Feb 7-11 Southern Rain Bomb and Miller B... potentially....

Well the groundhog says spring. But the models say nope, cold. Which one should I trust, an animal, or the collective work of thousands of people who have dedicated their lives to studying the weather. I'm inclined to trust the models, at least through mid month. That being said, the models could use some work. Many of you have heard about early next week as our next window as a storm and that is true. However, the setup will be very complicated, with multiple pieces of energy moving through the area in a couple of days.

Before we get into that, I do want to mention that there is a non-negligible chance at some snow even before that period. After the cold front pushes SE of us tonight, low pressure will develop, throwing moisture north. Although it looks like the bulk of the precipitation will be south and east of us, flurries and snow showers will be possible Friday. Little, if any, accumulation is expected and there should be no major impacts. 

NAM 4km Nest Forecast for Friday nudged the storm north. The edge of the precipitation shield is right over us. A little more north and we get more snow. More south and we will get nothing.

 After this storm clears out (the friday event forms off the front that just passed through tonight), we will hopefully be able to see more clearly what will go on next week.

Here's what we know now:

• There will be two shortwaves that will impact the area. First one comes through Sun-Mon and the second one comes through Tues-Weds.
• First shortwave will be a subtropical jet stream system
• Second shortwave will be a polar jet system
• It's more or less one storm hits us or the other. 
• Or nothing.

So in long words, the situation goes like this: There are two closely spaced waves that will move to the east coast, rounding the base of a large trough. The trough will bring cold air into the area since it is associated with a lobe of the polar vortex.

The first wave, originating from the subtropical jet, will be moisture laden, but warm. Since temperatures will not be exactly cold before the first storm, if it comes up the coast, there will likely be temperature problems, meaning snow to rain or just rain. 

The second wave will drop out of Canada along the polar jet stream. The primary low pressure will drop into eastern US before transferring to a coastal low. This transfer situation is referred to as a "Miller B" storm. Be forewarned, Miller Bs have a long history of screwing us over while the primary low dies to our west and the new low doesn't get going until it is north of us, leaving us with only snow showers. Miller Bs are notoriously hard to forecast for our region because there is no easy way to pin down the transfer location this far out. We do know that the farther the trough (and therefore the primary low) digs, the farther south the coastal forms. The farther south it forms, the better for us since the new coastal low would have more time to get going before it gets to us.

If I had to pick which shortwave to succeed, I would pick the second wave. There will be ample cold air and seems more promising for snow, than the first wave. Now the task is making sure the first wave doesn't mess up the second one. These storms don't like being close to each other. Close enough and the waves phase (merge) but these two are too far for that. But they are close enough to fore the first one to interfere with the second one's development. We already walk the line with Miller Bs so if the first storm hangs around  then the second storm can't get its act together fast enough and we're out of the game for accumulating snow. Since humans can't model atmospheric conditions in their heads, this is where models come in-to insert even more uncertainty.

00z Euro Feb 2 2016 for 7PM Wednesday shows a weaker low farther north and a stronger primary low

00z Euro Feb 3 2016 for 7PM Wednesday shows a strong low in an ideal position

The short intervals between each shortwave are wreaking havoc on the model projections.  The vary between each other and run to run a lot. For example, one run of the Euro bombed the second low off the coast of MD while the run a day before showed only a weak coastal low. Lately, they have been keying in on bombing the first low off the coast of SC (to different degrees) and running the storm out to sea (miss). However, the storm hangs around just long enough to delay the development of our second storm. At the moment, neither storm seems really promising. This can change though. What we are watching is for s trend for a weaker southern wave and a northern wave that digs farther south. Simple, right? Yeah no. It's one thing if a model shows something, it's another thing if the model is right. Likely the only thing the models will get right before this weekend is the fact that after the two waves comes a third one-the lobe of the PV itself. We're going to be cold next week.