Medium Range Discussion Summer 2012

[icebreaker5221]

interesting. I had thought the el nino pattern without a given NAO state tended toward cooler trends the further NE one went. Because of the summer wavelengths, I was under the impressions that a -NAO produced a tendency toward warmer weather, or is that not true the further one goes NE toward the anomoly?

It's true that at shorter summer wavelengths, -NAO favors cooler weather but only for the northern half of the country. This is particularly true for developing first-year Ninos.

Of developing 1st year Ninos, years with Jul-Aug-Sep trimonthly mean NAO negative:

Of developing 1st year Ninos, years with Jul-Aug-Sep trimonthly mean NAO positive:

So actually, +NAO is often a cooler outcome this time of year in developing Ninos for the southeast, while -NAO is generally cooler elsewhere.

Another question I would have is does a budding Nino produce a tendency toward -NAO, thus causing the cooler climatology in the NE summers during ninos?

Actually, of developing Ninos, +NAO outnumbers -NAO 2 to 1 late summer/early fall. I'm not sure if there is a physical mechanism behind this or if it is just coincidence. Ninos are often cooler than Ninas reguardless of NAO in the summer, which seems to be a factor of the strength of the midwest/east coast ridge. That said, if we have a developing Nino as we do now, -NAO favors a cooler pattern for most of the country than would a +NAO this time of year (although not for you in SC! )

[Sunny and Warm]

Icebreaker5221,

Thank you for the wonderful response. I never would have guessed that a +NAO was cooler for the south, or that a -NAO was colder further north given what I always read about -NAO providing the opposite response in summer versus winter. I guess a 1st yr Nino has a lot to do with that. Enjoy your weekend.

[donsutherland1]

June update:

The NOAA revealed that June 2012 was the 14th warmest on record. The monthly mean temperature of 71.2°F was 2.0°F warmer than the 20th century average.

[cooling climate]

June update:

The NOAA revealed that June 2012 was the 14th warmest on record. The monthly mean temperature of 71.2°F was 2.0°F warmer than the 20th century average.

Urban heat islands etc,etc mean that the statistic is really quite meaningless.

[am19psu]

Urban heat islands etc,etc mean that the statistic is really quite meaningless.

Your posts are really quite meaningless. Add something to the discussion or keep your drive by posts to yourself.

[donsutherland1]

Urban heat islands etc,etc mean that the statistic is really quite meaningless.

Putting aside the climate change issue related to UHI (wrong forum for that discussion), the outcome provides an important clue that the July forecast (#49) may well be on track. Pattern persistence can be an important factor in developing forecasts.

[SACRUS]

MEI Value

May/Jun: .903

closest actuals

1958: .896

2009: .943

2002: .864

1982: .951

1980: .851

1965: .956

closest trends.

2012 -1.046 -.702 -.41 .059 .706 .903

2002 -.05 -.208 -.196 .339 .78 .864

2009 -.753 -.715 -.713 -.159 .37 .943

1965 -.525 -.323 -.25 .104 .535 .956

1976 -1.624 -1.396 -1.253 -1.191 -.481 .342

1951 -1.068 -1.196 -1.209 -.437 -.275 .464

[Ed Lizard]

MEI Value

May/Jun: .903

closest actuals

1958: .896

2009: .943

2002: .864

1982: .951

1980: .851

1965: .956

closest trends.

2012 -1.046 -.702 -.41 .059 .706 .903

2002 -.05 -.208 -.196 .339 .78 .864

2009 -.753 -.715 -.713 -.159 .37 .943

1965 -.525 -.323 -.25 .104 .535 .956

1976 -1.624 -1.396 -1.253 -1.191 -.481 .342

1951 -1.068 -1.196 -1.209 -.437 -.275 .464

Is there any relationship between the rate of change of MEI going into a warm ENSO event and the magnitude and length of the event? I don't see an obvious link, but the compressed time scale makes it hard to judge.

[The_Global_Warmer]

June AMO reading is 0.340 up from 0.199 in May and up from -0.033 in January.

Quite a bit of the warm ssts are off the coast of North central North America.

[easternsnowman]

Urban heat islands etc,etc mean that the statistic is really quite meaningless.

I agree. There is a big difference between the cities and more rural areas outside of the city especially during the night temp wise.

[HM]

Your posts are really quite meaningless. Add something to the discussion or keep your drive by posts to yourself.

Someone tell Piers Corbyn that the climate isn't cooling.

[Mencken_Fan]

I agree. There is a big difference between the cities and more rural areas outside of the city especially during the night temp wise.

Rural areas will always be cooler than cities -- so what?

The great bulk of our forests are gone; replaced by farms, towns, and cities.

The whole country is effectively a "heat island."

Three fourths of the non-frozen land on earth has been "terraformed" in this manner.

Geez, might it be possible our biosphere is undergoing a change -- one that we are causing?

Can we think for ourselves or must we be lemming-like parrots?

[am19psu]

This is not the climate change forum

[donsutherland1]

Some morning thoughts...

1. Yesterday, the Temple/Miller, TX automatic observation site recorded a temperature of 129°F (53.9°C). It remains to be seen whether this recording will be validated. What is more clear is that the focus of the heat has shifted to the Western Third of the U.S. and Canada.

2. Ensemble forecasts have persistently called for the development of a strongly negative PNA after mid-month. A negative PNA correlates increasingly with heat in the Central and Northern Plains and Great Lakes toward the end of July and in August. If the PNA forecast verifies and if the outcome is consistent with the correlation, this could be a signal that the relief from extreme heat in that portion of North America could be temporary.

3. For now, the GFS ensembles keep the focus of the anomalous heat in the Western Third of North America through 360 hours, including the Pacific Northwest. That outcome would be at odds with a strong PNA-.

[winterymix]

Some morning thoughts...

1. Yesterday, the Temple/Miller, TX automatic observation site recorded a temperature of 129°F (53.9°C). It remains to be seen whether this recording will be validated. What is more clear is that the focus of the heat has shifted to the Western Third of the U.S. and Canada...

Wouldn't you probably prefer to have that data tossed?

That measurement seemed to occur at night after a two hour window of missing measurements and yet the dew point

remains almost constant during the entre periord.

[NJwinter23]

Some morning thoughts...

1. Yesterday, the Temple/Miller, TX automatic observation site recorded a temperature of 129°F (53.9°C). It remains to be seen whether this recording will be validated. What is more clear is that the focus of the heat has shifted to the Western Third of the U.S. and Canada.

2. Ensemble forecasts have persistently called for the development of a strongly negative PNA after mid-month. A negative PNA correlates increasingly with heat in the Central and Northern Plains and Great Lakes toward the end of July and in August. If the PNA forecast verifies and if the outcome is consistent with the correlation, this could be a signal that the relief from extreme heat in that portion of North America could be temporary.

3. For now, the GFS ensembles keep the focus of the anomalous heat in the Western Third of North America through 360 hours, including the Pacific Northwest. That outcome would be at odds with a strong PNA-.

Don,

It looks like a good troughing signal in the eastern U.S. in the 11-15 day window, following next week's heat wave, would lead to another wave of more seasonable (likely +1 to +3) anomalies across the Northeast. Mean ridge axis shifts to the rockies with greatest warmth centered across mid-continent, and mainly aboves in the west too (aside from monsoon undercutting the ridge)...Remains to be seen if this pattern would persist beyond heading into August (developing el nino might argue for that) or if the general La Nina hang over/-PDO influences that have largely defined the over all pattern this summer will continue.

[CoastalWx]

Don,

It looks like a good troughing signal in the eastern U.S. in the 11-15 day window, following next week's heat wave, would lead to another wave of more seasonable (likely +1 to +3) anomalies across the Northeast. Mean ridge axis shifts to the rockies with greatest warmth centered across mid-continent, and mainly aboves in the west too (aside from monsoon undercutting the ridge)...Remains to be seen if this pattern would persist beyond heading into August (developing el nino might argue for that) or if the general La Nina hang over/-PDO influences that have largely defined the over all pattern this summer will continue.

It looks like the euro ensembles also shows this with some sort of a front hung up near the East coast...possibly again down by the Mid Atlantic. The airmass itself still looks on the warmer side like you said....perhaps more of a relief from TDs and not necessarily temps in the northeast? MJO forecasts still are sort of everywhere with the NCEP models going to P1 and the others weakly in 2-3 or the COD.

[NJwinter23]

It looks like the euro ensembles also shows this with some sort of a front hung up near the East coast...possibly again down by the Mid Atlantic. The airmass itself still looks on the warmer side like you said....perhaps more of a relief from TDs and not necessarily temps in the northeast? MJO forecasts still are sort of everywhere with the NCEP models going to P1 and the others weakly in 2-3 or the COD.

Yeah I'm almost picturing something similar to the "cool down" that is going on this current week when i look at the euro ensembles...really fighting over August in the east though.

[cooling climate]

Your posts are really quite meaningless. Add something to the discussion or keep your drive by posts to yourself.

Man some of you really are quite thick. LOL.

[donsutherland1]

Wouldn't you probably prefer to have that data tossed?

That measurement seemed to occur at night after a two hour window of missing measurements and yet the dew point

remains almost constant during the entre periord.

Yes, IMO it should be tossed.

Today's anomalous reading and yesterday's are greatly inconsistent with temperatures elsewhere Texas. I believe the sensor is malfunctioning.

[Ed Lizard]

Man some of you really are quite thick. LOL.

That is a good way to impress the mods, keep it up.

[am19psu]

Man some of you really are quite thick. LOL.

Bye.

[donsutherland1]

July 24-31, 2012 Thoughts:

The GFS ensembles continue to suggest that the PNA could go strongly negative prior to the start of this period (values -1.00 or below). At the same time, the development of a possible El Niño event continues albeit on a gradual basis. As a result, one could continue to see widespread warmth (with some exceptions) across North America to close July.

The chart below shows the composite temperature anomalies for ENSO Region 3.4 anomalies of +0.20°C to +0.80°C, a PNA of -1.50 to -0.50, and an AO of -0.25 to +0.50 for North America.

The NAEFS for the July 22-28 timeframe shows a probability of warm anomalies across virtually all of North America, except Texas, New Mexico, Colorado, and part of the West Coast. Some of the ensemble guidance suggests that the Arctic region could see readings become closer to normal toward and during the last week of July and perhaps even somewhat cooler than normal in areas. Should such a regime develop and persist, it could have implications down the road, particularly as August evolves.

Taking into consideration the upstream conditions, teleconnection analogs, ensemble guidance, and decadal trends, I expect the following for the July 24-31 timeframe:

- Warmer than normal across most or all of Canada

- Near to perhaps somewhat cooler than normal across Texas

- Cooler than normal in the Pacific Northwest

- Warmer than normal across the rest of the U.S.

Given some of the analogs that are in the mix and pattern repetition over the past 6 months, one cannot rule out the possibility of some much above normal readings in parts of the Central Plains, Great Lakes (U.S. and Canada), and Eastern U.S. during a portion of the July 24-31 period.

[JamieOber]

A suggestion - given drought conditions, we likely should start including precipitation discussions in these. It's notably absent from much of the conversation and I would argue right now is more important then temperatures.

[donsutherland1]

A suggestion - given drought conditions, we likely should start including precipitation discussions in these. It's notably absent from much of the conversation and I would argue right now is more important then temperatures.

A good point. I'll include that in my next set of thoughts (probably 1st week August and/or overall August idea).

[WxMidwest]

Wow, we are on the threshold of a multiyear drought if this continues. We have already caught up to 1956 drought analog wise. If we start getting into analogies like the 1930's by the end of August, we will have arrived at that threshold.

[donsutherland1]

A quick drought-related thought...

June 2012 ranked as the 10th driest June on record for the contiguous U.S. Since 1895, 20/30 (67%) of such cases also saw the summer rank as among the 30 driest. To date, summer 2012 appears on course for such an outcome.

An exceptionally dry summer often heralds a dry winter. Among the 30 driest summers on record, 20 (67%) were followed by among the 50 driest winters. 11 (55%) of those dry winters were followed by a dry fall (50 driest on record), while 9 (45%) were followed by a wet fall (50 wettest on record).

For the first 6 months, 2012 was the 16th driest year on record. The last time the U.S. had less precipitation in the first half of the year was 2002 (11th driest). Whether or not the U.S. has moved into a regime that will feature generally dry years remains to be seen.

[donsutherland1]

August 2012 Forecast:

The hot and dry summer of 2012 will go on.

Key Assumptions:

• A weak El Niño event will be underway in August

• The AO will likely be somewhat positive

• The PNA will likely be somewhat negative

The top analog was 2006.

The charts on which my August idea is based are:

Top Left: Analogs for August 2012

Top Right: Analogs (Temperature and Drought) for August 2012

Bottom Left: CFSv2 Forecast for August

Bottom Right: Observed decadal temperature trend

Although the GFS ensembles have hinted that the Arctic region could grow slightly cooler than normal toward the end of July, the GFS ensembles have recently been somewhat too cool there. The assumption is that the Arctic region will likely be somewhat warmer than normal. Hence, the source region of potential cool air masses will have less cool air than usual available.

At the same time, on account of the increasingly widespread drought, the Southwestern and Plains States will remain unusually dry. This means more of the sun's energy will be devoted to direct heating relative to evaporation of soil moisture. As a result, hot air masses that come eastward will be warmer than usual.

To date, Summer 2012 has been exceptionally hot in the Northern Hemisphere. As per the latest NCDC data, the Northern Hemisphere's land area had a June temperature anomaly that ranked highest on record (2.42 sigma above the 1981-2010 climate baseline). The combination of less cool air than usual in the Arctic, drought across a significant portion of the U.S., and general exceptional warmth in the Northern Hemisphere all suggest that odds favor a warmer than usual outcome than is typical for the onset of an El Niño.

As a result, my thoughts are as follows:

- Alaska will be mainly cooler than normal

- The West Coast of the U.S. perhaps into British Columbia will be somewhat cooler than normal

- The remainder of North America will be warmer than normal. An area running from the Southern and Central Plains into the Great Lakes region (U.S. and southern Ontario) could be much warmer than normal. Another area in northern Canada could also be much warmer than normal.

The ongoing drought has increased in expanse and severity in recent weeks. The July 10, 2012 Drought Monitor reported that 60.84% of the U.S. was experiencing moderate or worse drought conditions and 11.61% was experiencing extreme or worse drought conditions. As a result, it makes sense to discuss precipitation outlooks.

2012 saw the 10th driest June on record in the contiguous U.S. 19 of the 30 driest cases in June were also among the 50 driest cases in July. July 2012 appears well on course for that outcome. 11 of 19 or 58% of those dry July cases were also among the 50 driest cases in August.

From that pool of cases, I selected the years that showed up most persistently as summer analogs. Two stood out: 1953 and 2002. 2002 was the top analog for July.

The charts below are:

Left: Drought Analogs

Right: CFSv2 Precipitation Forecast for August

My thoughts are as follows:

- The Central and Southern Plains will remain drier than normal in August

- Dry anomalies will likely expand across the Ohio Valley into New England

- The Gulf Coast and Southeast could experience near normal precipitation

- With the exception of the Southwest, which should have near normal preciptitation, the rest of the western third of the U.S. could be wetter than normal

Finally, some historical photos from the Dust Bowl are below:

[JamieOber]

Thanks Don, and this last post is fantastic.

I guess the wild card is in the tropics but El Nino puts the kibash somewhat on that hope.

[donsutherland1]

Thanks Jamie.

Hopefully, there will be at least some opportunities for tropical moisture to help slow or reverse the growing drought. Sometimes these patterns can become very persistent. The 1960s featured a number of dry years and summers. The 1950s featured even more.