Medium Range Discussion Spring 2012

[SpartyOn]

Interesting data on the 1910, 1945, 1946 analogs. A cold May would not be good for agricultural interests. - possibly devastating to growing season that has already started.

Not really. More like upper 50s and low 60s.

[NJwinter23]

I mostly agree with this except for the actual numbers. With little cold airmass generation thanks to bootleg snow cover, I'd imagine the cold anoms will be a little less cold than we'd expect from the pattern and the warm anoms a little warmer than we'd expect.

Yeah whenever it reaches 70º all the way to the shores of James Bay in March, the remaining snow cover is probably not too good lol

[donsutherland1]

With the MJO poised to move into Phase 8, I took a look at all April cases where the MJO was in Phase 8 (Amplitude 1 to 2.5) and ENSO R3.4 anomaly of -0.50°C to 0.00°C. For those looking for cool anomalies, there was a pronounced cool anomaly in the Southeast/Gulf States. That contrasts with the March-April-May composite, which shows a cool anomaly along a narrow stripe of the entire East Coast. Interestingly enough, the 4/3 12z run of the ECMWF shows anomalies in the East that would be consistent with the MJO's being in Phase 8.

[Tropical]

With the MJO poised to move into Phase 8, I took a look at all April cases where the MJO was in Phase 8 (Amplitude 1 to 2.5) and ENSO R3.4 anomaly of -0.50°C to 0.00°C. For those looking for cool anomalies, there was a pronounced cool anomaly in the Southeast/Gulf States. That contrasts with the March-April-May composite, which shows a cool anomaly along a narrow stripe of the entire East Coast. Interestingly enough, the 4/3 12z run of the ECMWF shows anomalies in the East that would be consistent with the MJO's being in Phase 8.

What did the midwest/lakes look like using that data?

[NJwinter23]

With the MJO poised to move into Phase 8, I took a look at all April cases where the MJO was in Phase 8 (Amplitude 1 to 2.5) and ENSO R3.4 anomaly of -0.50°C to 0.00°C. For those looking for cool anomalies, there was a pronounced cool anomaly in the Southeast/Gulf States. That contrasts with the March-April-May composite, which shows a cool anomaly along a narrow stripe of the entire East Coast. Interestingly enough, the 4/3 12z run of the ECMWF shows anomalies in the East that would be consistent with the MJO's being in Phase 8.

CPC analogs are very cold extrapolated right through the end of April..and you can imagine a way the MJO progression could support this..I'm kind of torn today.

[donsutherland1]

CPC analogs are very cold extrapolated right through the end of April..and you can imagine a way the MJO progression could support this..I'm kind of torn today.

It will be interesting to see if those analogs persist over the next week or so. The MJO could support such an outcome. The CFSv2's weekly runs seem to support it. On the other hand, a number of the teleconnection analogs I have for later this month favor warmth, especially in the last 7-10 days of April. The 18z GFS ensembles go warm after mid-month. The ECMWF ensembles don't go out as far, but it seems that warmth is progressing eastward at the end of their timeframe. All said, it's a challenging forecast.

[donsutherland1]

What did the midwest/lakes look like using that data?

Much of the Midwest was cool. The Great Lakes area was near normal.

[Met1985]

Great discussion on here as always. I am learning a lot this year about the MJO and its phases. Very neat stuff!

[NJwinter23]

It will be interesting to see if those analogs persist over the next week or so. The MJO could support such an outcome. The CFSv2's weekly runs seem to support it. On the other hand, a number of the teleconnection analogs I have for later this month favor warmth, especially in the last 7-10 days of April. The 18z GFS ensembles go warm after mid-month. The ECMWF ensembles don't go out as far, but it seems that warmth is progressing eastward at the end of their timeframe. All said, it's a challenging forecast.

At the very least, I'm satisfied to hear this confirmed. I wasn't sure if I was missing something. Should be interesting!

[phlwx]

FWIW, the EC ensemble mean for both 12z and 0z suggest warmer than average in the Southeast and Mid Atlantic after day 10.

[donsutherland1]

The latest run of the CFSv2 weekly forecasts has removed cold anomalies East that the model had persistently been showing for the second half of April in the eastern quarter of the U.S.

[bluewave]

CPC analogs are very cold extrapolated right through the end of April..and you can imagine a way the MJO progression could support this..I'm kind of torn today.

I have noticed that the CPC analogs have been running too cool especially since 2010.

The older analogs that show up in the composites had more cold air to work with in

North America than has been available lately. Even when we finally get a trough in

place, the lack of available colder air leads to a warmer solution than under older climo.

August 2011 and October 2010 are just two examples of a tough pattern with no colder

air available. The actual temperatures are warmer than you would expect to see for

the 500 mb composites.

[NJwinter23]

I have noticed that the CPC analogs have been running too cool especially since 2010.

The older analogs that show up in the composites had more cold air to work with in

North America than has been available lately. Even when we finally get a trough in

place, the lack of available colder air leads to a warmer solution than under older climo.

August 2011 and October 2010 are just two examples of a tough pattern with no colder

air available. The actual temperatures are warmer than you would expect to see for

the 500 mb composites.

Thanks. I suspected that could be the case given persistence back through the winter , and the lack of snow cover remaining up north...I hedged on the warmer side April 16-30th

[Isotherm]

I have noticed that the CPC analogs have been running too cool especially since 2010.

The older analogs that show up in the composites had more cold air to work with in

North America than has been available lately. Even when we finally get a trough in

place, the lack of available colder air leads to a warmer solution than under older climo.

August 2011 and October 2010 are just two examples of a tough pattern with no colder

air available. The actual temperatures are warmer than you would expect to see for

the 500 mb composites.

Nice post. I think this demonstrates that pattern persistence is also an important aspect of every medium range forecast. There hasn't been much cold air to work with in North America since November, and again, this month, Canada continues to run warmer than normal overall. One can see the SE corner is near normal which implies the slightly below normal week in the Northeast for 4/8-4/15

[Ginx snewx]

<p>

Thanks. I suspected that could be the case given persistence back through the winter , and the lack of snow cover remaining up north...I hedged on the warmer side April 16-30th

A trough in the East could tap some of Eastern Canada snow cover cold easily.

[bluewave]

Thanks. I suspected that could be the case given persistence back through the winter , and the lack of snow cover remaining up north...I hedged on the warmer side April 16-30th

Sure,it looks like warmer temperatures return by mid-month after the trough lifts out next week.

Nice post. I think this demonstrates that pattern persistence is also an important aspect of every medium range forecast. There hasn't been much cold air to work with in North America since November, and again, this month, Canada continues to run warmer than normal overall. One can see the SE corner is near normal which implies the slightly below normal week in the Northeast for 4/8-4/15

Next week looks cooler than this one as the models have that trough hanging around. I don't think that the temperatures

will average too far below normal around our area but may be cooler relative to the means to our south. You can also see the trough underperforming for cool around our area this week.

[easternsnowman]

It is becoming clear that we are now in a warmer climate and the models will overplay the cooler temps.

[SnoSki14]

It is becoming clear that we are now in a warmer climate and the models will overplay the cooler temps.

While I agree that the climate is certainly warmer than it was 20-30 years ago, I think there are other factors that have played a role in warmer than model forecast temps. The indices were not in favor of cold and the lack of snow cover allows temps to moderate significantly so the warm winter leads to warmer temps. Also the dry weather will also aid in warmer temperatures.

Just because these past several months were like this doesn't mean it can't be colder in a couple or few months relative to normal.

[easternsnowman]

While I agree that the climate is certainly warmer than it was 20-30 years ago, I think there are other factors that have played a role in warmer than model forecast temps. The indices were not in favor of cold and the lack of snow cover allows temps to moderate significantly so the warm winter leads to warmer temps. Also the dry weather will also aid in warmer temperatures.

Just because these past several months were like this doesn't mean it can't be colder in a couple or few months relative to normal.

I agree that the indices and dryness have added to the warmth, but the last 25 month have featured only 2 or 3 months below the 30 year norms.

[nzucker]

All the 500mb maps shown have a strong GoA low...even with below normal heights in the East, you're not going to get below average temperatures when there is a +EPO that blocks out the cold from North America.

[N. OF PIKE]

zucks the euro 0z and 12z ens as well as gfs have a -EPO FWIW. i see below normal temps zucks...(for NE) enjoy it. you may even score some snow a week from today. i know the upslope snow should continue next week for NNE (>1500'). stowe got another few last nite.

[Harry]

zucks the euro 0z and 12z ens as well as gfs have a -EPO FWIW. i see below normal temps zucks...(for NE) enjoy it. you may even score some snow a week from today. i know the upslope snow should continue next week for NNE (>1500'). stowe got another few last nite.

This. Not sure where some are getting the +EPO stuff? The euro weeklies now have at or below normal for the last week of April and first week of May in the east and at or below normal from now till early May for the GL and Mid Atlantic on south. Both GFS and euro ensembles have been trending colder as well the past few runs. Chances for any extended above normal temps are looking low and lower with each new model run after next week. The pattern HAS already begun to change and all the above normal temps in Canada should be mostly gone as well at some point next week and especially beyond except perhaps up towards NW Canada/AK.

[wxdudemike]

It is becoming clear that we are now in a warmer climate and the models will overplay the cooler temps.

Somehow I knew absurd comments like that would happen after the warm winter and early start to spring. I think people assuming this means a hot summer could be fooled. Harry brought up some good points. Looks like cool is the way to go for the next several weeks and possibly even this summer. Although that is still speculative obviously.

[bluewave]

Somehow I knew absurd comments like that would happen after the warm winter and early start to spring. I think people assuming this means a hot summer could be fooled. Harry brought up some good points. Looks like cool is the way to go for the next several weeks and possibly even this summer. Although that is still speculative obviously.

Sure, long range forecasts are always speculative. But you can't deny that warm has been running the board especially

since 2000 in the US. The chart from TWC blog shows all the red or above normal seasons in the US since 2000 (NCDC).

The last two years are just the exclamation point on a longer term pattern.

[wxdudemike]

Oh it's been running above average as a whole especially compared to the 20th century averages because in the past 100 years we've warmed up. I don't want to start a climate change discussion in this thread, but I was just expressing frustration over using a small period of time to make claims about climate that's all.

[donsutherland1]

April 16-22, 2012 Thoughts:

The April 16-22 timeframe is filled with a lot of uncertainty, particularly with regard to the Arctic Oscillation (AO). Run-to-run continuity on the ensembles has been lacking recently. The most recent guidance has an enormous spread among ensemble members. In addition, the 2011-12 La Niña event has either ended or is now ending.

.

The chart below shows the composite temperature anomalies for ENSO Region 3.4 anomalies of -0.4°C to +0.1°C, a PNA of -1.25 to +0.25, and an AO of -0.50 to +1.25 for North America.

On account of the large spread for the AO, there are 81 dates that show up in the teleconnection analogs. There is quite a variation among them, but a tendency that favors milder weather in parts of the East (except for New England/eastern Canada) and cooler readings in parts of the West.

The April 14-20 timeframe on the NAEFS shows warm anomalies across much of North America except for the Great Lakes region and parts of the West. In those areas, the NAEFS shows near normal readings.

Conclusion:

Using the NAEFS to help corroborate the teleconnection analogs, I pretty much agree with the teleconnection analogs except for the following modest changes:

1. Near normal readings are likely in the Great Lakes area (there was a signal for wetter than normal conditions in that area)

2. Warmer than normal in southern Alaska but colder than normal in northern Alaska

[easternsnowman]

Somehow I knew absurd comments like that would happen after the warm winter and early start to spring. I think people assuming this means a hot summer could be fooled. Harry brought up some good points. Looks like cool is the way to go for the next several weeks and possibly even this summer. Although that is still speculative obviously.

I have never said it would stay warm all year, my thoughts are that it would change in mid to late summer.

[donsutherland1]

Some quick thoughts...

The latest MJO guidance is suggesting that the MJO could move into the low amplitude ranges sometime during the third week in April. This development might indicate a warmer-than-normal second half of April for much of eastern North America.

Below is a chart showing the April 16-30 temperature anomalies for cases during which the MJO was in Phases 1 or 2 with an amplitude <1 and ENSO R3.4 anomalies were in the -0.4°C to +0.1°C range (where the MJO is likely to move during and just beyond the third week of April):

Such a development would be consistent with some of the analogs that came up for April. In the first message in this thread, it was noted that 1976 and 2009 were among the leading analogs for April. Excerpts:

Both 1976 and 2009 featured a significant outbreak of heat during the second half of the month (1976 just after mid-April and 2009 in late April). The first half of each of those two cases did feature some colder than normal readings, so some cold shots would appear plausible in eastern North America, especially during the first 1-2 weeks of April.

The teleconnection analogs for the April 16-22 timeframe also indicated warmth in the East. The map from Message #86 is below:

The latest weekly CFSv2 forecast has now reverted from cold anomalies to warm ones in the East. Below are the April 15-21 and April 22-28 CFSv2 weekly forecasts:

In sum, there ensemble support for a warmer-than-normal second half of April in much of eastern North America appears to be growing. Whether or not a period of excessive warmth will take place during the second half of April remains to be seen. Given some of the past analogs and also the recent developments in the long-range ensemble guidance, such a development remains on the proverbial table.

[am19psu]

Don,

The statistical guidance is showing a higher likelihood of a higher amplitude MJO wave than the dynamical guidance. What would happen if you bumped your MJO amplitudes up to between 0.5 and 1.5?

[donsutherland1]

Don,

The statistical guidance is showing a higher likelihood of a higher amplitude MJO wave than the dynamical guidance. What would happen if you bumped your MJO amplitudes up to between 0.5 and 1.5?

I'll run the numbers tonight and post the map. My guess is that one would see a less warm outcome in the East, but I'll run the numbers just to be sure.