Friday, January 14, 2011

Mid Term Grades-- The Good, the Bad and the Ugly

Well, the half of winter is just now on the books--

First, quick updated about the earlier snow. My 1-3 inch call was a little too aggressive and we did have a longer period of freezing drizzle than first anticipated. My great intentions of updated the blog went under. If you read this and do not have me as a friend on Facebook, please add me as I will stream updates on there or add me on your twitter account.

Despite December coming in as record cold-- we are heading towards a pattern breakdown for a while. IF, the pattern would remain warm, my season outlook would be pretty good despite all things. (but it won't)

The good-- The cold pattern developed late in November as anticipated and lasted all month in December. Mid January the pattern has broken down,. As foretasted, it has been dry with no major snow events. The December 16th event has been our largest snowfall of the season. My snowfall outlooks have verified well, all within, even if just barely the range allotted. ( December 16 was a 3-6 inch call with 3 inches and 2.2 for a 2-4 for Christmas day.

The Bad-- While getting the general idea for a cold December right makes me happy, the pattern was much more amplified than I first anticipated. Much more is code for record setting amplified.  My thoughts of a HISTORIC cold outlook from 10 days ago looks really bad. Yes, its been colder than normal but nothing historic.

The Ugly-- Nothing remotely close to a pattern that resembles ice threats, much more intense blocking. Also, while the pattern is shifting, I doubt the cold is mostly gone for the winter.

From this point forward-

We have a rain threat Monday with MAYBE a little sleet or freezing rain in the front side.*Nothing major* Something called the PNA spikes (PNA is a ridge over the west coast). This brings a colder pattern to the east, but NOTHING to lock in cold air or slow down a storm.

Something called a "Sudden Stratospheric Warming" is linked to a -AO -- and one of those could be in the works (I'm no expert in the this process, just know the impact, here is a wiki link of you want to read more http://en.wikipedia.org/wiki/Sudden_stratospheric_warming  ). What this COULD mean is a return to the stronger blocking we had in December. I've not noted the updated information from this, but this usually takes a few sides of 10 days to  re establish the colder pattern. The bottom line is it weakens the polar vortex. When the polar vortex is weaker or in several smaller pieces it allows for blocking to dominate.

Moving forward, My guess is that the first half of my winter outlook is going to be MUCH better than the remainder. It does seem like this will be a more intense winter cold wise and the snow card has basically 8 viable weeks to play out somehow seems bleak to verify with a 5-10 inch allowance I predicted.. La Nina winters are NOT known for historic events, and yet we've had 2 on the east coast--- the Boxing day event and this past Sunday to Wednesday event that just slide past our region with a minor dusting. We've officially clocked 7.4 inches this winter in Lynchburg and I expect this to increase. Putting aside the dry nature of this winter, the overall pattern has been NOTHING like a La Nina and there are not many signs that this will end anytime soon, just breaks.

One of the points of my outlook was that seasonal pattern changes often weaken and mute the impact of La Nina's. If we get a Sudden Stratospheric Warming-- the impact would likely be the first 2 weeks of February. At that point, the long wave pattern  is starting to make the seasonal change to spring and the impact of La Nina is drastically dropped.  So, I'm hedging colder overall for the remainder of the winter, just not as cold as December. Snowfall hasn't been hard to come by--but hasn't been anything significant. My guess is that we could move the seasonal total is more like 10-15 inches this winter rather than the 5-10 forecast.

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