A lot of interesting things are going on in the tropics right now that point to the Madden Jullian Oscillation going into the cold and stormy phase of 8-1.  We are currently in a phase 7 and as we head into February phase  7 becomes a much warmer phase hence the 60's we are going to feel tomorrow.  But as the pattern reloads we are beginning to see signs of a quick east movement of the MJO.  Models originally wanted to stall in phase 7 for a little bit before moving east, but IR and latest model data says that will not be the case.  

First a healthy tropical cyclone off Madagascar is our first clue of the eastward propagating MJO.  Tropical Cyclone Felleng is developing nicely under increasing upper air divergence.  The main bulk of the convection is now pushing east spreading from the dateline towards 160W.  Convection over Brazil is very phase 8ish but we are currently lacking convection where the black circles are located.  As stronger upward vertical velocities push over this area convection is expected to increase.  This should occur over the next few days. 

Now what does a phase 8 mean for us...

A negative NAO and a positive PNA and a negative AO!  Too good to be true.  

This kind of set up applied to the ensembles (although it is only 2 members right now) the confidence amongst ensembles and operational models is low for this event.  But something to watch for is this pattern above setting up for this event or a potential event down the road:

The operational run was actually a great one for snow (See below) but it did not have our ingredients.  It did this with a positive NAO.  In this type of set up a positive NAO could deliver a good snow event but only of weak to moderate significance.   The bigger event needs more blocking.  And without a negative NAO we are vulnerable to a warmer solution as shown on a few ensemble members.   But in the two frames above one labeled with the neg NAO and 50/50 and the other directly above it show a coastal going up the coast.  The one not labeled shows more of a New England snow event, but the one labeled is a huge hit for the Middle Atlantic.  

Many ensemble members show this event and all have a different solution, but there are fall in pretty much 3 categories.  The first being a weak warmer event, the second being a snow event low to moderate level, and the third being a big hit.  The 50/50 low outlined above is showing up in different areas, but for the most part it is in a general area to allow us to benefit from a snow event.  Whether it be a trace-2" event or a 3-6" event or a 6+" event is the question.  

MODEL DIFF

The Canadian model above does show a nice moderate snow event for the Middle Atlantic but notice the very strong low.  This is our weekend clipper system that bombs out and it heads north.  The GFS says that is not going to be that strong:

The European model agrees with the GFS but the GFS ended up showing a nice snow event for the Middle Atlantic also.  The Euro shows a non event as the polar vortex stays strong over the Hudson Bay helping to accelerate the northern stream ahead of the southern stream. Notice the lack of separation between the PV and the northern stream s/w, this results in a non event.

Conclusion:

-Models are going to be all over the place the next few days with this system

- Models need to get the Saturday clipper right before coming to a conclusion on this system

- Potential exists anywhere from a big snow storm to nothing depending on the blocking or lack thereof sets up

-Many solutions in this set up will deliver snow of some kind to the Middle Atlantic, but most would be anywhere from a trace to a few inches.  

CLICK HERE FOR ROB GUARINO BLOG ON THUR/FRI SNOW & STORMS