Griteater's Winter Outlook ('14-'15)

[BIG FROSTY]

Great write up grit, thanks for all the time and hard work you put into it. I hope it verifies would be a great winter for us snowmen!! ️

[Bob Chill]

Really nice writeup, Grit. Enjoyed it. Dec looks tricky. The current pattern is a bit of a flag to a step down through DJF. I'm not sure which way it goes. It's either a sign of front loaded cold anoms in the east or part of a process where we relax in early December and then get back to business.

If the current -ao pattern ends up being like what we see when it starts in Dec then Dec-Jan could be the coldest relative to normal and tailing off in Feb.

OTOH- if we flip warm for a couple weeks in Dec and reload then your forecast looks pretty sweet.

One thing for sure, Nov is behaving like we are going to have fun this winter. I despise that "sinking feeling" when a stable and hostile pattern sets up during the second half of Nov. Blech

[griteater]

Really nice writeup, Grit. Enjoyed it. Dec looks tricky. The current pattern is a bit of a flag to a step down through DJF. I'm not sure which way it goes. It's either a sign of front loaded cold anoms in the east or part of a process where we relax in early December and then get back to business.

If the current -ao pattern ends up being like what we see when it starts in Dec then Dec-Jan could be the coldest relative to normal and tailing off in Feb.

OTOH- if we flip warm for a couple weeks in Dec and reload then your forecast looks pretty sweet.

One thing for sure, Nov is behaving like we are going to have fun this winter. I despise that "sinking feeling" when a stable and hostile pattern sets up during the second half of Nov. Blech

 

Thanks Bob, I thought the recent blog post from Cohen was interesting for Dec - http://www.aer.com/science-research/climate-weather/arctic-oscillation

[Bob Chill]

Thanks Bob, I thought the recent blog post from Cohen was interesting for Dec - http://www.aer.com/science-research/climate-weather/arctic-oscillation

That's a very interesting read. Leads to more anticipation of what's next...

I'd be totally happy with a "normal" winter. But the grip of greed is always tugging...

[wncsnow]

Great job Griteater, nicely done and easy to comprehend

[griteater]

This is a post-winter summary and outlook verification post.  Original outlook text in black; verification text in red.

 

 

Winter Forecast Calls

 

500mb Pattern

On the left was my forecasted 500mb pattern.  On the right is the Dec-Mar actual.  I couldn’t have been any worse with the AO and NAO / North Atlantic forecast call…it was exactly opposite of my projection.  On the flip side, I was pleased with my call for the strength and location of the Aleutian Low in the north Pacific and general above normal anomalies in Alaska and western Canada.  I’d like to think that I would have gone with more ridging in the western U.S. if I had known we would see a ++AO / ++NAO, but that’s all conjecture at this point. 

 

 

 

Temperature Anomalies

On the left was my temperature anomaly forecast.  On the right is the Dec-Mar actual.  The big picture call of warm west / cool east was OK, but I was way off on the specifics in several areas.  Despite the favorable North Pacific / Western North America pattern for cold air in the southeast, the actual near normal temperature result shows the importance of a –AO/–NAO pattern for getting consistent cold way south.

 

 

 

Here are my thoughts on wintry precipitation: I believe the southern stream will be a little more active than climo, but I’m not of the belief that we will see a parade of southern stream storms representative of higher level Ninos in the mold of 82-83, 86-87, 02-03, and 09-10.  This was an excellent call; more on this topic later.

 

As for wintry precipitation (snow & ice), I will go with a blanket “slightly to moderately above average” projection for the entire southeastern U.S., with no preference for any specific region to receive more, or less, wintry precipitation (compared to climo).  For the purposes of this outlook, the southeastern U.S. covers: E TN, AL, GA, N FL, SC, NC, SE VA.     

For snowfall, the northern areas of the SE saw slightly above normal snow, while the central to southern areas were near normal to below normal.  Charlotte saw 1.42 inches liquid equivalent of wintry precipitation (snow & ice).  That’s in the 62^nd percentile (slightly above normal) for data that I’ve compiled back to 1973 and compares favorably to the winters of 2003-2004 and 2009-2010.

 

 

“Preseason Rating”:

For the southeast as a whole, I’ll give a general rating from 0 to 10, based on the following:

 

0 = well above normal temperatures, well below normal amount of wintry precipitation (snow & ice), well below normal # of winter storm threats

10 = well below normal temperatures, well above normal amount of wintry precipitation (snow & ice), well above normal # of winter storm threats

 

My call for this winter for the southeast (E TN, AL, GA, N FL, SC, NC, SE VA):  7.5

 

Let’s look at each element of the above criteria for the SE:

I’d give temperatures a rating of 6.5.  Temperatures overall were near normal to slightly below normal across the SE areas mentioned.  Charlotte recorded 2 days with single digit lows which has only occurred in 12 winters since 1950.

I’d give winter precipitation (snow & ice) a rating of 6.0

As for winter storm threats, I’d give it a subjective rating of 5.0-6.0

 

Putting it all together, I’d give this winter a Post-Season rating of 6.0 (C+), which was an OK forecast call.

 

 

Forecast Calls For Charlotte:

Temperature Departures:

Dec: -1 to -2  Actual: +3.3 (Poor forecast)

Jan: -3 to -4  Actual: +0.2 (Poor forecast)

Feb: -3 to -4  Actual: -6.5 (Good forecast, though not cold enough)

Mar: 0 to -1  Actual: +2.9 (Poor forecast)

 

 

Summary of Other Forecast Calls:

1.       The Dec-Mar averaged AO and NAO will end up moderately to strongly negative.  Horrendously bad call.  The Dec-Mar AO was the 4^th most positive on record since 1950, while the Dec-Mar NAO was the #1 most positive on record.

2.       Total number of southern stream storms (as defined earlier) will be 11 (Avg is 8.9).  Excellent call.  Using the criteria I defined in the outlook, there were exactly 11 southern stream storms this winter; 1 in Dec, 3 in Jan, 2 in Feb, and 5 in Mar.  In terms of the number of southern stream storms compared to normal by month, Dec was below normal, Jan-Feb was near normal, and March was above normal.

3.       The Fall/Winter ENSO will be best classified as Weak El Nino (combination of MEI, ONI, and Weekly Averaged SST).  Good call.  This was a Weak El Nino winter per MEI, ONI, and Weekly Averaged SST.

4.       The Dec-Mar averaged PDO will be moderately to strongly positive.  Good call; the Dec-Mar PDO was actually the most positive on record (+2.32) using the Univ. of Washington data back to 1900.

5.       The Jan-Feb averaged QBO will be classified as Negative and Falling at 45mb.  Good call; the –QBO is descending through the stratosphere, but the core of the –QBO has yet to reach the 45mb level.

6.       The 90 day, Dec-Feb averaged, observed solar flux will fall in the neutral range: 105-150 (x 10 ^-22 W m^-2 Hz^-1).  Technically this was a good call with the Dec-Feb averaged solar flux coming in at 143, but there was a spike in solar flux in the Sept-Dec timeframe that possibly contributed to locking in the +AO/+NAO regime for the winter.

 

 

A couple final notes:

1.       From time to time we discuss the idea of the cold air getting flooded on the ‘other side of the pole’.  Well, this past winter, E North America was one of the few areas with cold anomalies.  Warm anomalies dominated Europe and Asia.

 

2.       And finally, with regard to western U.S. ski resorts, the ski season progress report on this website says, "The West remains on track to match its second worst snow season of 1980-1981, with a few areas threatening the record lows of 1976-1977."  Heavenly ski resort in Lake Tahoe recorded 85 inches of snow, 24% of normal.

[GaWx]

Grit,

 Very nice post-mortem! I'm glad you included ice in the Charlotte total wintry precip. Too often imo it is neglected in the SE, where it can easily dominate the wintry precip. for any winter for the main CAD areas especially. Because it isn't as easy to find ZR as it is for SN/IP when looking back, it can easily be ignored.

 

 I know you looked at DJFM as opposed to DJF. However, I'm sure you realize that DJF, alone, was a good bit colder since Mar was pretty warm. I wonder what you would have forecasted had you done just DJF. I bet you would have come very close. I think you sort of got a bad break with the warm March. Also, fwiw, NDJFM was, of course, also colder since Nov was so cold.

[griteater]

Thanks GA.  Problem is, if I had limited it to Dec-Feb, I would have gone colder....ha

[mackerel_sky]

Thanks GA. Problem is, if I had limited it to Dec-Feb, I would have gone colder....ha

Good job man! Looking forward to the 15-16 winter outlook! I am willing to bet you will go with a cold winter, that 2nd year Niño will bring the goods, just be nice if -NAO would show up for a change!

[griteater]

Good job man! Looking forward to the 15-16 winter outlook! I am willing to bet you will go with a cold winter, that 2nd year Niño will bring the goods, just be nice if -NAO would show up for a change!

 

Thanks Mack.  Early call does look like we will have another nino/+pdo