Folks Its All About The Pattern

Here at Real Wx Services we like to focus on what should be the focus and that in this case is once again High Latitude Blocking with huge positive height anomoly working its way west south west from Southern Greenland to North Central Canada. The first important feature with this is that cold air is going to be abundant to the south and southeast of this block into the Mid Atlantic and Northeast which is going to once again mean much below normal temperatures. We here at Real Wx Services are strong believers in the pattern controls the weather.

With the latest 12 Z guidance there is agreement on the above over all weather pattern. However..model solutions spread in their guidance when it comes to the small scale issues involving shortwaves and the possibility of what they can do in this type of weather pattern.

So lets look at the latest 12 Z guidance and see what is happening.

Above is the 12 Z GFS which would bring a major snowfall to places in PA into the Northeast…this is a northern stream disturbance. Basically what we see here is a Miller B where there is a clipper system dropping into the lakes and it redevelops off the Delmarva and rapidly deepens. This type of solution makes sense given where the greatest thermal gradient would be.

The above is the GGEM and this is overall similar to the GFS, only slightly progressive but the theme is the same with a Miller B system redeveloping to the south and then moving off towards the Northeast. There are a few frames missing due to the site not updating those missing frames.

12 Z ECM essentially has a Miller B solution as well but only shows a very light surface reflection of a secondary at 120 and then it is actually on the northern extreme end of guidance and will have more on this in a little bit .

The main differences when you look at the GFS/GGEM versus the ECM is the height falls across the mid atlantic are further south which allows the energy to dig further to the south. This is quite important in the long run & will explain why right after this next bit of guidance.

Real Wx Services always likes to look at two pieces of guidance to see whether or not the European Computer model is actually correct with its depiction. These two pieces of guidance very often serve as  a red flag to the ECM.

We are looking at the 12 Z UKMET & 12 Z Navy Nogaps. First with the UKMET..the first thing one notices is that the UKMET also develops a secondary south of the Delmarva area and is more in line with the GFS/GGEM and it ends up south of LI at 144 hrs.

With the NOGAPS ..it keeps the primary over the lakes stronger..AKA ECM and ends up more to the North just not as far north as the ECM. Overall though the evolution of the NOGAPS is quite similar to the ECM solution and raises a red flag along with the UKMET to the ECM.

As we previously mentioned this is a Northern Stream system and just like the last event the ECM had a difficult time with its evolution as the GFS was the first to catch on to the Blizzard that occurred across the region.

To take this a step further in recognition with the pattern that the teleconnections are showing is the NAO while negative is once again starting to relax and the PNA is indeed slightly positive and the MJO is heading into phase 6.

 

 

Current thinking is that the ECM is a Northern outlier because of the red flags mentioned above and the pattern itself. With high latitude blocking in place which is only slightly weakening at this time period,  this implies that the push of cold air (sinking air) would force the secondary to be further south more in lines of what the GFS/GGEM/UKMET would imply versus the ECM.

Overall a snow threat lies on the table for this time period from PA/MD border north and east but the magnitude of this system is too early to go into details. Stay tuned for more updates!