Winter 2015-16

[John1122]

A note about cold temps and suppression. It's more about blocking versus no blocking. I have seen below zero weather one day, with the temp the next day above freezing the next. Also, a juiced southern stream tends to maximize warm air advection.

 

We had a huge winter storm in the 1990s, it was 2 degrees at the onset and sleet changed to freezing rain, the mass warm air advection was very strong and we went from 2 to 30 in about 2 hours. I never doubt the power of WAA and moisture transport if we get a low in the right place. It's actually the most under modeled aspect of almost every miller A storm we get. The precip shield is almost always too suppressed by the cold air in place. You can get monster outbreaks that send the storms to the central gulf, but that's when you end up with those rare December 1989 cold outbreaks and monster storms that bring big snows to North Florida up to Charleston.

[Carvers Gap]

The 1.1.16 0z GFS says,"Happy New Year," to the Tennessee Valley. Beautiful look. Blocky. Cold. Lots of energy.

[tnweathernut]

The 1.1.16 0z GFS says,"Happy New Year," to the Tennessee Valley. Beautiful look. Blocky. Cold. Lots of energy.

Happy New Year all! I agree, BIG storm signal around the 11th.

[tnweathernut]

The parallel EPS ensemble mean at 500mb from last night shows a pattern that would likely be colder than normal for the next 45 days in the southeast. After very cold days 11-25 it relaxes a bit (though likely still colder than normal in the SE) for the next week or so (through day 32ish), followed by a re-strengthening PNA and deep eastern trough, similar to what is before us now... albeit with no real signal of a -NAO after day 25. FWIW

[1234snow]

I'll take this look all day on the 12z GFS. Big Miller A with tons of moisture and the bottom of the vort goes to the southeast of us. I'll worry about the cold air 240 hours from now lol!

[1234snow]

We are really in the same boat as last year as far as snow cover goes. We rebounded amazingly well last year. I have a feeling this year will be similar but a little less extreme.

[jaxjagman]

One of the top analogs from CPC for the 12th upcoming is based off the analog from 1-21-85,it wasn't a enso year,just thought i'd post it anyways

 

 

[ShawnEastTN]

Not a bad place to be 8 days out.  If tracked a tad further north and west...  Not to mention the under modeled precip shield which is always the case with Millers.  Wouldn't mind kicking off our belated winter with a good Miller A.

 

Glad to see everyone this year.  Just started really watching the forum since we are starting to finally get into some tracking scenarios.   

[tnweathernut]

Not a bad place to be 8 days out. If tracked a tad further north and west... Not to mention the under modeled precip shield which is always the case with Millers. Wouldn't mind kicking off our belated winter with a good Miller A.

Glad to see everyone this year. Just started really watching the forum since we are starting to finally get into some tracking scenarios.

Nice to see you again Shawn, hope you have been doing well. Thanks for posting. It would be nice to have a shot at something around the time frame you mention. Not impossible, but probably more likely a little later in the period. That said, good point about under modeled precipitation shields for Miller A's. Typically happens with overrunning too. North and west with a track is always a concern in the TN Valley....

[Stovepipe]

Not a bad place to be 8 days out.  If tracked a tad further north and west...  Not to mention the under modeled precip shield which is always the case with Millers.  Wouldn't mind kicking off our belated winter with a good Miller A.

 

Glad to see everyone this year.  Just started really watching the forum since we are starting to finally get into some tracking scenarios.   

 

Getting the old band back together! 

 

[Carvers Gap]

CPC ensemble teleconnections continue to look good. The models, as expected w a pattern change, produce a different variation of the new pattern with each run. But the overall theme is a trough of varying amplitude in the East, rising heights around Greenland, a strong PNA, and Arctic air poised to slide into Montana. Hard not to like the setup. Light snow chances have been introduced for KTRI early this week. Then a brief warmup with more southern jet activity the next week...several pieces of energy.

[Carvers Gap]

Sutherland also has a great post on the main forecasting and discussion page. I read that after my comments above...similar themes. Sutherland is like money in the bank though.

http://www.americanwx.com/bb/index.php/topic/47332-winter-2015-2016-medium-term-discussion/page-5?

[Stovepipe]

Sutherland also has a great post on the main forecasting and discussion page. I read that after my comments above...similar themes. Sutherland is like money in the bank though.

http://www.americanwx.com/bb/index.php/topic/47332-winter-2015-2016-medium-term-discussion/page-5?

 

[1234snow]

The 6z GFS looked amazing with a big storm coming out of the southwest after the 1/11 frame and the PV pushing down. 12z GFS looks completely different. No storm and no cold air at all after the 1/11 frame.

I think I've looked at the GFS for the past 10 and I none of them have even been close to the previous runs. This split flow pattern is giving the GFS fits. So much energy is flying around. It may be a pattern where we won't see a hit coming until 3-4 days out. It may be time to get a WeatherBell sub as this unfolds.

[Carvers Gap]

The 6z GFS looked amazing with a big storm coming out of the southwest after the 1/11 frame and the PV pushing down. 12z GFS looks completely different. No storm and no cold air at all after the 1/11 frame.

I think I've looked at the GFS for the past 10 and I none of them have even been close to the previous runs. This split flow pattern is giving the GFS fits. So much energy is flying around. It may be a pattern where we won't see a hit coming until 3-4 days out. It may be time to get a WeatherBell sub as this unfolds.

Even the 12z Euro 1/11 event went from a Piedmont runner at 0z to a cutter. Things are just so far out there. They are going to be all over the place. Still, the theme appears cold and stormy in the East...even if the specifics of the events vary wildly.

Very cool! Man, that ranks up there with the giant snow man. Dr. Yes? I think Don would be proud.

[1234snow]

The 0z GFS is out and it really looks much better to my untrained eye than the 12z run. The differences are night and day at the 500 mb level. The 0z has two southern storms around the 10th and the 13th. Both of the storms miss us to the south. After the 2nd storm slides by the cold air really comes in. The cold air really didn't come in on the 12z GFS. The 12z seemed much more zonal in the long range.

Really to be honest in my few years of model watching I can't recall seeing such a big difference between runs (0/12z and 6/18z) on the GFS as today. I mean it is hundreds of miles different with the placement of the upper level features.

12z GFS:

0z GFS:

As you can see this 0z GFS has a much taller western ridge that reaches into Alaska. The 12z is really the opposite. Runman posted a video in banter that may explain the reasoning behind this pretty well. The reasoning in the video is that the GFS likes to push the Aleutian low to far to the east (progressive) when in real time it stays closer to the Aleutian Islands.

I think this observation is going to be a key thing to look at with the pattern change. I've never really payed much attention to the position of the low but I will now. When the low stays further west over the islands it pumped the PNA ridge up really tall out west. This allows the cold air to surge in from Canada and it allows any shortwave to dig and become more amplified. When the Aleutian low settles more to the east (toward the Gulf of Alaska) it flattens the PNA ridge and we get more of a zonal flow. Then we get flooded with Pacific air which is not good.

I still think we are entering a period with some better than normal chances to cash in.

[Runman292]

Here's the video that 1234snow was talking about.

[John1122]

We will have to see where this goes, but I'll take my chances with this track and a big HP in the upper midwest.

 

[nrgjeff]

This weekend: Looking like a better chance of snow this weekend in the northwest half of the Mid-South; unfortunately, that is not many of us outside of West Kentucky and NW Tenn. However I think the Plateau and Mountains could get snow on the back side before precip ends. I'd wait until it is within 120 hours to start a thread, but models are lining up and more consistent on it.

 

Next week: Behind the weekend system a stout arctic front is scheduled. GFS buries midweek lows in the teens; Euro favors 20-25. I might split them and watch upstream snowpack for modification or not. Late week (Day 12) reinforcement is in question depending on the track of systems coming out of the Plains. Gliding up over the Ohio River is not going to get the job done. Get one to dig through Texas and we're in business!

 

For snow around here I'd rather get buried in sustained cold air and worry about the system later. Deep South system can still bring the Valley light snow if cold enough. Trouble is forecasts are instead showing glances of cold (even strong) and then tracking borderline systems in between. Yuck! Maybe up North they might think about being too cold or the track too south, but that is rarely an issue in the South w/o a full phased deep meridional trough buried from Texas to Florida (not the case now with just one Gulf Coast branch). In split(-ish) flow generally the colder the better within this weather pattern. More help North branch please.

 

End of January: Appears that the El Nino forcing will return. AO/NAO may double-dip next week, so I'd still watch for a second front Day 12-ish regardless of model zig-zags. After that AO/NAO may start to rise as the Arctic puts itself back together again. Again during strong El Nino blocking usually verifies less intense and less strong; this is in direct contrast to the general rule just the opposite. Return to somewhat mild is in line with other strong Ninos like 1982-83. In 1997-98 January returned to even milder. On the bullish side, PNA may linger in the cold positive phase. If so I envision more cold into Texas from the Plains, than into the Valley from the Midwest; but, that could gen up systems out of Texas.

 

Bottom line: I do not want to sound pessimistic even though I'm somewhat mild second half of January. Believe we have a 7-10 day window for a chance, frankly on par for the South and certainly not below par. Then February could still offer multiple chances. Even with my milder forecast, I'm looking for more action in Feb. I really do like snow as much as severe, and as much as most here. Cross our fingers...   

[Runman292]

This weekend: Looking like a better chance of snow this weekend in the northwest half of the Mid-South; unfortunately, that is not many of us outside of West Kentucky and NW Tenn. However I think the Plateau and Mountains could get snow on the back side before precip ends. I'd wait until it is within 120 hours to start a thread, but models are lining up and more consistent on it.

Next week: Behind the weekend system a stout arctic front is scheduled. GFS buries midweek lows in the teens; Euro favors 20-25. I might split them and watch upstream snowpack for modification or not. Late week (Day 12) reinforcement is in question depending on the track of systems coming out of the Plains. Gliding up over the Ohio River is not going to get the job done. Get one to dig through Texas and we're in business!

For snow around here I'd rather get buried in sustained cold air and worry about the system later. Deep South system can still bring the Valley light snow if cold enough. Trouble is forecasts are instead showing glances of cold (even strong) and then tracking borderline systems in between. Yuck! Maybe up North they might think about being too cold or the track too south, but that is rarely an issue in the South w/o a full phased deep meridional trough. In split(-ish) flow generally the colder the better within this weather pattern.

End of January: Appears that the El Nino forcing will return. AO/NAO may double-dip next week, so I'd still watch for a second front Day 12-ish regardless of model zig-zags. After that AO/NAO may start to rise as the Arctic puts itself back together again. Again during strong El Nino blocking usually verifies less intense and less strong; this is in direct contrast to the general rule just the opposite. Return to somewhat mild is in line with other strong Ninos like 1982-83. In 1997-98 January returned to even milder. On the bullish side, PNA may linger in the cold positive phase. If so I envision more cold into Texas from the Plains, than into the Valley from the Midwest; but, that could gen up systems out of Texas.

Bottom line: I do not want to sound pessimistic even though I'm somewhat mild second half of January. Believe we have a 7-10 day window for a chance, frankly on par for the South and certainly not below par. Then February could still offer multiple chances. Even with my milder forecast, I'm looking for more action in Feb. I really do like snow as much as severe, and as much as most here. Cross our fingers...

I appreciate your thoughts. I have a question. What do you think about the person on the video's thoughts? He seems to have a different view of what's going to happen.

[nrgjeff]

I appreciate your thoughts. I have a question. What do you think about the person on the video's thoughts? He seems to have a different view of what's going to happen.

 

Thanks for reading. Can't get the video to play at work with IT security. However I've heard he is colder longer, per the general rule blocking outlasts models. I'm keying in on the El Nino specific rule that goes just the opposite. Believe we may also be thinking different MJO trends. It all ties together. Plus models tend to bring forward brutal 11-15 day cold in a weaker fashion by 6-10 days. Some years it just takes a few tries to verify, but I'm not sure this is one of them. Finally, a late November early December cold scare fizzled after a brief chill. Now this is going to come in, but I just think not as strong or for as long compared to some forecasts. I can appreciate his logic even though I go a different direction with my forecast. Weather can go either way so I try to keep humble while standing by my reasoning. Cheers!

[Carvers Gap]

We will have to see where this goes, but I'll take my chances with this track and a big HP in the upper midwest.

12z Euro basically brings a wave(?) up the front. The Euro is more of a west TN event. If so, good for them! Personally, I think it is too far west. My hunch, and it cout be wrong, is a stronger wave or even SLP that rides very close to the spine of the Apps or western Piedmont. Sure , it could cut...but also blocking would seem to force it more south and east. I am 50/50 on which scenario plays out. Even MRX mentioned it this AM as something to watch.

[Carvers Gap]

As for for the rest of the 12z Euro, man it is cold. Relaxes a bit late. Looks like a continued cold pattern with periods of warmth mixed in. A truer Nino pattern. Rainy. Some snow. Cold. A few warm days. Wash, rinse, repeat. But a very significant change from December. All releconnections have flipped. There are events to follow. Much improved. And let us always remember, we live in the South...not Buffalo, NY. But at least for the lion's share of the rest of winter...it will feel like winter and act like winter.

[Carvers Gap]

DonS also has an update on the main board. Some good nuggets in there. I like what DT says. Nail the pattern. Nail the events. I am going to roll with a pretty wintery pattern for the rest of winter with periods of relaxation (5-10 days) in between wintery events. I don't see a 97-98 redux. Heck, I don't remember much cold at all that January. A piece of the PV(several models and runs) looks to slide down along the US/Canada border next week. Where it goes will have a lot to do with where the storm track is. Some days, it is in Montana, others the northern Plains, others the Great Lakes. Personally, I want the PV to be pressing just to our west. Give me that, and the rest usually falls into place. To far East....dry. WxSouth has a great write-up this AM about that.

[nrgjeff]

Don is right on as usual. He mentions a Plains to Mid-Atlantic track, which is why he is talking so cold and stormy. Remember he is in NYC, where you wanna be for snow if a low goes through the Mid-Atlantic. Northeast US is greatly helped by the -AO deal. Sure the +PNA gets the Southeast in the mix, but everything does not all stay together longer than a few to several days. Southeast still has to time southern stream systems right with cold air, at least for the Valley, a daunting challenge as usual. Our chances are average or better mid-January, but the coming setup is not the all-star deal for the Southeast. Plateau and Mountains have more reason to anticipate snow. Again I want it to snow, but I'm willing to wait until February if needed.

[John1122]

DonS also has an update on the main board. Some good nuggets in there. I like what DT says. Nail the pattern. Nail the events. I am going to roll with a pretty wintery pattern for the rest of winter with periods of relaxation (5-10 days) in between wintery events. I don't see a 97-98 redux. Heck, I don't remember much cold at all that January. A piece of the PV(several models and runs) looks to slide down along the US/Canada border next week. Where it goes will have a lot to do with where the storm track is. Some days, it is in Montana, others the northern Plains, others the Great Lakes. Personally, I want the PV to be pressing just to our west. Give me that, and the rest usually falls into place. To far East....dry. WxSouth has a great write-up this AM about that.

 

This has been a way different fall and December vs 1998, that January was very warm too, Knoxville was only below normal for 2 or 3 days the entire month. It was just cold enough for the epic late month snow storm in NE Tennessee at the end of that January.

[John1122]

MRX afternoon disco. The last line is probably the most important.

 

 

 

ANOTHER BURST OF MOISTURE WILL MOVE UP AHEAD OF COLD AIR FUNNELING
IN FROM THE NORTH. WE WILL SEE INCREASING RAIN SHOWER CHANCES ON
SATURDAY NIGHT BEFORE THE COLD AIR MAKES IT`S WAY IN. AT SOME POINT
IF THE PRECIPITATION CONTINUES INTO SUNDAY NIGHT AIR WILL COOL ENOUGH
FOR THE PRECIPITATION TO SWITCH OVER TO SNOW SHOWERS. AN IMPORTANT
NOTE IS THAT THIS FAR OUT IT IS DIFFICULT TO FORECAST
CHANCES/TIMING/AMOUNTS. CURRENTLY MODELS HAVE TEMPERATURE PROFILES
CHANGING OVER TO SNOW SOMETIME ON SUNDAY EVENING AND THE
PRECIPITATION EXITING THE REGION BY MID DAY ON MONDAY. IF THIS
SCENARIO DOES PLAY OUT WE COULD SEE THE HIGHER ELEVATIONS OF
SOUTHWEST VIRGINIA AND NORTHEAST TENNESSEE PICKING UP A FEW INCHES
OF SNOWFALL AND PLACES IN THE NORTHERN VALLEY PICKING UP ABOUT A 1/2
INCH TO AN INCH. AGAIN, IT CAN`T BE STATED ENOUGH THAT WITH WINTER
WEATHER EVENTS, MANY THINGS CAN AND WILL CHANGE BETWEEN NOW AND 6/7
DAYS FROM NOW.

[John1122]

The Memphis disco. Feels like things are about to get busy for some if not all of our region.

 

 

 

THE GFS/ECMWF BEGIN TO DIFFER ON TIMING OF THE NEXT SOUTHERN
BRANCH SHORTWAVE...AS SIGNIFICANT UPPER LEVEL HEIGHT FALLS OCCUR
OVER THE PLAINS. THE ECMWF MODEL IS FASTER WITH SHORTWAVE PASSAGE...
BRINGING PRECIP TO THE MIDSOUTH SATURDAY INTO SATURDAY NIGHT...
WHILE THE GFS LAGS 6 TO 12 HOURS. TIMING DIFFERENCES ASIDE...
FORECAST SOUNDINGS FROM EITHER MODEL INDICATE A POTENTIAL FOR
SNOW ON THE BACKSIDE OF THE DEPARTING SHORTWAVE. HAVE GIVEN
EXTRA WEIGHT TO THE ECMWF...WHICH HAS SHOWN BETTER INTERRUN
CONSISTENCY OF LATE. THIS WOULD LEAD TO A CHANCE OF MEASURABLE
SNOW SATURDAY NIGHT...MAINLY NORTH OF INTERSTATE 40. FAR TOO EARLY
PREDICT AMOUNTS...BUT GIVEN THE SPEED OF THE SHORTWAVE AND PARTIAL
MIX WITH RAIN EARLY ON...IT APPEARS ACCUMULATION POTENTIAL WOULD
BE LIMITED.

ONCE THE SHORTWAVE HAS DEPARTED SUNDAY...ARCTIC HIGH PRESSURE
WILL SWEEP IN SUNDAY AFTERNOON. MULTI-RUN MULTI-MODEL SUPERBLEND
TEMPS FOR SUNDAY WERE FAR ABOVE 12Z ECMWF AND GFS RAW SURFACE
TEMPS AND 12Z GFS MOS TEMPS. HAVE UNDERCUT SUPERBLEND FORECAST
TEMPS FOR SUNDAY AND SUNDAY NIGHT...AND THESE TEMPS MAY NEED
FURTHER TRIMMING IN FUTURE FORECAST UPDATES.

IT APPEARS A STRONGER ARCTIC COLD FRONT WILL ARRIVE THE FOLLOWING
TUESDAY...BRINGING MUCH BELOW NORMAL TEMPERATURES OVER THE EASTERN
U.S...INCLUDING THE MIDSOUTH...FOR THE MID/LATE PORTIONS OF NEXT
WEEK. DEFINITELY SIGNS OF A PATTERN CHANGE.

 

[John1122]

JKL this afternoon.

 

 

 

MODELS ARE STARTING TO COME INTO BETTER AGREEMENT WITH A STRONG
UPPER LEVEL LOW DEVELOPING ACROSS SOUTH CENTRAL CANADA FRIDAY NIGHT
INTO SATURDAY...SHIFTING SOUTHEAST INTO THE UPPER GREAT LAKES REGION
DURING THE DAY SUNDAY. THIS COULD PULL SOME POTENTIALLY VERY COLD
CANADIAN AIR INTO THE REGION AS IT CONTINUES TO TRACK ACROSS THE
GREAT LAKES THROUGH THE DAY MONDAY. A COLD FRONT WILL ACCOMPANY THE
SURFACE LEVEL LOW PRESSURE SYSTEM...PULLING YET ANOTHER ROUND OF
POPS INTO THE REGION SUNDAY INTO MONDAY. HOWEVER...WITH NORTHERLY
WINDS AND COLD CANADIAN AIR BEING FILTERED IN...IT IS LIKELY THAT
TEMPERATURES WILL BEGIN DROPPING TO BELOW FREEZING AS THE PRECIP IS
ONGOING. THIS COULD RESULT IN A CHANGEOVER FROM RAIN TO SNOW TO
FINISH OUT THE PERIOD. STILL EXPECT THE GFS OR ECMWF TRACKS TO SHIFT
SOMEWHAT OVER THE NEXT FEW DAYS AS WE CONTINUE TO NEAR THIS PORTION
OF THE FORECAST...WHICH COULD MAKE THE DIFFERENCE BETWEEN MORE SNOW
OR MORE RAIN.

&&

[Carvers Gap]

MRX afternoon disco. The last line is probably the most important.

 

Just looked at the EPS(am going to use WxBell for two months so I have access to better ensembles).  It brings the wave of slp up the spine of the Apps.  Plateau westward looked pretty good speaking only of the set-up...not looking at anything else.   I almost wonder if the models won't settle on a hybrid.  Some energy is sent up west of the Apps while the rest turns the corner and heads up the Coastal Plain.  Definitely a signature for a winter storm.  Interesting that the forecast offices are mentioning it.  Seems like that is a good way to bring everyone's focus up a bit.  I would think someone in the Valley(Memphis to Tri) might get a little more than two inches.  Just depends on where that energy goes.  Several folks are concerned with the low in the GLs.  That has to be watched.  Until this event, I have never been concerned about that feature.  But evidently, it can make a mess out of an otherwise good set-up.