S our thoughts have not changed from what they were 30 + hours ago and that is a coastal hugger tracking 50 miles or less along the coast with even that potential of riding the eastern edge of the Jersey coastline.
This storm is loaded with QPF. This has the potential to lay down heavy heavy heavy wet snow in large amounts as it is currently being modeled by the guidance. This storm will also have the potential for coastal flooding. This storm will also have the potential for strong gusty winds. This is likely going to be a storm that will be remembered in one way shape or another! This is all potential at this point and time but it is important to get this out there so you the readers are aware! This is going to be a potentially dynamic situation!
So do to all the above..R.W.S is keeping in effect the level 2 Alert! Be prepared for the potential of a Significant Winter Weather Event!
Stay tuned for more information on this developing storm!
No comments:
Post a Comment