Friday, February 10, 2012

February 14-18 Possible Snow Event Discussion (2/10/12)

This is a model analysis.

In case you haven't heard, the ECMWF is now in its turbulent phase, taking one piece of energy up the Northeast and the other piece who knows where.

Here's the gist of the possible storm.
•There may be 2 pieces of energy involved.
•The past ECMWF images I had been posting was a solution where they phased, or combined as one.
•The models are not good with possible phasing of storms.

Let's start out with the GFS.
GFS Extratropical Cyclone Tracks
This is the 12z run of the GFS model. We see the current GFS run as well as the past 2 runs of the GFS. The most recent run is in red, the second most recent is in orange, and the least recent is in green. That said, you can see just how much the model has fluctuated in just 2 runs from green to orange. Notice how there is no red line where the orange line is (the orange/green lines indicate the piece of energy we are watching). I cannot determine why, but I am thinking it will be taking a very similar path to the 2nd most recent GFS (orange) track in the south just by looking at the actual model run images. Due to the massive fluctuations the GFS is experiencing I am not going to go along with its forecast this time around.

NCEP Ensemble Cyclone Tracks
These are the NCEP Ensemble Individual Member extratropical cyclone tracks. What I am seeing here is a lot of members wanting to go with the southern solution. That is, take the piece of energy in question, ride it through the south, and re-emerge it north and ride it up the Eastern Seaboard. The NCEP Ensemble Control forecast disagrees in one way, taking a more northerly path while still going with a southern solution like the ensembles. This far out, even with ensembles, I am not going to take these opinions just yet.

CMC Ensemble Cyclone Tracks
As I had previously explained, there may be two pieces of energy involved in this system. The 12z GGEM (CMC) model run may have showed both pieces but did not end up phasing them. instead, the CMC model took one piece on a southern solution, much like the NCEP Control member, and made for a big snowstorm in Ohio. The CMC Ensembles took possibly that same piece of energy and instead diverted it north, through central Illinois and Missouri, before shooting north through Michigan and well into Canada. The individual members agree with this control member, showed in pink. I am still not biting, as the models remain very turbulent.

12z NOGAPS Ensembles

What we have here are the NOGAPS model ensemble members. I know it looks like a giant jumbled mess, and it is hard to understand and pick out which tracks are for which storms. I am seeing the lines from southern Wisconsin to Tennessee moving northeast as the lines for the storm to watch. Needless to say, the ensembles are very confused with the storm, as are all models and ensembles right now. However, the NOGAPS ENS appear to be pushing for a more northern track than what other models may be showing.

Something I have learned is that sometimes models can take a storm way south and eventually correct its forecast of the storm back north to where it previously was. I have found that this can work with any model. This may hold true for both the ECMWF and GFS models, which both at one point showed the storm affecting the Midwest and Ohio Valley.

You may ask questions if you would like, but please do not ask questions of if your area will get snow or how much will your area get, because right now I honestly don't know. I don't have enough time to delve deep enough and get a good feel for the new model flips.


StormTrack: Long Range- Alaskan Vortex (2/10/12)

Something I look to for support in forecasting is the Alaskan Vortex. It is a low pressure system that sits in the Gulf of Alaska and typically makes for warmer weather over the US. Recently, we have been seeing a ridge over that region. So here's the forecast for 108 hours out.
12z GFS Hour 108 500mb Height Anomalies
See the dark blue on the upper left hand corner of the image? That is a key player in the forecast. That is a form of the Alaska Vortex. Check out how there is a ridge (orange) stretched out into Alaska trying to make a move. This low pressure system will see the ridge and beat it down, and I expect this pattern to go on for a while, where a ridge tries to move north but the low pressure system beats it down. This ought to lead to some more active weather as the two opposing factors (ridge and low pressure system) fight each other and try to get to Alaska, which appears to be the place to be.
Here's 500mb height anomaly forecasts produced by the ESRL forecast agency. The ESRL is showing a strong ridge to be present in much of the Pacific for the 6-10 day timeframe, which is what this image is for. However, notice the darker blue colors in west Alaska. What this could easily do is manipulate the polar jet stream to throw some systems from the big vortex out east into the West US, which is likely why we are seeing the darker blue colors in west/central US. (For verification, blue colors are a general stormier pattern and red colors are a general quieter pattern.)