Re: January 2013 Long Range Thread

[aiannone]

Sorry this is such a long post but this is from the HPC...

THE SECOND PATTERN CHANGE WILL BEGIN TO SHOW ITS CARDS BY THE MIDDLE
OF THE MONTH. A MAJOR SUDDEN STRATOSPHERIC WARMING EVENT IS UNDERWAY
AND NEARING COMPLETION. SUDDEN STRATOSPHERIC WARMING EVENTS ARE
FAVORED TO OCCUR DURING AN EASTERLY PHASE OF THE QUASI-BIENNIAL
OSCILLATION /QBO/…WHICH IS THE PHASE THE STRATOSPHERE IS IN THIS
WINTER. THE SUDDEN STRATOSPHERIC WARMING CAUSES A DRAMATIC
WEAKENING…AND SOMETIMES ENTIRE BREAKDOWN OF THE STRATOSPHERIC
POLAR VORTEX…AND A GREAT WEAKENING OR EVEN REVERSAL OF THE
STRATOSPHERIC POLAR NIGHT JET. THE GFS FORECASTS THIS TO OCCUR OVER
THE NEXT WEEK AT THE 2MB LEVEL.

THE RESULT OF ALL OF THIS IS THE GENERATION OF STRONG HIGH LATITUDE
BLOCKING AS THE DRAMATIC CHANGES IN THE STRATOSPHERE FEED DOWN INTO
THE TROPOSPHERE. HIGH LATITUDE BLOCKING FORCES THE COLDEST AIR SOUTH
OUT OF THE HIGH ARCTIC AND TOWARDS THE MID LATITUDES…AND ALSO
FAVORS LASTING STRONGLY NEGATIVE EPISODES OF ARCTIC OSCILLATION /AO/
AND NORTH ATLANTIC OSCILLATION /NAO/. THIS TYPICALLY BEGINS TO TAKE
PLACE 10-15 DAYS AFTER THE SUDDEN STRATOSPHERIC WARMING EVENT. HOW
LONG IT LASTS CAN VARY…BUT TYPICALLY THE COLD PATTERN LASTS FOR AT
LEAST A FEW WEEKS…AND OCCASIONALLY CAN PERSIST THROUGH THE REST OF
WINTER.

AS ALL OF THIS IS OCCURRING…THE MJO IS FORECAST BY THE GEFS
ENSEMBLES TO WEAKEN AND FADE AWAY IN ABOUT 10 DAYS. THE PACIFIC
NORTH AMERICAN PATTERN /PNA/ IS FORECAST TO REMAIN NEGATIVE OVER THE
NEXT 10 DAYS…WHICH WILL DIRECT THE FIRST BATCHES OF COLD INTO THE
WESTERN AND EVENTUALLY CENTRAL UNITED STATES. GEFS ENSEMBLE MEMBERS
SUPPORT A TREND TOWARDS A NEUTRAL OR POSITIVE PNA BY THE MIDDLE OF
THE MONTH…WHICH SHOULD ALLOW THE GROWING COLD TO SPREAD EASTWARD.

WHAT ALL OF THIS TECHNICAL JARGON MEANS IS THAT THERE IS MODERATE TO
HIGH CONFIDENCE IN A PATTERN CHANGE TOWARDS MUCH COLDER WEATHER FOR
THE CENTRAL AND EASTERN UNITED STATES STARTING AROUND THE MIDDLE OF
JANUARY…WITH COLD LIKELY PEAKING IN LATE JANUARY INTO EARLY
FEBRUARY. THERE IS THE POTENTIAL FOR THE COLDEST AIR WE HAVE SEEN IN
AT LEAST SEVERAL YEARS DURING THIS PERIOD. WHAT SNOW POTENTIAL THIS
WILL BRING IS MUCH MORE UNCERTAIN DUE TO UNKNOWN DETAILS WITH
SYNOPTIC STORM TRACK AND LAKE EFFECT POTENTIAL.

[NjWeatherGuy]

Figured maybe I posted this is the wrong thread.

From what i've seen before the pattern change arrives a very slow moving cold front will move over the region. To me it looked pretty strong so I checked the GFS and today's 18z run at hour 192 shows elevated CAPE, lifting and showalter indeces over our area. Nothing too extreme but I think we cant rule out some rumbles of thunder or lightning as this passes through. Of course, it's too far away at this time to know what will happen exactly.

[NjWeatherGuy]

EURO in the long range has the trough over us, but then it quickly begins to shift the axis of the trough further to the east suggesting the cold shot may not be long lived and break down.

[Frank_Wx]

Just keep in mind of its bias of holding back southern energy and developing them into cut-off's. That would obviously promote eastern warmth. Most of the time, those cutoffs never come to fruition.

[Frank_Wx]

18z GEFS are cold throughout the entire run once the cold front passes through.

Also, did anyone notice the UKMET MJO? It gets into phase 7, unlike some models showing once the MJO gets into phase 6 it dies

[amugs]

Seems to be good news! Any word Frank on why I cannot post an external link or has this issue been cleared up?

[Frank_Wx]

Seems to be good news! Any word Frank on why I cannot post an external link or has this issue been cleared up?

I thought I fixed this problem. Let me try again.

[amugs]

http://www.accuweather.com/en/weather-news/timing-the-arctic-cold/3777976

Here is the update from Accuweather and they are reflecting what you guys are saying that the cold air will be here but only last a few days and then warm up and this back and forth for the last weeks of Jan into early Feb due to this stubborn SE ridge/ High Pressure off the Southeastern US/Atlantic.

Question - what can move or breakdown this sort of cold air blocking mechanism? Just trying to learn.

[amugs]

Thanks Frank you fixed this issue.

[Noreaster]

I hope the MJO progresses through stage 7. Most models have it dying, or curling in on itself in stage 6. I'm not sold on long lasting cold yet, but indications are that we do get cold at some point next week. I really hope we can break down the SE ridge or push it east or souh.

[Frank_Wx]

http://www.accuweather.com/en/weather-news/timing-the-arctic-cold/3777976

Here is the update from Accuweather and they are reflecting what you guys are saying that the cold air will be here but only last a few days and then warm up and this back and forth for the last weeks of Jan into early Feb due to this stubborn SE ridge/ High Pressure off the Southeastern US/Atlantic.

Question - what can move or breakdown this sort of cold air blocking mechanism? Just trying to learn.

That's the big question going forward. I'm going to have to disagree with Accuweather here.

I think the active MJO cycle will be enough to push the southeast ridge further east and out to sea. Once the PV situates itself over south-central Canada, a trough will build in over the east and supply cold air. I don't think it will be arctic air, but definitely cold.

The -NAO signal over Greenland should be enough to maintain the PV and prevent it from moving, thus preventing the southeast ridge from returning.

[NjWeatherGuy]

Yep, looks like significantly colder air is a lock now, wasn't quite buying it earlier but the signals and models as they enter the shorter range look like this is finally gonna happen after some upper 50s and maybe a 60+ reading here or there this weekend.

[Frank_Wx]

LOVE the look of the MJO today. Once it gets into phase 7, it looks to want to stay and loop around in there. I highly doubt it reverses back into phase 6 as some guidance showed yesterday.

[Frank_Wx]

00z GFS brings the PV south of the Hudon Bay...LOL!!

[Frank_Wx]

Storm signal around the 20th just misses a phase as well...

[Frank_Wx]

Finally!! A storm threat on the 22nd per 12z GFS!!

[Quietace]

Wow! thats all i got to say. Its gonna be a awesome time tracking these!

[Frank_Wx]

Storm signal is VERY much alive and REAL between the 20th-24th. Just 10 days away. Lol

[ltthedog]

Frank your thoughts on the midweek storm potential. 12Z GFS basically lost it but GGEM, and the CFS still have a major overruning event while with marginal temps certainly looks like a lot of precip may fall looking at these models verbatim.

[Frank_Wx]

Frank your thoughts on the midweek storm potential. 12Z GFS basically lost it but GGEM, and the CFS still have a major overruning event while with marginal temps certainly looks like a lot of precip may fall looking at these models verbatim.

We're talking about it in the other thread.

[Dunnzoo]

Wow, the MJO forecast changed quite a bit in the last day or two. It looked like it was going to stay in 6 forever! Signs of good things to come!

[Frank_Wx]

00z GFS not as robust with the cold air at hours 182 so far like it was with 12z. We'll see if it shows any storm signals between 20th-25th time period.

[Frank_Wx]

Hour 252. OMG

[Frank_Wx]

Holy crap...

[Frank_Wx]

If one were to extrapolate the 00z EURO beyond 240, I think it would have shown some sort of east coast storm around the 23rd. The PV split, allowing for relaxation in the pattern, and there is a nice nagative tilt in our trough coupled with a +PNA/-EPO/-NAO

Honestly, if the upcoming pattern does not produce something between the 20th-25th, I'll be shocked.

[Frank_Wx]

The GFS run today was very fun to see.

Incredible blocking

Great ridging

MJO progression through 7

Storm signals between 20th-26th.

Sometime in that time period, there will be a storm.

[Frank_Wx]

Euro is showing 850mb temps sub -20C in the long range. Downright frigid!!!!

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