Medium Range Discussion Spring 2012

[andyhb]

Fast forward that 3-9 hours as the mid/upper jet streak noses in and the LLJ intensifies...

[donsutherland1]

The following are some probabilities for Washington, DC (DCA):

Reaching or Exceeding:

80° Once every 0.4 years; Last reached: 2011

85° Once every 0.8 years; Last reached: 2011

90° Once every 2.6 years; Last reached: 2011

95° Once every 10.0 years; Last reached: 2002

100° Once every 47.2 years; No 100° temperatures on record

Keep in mind, these are statistical probabilities based on a normal curve using the 1981-2010 base period.

[Sstorm]

Don, before I ask my question I just want to say that I have been reading your thoughts and forcasts for quite a few years now. The strangest thing is that I live in Louisiana, but I've learned that you are the most accurate when it comes to medium/long range predictions.

My question pertains to the 1976 analog you are now referencing. At what point during any given year do you move from one analog year to a totally different one? My reason for asking is cause 1976/77 was an extremely cold year in the deep south from what I remember as a kid. So, will your reference analog year change? And when?

Thank you. Sstorm

[andyhb]

Pretty impressive severe setup showing up on the 18z GFS for next weekend/early the next week.

00z GFS too now, and of course it's from Palm Sunday to April 4th...

[Geos]

Noticed the new CPC outlook for the 6-10 day, 8-14 day has erased the positive anomalies in the GL states and the eastern 1/4 of the nation. Even below normal temperatures for the mid-Atlantic.

[andyhb]

Probably means it is seeing some kind of big system moving through and getting rid of the ridge in the east.

[Tropical]

Noticed the new CPC outlook for the 6-10 day, 8-14 day has erased the positive anomalies in the GL states and the eastern 1/4 of the nation. Even below normal temperatures for the mid-Atlantic.

This is much more accurate, IMO.

[Geos]

This is much more accurate, IMO.

Interesting on how spread out the positive anomalies are vs. the CPC's outlook. The below normal temperature area on the CPC is right where there is a 90-100% chance of warmer air. Today's CPC outlook really confines all the above normal temperatures west of the 100th meridian.

[donsutherland1]

Several morning thoughts:

1. In recent days, the objective analogs and also CPC's forecasts have pointed to the possibility of cold anomalies in parts of eastern North America. The NAEFS have also shown a reduced probability of warm anomalies in parts of the East.

2. Such an outcome, if it were to verify, would reflect one or two cold shots that could tip the balance toward closer to normal or perhaps even a little below normal in parts of the East. At the beginning of this thread, I cited 1976 and 2009 as two leading analogs for April 2012. Both years featured cold shots during the first half of the month.

3. Both years also featured a strong rebound in temperatures during the second half of April.

In sum, the possibility of some cold weather is a realistic possibility. Any such cold does not necessarily mean that the month won't end with warm anomalies in the East. Indeed, the warmth has outdueled the cold throughout the winter and early spring, so persistence would also argue against the month's ending with cold anomalies.

[easternsnowman]

Several morning thoughts:

1. In recent days, the objective analogs and also CPC's forecasts have pointed to the possibility of cold anomalies in parts of eastern North America. The NAEFS have also shown a reduced probability of warm anomalies in parts of the East.

2. Such an outcome, if it were to verify, would reflect one or two cold shots that could tip the balance toward closer to normal or perhaps even a little below normal in parts of the East. At the beginning of this thread, I cited 1976 and 2009 as two leading analogs for April 2012. Both years featured cold shots during the first half of the month.

3. Both years also featured a strong rebound in temperatures during the second half of April.

In sum, the possibility of some cold weather is a realistic possibility. Any such cold does not necessarily mean that the month won't end with warm anomalies in the East. Indeed, the warmth has outdueled the cold throughout the winter and early spring, so persistence would also argue against the month's ending with cold anomalies.

It has been very hard the last 2 years to get below the 1981-2010 normals and I don't see any months coming up that will be, maybe this trend is permanent.

[RodneyS]

It has been very hard the last 2 years to get below the 1981-2010 normals and I don't see any months coming up that will be, maybe this trend is permanent.

I think you have to be cautious here. For example, while 20 of the last 24 months in DC have been above the 1981-2010 normals, seeming to support your contention, the trend can change in a hurry. That happened two decades ago: DC's warmest year was 1991, with an average temperature of 60.2 (compared to 59.9 in 2011). However, starting in March 1992, there were ten straight months below the 1981-2010 normals, followed by an above normal January and then three more consecutive months below those normals, for a total of 13 out of 14 months below those normals. 1992 as a whole was only the 66th warmest in DC history, with an average temperature of 56.7. Now, that was a Nino year, but four years later, in 1996, a Nina year produced an average temperature of only 56.9, the 60th warmest in DC history.

[donsutherland1]

April 8-15, 2012 Thoughts:

Although the possibility exists that there cold be at least a moderate cold shot to the Ohio Valley and East Coast during the second week in April, the period could wind up somewhat warmer than normal in both areas. The warmth could follow a somewhat cooler than normal to near normal first week of April in that part of the U.S.

In contrast, a large part of Canada could see cooler than normal readings for the period as a whole. Eastern Canada, particularly Quebec, Nova Scotia, Newfoundland, New Brunswick, and PEI could be near normal to somewhat above normal.

.

The charts below are as follows:

Top Left: The composite temperature anomalies for ENSO Region 3.4 anomalies of -0.8°C to -0.1°C, a PNA of -1.00 to -0.25, and an AO of -0.75 to +0.25 for North America.

Top Right: NAEFS probabilities for the 4/6-12/2012 timeframe

Bottom Left: The Objective Analogs centered on April 9, 2012 but rolled forward 3 days

Bottom Right: Verification of the AO 14-day forecast

A wildcard is the AO forecast. Recently, the 14-day AO forecast has been verifying well below the forecast. Hence, greater weight was placed on the idea of a negative AO. There is a possibility that the AO could be even more negative than expected. If so, a colder outcome in the eastern U.S. could prevail. At the same time, cold anomalies in the Arctic region are not very expansive. Barring a buildup of cold, there will be potential that cold anomalies in Canada could be more limited than what I anticipate. Pattern persistence has favored warmer-than-forecast outcomes.

Conclusion:

Taking into consideration the observed decadal temperature trend, I believe the eastern two-thirds of the U.S. will likely see generally somewhat above normal temperatures for the period as a whole. Eastern Canada could wind up with near normal to somewhat above normal readings, with some scattered cool anomalies. The rest of Canada, as well as the immediate West Coast of the U.S. could see cooler than normal readings. The western half of Alaska could also experience warmer than normal readings.

[The_Global_Warmer]

90 in Minnesota, 100 in Texas.

[easternsnowman]

As state previously don't look for any below 1981-2010 so-called norms anytime soon, if we average 2 or 3 above normal I consider that to be average,I still believe by late summer this may change.

[Chinook]

Warmest January through March ever in Contiguous 48 states? (I'm not sure if is is/will be or not.)

[MN Transplant]

Warmest January through March ever in Contiguous 48 states? (I'm not sure if is is/will be or not.)

Prior warmest

[Minnesota Meso]

The operational Euro is starting to react to the MJO going into phase 1

the new Euro at 240 hrs. I know it's 10 days out but good grief

[NJwinter23]

Yeah I'm interested to hear what folks think of this MJO progression. Going off the 2 week forecasts would have the MJO about to enter phase 2 by mid-month. Going off the MAM temperature correlation maps on cpc, this would mean a cool eastern U.S. Especially phase 3 would have a good correlation to such and that would be in later April. I know Don and others have speculated on another excessive warm period playing out in late April, be it through the analogs or what not, so I'm curious on what the MJO could mean for this scenario.

[Minnesota Meso]

The maps for the MJO I posted earlier were for the Euro ensemble, this is from the Euro seasonal ensemble run. Notice how it goes to the center, meaning a weak MJO signal.

if in fact it enters the circle, than I think some of past analogs will have some merit, but if stays outside the circle than using analogs to forecast out to 30 days is useless IMO, most of the doom and gloom winter forecast were based on analogs, when if fact it looks like the MJO was the driver behind this winter. I don't know how to pull up analogs (just a amateur weather geek), but I can tell you that Joe Bastardi is looking at 1910 real close. Yeah I know sometimes he swings for the fences (using a baseball analogy), and every once in a while he hits a home run. 1910 was very cold in May if I remember right, after the warmest March on record for the US as a whole, at least up to this year.

[Minnesota Meso]

First off thank you to Matthew Hollliday at first hand weather for posting these maps and allowing me to copy them.

March 1910

the following May....not good for the AG business, I hope this doesn't happen this year.

This would not be good

[uncle W]

First off thank you to Matthew Hollliday at first hand weather for posting these maps and allowing me to copy them.

March 1910

the following May....not good for the AG business, I hope this doesn't happen this year.

This would not be good

things have a way of evening up in weather...1945 and 1946 had the same outcome...

[Minnesota Meso]

things have a way of evening up in weather...1945 and 1946 had the same outcome...

Thanks Uncle, never have seen anyone post 45-46 interesting indeed.

[Geos]

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.

[donsutherland1]

A few morning thoughts...

After the extraordinary record-smashing days of March, April 1 marked a return to normalcy. The preliminary data shows that not a single daily record was tied or broken. However, even as the seemingly placid start to April might leave the impression that a quiet month is getting underway, big changes are occurring in the Pacific that will likely have important consequences later in the spring and during the summer.

The SOI is currently having its strongest negative burst since the June 12-June 18, 2011 timeframe. In addition, the 30-day moving average of the SOI just slipped below zero today and the 90-day moving aveage has accelerated its decline. The weakening easterlies very likely indicate that the 2011-12 La Niña event is either ending or has just ended. Already, the week centered around March 28 saw the ENSO Region 3.4 anomaly rise to -0.2°C (neutral ENSO levels).

The PNA is currently forecast to go negative over the next 7-10 days, while the AO remains generally positive. In April, a PNA- often correlates with cooler than normal conditions in the northern tier of the U.S. However, an AO+ often sees mild readings in the eastern two-thirds of the U.S. In short, one probably can expect some shots of cold in the eastern half of North America during the next 7-14 days, but the cold shots could be transient as the AO and PNA compete for dominance in an environment of shortening wave lengths. Such an outcome would leave the mean temperature for the first half of April much closer to normal in the Great Lakes, Ohio Valley, East Coast, southern Ontario, and southern Quebec than it has been in quite some time.

[donsutherland1]

Yeah I'm interested to hear what folks think of this MJO progression. Going off the 2 week forecasts would have the MJO about to enter phase 2 by mid-month. Going off the MAM temperature correlation maps on cpc, this would mean a cool eastern U.S. Especially phase 3 would have a good correlation to such and that would be in later April. I know Don and others have speculated on another excessive warm period playing out in late April, be it through the analogs or what not, so I'm curious on what the MJO could mean for this scenario.

Right now, my guess is that the timing of excessive warmth would probably be closer to 2009 than 1976 in April (probably last 7-10 days vs. just after mid-month). 2009 was a somewhat stronger analog case than 1976, especially when ENSO evolution is considered. The MJO's progression may also be hinting at a slower rebound to much warmer than normal conditions. Also, with the La Niña ending or having ended, there could be the prospect that just as had been the case in March, the warmest anomalies relative to normal could occur the farther north one goes e.g., New England could see greater warmth relative to normal than the Southeastern U.S.

[donsutherland1]

First off thank you to Matthew Hollliday at first hand weather for posting these maps and allowing me to copy them.

I'd be somewhat cautious about assuming that things will unfold much as they did in 1910, 1945, and 1946. 1910 saw La Niña conditions strengthening in the spring (March through May). 1945 saw La Niña conditions persist though April and then give way to neutral, but still borderline La Niña, ENSO conditions in May. 1946 saw neutral ENSO conditions throughout the Spring.

The current La Niña appears to have ended or be ending. Region 3.4 anomalies have warmed to -0.2°C. The easterlies have weakened dramatically in recent days. A faster rise in R3.4 anomalies appears to be in order than in 1945 or 1946. Based on the guidance and actual trends underway, April and especially May could feature solidly neutral ENSO conditions. 2009 might offer some insight, should it remain a reasonable analog.

[uncle W]

I'd be somewhat cautious about assuming that things will unfold much as they did in 1910, 1945, and 1946. 1910 saw La Niña conditions strengthening in the spring (March through May). 1945 saw La Niña conditions persist though April and then give way to neutral, but still borderline La Niña, ENSO conditions in May. 1946 saw neutral ENSO conditions throughout the Spring.

The current La Niña appears to have ended or be ending. Region 3.4 anomalies have warmed to -0.2°C. The easterlies have weakened dramatically in recent days. A faster rise in R3.4 anomalies appears to be in order than in 1945 or 1946. Based on the guidance and actual trends underway, April and especially May could feature solidly neutral ENSO conditions. 2009 might offer some insight, should it remain a reasonable analog.

May temperatures in 2009 were near average east of the Rockies...1910 was very dry in March...I'm not sure if the entire east coast was as dry as 1910 was but the North East saw near record dryness this year...

[NJwinter23]

Right now, my guess is that the timing of excessive warmth would probably be closer to 2009 than 1976 in April (probably last 7-10 days vs. just after mid-month). 2009 was a somewhat stronger analog case than 1976, especially when ENSO evolution is considered. The MJO's progression may also be hinting at a slower rebound to much warmer than normal conditions. Also, with the La Niña ending or having ended, there could be the prospect that just as had been the case in March, the warmest anomalies relative to normal could occur the farther north one goes e.g., New England could see greater warmth relative to normal than the Southeastern U.S.

I agree Don. It is looking most likely the last week of April heading into early May would be the best chance of a sustained warm pattern returning to the east. Definitely some good warm shots will still push east before then, but they would likely be transitional (like this upcoming weekend). Troughiness will win out in general I believe, but like has been the case all winter, any warm anomalies would probably out-dual the cold anomalies such that things probably end up around normal.

[phlwx]

I agree Don. It is looking most likely the last week of April heading into early May would be the best chance of a sustained warm pattern returning to the east. Definitely some good warm shots will still push east before then, but they would likely be transitional (like this upcoming weekend). Troughiness will win out in general I believe, but like has been the case all winter, any warm anomalies would probably out-dual the cold anomalies such that things probably end up around normal.

Even this upcoming weekend in the East will not be all that warm (compared to average). +3 to +5 is pretty run of the mill ahead of a cool front.

Next week *could* be a bit cooler than average in the East, specifically Tues-Thurs...we could have some 40's for highs in the Apps.

If anything, April is shaping up as a variable month that averages out to near average for most of it...but if that end of month torch does result we probably end up +2 or 3 when all is said and done.

[am19psu]

Even this upcoming weekend in the East will not be all that warm (compared to average). +3 to +5 is pretty run of the mill ahead of a cool front.

Next week *could* be a bit cooler than average in the East, specifically Tues-Thurs...we could have some 40's for highs in the Apps.

If anything, April is shaping up as a variable month that averages out to near average for most of it...but if that end of month torch does result we probably end up +2 or 3 when all is said and done.

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.