December Medium/Long Range Discussion

[WxUSAF]

21 minutes ago, osfan24 said:

I don't remember that one.

Ended up with 1.5” in mid November. Even DC got snow. 

[PivotPoint]

12 hours ago, psuhoffman said:

Yes this. Wes did an amazing correlation chart and DC snow correlates to the AO more then any other single factor. Adding to this...if you want a HECS then you need a -NAO. Only one of our region wide 18”+ storms in the last 50 years didn’t have a killer block and that one PD2 featured a perfectly timed Arctic high. We got kinda lucky. But that still changed to a LOT of sleet...so had timing been any less perfect...you get it. But oddly the really big ones that feature a great block also usually feature what under a non blocking regime would be a bad pacific. I talked about this some in the snow climo thread. Our HECS look is a weird combo that doesn’t work under normal circumstances. That kind of block would often suppress an event...but a trough near AK that amplified the ridge/trough downstream or a trough crashing the west that tries to ridge in the east actually helps get something to force its way up into what is likely locked in cold and a high pressure due to the confluence. It’s a weird combo that leads to those crazy anomaly storms. But if we just want snow...a good old fashioned warning event snowstorm, a -AO and a PNA or EPO ridge are the way to go. 

That's cool. Wow, I didn't know we only had one HECS in 50 years without a -NAO. Geeze.

Timing seems to almost always be a must at my latitude, but it's fascinating that if you just go 50-70 miles to my northwest, you can score with with a less than perfect solution.

I really feel like our snow success this year (as well as many other winters) is especially linked to how the PNA performs. We all know that a +PNA can influence higher chances for gulf moisture, and of course features an above avg chance we see some cooler temps on this side of the country. With that said, I also have a sense that we see (hopefully) a few periods of blocking, especially into the early part of January, as ridging in (or near) our ideal NAO space seems to be (possibly) the preferred position this season. I noticed back in October that the north Atlantic was rotating higher heights through Greenland/N. Atlantic, at least more than I have seen prior to the last couple of winters. I always feel like October through early November can give us a glimpse of some of the pieces that become featured during winter. Totally anecdotal though. I can't prove it.

Long and short - I'm really hoping for a PNA that cycles through some stable + periods. I feel like we will we get a couple "hum-dingers" if we get this.

[Eskimo Joe]

27 minutes ago, WxUSAF said:

November 2018...

 

24 minutes ago, osfan24 said:

I don't remember that one.

That was a good early season snow boom. 12z RAOB from IAD show the mid levels were about 2 or 3 degrees colder than even the meso guidance. Everyone wet bulbed right down towards freezing and held there and it was a clusterf*ck on the roads. We had like a 15 car accident on I-270 in Hyattstown that jacked everything up.

[ryanconway63]

EARLY Chrismas Morning, CMC and GFS.....hmmmmm

 

 

[JakkelWx]

2 minutes ago, ryanconway63 said:

EARLY Chrismas Morning, CMC and GFS.....hmmmmm

 

 

Yeah but does the JMA also have it?

[Chris78]

4 minutes ago, WxUSAF said:

Ended up with 1.5” in mid November. Even DC got snow. 

That was a nice surprise. Ended up with over 7" up in Hagerstown. Can't remember what was forecasted but it definitely over performed.

[osfan24]

1 minute ago, JakkelWx said:

Yeah but does the JMA also have it?

Or Dr. No?

[frd]

2 hours ago, CAPE said:

We probably need the AO to be significantly negative to mitigate that somewhat, and allow TPV lobes to break off and come south.

 

YES ! 

 

 

[PivotPoint]

Stupid one-eyed monster in AK needs to go away. So many things working for us. This is not one of them

[CAPE]

34 minutes ago, WxUSAF said:

November 2018...

We need something like the mid Feb 2015  event that kicked off our backloaded winter. Not sure how to characterize that one, but it was along a sharp cold front and intense af. That would be fun to have on Xmas eve.

[40westwx]

2 minutes ago, osfan24 said:

Or Dr. No?

It does have it!!... just further west.

[WinterWxLuvr]

5 minutes ago, osfan24 said:

Or Dr. No?

Euro sucks. Did you not watch it on the last storm?

[GATECH]

17 minutes ago, WxUSAF said:

Ended up with 1.5” in mid November. Even DC got snow. 

This was south of Alexandria for that storm...it can snow in November and stick, even to roads! Rates!

 

[Scarlet Pimpernel]

35 minutes ago, WxUSAF said:

November 2018...

I remember that, too.

Was the March 2015 event (6.5" where I'm at, general 4-8" area-wide) also a case of a low forming along a cold front?  Front went through in the early morning I recall, and a decent wave moved up shortly after during the day.  Or that's how I recall how that evolved.  I sort of remember @Deck Pic telling people beforehand to not freak out when they woke up in the morning and it's not snowing yet, because there was going to be a "lull" between the front going through and the main show.  And like clockwork of course, people freaked out early that morning when nothing was happening.  And sure enough, it began snowing like crazy starting around 9AM.

[adelphi_sky]

6 minutes ago, 40westwx said:

It does have it!!... just further west.

Rain all the way up to New Brunswick in late December. Yeah. That works. 

[CAPE]

2 minutes ago, WinterWxLuvr said:

Euro sucks. Did you not watch it on the last storm?

I watched the globals pretty closely from the perspective of my yard, and the Euro was showing next to nothing here due to the warm temp profile, while the CMC still had significant snow, and the GFS was somewhere in between depending on the run. I am not into grading model performance, but among the globals none of them were very good 4-5 days out(surprise). The EURO(and the NAM) seemed to do better with depicting the extent of warm air intrusion inside 3 days.

[WxUSAF]

15 minutes ago, CAPE said:

We need something like the mid Feb 2015  event that kicked off our backloaded winter. Not sure how to characterize that one, but it was along a sharp cold front and intense af. That would be fun to have on Xmas eve.

That was the arctic front event that was the first real MoCo-HoCo deathband?  Forecast was flurries or a dusting and ended up with over 4" of powder.  We had family over for my son's birthday party and it was a disaster for them getting home.  

[nj2va]

11 minutes ago, WinterWxLuvr said:

Euro sucks. Did you not watch it on the last storm?

I hear you on this one.  The Euro is taken as gospel and we’ve seen it struggle at times (this last storm as a good example).  All of the models were way too wet out here...HRRR actually did the best with sniffing out lower QPF out of the all of the mesoscale/short term models.

[frd]

2 minutes ago, CAPE said:

I watched the globals pretty closely from the perspective of my yard, and the Euro was showing next to nothing here due to the warm temp profile, while the CMC still had significant snow, and the GFS was somewhere in between depending on the run. I am not into grading model performance, but among the globals none of them were very good 4-5 days out(surprise). The EURO(and the NAM) seemed to do better with depicting the extent of warm air intrusion inside 3 days.

Ah, the old days of the Euro/ ETA combo ..... when they agreed Accu-Weather looked like a genius, versus the American models back in the 1980's and 1990's.  

Hopefully the old NAM was called the ETA, little early still.  

[CAPE]

4 minutes ago, WxUSAF said:

That was the arctic front event that was the first real MoCo-HoCo deathband?  Forecast was flurries or a dusting and ended up with over 4" of powder.  We had family over for my son's birthday party and it was a disaster for them getting home.  

I recall it being pretty well forecast at least a couple days leading up to it. It was convective in nature but fairly widespread. Totals ranged from 1 to maybe as high as 4". I maximized here pretty good with over 3. It all fell in an hour or so, and the end had a mini whiteout as the actual arctic cold came in.

[H2O]

Dec 2000 had a decent frontal snow IIRC

[nj2va]

@frd - curious how that will impact things if it happens as depicted for the rest of winter coupled with DTs recent post about ensemble guidance moderating Nina in the middle/end of the winter.  I’m not a LR guy at all and I haven’t finished my coffee so I’m probably barely sounding intelligent (as usual!).

[WinterWxLuvr]

12 minutes ago, CAPE said:

I watched the globals pretty closely from the perspective of my yard, and the Euro was showing next to nothing here due to the warm temp profile, while the CMC still had significant snow, and the GFS was somewhere in between depending on the run. I am not into grading model performance, but among the globals none of them were very good 4-5 days out(surprise). The EURO(and the NAM) seemed to do better with depicting the extent of warm air intrusion inside 3 days.

I was joking. 

[JakkelWx]

@CAPE That mid-Feb 2015 snow event was a true arctic airmass with temps in the teens with about a half foot of snow accumulations here. 

ETA: A couple days after featured highs in the high teens with lows close to zero IIRC

[WinterWxLuvr]

9 minutes ago, nj2va said:

I hear you on this one.  The Euro is taken as gospel and we’ve seen it struggle at times (this last storm as a good example).  All of the models were way too wet out here...HRRR actually did the best with sniffing out lower QPF out of the all of the mesoscale/short term models.

To be fair, from about 4 days none of them did that great. But also to be fair, the euro had the low almost in Baltimore from about 36 hours out. I guess my thing is that I wouldn’t put too much faith in anything for next week until about Sunday

[CAPE]

1 minute ago, WinterWxLuvr said:

I was joking. 

lol sorry. Hard to know when it comes to 'objectively' assessing model performance.

I will say I think some folks here would be better served to never look at the ridiculous WB snow/ p-type maps and do some actual analysis of the data. I literally never look at them when I am analyzing a model run. Unfortunately I get to see them here ten times over. 

[frd]

1 minute ago, nj2va said:

@frd - curious how that will impact things if it happens as depicted for the rest of winter coupled with DTs recent post about ensemble guidance moderating Nina in the middle/end of the winter.  I’m not a LR guy at all and I haven’t finished my coffee so I’m probably barely sounding intelligent (as usual!).

 

I continue to feel that any weakening of the Nina has a lag effect, based on the readings of several highly respected mets. I value DT's thoughts on the matter, we will have to see how it plays out. 

Having a weaker SPV and an improved NAM state can only help us, in a broad brush view.  As psu stated we really need a - AO to get opportunities of snowfall, and then beyond that a -NAO in the correct area, and maybe rising or oscillating such as a HA event for the big one. A delicate balance as we all know. 

This year there seems to be a disconnect the SPV and the TPV. Also it appears, at least so far that we are in play when it comes to cold air delivery. As CAPE mentioned the one thing is the source region has been an issue. Canada has  gotten colder, but not severely so, at least not yet. In Jan that source region concern becomes less of an issue. Another positive has been AAM. 

Moving forward, a jet extension and the eventual outcome hopefully of a +PNA and even a -EPO will set the stage for a colder and and snowier January. 

January looks to have decent potential to produce for our area. 

Also, look for any PV  displacements and even minor SSWEs. Again, maybe our area seems favored for a PV orientation near Hudson Bay. Feb. to hard to take a jab at. 

 

[osfan24]

34 minutes ago, WinterWxLuvr said:

Euro sucks. Did you not watch it on the last storm?

Thermals were pretty good. Low location was awful.

[CAPE]

7 minutes ago, JakkelWx said:

@CAPE That mid-Feb 2015 snow event was a true arctic airmass with temps in the teens with about a half foot of snow accumulations here. 

ETA: A couple days after featured highs in the high teens with lows close to zero IIRC

I don't recall any snow amounts that high. The event was in and out in under 2 hours. It started with marginal temps, 33-34. Most of the snow here fell at 32 degrees, with massive aggregates. It piled up fast despite the temps. Yes the cold behind the front was impressive.

[Scraff]

21 minutes ago, CAPE said:

lol sorry. Hard to know when it comes to 'objectively' assessing model performance.

I will say I think some folks here would be better served to never look at the ridiculous WB snow/ p-type maps and do some actual analysis of the data. I literally never look at them when I am analyzing a model run. Unfortunately I get to see them here ten times over. 

Always need to keep in mind that in this forum, the WB snow / p-type maps are specifically for feeding the weenies. Gotta make sure everyone eats.