Historic Warmth Across the Midwest and Eastern United States

[phil882]

Hi Everyone,

I think this deserves its own thread outside of the Mid-Range weather discussion. The Mid-west and Eastern United States is currently experiencing a historic warmth episode that has never been experienced before. Many locations have already set their all time record highs for the month of March, some by multiple degrees. I want to take a moment to look at the pattern in place that is resulting in such an anomalous pattern and why our situation has strongly been influenced by ENSO phase, MJO phase, and the prevailing lack of snowpack over a large portion of North America.

Firsts of all, lets just look at some of the recent records. We are now going on a week plus of widespread record highs being set across portions of the midwest and Ohio valley. Some of these record highs have also been quite substancial at times. For example, International Falls, MN is going on 8 straight days of record highs. Even more impressive, it has set the all time record high for the Month of March (79 degrees) exceeding the previous value by 6 degrees!

Now for the ridiculous. International Falls, MN yesterday managed to attain a minimum temperature of 60 degrees. What is significant about this is that the record high for the day was 60 degrees. Thus, International Falls has experienced a 24 hour period where its record high was exceeded or tied at all times during the day. Thats just unbelievable and in my opinion and an exceptionally rare event. Never mind the fact the record high was absolutely shattered by 18 degrees! Looking at the record high animation above, it appears this event was not an anomaly, but there was actually a widespread area in Minnesota that never dipped below its record high for the day, even if it was in the middle of night! As a result, a typical summer type regime has evolved over the mid-west where squall lines of thunderstorms were able to parade across the State, with both hail and damaging wind reports observed over large portions of the upper midwest.

The long duration and sheer intensity of the warmth this March will ensure most locations in the Midwest and Northeast will record their warmest March on record, some by a significant margin. However, probably more important is why are we experiencing this warmth, and is some of this related to how little snowpack there was across the continent this winter. I think the answer lies somewhere between the atmosphere and the current cryosphere. I will carefully go through the influence that have lead to a flurry of incredible temperature anomalies across the Central and Eastern United States.

1. The MJO is also off the charts and is playing a large role to this recent record warmth!

We have had an extensive discussion of the MJO so far, but I think we are currently witnessing one of the more substancial episodes of its influence on North America Weather. Currently the MJO is once again near record amplitude in phase, with only the MJO episodes in 1996-1997 which were a precursor to that record El Nino season.

In terms of RMM space, a phase 6 typically signals warmth across the Central and Eastern United States. Given 100 particular days of the MJO is phase 6, a large portion (70 out of the 100 days) have warm anomalies in the Eastern United States, many with significant amplitude. I think its safe to say the MJO is certainly not hurting this recent warmth occurring over large portions of Eastern North America.

The MJO signal shows up well currently in the West Pacific. You can see the increase convection over the far West Pacific near Indonesia has helped to enhance the subtropical ridge. This is coupled with a very anomalous trough over Japan. This combination helps to enhance the jet streak just off the Asian continent (somewhere around 90 m/s ~ 180 knots). However, since this stronger than normal height gradient does not persist into the Central Pacific, we see anomalous ridging over the Central Pacific from 30N and above, with a deep trough over Alaska. This is due to the mid-latitude storm track, which will tend to allow surface cyclones to intensify over the region of strongest upper level divergence (given by the outward moving irrotational winds). The downstream response to this surface cyclogenesis is enhanced ridging over the Central Pacific and ultimately enhanced troughing over Alaska. This pattern then leads to ridiging somewhere over Central and Eastern North America, and this is what we have witnessed thus far. This pattern is consistent with the pattern we witnessed in December through Mid January 2012 when the MJO was hanging around in phase 6-7 for an extended period of time.

2. The Weakening La Nina plays a minor role:

Now in addition to this strong MJO signal, we also have the remains of a La Nina phase. Think of this interannual signal basically helping to enhance the already potent MJO signal for continued warmth over the Central Eastern North America. Typically a La Nina signal promotes warmth across the Eastern United States.

With that said, this La Nina is quickly waning, and as this MJO continues to propagate westward, things are quickly shifting towards an El Nino regime. Already a strengthening western wind burst from this latest MJO propagating is being observed near the dateline, and this should continue to progress eastward with time. Thus, in my opinion, this factor is having the least influence on the huge temperature anomalies over the United States and Canada.

3. Lack of a Snowpack over North America.

Finally I want to end this post with a discussion on the lack of snowpack across almost the entire Midwest and Eastern United States. No doubt the lack of snowfall has aided in helping the warm anomalies this week, since little to no snow-melt has occurred across the United States which would normally help to keep the temperatures down. A good example of why this is important is looking at the dwindling snowpack across southeastern Canada. Notice that there is a strong correlation between ares with 1" or greater snowpack, and areas that are significantly cooler (10-15 degree differences!) compaired than the surrounding region with little or no snowpack. This is likely why International Falls, MN is currently experience such record breaking highs, since this is likely one of the earliest years on record that the vast majority of the state is completely snow free.

One last important note. Given this earlier than expected melt of the snowpack, the models may significantly underforecast the surface temperatures for the next few weeks. The main reason: most of the models assume as soon as the snowpack melts that trees have already started to bloom and grow leaves. This is not the case for the vast majority of the northern states, where most trees remain bare without many leaves for at least the next week. Thus, the models could be overestimating the amount of evapotranspiration that will occur, falsely increasing the moisture across the region and overall lowering the temperature given increased moisture. Since most trees haven't bloomed as of yet (at least across the north) the relative lack of moisture in the atmosphere should also be a boon for increased temperatures, perhaps more than the forecast modeling. Thus, don't be surprised if surface temperatures the next 2-3 days across the northeast end up verifying significantly higher than both MOS and 2m temperature guidance from the vast majority of the global models.

And with that I'll bring this post to a close... its a combo of the MJO, La Nina, and No Snowpack that has driven this March record heat to exceptional levels.

[MN Transplant]

Nice post. This is definitely a historic event, and I can't recall seeing an F-6 quite this exaggerated in the lower 48. A +44 departure is incredible.

[Bryan Wood]

One last important note. Given this earlier than expected melt of the snowpack, the models may significantly underforecast the surface temperatures for the next few weeks. The main reason: most of the models assume as soon as the snowpack melts that trees have already started to bloom and grow leaves. This is not the case for the vast majority of the northern states, where most trees remain bare without many leaves for at least the next week. Thus, the models could be overestimating the amount of evapotranspiration that will occur, falsely increasing the moisture across the region and overall lowering the temperature given increased moisture. Since most trees haven't bloomed as of yet (at least across the north) the relative lack of moisture in the atmosphere should also be a boon for increased temperatures, perhaps more than the forecast modeling. Thus, don't be surprised if surface temperatures the next 2-3 days across the northeast end up verifying significantly higher than both MOS and 2m temperature guidance from the vast majority of the global models.

This is a really good point. We're just beginning to see some trees bud/bloom in Ohio.

[Hoosier]

A lot of the Midwest is running +13 to +16 right now (Flint, MI is +16.4) and will likely finish the month somewhere in that range if not a bit higher in some spots. Truly amazing stuff. A forecaster out of NWS Chicago had this to say in this morning's AFD:

UNREAL. THAT IS ABOUT THE ONLY (AFD FRIENDLY) WORD THAT COMES TO MIND WHEN TRYING TO WRAP MY MIND AROUND THE CURRENT WARM SPELL. IT IS REMARKABLE ENOUGH TO WATCH LONG STANDING ALL TIME RECORD TEMPS BE THREATENED...BUT THE TOTAL SCOPE (DURATION AND INTENSITY) OF THIS WARM SPELL IS SOMETHING THAT HAS HISTORIC AND UNLIKELY TO BE MATCHED IN OUR LIFE TIME.

[phil882]

This is a really good point. We're just beginning to see some trees bud/bloom in Ohio.

The MOS guidance here has been consistently 4-5 degrees too low here at KALB the past few days. In addition, the 2 meter temperatures have been on the low side a well. It will just be something to keep in mind for the next week or so until we see full blooming from most trees and plants.

[donsutherland1]

Fantastic discussion. The point about the general lack of a snowpack is probably a key ingredient in tipping what would be an exceptional period of warmth into a historic one. INL had three consecutive days on which the previous monthly record fell. Today, monthly records are being shattered across parts of Ontario and Quebec where a still sizable snowcover typically helps blunt the warmth.

[tornadojay]

Excellent Post!! I don't know if anyone could have dreamed up more extreme records than the ones going on in Minnesota.. Simply unreal!

[phil882]

The MJO connection needs to be emphasized though. Despite both the GFS and ECMWF trying to slow down the propagation of the MJO beyond one week, I have a hunch they may be up to their usual tricks of not properly propagating the signal westward with time. Paul Roundy's statistical model show no such stalling, and continues to propagate the MJO well out into April (follow the red contours). Were this to verify, we should see a major pattern shift start in about a week to significantly reduced warming. It likely won't come soon enough to prevent a record warm March, but April is looking much cooler from a tropical perspective.

[bluewave]

Great Thread. I would also add the tendency for more extreme and longer duration blocking events recently

is contributing to this also. This is occurring here just as the long duration block near the Kara and Barents

Sea region is finally beginning to shift. The strongest blocking is over portions of Eastern North America this month.

I believe 400m + anomalies are just about the highest that I have seen in our region during the month of March.

The warm temperatures also reflect a lack of any really cold air over much of North America going back into 2011.

[RCNYILWX]

Amazing stuff, thanks for posting! Your look at the MJO will be helpful in trying to predict a period at risk for a damaging freeze, such as occurred Easter weekend 2007. With the explosive tree and plant growth we are witnessing across the region, we are at a high risk of a tremendously damaging freeze if we get a period at the end of March or in early April where we have widespread temperatures dipping to 28F or lower.

Here's a chart we put together at WFO Chicago about the probability of experiencing freezing temperatures moving through the spring: http://www.crh.noaa.gov/news/display_cmsstory.php?wfo=lot&storyid=80803&source=0

Last year, for instance, all of our official NWS observation sites dipped to 32 or lower (32 at Chicago-O'Hare 28 in Rockford, IL) on April 21st, except for Midway Airport and downtown Chicago. Although the extreme early season warmth is enjoyable for outdoor activities, concern is growing for a multi-million dollar disaster for the agricultural community once this pattern does break.

[icebreaker5221]

Nice post Phil. As I had brought up in the medium range discussion thread, it's probably best to look at the MJO composites for FMA rather than JFM right now, as warm patterns associated with phase 5 tend to occur more frequently in late winter, and are more robust in phase 6/7 in early spring. For most of the last 10 days, we were in phase 5, which is not a particularly warm phase according to the FMA composites, so I would be careful not to overemphasize it. I agree with your thinking that latent heat release over the west Pac will build the ridge, and via downstream development, enhance ridging over the U.S. However, the start of the current warm spell seems to have been brought on more quickly than this ought to have occurred. So perhaps the start of the event was more of a chance alignment of strong ridging over the central U.S., and the longevity of the event can be more attributed to favorable tropical forcing.

Either way, the current magnitude of the MJO is near the upper limits to what we have seen, and the composite sample size does not include many extreme events, so one would expect greater downstream implications than what the composite plots suggest. Regardless, the MJO has more recently entered phase 6, and therefore more records should fall over the next 2/3 days or so before the cutoff low ushers in some colder air.

I like your thinking going ahead, in that the models are likely too quick in stalling and weakening the current MJO wave per usual biases. This current wave has been very progressive, and often persistence makes the best MJO forecast, so forecasting a moderate to strong 7/8 over the next week or two is probably not a bad forecast. If we can make it all the way to phases 1-3 in April, then we've most likely seen an end to the extreme warmth for a while.

[Stebo]

The incredible thing about that loop of records, there are times where places are hitting records at midnight for the next day and then staying above the record high temperatures through the night.

[Met1985]

Great post and discussion guys. Ya this heat wave is crazy. I am also worried about a killing freeze coming. I hve tried to tell people wait before planting.

[phil882]

Nice post Phil. As I had brought up in the medium range discussion thread, it's probably best to look at the MJO composites for FMA rather than JFM right now, as warm patterns associated with phase 5 tend to occur more frequently in late winter, and are more robust in phase 6/7 in early spring. For most of the last 10 days, we were in phase 5, which is not a particularly warm phase according to the FMA composites, so I would be careful not to overemphasize it. I agree with your thinking that latent heat release over the west Pac will build the ridge, and via downstream development, enhance ridging over the U.S. However, the start of the current warm spell seems to have been brought on more quickly than this ought to have occurred. So perhaps the start of the event was more of a chance alignment of strong ridging over the central U.S., and the longevity of the event can be more attributed to favorable tropical forcing.

Either way, the current magnitude of the MJO is near the upper limits to what we have seen, and the composite sample size does not include many extreme events, so one would expect greater downstream implications than what the composite plots suggest. Regardless, the MJO has more recently entered phase 6, and therefore more records should fall over the next 2/3 days or so before the cutoff low ushers in some colder air.

I like your thinking going ahead, in that the models are likely too quick in stalling and weakening the current MJO wave per usual biases. This current wave has been very progressive, and often persistence makes the best MJO forecast, so forecasting a moderate to strong 7/8 over the next week or two is probably not a bad forecast. If we can make it all the way to phases 1-3 in April, then we've most likely seen an end to the extreme warmth for a while.

Good point, it would have probably been better to look at the FMA composites although the signal is still there. However, I do think you see a typically MJO teleconnection from phases 4-6 through the fact that the 500 hPa ridging has shifted from the Central US to the Eastern US over the past 5-10 days. Beforehand, we had a widespread ridge stretching from coast to coast, but now the ridge is more amplified and focused in the Eastern United States. The coorelations from the CPC seem to focus on looking at surface temperatures, but I think you would find a more coherent pattern if you looked aloft with 500 hPa heights. Obviously there are going to be rossby waves that keep this pattern from being entirely consistent, but looking through the last two weeks to do see more migration from a more frequent upper level west coast ridge to now a persistent upper level east coast ridge.

3-10-12: Phase 4, mean 500 hPa ridge should be centered over the Western US.

3-14-12: Phase 5, mean 500 hPa ridge Should be over Central US

3-20-12 Phase 6, mean 500 hPa Ridge should be over Eastern US

[wxnut]

Here in southern Manitoba, we've also been spoiled by this incredible spell of warm weather which began here on the weekend of the 10th. At that time, we still had about 10" of snow on the ground, but within 4 days, it was all gone (which is an amazing feat around these parts) Yesterday, March 19th, Winnipeg recorded it's warmest March day ever in 140 years at 23.7C beating the old mark of 23.3C on Mar 27 1946. It was the city's 5th consecutive record high, and 7th in 9 days. From the 16-19th, Winnipeg recorded 4 consecutive days with a temperature over 19C. Prior to this year, that mark was reached on only 4 days in March in the entire 140 years of records! On the 18th, the city registered it's earliest 20C day ever with a high of 21C. Yesterday evening, we recorded our earliest thunderstorm on record, with a cold front tapping unheard of 15C dewpoints in March to give us a summerlike squall line of thunderstorms with vivid lightning and heavy downpours. Just bizzare stuff. Simply put, it's never been this warm, this early, this long in southern Manitoba in 140 years of records.

We cannot forget to mention the important role that the +AO played this year to set up this extraordinary event. It basically negated the effects of La Nina, and gave us an exceptionally mild winter with little snow. It was our 4th mildest winter on record, and for only the 2nd time in the past 140 years, Winnipeg failed to hit -30C during an entire winter season. We just didn't get cold this winter. And March will be our 9th consecutive month above normal going back to last July. We're all waiting for Mother Nature to pay us back big time, but so far we're just enjoying the ride. Increasingly though, people are becoming concerned with abnormal warmth and extended dryness leading to drought conditions.. such as in 1980 or 1988.

[QVectorman]

Great work Phil! Was pondering the series of events that got us to this point myself! Excellent write up!

[donsutherland1]

FWIW, I ran the composite temperature anomalies for all dates on which the MJO was in Phase 5 (amplitude 1.8 or above) after March 10 and also for all dates on which the MJO was in Phase 6 (amplitude 1.8 or above) after March 10. Phase 5 actually provides an excessive heat signal. The memorable March 1990 heat occurred late in Phase 5. I did not include any April dates.

The dates were as follows:

Phase 5:

March 11-14, 1979

March 26-29, 1988

March 11-13, 1990

March 16-20, 2004

Phase 6:

March 30-31, 1988

March 14-15, 1990

March 21-25, 2004

The various charts I came up with were:

[Hoosier]

Traverse City, Michigan had a high of 86 degrees, 45 degrees above the average high.

[cbmclean]

Kudos to all thread posters for this type of discussion. I am a layman when it comes to weather, but over the last 10 years or so iI have been becoming more and more interested in weather and climate. I am a "scientific" personality if you know what I mean, and am always wanting to know why why why an even occurs, to the extent possible. Descriptions of the phenomena are nice, but for me, and I am sure many of you understandin gthe why of a phenomenon can get to be a craving.

Anyway, as a layman, I wonder if you guys have any recollection or knowledge of any similarly incredible anomalies on the OTHER side of the coin: i.e. cold.

I am 30 years old and have lived in North Carolina for my entire life. I certainly have no memory of ever experiencing a cold anomaly period of cold anomales of this magnitude. Nor do I have any memory of hearing of such a thing, either in the US/Canada or throughout the entire world.

I have heard/read of some pretty notable cold periods. As a weather-interested layman, one of my favorite references is EXTREME WEATHER by Christopher C. Burt. The book mentions the exceptional cold wave of Feb 1899, which I believe may be somewhat famous. It also mentions an extreme winter experienced by the Great Plains in 1935 - 36, when the town of Malta, Montana apparently averaged 31.4 degrees below "normal" for the entire month of February (quite impressive). It is further mentioned that most of Montana averaged 20 degrees below normal for that month (the book does not comment on what "most of Montana" consists of). I also know that in the late 1970s the eastern portion of the US had some memorable overall winters, but I cannot comment of any period comparable to this March, but in the other direction.

A general observation as a layman: its seems that most popular focus is on what you could call "with the grain" type anomaly periods: by that I mean cold waves in winter and heat waves in summer. There is also some discussion of mild winters. Anomalously cool summers seem to be very rarely mentioned in popualr dsicourse (by popular I mean outside scholarly or technical literature). Similarly Wam or cool springs/falls don;t seem to be as memorable.

[uncle W]

this unpresidented warmth rivals or beats the two back to back warm March's of 1945 and 1946...The difference this year is the heat comes after a very mild winter...The warm March's of 45 and 46 came after a relatively cold winter...

[michsnowfreak]

this unpresidented warmth rivals or beats the two back to back warm March's of 1945 and 1946...The difference this year is the heat comes after a very mild winter...The warm March's of 45 and 46 came after a relatively cold winter...

Locally....the 3 were all different wrt temperature and snowcover, but similar in total snowfall at Detroit.

NORM....27.9F.....42.7".....50 days (DJF temp...total snowfall...1"+ snwcvr days)

1944-45...23.4F....25.8".....74 days

1945-46...26.4F....22.0".....39 days

2011-12...33.0F....26.0".....20 days

[Quakertown needs snow]

Nice post, thanks.

[stellarfun]

Looked at a longer climate series from across the pond to see how anomalously warm this March has been in much of North America..

Monthly temperature records for Oxford England exist from 1853 on, so a longer, continuous series than anything in North America.

Set 12C (54F) as the high end of normal.

Below are the years from 1853 until now when 12C was exceeded, and the average March temp for that year.

1882 12.6

1893 13.7

1929 12.9

1933 12.9

1938 15.5 / 60F

1945 13.1

1948 14.0 / 57F

1957 13.6

1961 13.6

1990 12.7

1997 13.3

2002 12.4

2003 13.3

2009 12.4

2011 12.4

The Spring of 1938 was described as extraordinarily dry, particularly in the south of England. Fair skies may have been the boost needed to set the record.

Using the Hadley CET series (more years, but temperature range is less) warmest March on record is 1957 @ 9.2C, 1938 was second warmest @ 9.1C Prior to 1853, warmest Marches were 8.2C in 1750, 8.1C in 1734, and 7.9C in both 1779 and 1780.

The extent that March temperature records are shattered at some stations may be unprecedented, observationally, for the month in the Northern Hemisphere, when contrasted with 160 years of records at Oxford, and 353 years of records at Hadley.

[icebreaker5221]

FWIW, I ran the composite temperature anomalies for all dates on which the MJO was in Phase 5 (amplitude 1.8 or above) after March 10 and also for all dates on which the MJO was in Phase 6 (amplitude 1.8 or above) after March 10. Phase 5 actually provides an excessive heat signal. The memorable March 1990 heat occurred late in Phase 5. I did not include any April dates.

The dates were as follows:

Phase 5:

March 11-14, 1979

March 26-29, 1988

March 11-13, 1990

March 16-20, 2004

Phase 6:

March 30-31, 1988

March 14-15, 1990

March 21-25, 2004

The various charts I came up with were:

Thanks for checking the numbers Don! So in that case, I'm willing to suspect that either: -A- a large sample of phase 5 March cases of amplitude < 1.8, or -B- the majority of phase 5 cases in April, are greatly reducing the warmth seen in the CPC composite for FMA.

[bluewave]

The last time that we saw really extreme monthly temperature departures was back in January 2006.

http://climate.umn.edu/doc/journal/record_january0601.htm

[MN Transplant]

Jeff Masters has weighed in: http://www.wundergro...l?entrynum=2057

Highlights

Pellston, Michigan in the Northern Lower Peninsula is called "Michigan's Icebox", since it frequently records the coldest temperatures in the state, and in the entire nation. But the past four days, Pellston has topped out at 80° - 84°F, the first 80°F March days in their history. Yesterday's 84° reading broke the previous record for the date (55° in 1976 and 1948) by an unbelievable 29°, and was 44°F above average.

Water temperatures at the South Lake Michigan buoy were 46 - 47°F yesterday (8°C), which is about 10°F above average for this time of year, and typical of early June temperatures.

So, if we have a 30-year history of high temperatures for a particular date, we'd expect 20 of those years to be 1-sigma years, when the temperature is plus or minus 34% of average (ten colder years, and ten warmer years.) Rare 2-sigma events occur 4.5% of the time, so we should have about 16 of these per year. Even rarer 3-sigma events occur just 0.27% of the time, or just one day per year, on average. Truly extreme 4-sigma events should only occur once every 43 years. Much of Michigan, Wisconsin, Illinois, Minnesota, Northeast Iowa, and the eastern Dakota have experienced multiple 4-sigma days over the past week.

[iceman56]

Nice post. This is definitely a historic event, and I can't recall seeing an F-6 quite this exaggerated in the lower 48. A +44 departure is incredible.

How about the 73 degree change from the 9th (-14) to the 10th (+59) with a foot of snow still on the ground?

Now that's a warm front!

[donsutherland1]

This afternoon, Bangor, Maine surpassed 80°F reaching 82° by 2 pm. That broke Bangor's monthly mark of 79° and was that city's earliest 80° reading by three weeks. The previous record of earliest 80°F temperature was April 11.

[A-L-E-K]

Jeff Masters has weighed in: http://www.wundergro...l?entrynum=2057

Highlights

Wild stuff, some near shore LM waters are now into the mid/upper 50s.

[buckeye]

some of the NWS AFDs across the midwest are becoming entertaining to read.

This is clip from Gaylord, MI's AFD:

ALL THE WHILE...TRAVERSE CITY CONTINUES TO CLIMB

TOWARD 90...AND IF THAT SHOULD HAPPEN...IT WOULD BE THE EARLIEST

RECORDED 90 DEGREE READING BY ALMOST 5 WEEKS...WITH THE CURRENT

RECORD COMING FROM APRIL 29TH...1970. IN OTHER WORDS...IF THE

TEMP HITS 90...IT WILL NOT ONLY SMASH THE ALL-TIME RECORD FOR

MARCH...BUT IT WILL TIE THE ALL-TIME RECORD FOR APRIL AS WELL.

UNBELIEVABLE!