Medium Range Discussion Winter 2011-12

[usedtobe]

Doesn't look that good for cold in the mid range, but it would only take some height rises in W Canada to bring most of the CONUS into the icebox with all that cold air bottling up in Canada.

Trouble is if you teleconnect to to the massive positive anomaly over Ak that is forecast to retrograde a little it usually starts opening the flood gates somewhere along west the coast as the ridge retrogrades west. I think that might be on the books somewhere down the line unless the retrogression is so strong that it then puts a trough far ehough west to allow a ridge to pop along the west coast. The -pna ridge makes me think it might be more likely for south of 40 to end up with warmer than normal temps than colder once we get by the next cold shot after out mid week rainstorm.

[wxmx]

Trouble is if you teleconnect to to the massive positive anomaly over Ak that is forecast to retrograde a little it usually starts opening the flood gates somewhere along west the coast as the ridge retrogrades west. I think that might be on the books somewhere down the line unless the retrogression is so strong that it then puts a trough far ehough west to allow a ridge to pop along the west coast. The -pna ridge makes me think it might be more likely for south of 40 to end up with warmer than normal temps than colder once we get by the next cold shot after out mid week rainstorm.

Completely agree, that's the reason I think that things doesn't look good for cold in the mid range.

[Srain]

Doesn't look that good for cold in the mid range, but it would only take some height rises in W Canada to bring most of the CONUS into the icebox with all that cold air bottling up in Canada.

Good point, Jorge. With the waffling day to day and run to run of the op guidance, I am not so sure all these forecasts of an all out torch are absolutely correct, at least for the Intermountain West and Plains. What is interesting to me are the changes going on in Canada. Finally we see our 'source regions' plunging into the deep freeze. That has certainly not been the case so far this winter. The other factors such as -WPO ~ -EPO remain to be seen. The PNA has flip flopped like a fish out of water. These details will work themselves out in the days ahead as well as the NAO. What we have needed was to get the ball rolling to dislodge the ever present AK Vortex and that appears to be happening.

[usedtobe]

Dasher of dreams!

It's all speculation, I think the location of the postive anomaly actually would put us near normal temps. I'm really more interested in what might happen along the west coast from northern Ca into Washington. Their pattern could put them in heavy precip or cold.

Now look at how wet a couple of the members are for northern CA. Before I retired I did a climo study of the 10 biggest rainfall events for the northern CA area and a large number of them had a massive positive height anomaly over or just west of AK. Note where the anomaly is for the biggest event.

#1

http://www.hpc.ncep....les/Page298.htm

for the second biggest

#2

http://www.hpc.ncep....les/Page298.htm

for the third biggest

#3

http://www.hpc.ncep....les/Page312.htm

On all three note where the positive anomalies are and then compare them with

I guess the question is whether the floodgates will open in the west and if so what that means for the rest of the county. I don't think for where I live it usually means arctic air but I haven't really looked at the three dates given.

[roardog]

Maybe we can at least get some cold at times here in the north even if most of the conus is mild.

[am19psu]

Good point, Jorge. With the waffling day to day and run to run of the op guidance, I am not so sure all these forecasts of an all out torch are absolutely correct, at least for the Intermountain West and Plains. What is interesting to me are the changes going on in Canada. Finally we see our 'source regions' plunging into the deep freeze. That has certainly not been the case so far this winter. The other factors such as -WPO ~ -EPO remain to be seen. The PNA has flip flopped like a fish out of water. These details will work themselves out in the days ahead as well as the NAO. What we have needed was to get the ball rolling to dislodge the ever present AK Vortex and that appears to be happening.

Yeah, clearly Scooter, Wes and myself are focused on the eastern 1/3 of the CONUS. It's going to be hard to transport that cold air to the East Coast with no -NAO and no big ridge along the West Coast. The Plains are in a whole different ballgame wrt transporting the cold air southward.

[usedtobe]

Yeah, clearly Scooter, Wes and myself are focused on the eastern 1/3 of the CONUS. It's going to be hard to transport that cold air to the East Coast with no -NAO and no big ridge along the West Coast. The Plains are in a whole different ballgame wrt transporting the cold air southward.

lol, I actually am a little more interested in the west coast and made a long post in this thread on it. I probably should have made it as a stand alone post.

[donsutherland1]

At this time, I still like the general idea put out in message #424 concerning the January 16-23 timeframe.

In that message, I suggested that I felt that the turn toward colder readings is likely to be gradual. As a result, much of the East will likely remain at least somewhat milder than normal during that timeframe, but pockets of near normal readings, particularly in the Southeast may occur courtesy of a transient cold shot. Stronger and more sustained cold might be building into the Northern Plains from western Canada and that could be sufficient for that part of the U.S. to have colder than normal readings for the period.

The temperature anomalies based on forecast teleconnections for all days during January 15-25 period (1950-2011) during La Niña events with ENSO R3.4 anomalies in the -1.5°C to -0.7°C range, AO in the -2.00 to 0.00 range and PNA in the -1.00 to +0.25 range were as follows:

I still think that's quite reasonable. I do note that a few previous runs of the GFS, particularly the 1/9/2012 12z run, showed extreme cold in the East along with a significant snowfall. However, given the ensembles and forecast teleconnections, I don't believe that kind of solution is a high probability one.

I don't yet take a position on the January 24-31 timeframe, but note that at least some members of the GFS ensembles are showing a PNA+ in the very extended range. If so, a colder outcome might be possible for that period. FWIW, the CFSv2, is also hinting at a cold close to January/opening to February in the East. Given the season to date, it is plausible that readings might be closer to normal during that timeframe, but not necessarily below normal, though I suspect some part of that timeframe will be colder than normal. It's too early for me to make a call for the January 24-31 period, though I have higher confidence that a good part of Canada could be colder than normal for that period.

Also, before one assumes the switch to cold in the East shown on the CFSv2 means a cold February, that same guidance is suggesting that much of North America will be warmer to perhaps much warmer than normal for February as a whole. That would imply that the cold would recede fairly quickly. My thinking is that a 2-3 week period of cooler (closer to normal but no assurances of the period as a whole being colder than normal) is likely, but a warm February (warmer relative to normal than January) is a real possibility for the East. The actual outcome for February will depend on the continuing evolution of the La Niña and the teleconnections.

[am19psu]

There is a strong blowtorch signal showing up in the models the last 1/3 of January basically nationwide except the Pac NW. Strong -EPO undercut by the Pacific jet, polar vortex dislodged into W Canada and a return of the SE ridge. Terrible set up for snow lovers.

[uncle W]

There is a strong blowtorch signal showing up in the models the last 1/3 of January basically nationwide except the Pac NW. Strong -EPO undercut by the Pacific jet, polar vortex dislodged into W Canada and a return of the SE ridge. Terrible set up for snow lovers.

could it be the January thaw?... In 2002 the NYC area was getting colder and we had some snow the last part of January...Then February torched again...This year might be different for February if January stays torchy until the end...Sort of what happened in 1950...

[donsutherland1]

There is a strong blowtorch signal showing up in the models the last 1/3 of January basically nationwide except the Pac NW. Strong -EPO undercut by the Pacific jet, polar vortex dislodged into W Canada and a return of the SE ridge. Terrible set up for snow lovers.

With the EPO forecast to go back positive and the PNA falling and forecast to go negative (correlating with the dreaded SE ridge), the MJO in the circle and at least the ECMWF's forecast of a quick return to Phase 4, the forecast AO- might be overwhelmed. North America could face a flood of Pacific air. It seems that every pattern shift toward a possible colder regime is quite short-lived. I'm not yet ready to buy a full-fledged blowtorch for the January 24-31 timeframe, but a mild albeit closer to normal outcome for the closing week of January appears more likely than one with widespread colder than normal readings. Unfortunately, at the same time, the risk of a notably warmer outcome is growing.

[usedtobe]

Though the pattern has changed and we have a negative AO, the pattern still is a bad

one

.

[CoastalWx]

When you have zonal PAC flow with heights rises in se Quebec, that's not good. Very warm signal.

[wxmx]

When you have zonal PAC flow with heights rises in se Quebec, that's not good. Very warm signal.

70s in DC

[wxmx]

Some daily high records for DC are plotted

Currently forecasted pattern just past day 10

[uncle W]

it was 72 degrees in NY on 1/26/1950...It became cold on the 31st with the first measurable snowfall since early December...We could be headed toward a similar scenario this year...February 1950 got extremely cold the second half and that pattern persisted into mid April...1989 was torchy around the first few days of February before it got colder, but not as cold as 1950...My thinking February would be close to what 1972 had looks shakey now...It looks like 1989 or 1975 will be good analogs for this year...TWT...

[wxsmwhrms]

As a south-central US forecast guy, I am definitely more concerned about severe weather than winter weather during this time period.

[Srain]

As a south-central US forecast guy, I am definitely more concerned about severe weather than winter weather during this time period.

I agree. A very active pattern is shaping up and the storm near the 25th crossing the S Plains, +/- a couple of days, may well be a severe weather event worth monitoring.

[MJO812]

This is really ugly for mid January.

[Clinch Leatherwood]

This is really ugly for mid January.

It's so far off it's not worth spending much time discussing but thanks for posting. If we see even somewhat of a verification of this type of pattern we may be seeing some record highs after the 20th.

[am19psu]

It's so far off it's not worth spending much time discussing but thanks for posting. If we see even somewhat of a verification of this type of pattern we may be seeing some record highs after the 20th.

[Ji]

JB says cold and wild next 10 days..followed by 10 days of Warm and Feb 1 back to cold

[Ji]

With the EPO forecast to go back positive and the PNA falling and forecast to go negative (correlating with the dreaded SE ridge), the MJO in the circle and at least the ECMWF's forecast of a quick return to Phase 4, the forecast AO- might be overwhelmed. North America could face a flood of Pacific air. It seems that every pattern shift toward a possible colder regime is quite short-lived. I'm not yet ready to buy a full-fledged blowtorch for the January 24-31 timeframe, but a mild albeit closer to normal outcome for the closing week of January appears more likely than one with widespread colder than normal readings. Unfortunately, at the same time, the risk of a notably warmer outcome is growing.

How do you see February Looking Don?

[NJwinter23]

JB says cold and wild next 10 days..followed by 10 days of Warm and Feb 1 back to cold

He was probably better off keeping January cancelled..

[donsutherland1]

How do you see February Looking Don?

At this time, I'm still thinking February will likely be warmer than normal in the East.

[winterymix]

At this time, I'm still thinking February will likely be warmer than normal in the East.

This suggests the possibility for some climate records to be set.

Perhaps somewhere D.C through NYC, there could be a record high minimum for the

entire season.

Probably not Baltimore, though.

Record high minimum for

January 61 degrees 1950

February 58 degrees 1891

[bluewave]

It's all speculation, I think the location of the postive anomaly actually would put us near normal temps. I'm really more interested in what might happen along the west coast from northern Ca into Washington. Their pattern could put them in heavy precip or cold.

Now look at how wet a couple of the members are for northern CA. Before I retired I did a climo study of the 10 biggest rainfall events for the northern CA area and a large number of them had a massive positive height anomaly over or just west of AK. Note where the anomaly is for the biggest event.

#1

http://www.hpc.ncep....les/Page298.htm

for the second biggest

#2

http://www.hpc.ncep....les/Page298.htm

for the third biggest

#3

http://www.hpc.ncep....les/Page312.htm

On all three note where the positive anomalies are and then compare them with

I guess the question is whether the floodgates will open in the west and if so what that means for the rest of the county. I don't think for where I live it usually means arctic air but I haven't really looked at the three dates given.

That's a really an impressive moisture feed being modeled in the long range for those areas.

[usedtobe]

That's really an impressive moisture feed being modeled in the long range.

It's going to be a impressive precip event/events out there, it also argues that lots of pac air floods the conus which for us south of 40 guys is not good.

[bluewave]

It's going to be a impressive precip event/events out there, it also argues that lots of pac air floods the conus which for us south of 40 guys is not good.

Yeah, that's for sure. You can see how especially the GFS has really picked up on the big PNA drop in the forecast.

After a brief cool down, there could be a real surge of warmth ahead of one of the Pacific systems cutting toward

the lakes in the long range.

[usedtobe]

Yeah, that's for sure. You can see how especially the GFS has really picked up on the big PNA drop in the forecast.

After a brief cool down, there could be a real surge of warmth ahead of one of the Pacific systems cutting toward

the lakes in the long range.

That forecast trend is pretty impressive. The pattern is starting to look very nina-ish, negative pdo-ish.