Wintry Winter 2018-19 Discussion

[ForsythSnow]

I got a slushy inch, yippee! I guess it was a white slop Christmas!

I remember that storm getting 4 inches. Still less than the original higher amounts they predicted, but regardless still part of one of the best winters for me.

 

[Snowfan]

That Christmas was the best Christmas present of my life.

 

[SimeonNC]

I love these types of winter "outlooks"

 

[Rain Cold]

From reading various blogs, forums, and tweets, and from looking at LR model forecasts, looking at various current indexes (as well as future progs for them), and looking at some solar stuff, I’m quite optimistic about winter. It looks like we’ll be anywhere from a warm neutral to a moderate Nino, and it looks like it might be central or west-based. Given everything else, that would bode really, really well for the east. Still a long way to go, but right now, it’s hard to be pessimistic.

 

[pcbjr]

From reading various blogs, forums, and tweets, and from looking at LR model forecasts, looking at various current indexes (as well as future progs for them), and looking at some solar stuff, I’m quite optimistic about winter. It looks like we’ll be anywhere from a warm neutral to a moderate Nino, and it looks like it might be central or west-based. Given everything else, that would bode really, really well for the east. Still a long way to go, but right now, it’s hard to be pessimistic.

 

[cd2play]

I don't mean to be so uptight, but my heart's been hurt a couple of times, by some winter storms that didn't treat me right...
I ain't gonna lie, ain't gonna lie.......

 

[SimeonNC]

A weak modoki Nino would be best for our region, it doesn't guarantee colder but it does raise the chance for cold. There is also the STJ which leads to more storm chances in general. A good thing to keep in mind is that we don't need a cold winter overall to have big storms, just have the right conditions align at the right time.

 

[Webberweather53]

December 2010 is great & all but let's just cut to the chase here, most in central NC know what they really want, one of these :weenie:

 

[Arcc]

Another last winter will suffice quite nicely.

 

[GaWx]

December 2010 is great & all but let's just cut to the chase here, most in central NC know what they really want, one of these :weenie:
View attachment 5522

Per records, ATL got 0.6" of S and/or IP 3/1-2/1927. The vast majority of the 0.84" of liquid equivalent 3/1-2/1927 was rain as the high was 47 but it apparently ended as a period of snow and/or sleet as a new cold airmass came in. The high on 3/2 was only 33, which appears to have been just after midnight.

 

[ForsythSnow]

Per records, ATL got 0.6" of S and/or IP 3/1-2/1927. The vast majority of the 0.84" of liquid equivalent 3/1-2/1927 was rain as the high was 47 but it apparently ended as a period of snow and/or sleet as a new cold airmass came in. The high on 3/2 was only 33, which appears to have been just after midnight.

If that happened today, I'm not sure if I'll be able to stay sane only getting less than an inch while NC gets 2 to 3 feet in places

 

[Brick Tamland]

When is the last time RDU had more than 6 inches of snow from a storm? Was it the 2010 Christmas storm? I think more than 6 inches of snow around here can be considered a big dog.

 

[Webberweather53]

I was looking at the orientation of that map and thinking I'd still be slightly upset if I was in RDU (or Wake Forest) and only got ~ half of those 24 to 36" totals.

Then I remembered, I've already lived that (multiple times ).

Was in RDU for this one. Senior year of undergrad, bet all of my classmates and my professor there would be 4" at RDU (they all laughed and thought it would be all rain). Then to miss it by that much was pretty painful.

Yeah there aren't too many storms like that which miss Raleigh to the south in March, I can certainly think of a few but they're rare relatively speaking. A similar storm in a general sense (synoptically) to March 2010 apparently showed up in early April 1899 and gave Wake Forest 6", while downtown Raleigh received ~3-4", everything evens out eventually even if we aren't old enough to realize it. It's pretty incredible to see totals like this near and SE of Raleigh towards Smithfield and Greenville, I'm sure folks (aside from snow weenies like us) probably were beyond done w/ winter at that point after what happened in February 1899.

 

[Webberweather53]

When is the last time RDU had more than 6 inches of snow from a storm? Was it the 2010 Christmas storm? I think more than 6 inches of snow around here can be considered a big dog.

We pretty much hit 6" on the nose this past January, December 2010 would have been the last one before that which legitimately topped 6".

 

[GaWx]

The July JAMSTEC predicted a cold DJF for the SE US, ~2 F colder than normal averaged out and the coldest of any region on the entire map:




I looked at the prior 10 years of JAMSTEC July SE US winter predictions to see how it did to give me an idea of how to treat the current cold prediction:

Winter..........Prediction...........Actual...........Missed by
18-19...............-2......................?...................?

17-18...............-1.....................+2.5...............-3.5
16-17................0......................+5..................-5
15-16................-1.....................+3..................-4
14-15...............-3.....................-1.5..............-1.5
13-14................+1....................-0.5................+1.5
12-13...............-0.5...................+3..................-3.5
11-12................+1.....................+4..................-3
10-11................+4.....................-3...................+7
09-10...............-2.....................-4.5..............+2.5
08-09................+2.....................+1..................+1

Avg....................0.......................+1..................-1

So, JAMSTEC has on average been 1 F too cold (indicative of a possible small cold bias). Both the average and median of the absolute value of misses have been 3.3 F (not good accuracy).

So, only one winter of the prior 10 was predicted by the July JAMSTEC to be colder than that for 2018-9: 2014-5, which did turn out to be cool but was 1.5 warmer than the prediction. OTOH, 2009-10 was predicted to be about as cold as that for 2018-19 but it ended up being 2.5 colder than the prediction.

What do 2009-10, 2014-5, and 2018-9 have in common? The July JAMSTEC DJF prediction for Nino 3.4 was +1.0. Furthermore, 6 of the 11 predictions have been for colder than normal and the 6 were all within the range of +0.4 to +2.4 in Nino 3.4 for DJF. The other 5 predictions were for either right at normal or warmer than normal and all 5 of these were within the range of -0.2 to -2.3 in Nino 3.4. So, there is a pretty strong negative correlation between its DJF Nino 3.4 forecast and its SE US DJF temperature forecast...i.e., it tends to predict cool for El Nino and mild for La Nina.

As mentioned, the July 2018 prediction for DJF Nino 3.4 is for +1.0. For the other two times it predicted +1.0 in 3.4, DJF ended up being weak El Nino (0.6 in 2014-5) and strong El Nino (+1.5 in 2009-10), respectively. On average, the July JAMSTEC missed 3.4's DJF only 0.2 too warm (likely indicative of only a small warm bias, if at all). The average and median of the absolute value of DJF 3.4 misses have been 0.5 and 0.4, respectively.

**Editing to make table more readable.

 

[pcbjr]

The July JAMSTEC predicted a cold DJF for the SE US, ~2 F colder than normal averaged out and the coldest of any region on the entire map:

View attachment 5535


I looked at the prior 10 years of JAMSTEC July SE US winter predictions to see how it did to give me an idea of how to treat the current cold prediction:

Winter..........Prediction...........Actual...........Missed by
18-19...............-2......................?...................?

17-18...............-1.....................+2.5...............-3.5
16-17................0......................+5..................-5
15-16................-1.....................+3..................-4
14-15...............-3.....................-1.5..............-1.5
13-14................+1....................-0.5................+1.5
12-13...............-0.5...................+3..................-3.5
11-12................+1.....................+4..................-3
10-11................+4.....................-3...................+7
09-10...............-2.....................-4.5..............+2.5
08-09................+2.....................+1..................+1

Avg....................0.......................+1..................-1

So, JAMSTEC has on average been 1 F too cold (indicative of a possible small cold bias). Both the average and median of the absolute value of misses have been 3.3 F (not good accuracy).

So, only one winter of the prior 10 was predicted by the July JAMSTEC to be colder than that for 2018-9: 2014-5, which did turn out to be cool but was 1.5 warmer than the prediction. OTOH, 2009-10 was predicted to be about as cold as that for 2018-19 but it ended up being 2.5 colder than the prediction.

What do 2009-10, 2014-5, and 2018-9 have in common? The July JAMSTEC DJF prediction for Nino 3.4 was +1.0. Furthermore, 6 of the 11 predictions have been for colder than normal and the 6 were all within the range of +0.4 to +2.4 in Nino 3.4 for DJF. The other 5 predictions were for either right at normal or warmer than normal and all 5 of these were within the range of -0.2 to -2.3 in Nino 3.4. So, there is a pretty strong negative correlation between its DJF Nino 3.4 forecast and its SE US DJF temperature forecast...i.e., it tends to predict cool for El Nino and mild for La Nina.

As mentioned, the July 2018 prediction for DJF Nino 3.4 is for +1.0. For the other two times it predicted +1.0 in 3.4, DJF ended up being weak El Nino (0.6 in 2014-5) and strong El Nino (+1.5 in 2009-10), respectively. On average, the July JAMSTEC missed 3.4's DJF only 0.2 too warm (likely indicative of only a small warm bias, if at all). The average and median of the absolute value of DJF 3.4 misses have been 0.5 and 0.4, respectively.

**Editing to make table more readable.

Thanks for the analysis and info, Larry!
Good read, and objective.
Best,
Phil

 

[malak05]

Well I got 11+ inches in the 17' December storm in GA it's always fun chasing but dont see how can get much better then last year.

 

[Webberweather53]

We're doing most of the little things correctly to put ourselves in position to see a cold/stormy winter here in the southeastern US, and there's also still a lot of ways we can still screw this up, even w/ a modoki NINO providing necessary dateline forcing to generate a -NAO this winter, the warming climate, -AMO, and inter annual persistence won't make it a slam dunk and will fight this favorable forcing. An unpredictable and poorly timed solar proton event could also easily stick a fork in a -NAO this year too by enhancing the production of NOx (Nitrous Oxides) in the polar stratosphere and mesosphere which destroys ozone, leading to cooling and the resulting circulation anomalies propagate downward from the mesosphere and stratosphere, eventually triggering a +AO/NAO. There's definitely a lot more to seasonal forecasting than meets the eye.

 

[Webberweather53]

Unfortunately, even though NC often does pretty well in El Nino, NINO winters like what we're probably going into are almost always pockmarked with winter storms that screw RDU over relative to the Triad region and rest of the NW piedmont, at least more of these so called "piedmont gradient" storms than what we normally see. I'm not sure exactly how much the probability of a storm like this increases in El Nino years, but I see these kind of storms a lot in El Ninos even in the early-mid 20th century. You don't have to go very far back to find examples of this, I have a few potential explanations why this might be happening but for now it's speculative on my part.

 

[GaWx]

Unfortunately, even though NC often does pretty well in El Nino, NINO winters like what we're probably going into are almost always pockmarked with winter storms that screw RDU over relative to the Triad region and rest of the NW piedmont, at least more of these so called "piedmont gradient" storms than what we normally see. I'm not sure exactly how much the probability of a storm like this increases in El Nino years, but I see these kind of storms a lot in El Ninos even in the early-mid 20th century. You don't have to go very far back to find examples of this, I have a few potential explanations why this might be happening but for now it's speculative on my part.
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For those curious if any of these were major at KATL (3.5"+ is my requirement for snow), several were:
- 1/23-4/1940: 8.3" (10" downtown), near the biggest on record downtown; biggest single ATL area snowstorm in general since the big one of 1/1893; this lead to snowcover that remained for perhaps the longest on record; 9.8" Athens
- 3/2-3/1942: barely cold enough with 3.7" from 2.13" liquid equiv..so a very wet snow with mixing with rain at times I think; Athens had only 1.0" despite 1.71" liquid equiv;
- 1/22-23/1987: barely cold enough with 3.6" S/IP from 1.14" liquid equiv. but tight NW/SE gradient with mainly heavy rain and flash flooding in SE metro ATL at least early on; near 5" S/IP NE Atlanta; 7.1" Athens from 1.45" liq equiv
- 2/25/2015: tight N/S gradient with only T at KATL but major just 40 miles N of KATL; 5.2" Rome and 7-10" far N GA