Decided to focus a bit on the pattern with this post to update everyone on where we stand...and what is likely ahead for us.
First off...the snow stats.
Louisville (official) site
November- 0.0"
December- 2.7"
January- 2.2"
February (s0 far)- 3.2"
____________________
Season total to-date 8.1"
That is -1.5" BELOW normal. Last year as of February 18th: 3.5"
Looking at the past 5 years...how often do we still see a measurable snow AFTER February 18th?
2008- 10.68" additional fell
2009- .09" additional fell
2010- 1.02" additional fell
2011- .03" additional fell
2012- 3.5" additional fell
Just looking at the past 5 years alone, measurable snow has fallen every year after this date. Some a decent amount...some just dusting. When looking at the month of March alone--- snowflakes have fallen in Kentuckiana every March of those years.
This isn't breaking news to natives. You guys know that we have had some big winter events in March. The upper low snowstorm of March 20, 1996 always stands out in my head. I was on spring break at WKU at the time...more than 12" fell! And of course, last years, our largest snowfall of the season fell just after the March 2nd tornado outbreak.
Winter is far from over. The data supports that. The pattern supports it.
While I have no idea if we will see a big snow soon before we rush into spring, I do have growing concerns that our jet stream pattern is about to become very active in that snow won't be our only problem. Severe thunderstorms have been a growing issue over the south the past few weeks. I fear that our very dynamic weather pattern that is shaping up for the country could lead to significant snow and severe thunderstorm events. I was hoping for a quiet season this year ---but I don't like the data I am seeing that lies ahead.
Either way, we just have to take this pattern one week at a time. We are now entering the battle zone period of the 2 seasons---and long term models are going to go bonkers. So for those of you that look at the long term models often---I urge caution with them beyond day 7 at this time.
So let's dive into what is ahead for us this week.
TONIGHT:
We made it to 60 or higher today. But now the rain will move in tonight...looks to be after 8pm. Most of the rain will likely fall when you all are sleeping. Some thunder is possible. We are not expecting severe storms.
EARLY TOMORROW:
There is still strong support that the cold air will catch up to the moisture over our area early tomorrow. Light snow flurries/showers are certainly possible. Especially along and north of I 64 where the cold air layer is deeper. A much different "feel" to tomorrow compared to today for sure!
WED/THU:
We see cold period during this time. Dry, but cold.
This will set the stage for our next storm that will develop to our west Thursday afternoon/night.
It will deepen pretty fast in the Plains. It will be a slow east mover, so initially the moisture will surge more north than east. So it will take it a bit to get the moisture into our area Thursday night.
When you look at the model at face value, you can see how the blue line (typical rain/snow line aloft) is north of us. This would mean rain.
But you have to look closer. The temps at the surface...are much colder. 29-33°. Aka, freezing rain threat.
And if we looked EVEN closer, we may be able to determine how thick our cold layer is at the surface as it may have more sleet than freezing rain---but that is too difficult to gauge this far out. So we plan to just leave at freezing rain chance for now.
The good news ---it will warm overnight. You can see how surface temps jump to near 40 by sunrise.
So at this point, there remains a small window of freezing rain/sleet/snow (depending on thickeness of cold layers) Thursday night...likely during the 8pm-2am window. Improving to just plain rain by morning and Friday.
We will monitor this one carefully as these are always tricky systems for us. But at last we are getting a good heads up on it to monitor.
PATTERN AHEAD
The jet stream is expected to remain very active over the lower 48. This means several areas of low pressure will traverse over the region.
But this is where my earlier comment about an extreme pattern come into play.
The indicies.
The AOis going negative. This means the cold air is on the move...and available for any storm to tap into that moves into the country.
The NAO--- going sharply negative for the first time in weeks. In fact, look at the last time it was sharply negative. Near Halloween. Remember that storm? Yes, that was Hurricane Sandy. Am I saying there will be another Sandy? Of course not. But a negative NAO is a blocking pattern that supports deep areas of low pressure. And if cold air is around---you can have one heck of an area of low pressure with that.
The PNA ---going positive. This means the cold air has some lasting power to it. Areas that get cold...likely will stay cold. That would only complicate future storms in the flow.
You can tell by looking at the indicies they have been fairly "neutral" the past several weeks. So our weather pattern has been fairly----quiet ---overall. The only exception would have been the NE blizzard.
But now a shake-up is in store with our weather pattern. The true battle of the seasons is looking to take shape.
Where we end up in all of this....no one knows. I certainly don't. But I do know that WE will be here watching it and informing you day by day. So no need to worry...let us do that for you :)
BOTS!
As I am ready for spring softball and motorcycle's something tells me that our biggest snow is yet to come.
Posted by: prelude | February 18, 2013 at 03:11 PM