Wednesday, December 19, 2012

Wednesday 7PM: It's Not Like We Don't Have a Shot

Source:weatherbell.com

Now wouldn't that be nice for someone who wants to see snow. That's total accumulated snowfall on December 27th.


I mentioned on my last post how without a positive PNA it is very hard to get a east coast snowstorm unless the high pressure to the north sets up in a perfect spot. Basically to have a storm develop off the coast under those conditions you need a cold air mass over our area ahead of a storm that is approaching. This creates a zone between cold and warm air on the Atlantic coast. We all know storms like to form when there is instability or cold and warm air clashing. Thus when we have this setup, an approaching inland low will jump and reform off the coast producing snow. Since we have not yet had a big outbreak of cold air ahead of one of these recent storms, the primary inland low has dominated and we were caught on the northern end. You can see this below which the storm approaching the area tomorrow. 


source:accuweather.com

Notice the storm in the central US and the lack of cold air over NJ (red lines mean warm). This results in this storm tomorrow cutting into the lakes and not redeveloping a surface low out in the Atlantic  This has been happening all month, resulting in rain. The next storm approaching on the 27th might be a different story however..

See how unlike the first graphic there is more cold air out ahead of this storm (left panel blue lines). This will allow the storm to jump to the coast (as seen on smaller panel) . Now of course this all assumes  the modeling is correct on where the high pressure setup to the north is- feeding the cold air into our area. If this trend continues, we will have a shot at a snowstorm between Christmas and New Years. If the trend breaks, then expect more rain like we have been used to seeing. Out past the 27th I think we still will see a setup that could favor snow if the situation on the 27th falters. The PNA looks like it wants to trend more positive after the new year which would result in these storms forming more in the gulf as opposed to needing to jump across the central plains to the east coast. In any event, even tho we have not had any snow in NJ this pattern is extremely active around the country. It is just a matter of time until our number is called. The GFS snowfall forecast as show in the beginning of this post suggests that. Don't rule out some light snow showers Christmas eve either.

Keep checking in. I will keep updating on what will evolve with the 27th situation.


No comments:

Post a Comment