2013 Fall Medium Range Discussion

[Isotherm]

The 0z and 6z GFS runs really backed down and both the severity of the upcoming cold, as well as its duration. I hear the 0z Euro did as well. Could this be a general backing down of the models as we saw with the New Years cold shot?

 

 

 

I think it has to do w/ the NPAC depiction and the SW US cut off. There's a clear weakening of the PNA ridge w/ lower heights in the NPAC, and so the -EPO is not as impressive. Additionally, the GFS is now cutting off the upper low in the SW US, agreeing w/ the overnight 00z Euro. This keeps the upper low disonnected from the long wave trough, and the trough itself is not as amplified into the Northeast due mostly to the change in height field depiction in the crucial north pacific region. The north atlantic still has height rises but it's unimpressive.

It can always head back in the other direction though. I think we might see the MJO wave propagate further east than currently progged, and once/if models begin seeing that, we may return to a more impressive H5 depiction for the latter part of January. However, right now, the past 12 hours we've been trending away from major sustained cold in the East.

[nzucker]

The 12z ECM came in very cold for the East with a huge -NAO block starting at Day 8 as well as rising heights over the West Coast from Days 8-10. The 12z ECM ENS were also even colder with the polar vortex over Canada being further south and thus in a better position to deliver the cold. 

[thunderbolt]

The 12z ECM came in very cold for the East with a huge -NAO block starting at Day 8 as well as rising heights over the West Coast from Days 8-10. The 12z ECM ENS were also even colder with the polar vortex over Canada being further south and thus in a better position to deliver the cold. 

 

nzucker - that would coincide with the MJO for that time period into phase 7.   However the cold should not last for that long because most of the MJO models have it going back into phase 6 or the circle of death aka the euro

[nzucker]

nzucker - that would coincide with the MJO for that time period into phase 7.   However the cold should not last for that long because most of the MJO models have it going back into phase 6 or the circle of death aka the euro

 

A lot of the cold is coming from the severe blocking due to the stratospheric warming (-NAO) and not the MJO, which mostly affects the Pacific side (PNA). I think the East could continue to see cold anomalies and snow, albeit tempered, if we lose the +PNA signal as the MJO/Kelvin Wave weakens. Also, a -AO in December argues for a renewed period of blocking later in the winter. 

[IntenseBlizzard2014]

Very interesting theory that I was thinking of for the past couple of days. It seems that the GFS/GFES having the MJO at Phase 6 and then hitting a brick wall near Phase 7 is just a trick. Notice that the MJO loops around at Phase 6? It looks like wants to progress towards Phase 7 between January 28th to February 5th.

[nzucker]

Very interesting theory that I was thinking of for the past couple of days. It seems that the GFS/GFES having the MJO at Phase 6 and then hitting a brick wall near Phase 7 is just a trick. Notice that the MJO loops around at Phase 6? It looks like wants to progress towards Phase 7 between January 28th to February 5th.

 

There's been a lot of discussion of this, and it has to do with a statistical filtering technique I believe. The MJO should continue to progress towards Phase 7 and potentially Phase 8 by the end of the month. We're lucky in that the favorable Pacific induced by these MJO phases should coincide with a favorable high-latitude blocking pattern brought about by the stratospheric warming. I'm looking at a snowstorm chance around 1/19 with a PNA spike, and then again towards the end of January as the PNA wants to rise again. Two big opportunities there assuming the -NAO develops as modeled and as theorized by the mid-winter warming.

 

BTW, I drive by Mt. Vernon every day on my way to my teaching job in NYC. My mom taught in Mt. Vernon for 11 years. 

[IntenseBlizzard2014]

There's been a lot of discussion of this, and it has to do with a statistical filtering technique I believe. The MJO should continue to progress towards Phase 7 and potentially Phase 8 by the end of the month. We're lucky in that the favorable Pacific induced by these MJO phases should coincide with a favorable high-latitude blocking pattern brought about by the stratospheric warming. I'm looking at a snowstorm chance around 1/19 with a PNA spike, and then again towards the end of January as the PNA wants to rise again. Two big opportunities there assuming the -NAO develops as modeled and as theorized by the mid-winter warming.

 

BTW, I drive by Mt. Vernon every day on my way to my teaching job in NYC. My mom taught in Mt. Vernon for 11 years. 

 

Cool. Very good. Didn't know that at all.

[Isotherm]

A lot of the cold is coming from the severe blocking due to the stratospheric warming (-NAO) and not the MJO, which mostly affects the Pacific side (PNA). I think the East could continue to see cold anomalies and snow, albeit tempered, if we lose the +PNA signal as the MJO/Kelvin Wave weakens. Also, a -AO in December argues for a renewed period of blocking later in the winter. 

 

 

Agree. I have little doubt the AO will turn negative in the medium range as will the EPO. The NAO will be negative but the jury's still out on the magnitude of the blocking. I think if we can keep the MJO wave propagating into phase 7-8 there's a better chance for sustained NAO blocking. We'll see. The Plains and Mid-west will certainly get their wintry weather.

[QVectorman]

Newest CCKW map shows the extra tropical rossby wave train at 155W 30N and the one continuing to develop at 150E 20N along with the CCKW at 165E 0N. Still on schedule the 155W RW should move over the eastern US on Jan 15-16 and the 150E should pass over the eastern US Jan. 22-23.

 

Also watching the GWO, the analogs are pointing to an arctic blast of air possible Jan 24-27 or Feb 2-4. I'm leaning more towards the 24-27 time frame since it coincides with the 2-3 week window after the SSW->PV split yesterday. Obviously models aren't feeling this yet but I think they will come around in the end. Lots of inconsistency run to run and model to model so no surpise. Still falls in line with my thoughts back on the the 5th that Jan 25-30 could see -33C 850 tmps sneaking over the northern plains or GLKS or NE.

 

[QVectorman]

Short on time today but want to thank you guys Mike and everyone for the great discussion 

 

I thought I would add my thoughts for today, I don't expect these cold solutions to be consistent I think we will still see lots of inconsistency until the events....Here is a recap of Dec. 20 from 20 days ago with mention of shortwave for eastern US Jan 10-11, on Jan 5 I amend the 10-13th to be another warm up (instead of cold air) based on a more powerful GWO signal. Obviously every saw a peak in temps on Jan 9 and expecting another peak on sun 13th. With colder air arriving after that.  Everything still jives for the rest of the thoughts through the beginning of Feb. especially in regards to 850 Temp forecasts. Again I think we will see the GFS/Euro hold back the coldest air until after the 24th. Even though it's on the edge right now bringing it in on the 23rd.

 

 

Posted 20 December 2012 - 03:49 AM

 

I extended my outlook through Jan 8 on Dec. 14. I still feel comfortable with those dates and with the newest GWO analogs and latest 10 and 30 mb temp forecast it appears the time frame between Jan 7-10 will see a warm up over the east with a short wave moving through the east Jan 10-11 with cooler air dropping in behind it for Jan 10-13 across the MW/GLKS and then pockets of cooler air arriving Jan 15-19 time frame for the east followed by a second reinforcement of cooler air Jan 20-24. My GWO analogs only take me out to Jan 9 so there may be another short wave or two to add to the 2 already expected for the Jan 9-24 time frame. I will update as the newest GWO numbers come out over the next week and half.

 

Posted  5 January 2013 - 12:18 AM

I think the GFS is being a little too bullish on the cold air and too fast. Based on GWO and strat. analogs I'm guessing the coldest core of the 850 temps behind the short waves for the Jan 12-19 time frame will remain warmer than -15C then be reinforced with a coldest core of -15 to -25C for Jan 21-25 with a core of cold in the -25 to -30C range possibly as cold as -36C at some point for Jan 25-30. With -33C sneaking over the northern plains or GLKS or NE. Of course the cores of the coldest air will probably remain north of the border but still one can extrapolate what kind of 850 temps would be making down to the central US with those types of 850 temps just north of border.  

 

Again since I'm short on time today here are my thoughts from last night that still hold water today for myself at least.  

 

Posted Yesterday, 06:29 PM

Well the 12z Euro has -36C in Maine for 1/19 12z and 12z GFS has -36C in northern MN at 12z for 1/20. And those types of temps have been showing up from time to time on the runs. That's obviously not the 24-27 time frame but gives credence that the models believe it's physically possible to achieve those type of temps in the next couple weeks. Plus as I recall the GFS was indicating these types of 850 temps arriving for Jan 15-16 back a week ago which now has been pushed back to the 19th. I mentioned previously that I thought that the models last week were rushing the coldest air in too soon. I still think that and think we will see this coldest air delayed again by the models for another 4-5 days til the at least the 24th 

[blizzardof96]

 

I extended my outlook through Jan 8 on Dec. 14. I still feel comfortable with those dates and with the newest GWO analogs and latest 10 and 30 mb temp forecast it appears the time frame between Jan 7-10 will see a warm up over the east with a short wave moving through the east Jan 10-11 with cooler air dropping in behind it for Jan 10-13 across the MW/GLKS and then pockets of cooler air arriving Jan 15-19 time frame for the east followed by a second reinforcement of cooler air Jan 20-24. My GWO analogs only take me out to Jan 9 so there may be another short wave or two to add to the 2 already expected for the Jan 9-24 time frame. I will update as the newest GWO numbers come out over the next week and half.

 

I am curious as to how you generate your GWO analogs and what method you use. Thanks.

[thenewbigmack]

I am curious as to how you generate your GWO analogs and what method you use. Thanks.

Would like to know as well actually

[Srain]

There are some indications that the longer range may become a bit more interesting as some very chilly air from Western Canada drops well S into the Lower 48 and even into Mexico as very cold air becomes entrenched from the Great Basin on E as we head toward the late January time frame. The EPO looks to remain negative while a PNA spike may well usher in Arctic Air across the Polar Regions from Eurasia/Western Siberia.

[wxmx]

Steve, that would be epic by day 12 or so for our region. Fireworks for most of the CONUS are appearing more likely for the last third of the month.

[Ed Lizard]

I am juiced for a 1985 style polar vortex in the Great Lakes and sub-500 dm heights into NYC around the 24th, myself.

[Hoosier]

In terms of 850 mb temps, the recent GFS runs would rival some of the great arctic outbreaks around here. Obviously it's a long way out and there is the potential issue of little snowcover outside of LES belts to try to modify things a bit as it moves in.

[Chinook]

I am juiced for a 1985 style polar vortex in the Great Lakes and sub-500 dm heights into NYC around the 24th, myself.

 

The 0z ECMWF develops a second (smaller) polar vortex at day 10, and drops it into Sault Ste Marie Michigan. It seems to be a bit of a wacky solution.

 

I have been watching a lot of the operational model runs recently. I am trying to get an idea on the polar vortex for next Thursday-Saturday (days 5-7) This is what I'm calling "the big kahuna," that is, -30C to -40C at 850mb in Ontario/Quebec on these days. The models keep changing their tune as to how much of the big kahuna drops into the United States.

[DaculaWeather]

Maybe that's what Robert was talking about when he said it might dumbell. 

[Jebman]

I'd love a revisitation of Jan 22 1985. We were treated to refreshing high temperatures in the LOW SINGLE DIGITS along with cool, bracing low temperatures in the NEGATIVE MID TEENS. The breeze was very refreshing, gusting up to 35 knots out of the NNE. We also got 2 inches of snow from the arctic front.

 

If I got 2 inches of powder snow off of an arctic front followed by a week of true vodka cold - I'd be content. That 1985 cool outbreak was pure nirvana. I took long jebwalks that morning. I faced into the wind, breathing in all of the cool refreshing arctic air that I could. I even walked backwards on the way home, keeping my face into the cool wind, relishing the gusts.

 

I LOVE VODKA COLD. I have zero empathy for china and russia. They hog my cold weather. They need to SHARE!

[WEATHER53]

I'd love a revisitation of Jan 22 1985. We were treated to refreshing high temperatures in the LOW SINGLE DIGITS along with cool, bracing low temperatures in the NEGATIVE MID TEENS. The breeze was very refreshing, gusting up to 35 knots out of the NNE. We also got 2 inches of snow from the arctic front.

 

If I got 2 inches of powder snow off of an arctic front followed by a week of true vodka cold - I'd be content. That 1985 cool outbreak was pure nirvana. I took long jebwalks that morning. I faced into the wind, breathing in all of the cool refreshing arctic air that I could. I even walked backwards on the way home, keeping my face into the cool wind, relishing the gusts.

 

I LOVE VODKA COLD. I have zero empathy for china and russia. They hog my cold weather. They need to SHARE!

Coldest thing I have ever experienced.  Out around 2am, temperature -2F, winds still frequently gusting to near 30; bitter stuff.

[Srain]

Attention in the medium range turns to our W as a short wave dives S into Northern Mexico Monday and a positive tilted trough lingers across the region. The guidance is having a very difficult time deciding if a closed core upper low develops or if the trough shears out. A closed core solution would offer the chance of wintry mischief and even the potential of a significant ice storm for portions of Central/N Central into NE Texas as well as NW Louisiana/Arkansas on N and E while a more progressive sheared out trough would limit the best chance of over running precip closer to the Gulf Coastal Areas. We will need to closely monitor this potential for Tuesday into Wednesday as the eventual solution could have high impacts for many if a close core low does develop across W Texas and will have an affect on just how things develop in the longer range.

 

Looking toward next week weekend, a brief warm up appears somewhat likely across the Southern Plains before all eyes turn to our N during the latter half of the weekend. The Euro is suggesting a very potent Arctic Air mass with a 1058mb Arctic High dropping S into the Plains along the lee side of the Rockies while the GFS is a bit weaker with the high pressure, but has not been consistent and continues to struggle with the evolving pattern. Both global models and their ensembles are suggesting the Polar Vortex will drop well S into the Great Lakes region as heights build across the Pacific into Alaska and a deep trough develops E of the Continental Divide. The European suite of ensembles and operational guidance has been rather consistent in developing a potential Arctic Outbreak early next week, so it will bear watching in the coming days exactly how things unfold. As we can see, the forecast is extremely tricky and has major implication on the sensible weather we can expect this week on into the early next week time frame.

 

HPC:

 

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
1245 AM EST SUN JAN 13 2013

VALID 12Z WED JAN 16 2013 - 12Z SUN JAN 20 2013

THE HPC MEDIUM RANGE FORECAST REMAINS STEADFAST DESPITE THE MANY
OFF-KEY VOICES FROM THE PEANUT GALLERY OF DETERMINISTIC MODELS. AN
AMPLIFIED RIDGE/TROUGH PATTERN WILL HOLD IN PLACE OVER THE NE
PACIFIC AND HUDSON BAY... RESPECTIVELY... AIDED IN PART BY
UPSTREAM RIDGING WELL TO THE NW OF ALASKA VIA TELECONNECTIONS.
WED-FRI/D3-5 WILL FEATURE A WEAKENING UPPER LOW MOVING OUT OF WEST
TEXAS THROUGH THE SOUTHEAST AS NORTHERN STREAM ENERGY PUSHES
THROUGH THE GREAT LAKES AND NORTHEAST AROUND THE SOUTHWARD SINKING
UPPER VORTEX IN CANADA. BY NEXT WEEKEND... ANOTHER SHOT OF
NORTHERN STREAM ENERGY MAY FURTHER PULL THE COLD CANADIAN UPPER
LOW CLOSER TO THE GREAT LAKES ALONG WITH COLDER AIR.

THE MODELS HAVE HAD MUCH TROUBLE WITH HOW QUICKLY THE SOUTHWESTERN
CONUS ENERGY MOVES THROUGH THE SOUTHERN PLAINS AND SOUTHEAST LATER
THIS WEEK... DUE IN PART TO HOW MUCH HEIGHTS LOWER IN THE EASTERN
CONUS. THE GFS/UKMET/CANADIAN HAVE SHOWN THE LEAST CONSISTENCY
WHILE THE ECMWF ENSEMBLE MEAN HAS PROVEN MOST RELIABLE... THOUGH
NOT PERFECTLY CONSISTENT. THE ECMWF HAS GENERALLY BEEN CLOSEST TO
ITS ENSEMBLE MEAN AND THAT REMAINED THE CASE WITH ITS 12Z/12 RUN.
IN THE NORTHERN TIER... THE ECMWF/CANADIAN AND ECMWF ENSEMBLE MEAN
CLUSTER AS A SLOWER SOLUTION THAN THE GFS WITH A COLD FRONT MOVING
THROUGH ON WED/D3 INTO THU/D4. THIS ENERGY HAS ORIGINS JUST
UPSTREAM OF ALASKA BUT THE GFS TAKES IT A BIT FARTHER SOUTH INTO
THE RIDGE BEFORE DIVING THROUGH CANADA WHILE THE ECMWF TAKES A
FARTHER NORTH TRACK THROUGH ALASKA. WILL SIDE WITH THE ECMWF
DESPITE EACH MODEL BEING RATHER CONSISTENT UP TO THIS POINT... THE
TIPPING POINT BEING THE ECMWF ENSEMBLE MEAN WITH ITS CONSISTENT
MESSAGE. BY NEXT WEEKEND... A COLD/DRY AIRMASS SHOULD OVERTAKE
MUCH OF THE CONUS EAST OF THE DIVIDE AND NORTH OF THE GULF AS
ANOTHER NORTHERN SHORTWAVE TUGS THE CANADIAN VORTEX TOWARD THE
GREAT LAKES. BOTH THE GFS AND ECMWF INDICATE THIS SECOND SURGE
THROUGH CANADA THOUGH WITH SOME EXPECTED DIFFERENCES. IF NOTHING
ELSE... IT WILL AT LEAST FEEL MORE LIKE WINTER IN THE EAST THOUGH
QPF POTENTIAL WILL BE LIMITED TO THE NORTHER PLAINS/GREAT LAKES
AND SOUTHEAST/FLORIDA.



FRACASSO

 

[QVectorman]

This fits into to Srain's post and the HPC's discussion since it appears the problems stem from the xt RWT. It looks like the 1st RWT was split by the ridge at 140W and part of the RWT energy went over the top and the other underneath with the part going underneath contributing to the piece of energy that gets strung out over the south on the 14/15th and the other energy comes over the top as a the clipper on the 16/17 that drops in the colder air in for the 17th. Anyways you can view this all if you go back and look at Mike's CCKW analysis map and the N. American sector of the GFS/EC 6hr sfc qpf and 5h vort maps a few days ago and track the RWT and watch qpf pocket/vorts split by Hawaii and do their thing. (vort. shows up better on wxunderground since they use a more sensitive scale than ncep.) The second xt RWT I discussed a couple days ago seems to be moving faster than I anticipated so it appears it may arrive a day and a half earlier, so Jan 20-21 which still fits (actually better fit) into the Jan 20-24 window I laid out. Which sets us up for a different entity to induce the short wave for the Jan 24-27 window.The 2nd RTW right now appears that it's far enough north that it's energy will just ride over the ridge and guessing the energy will become a clipper for the 20/21.  In the image below I circle the southern portion left of the 1st RWT and then the 2nd RWT

[QVectorman]

I am curious as to how you generate your GWO analogs and what method you use. Thanks.

 

 

Would like to know as well actually

Just went through by hand. Working on a fortran program to do it for me. Maybe then I can get some temp anomaly numbers to go along with them.

[Srain]

The 00Z NAEFS and GEFS continue to advetise some very chilly air settling well S across most of North America in the extended range.

[cbmclean]

Did everybody agree to end this thread and not tell me about it?

[DaculaWeather]

LOL!!! Some things are more important right now, especially in the SE!

[Srain]

The Euro Ensembles and GEFS as well as the CPC Super Ensembles are suggesting the Western Ridge breaks down and a cold and stormy regime becomes established once again across the West Coast/Great Basin and into the Plains.

 

[DaculaWeather]

Yea, not a good look. No blocking at all right now

[am19psu]

Major battle between the seasonal base state and the robust MJO wave upcoming...

[DaculaWeather]

Major battle between the seasonal base state and the robust MJO wave upcoming...

What are your thoughts on that? I noticed it appeared it could be a moderate event.