Winter 2014-15 Outlook for Southeast Lower Michigan William R Deedler; Southeast Michigan Weather Historian
This winter's data presents a mixed picture for the upcoming season as natural forces and oscillations vie for domination. This revelation comes from various data sources past and present. Keeping one eye on recent upper air and surface patterns - and the other on this season's analogue and upper air data leads me to a relatively confident conclusion....
Temperatures: Below Normal /-1.0 to -4.0 degrees of the norm/
Temperatures are more variable in this winter's analogues and guidance as opposed to last winter when nearly all headlined a cold winter. That being said, normal to below normal temperatures dominate this winter again in the analogues and is suggested in other meteorological data presented here and why the below normal temperature range of -1 to -4 degrees. The largest below normal departures this winter are projected to be south and southeast of the Great Lakes. In addition; recent past seasons along with very recent unfolding conditions and the subset of preferred analogues also predict another colder than average winter. Analogue timing of the coldest parts of the winter varies but majority suggest temperatures most likely to be below normal mid and late winter. Again, like past seasons, timing issues will most likely present themselves this winter. Recent upper wind patterns (along with the consensus of the analogues snowfalls), do suggest an early start to the winter anyway, in November. The data does imply breaks however, along the way unlike last winter.Snowfall: Normal to Below /+5" to -10" of the norm/
With the expected jet axis and timing this season, I look for closer to normal snowfalls, if not some below normals. Upper air patterns and storm track map below suggests a somewhat busy winter across the eastern half of the country. However, I look for the substantially above normal snowfalls to be south and east of Southeast Lower Michigan. This could change depending on evolution of expected storm tracks and their ensuing placement and updates will be sent.Analogues suggest snowfalls around normal over metro Detroit and areas north up to around 1-69... and normal to below, north of that region in the Saginaw Valley and Thumb Region - away from the lake effect regions of Lake Huron. Lake effect snows should actually be fairly busy this winter. More discussion on the analogues are below and also will be sent as the winter evolves.
SOUTHEAST LOWER MICHIGAN WINTER 2014-15 ANALOGUE DATA
BROAD SCALE DISCUSSION
As we move toward the winter of 2014-15; the near normal or neutral sea surface temperatures /SST/ that dominated the past several seasons are expected to drift into a very weak El Nino. Gone is the idea of a stronger El Nino that the model projections intimated earlier in the spring and summer. This idea of a weak El Nino (or even borderline Neutral) after several seasons of Neutral conditions, limited the number of similar hemispheric analogues for this winter to just ten (Detroit).
It is still assumed however, that the weak El Nino will affect the cold season upper and surface wind flow by aiding and abetting the subtropical flow into the country. In addition, another item of importance is the large area of above normal water temperatures seen out in the mid Pacific north of the standard El Nino. I feel this too will also influence the sub-tropical jet, especially the late Autumn into early winter anyway (see Nov map below). By mid to late winter, the warmer waters all around the central Pacific are understandably projected to wane (Feb map).
The below Pacific water temperatures pattern is now reminiscent of a positive PDO /PDO+/ along with the weak El Nino. Recently, negative PDO conditions have held sway out over this region. Below are the current November water temperatures including the positive PDO with warmer waters surrounding cooler waters in a horse-shoe shape.
Downstream positive PDO /PDO+/ affects on the US are mapped out below. As you we see, this pattern matches well with our analogue set of composite maps this winter of the US temperature and precipitation departures section, further down below.
North Atlantic Oscillation/Arctic Oscillation - NAO/AO
One of the most important aspects this winter will be the phases of the NAO and subset AO. Much has been learned about the NAO/AO and its accompanying phases in the past several decades. From the Climate Prediction Center's NAO discussion page:
The
NAO exhibits considerable interseasonal and interannual variability,
and prolonged periods (several months) of both positive and negative
phases of the pattern are common. The wintertime NAO also exhibits
significant multi-decadal variability (Hurrell 1995, Chelliah and Bell 2005).
For example, the negative phase of the NAO dominated the circulation
from the mid-1950's through the 1978/79 winter. During this
approximately 24-year interval, there were four prominent periods of at
least three years each in which the negative phase was dominant and the
positive phase was notably absent. In fact, during the entire period the
positive phase was observed in the seasonal mean only three times, and
it never appeared in two consecutive years.
An
abrupt transition to recurring positive phases of the NAO then occurred
during the 1979/80 winter, with the atmosphere remaining locked into
this mode through the 1994/95 winter season. During this 15-year
interval, a substantial negative phase of the pattern appeared only
twice, in the winters of 1984/85 and 1985/ 86. However, November 1995 -
February 1996 (NDJF 95/96) was characterized by a return to the strong
negative phase of the NAO. Halpert and Bell (1997; their section 3.3) recently documented the conditions accompanying this transition to the negative phase of the NAO.
Many (myself included) believe this winter will be dominated by a more negative phase of the NAO/AO through observations and some various newly discovered indexs.
Here is the experimental NAO/AO forecasts into early this winter I post every year from Kyle Macritchie a Ph.D. candidate in Atmospheric Science at the University at Albany. As you can see, his experimental projections, based on the CFSv2 analysis are decidedly negative for both indices into the winter as of early November. Again, the PNA pattern projection is decidedly positive.
October Pattern Index /OPI/
The OPI strongly suggests a negative NAO/AO pattern to dominate this winter, any negative value indicates this and a preliminary value of -2.2 was reached. Click on the /OPI/ above for an explanation and how this is calculated.
High Latitude Eurasia October Snow Cover
The snow cover over Siberia/Eurasia is the second highest on record behind 1976-77 (and we all know what that winter was like). It been theorized that the snow cover over that part of the country in October directly relates to the building cold air masses for the upcoming winter. However, still exactly where it will be delivered is more problematic.
Long Term Snow Cover Analysis
Short Term analysis since 2007 (-2008)
Flow Chart for the Snow Cover
What Upper Air Features to Watch For This Winter
As discussed above, this diagram displays the main players to this winters expected pattern.
Creating the Winter 2014-15 Analogues
These selected analogue winters below followed a similar
sequence of events (though timing
may vary a bit) that recently
were observed over the Pacific during the past several seasons. Neutral conditions prevailed
for a considerable time period (generally two to three years) then they were followed by a primarily weak El Nino. Their numbers were smaller than in previous years as this particular type ENSO pattern in sequence is less common.
This year, I also included the ongoing solar cycle chart at the time of the analogues and compared it to the cycle threshold we are presently in.
More studies have been formulated as to the connection of the solar cycle (max/min) and the QBC. The QBC is a tropical stratospheric wind that descends in an easterly then westerly direction over a period of around 28 months. This can have a direct influence on the strength of the polar vortex in itself. The easterly (negative ) phase is though to contribute to a weakening of the stratospheric polar vortex, while a westerly (positive) phase is thought to increase the strength of the stratospheric vortex. However, in reality the exact timing and positioning of the QBO is not precise and the timing of the descending wave is critical throughout the winter. At this time, the QBO is easterly and is this expected continue throughout the winter.
A strong polar vortex is more likely to herald a positive /AO+/ with the resultant jet stream track bringing milder conditions to the Great Lakes as the vortex contracts north and the Pacfic onshore flow dominates in its absence (figure on the left). Whereas, a weaker polar vortex (under a less cold stratosphere) can contribute to a negative /AO-/ with the resultant jet stream track of colder air from the north pole and a more blocked pattern, more typical. Therefore, a warmer stratosphere and subsequent negative /AO-/, leads to a colder winter and higher chances of blocking. This is the pattern much of the early data suggests.
The main influence on the QBO from solar cycles has been studied
While this is typical it is not always the cause and effect for a cold winter; case in point - last winter's very cold winter. One of the main culprits was the negative Eastern Pacific Oscillation in which, in a negative phase, encourages strong ridging high up into the northern latitudes over Alaska and extreme western Canada and thus, sends a "waterfall" of Arctic air cascading south through Canada and into the US. While this happened frequently last winter, back in my Winter Outlook of 2002-03, I explained this while analyzing past winters...
"The Eastern Pacific Oscillation (EPO) is the upper wind flow over the Eastern Pacific influenced by the ocean. When in a positive phase, the EPO generally is reflected by dominant stronger zonal flow and/or troughing along the West Coast of the U.S. This combination, in turn, tends to funnel milder Pacific air well inland into the country and thus, limits arctic outbreaks by holding them at bay up in Canada. When the EPO is dominated by a negative phase (as with the NAO), more ridging develops along the West Coast as higher pressure extends from the Gulf of Alaska south along the West Coast of Canada (opposite of the positive phase). This, in turn, encourages a northwesterly flow from Canada into the middle and eastern sections of the US and thus, the delivery of polar or arctic air."
Cooler Northeast Pacific waters are more favorable or encourage troughing and thus a positive /EPO+/, while warmer waters over the same region area more favorable for ridging and a negative /EPO-/.
Winter of 2013-14
The main influence on the QBO from solar cycles has been studied
This year, I also included the ongoing solar cycle chart at the time of the analogues and compared it to the cycle threshold we are presently in.
More studies have been formulated as to the connection of the solar cycle (max/min) and the QBC. The QBC is a tropical stratospheric wind that descends in an easterly then westerly direction over a period of around 28 months. This can have a direct influence on the strength of the polar vortex in itself. The easterly (negative ) phase is though to contribute to a weakening of the stratospheric polar vortex, while a westerly (positive) phase is thought to increase the strength of the stratospheric vortex. However, in reality the exact timing and positioning of the QBO is not precise and the timing of the descending wave is critical throughout the winter. At this time, the QBO is easterly and is this expected continue throughout the winter.
A strong polar vortex is more likely to herald a positive /AO+/ with the resultant jet stream track bringing milder conditions to the Great Lakes as the vortex contracts north and the Pacfic onshore flow dominates in its absence (figure on the left). Whereas, a weaker polar vortex (under a less cold stratosphere) can contribute to a negative /AO-/ with the resultant jet stream track of colder air from the north pole and a more blocked pattern, more typical. Therefore, a warmer stratosphere and subsequent negative /AO-/, leads to a colder winter and higher chances of blocking. This is the pattern much of the early data suggests.
The main influence on the QBO from solar cycles has been studied
with 65 years of data studied. The results
for the entire data set fully confirm the early findings and suggest a significant
effect of the sunspot cycle /SSC/ on the strength of the stratospheric polar vortex and on the mean
meridional circulation.
EPO- or NAO-?
While this is typical it is not always the cause and effect for a cold winter; case in point - last winter's very cold winter. One of the main culprits was the negative Eastern Pacific Oscillation in which, in a negative phase, encourages strong ridging high up into the northern latitudes over Alaska and extreme western Canada and thus, sends a "waterfall" of Arctic air cascading south through Canada and into the US. While this happened frequently last winter, back in my Winter Outlook of 2002-03, I explained this while analyzing past winters...
"The Eastern Pacific Oscillation (EPO) is the upper wind flow over the Eastern Pacific influenced by the ocean. When in a positive phase, the EPO generally is reflected by dominant stronger zonal flow and/or troughing along the West Coast of the U.S. This combination, in turn, tends to funnel milder Pacific air well inland into the country and thus, limits arctic outbreaks by holding them at bay up in Canada. When the EPO is dominated by a negative phase (as with the NAO), more ridging develops along the West Coast as higher pressure extends from the Gulf of Alaska south along the West Coast of Canada (opposite of the positive phase). This, in turn, encourages a northwesterly flow from Canada into the middle and eastern sections of the US and thus, the delivery of polar or arctic air."
Cooler Northeast Pacific waters are more favorable or encourage troughing and thus a positive /EPO+/, while warmer waters over the same region area more favorable for ridging and a negative /EPO-/.
Winter of 2013-14
The main influence on the QBO from solar cycles has been studied
with 65 years of data studied. The results
for the entire data set fully confirm the early findings and suggest a significant
effect of the sunspot cycle /SSC/ on the strength of the stratospheric polar vortex and on the mean
meridional circulation. Again below are this winter's analogues...
SOUTHEAST LOWER MICHIGAN WINTER 2014-15 ANALOGUE DATA
(CLICK-ON TO ENLARGE)
Note how all the solar sunspot cycle numbers during our analogue winters were in the lower half of the solar cycle. The current solar cycle amplitude this year also duplicates this well with the sunspot numbers mainly below 100 Rt
(see chart below).
TEMP COMPOSITE MAPS FOR ANALOGUES
PRECIPITATION COMPOSITE MAPS FOR ANALOGUES
COMPOSITE JET STREAM /500 MB/ MAP OF ANALOGUE YEARS
Referring back to our main players map and upper air anomaly for continuity below, shows the polar vortex occasionally exudes it influence well to the S-SE
Next Up; Winter Get's An Early Start!
Making weather fun while we all learn, Bill Deedler -SEMI_WeatherHistorian
Winter 2013-14 Epilogue
Overall, last years analogues and Outlook held up considerably
well...even to the point of having and projecting some of the most
brutally cold and snowy winters combined ever experienced in modern
times across Southeast Lower Michigan. That being said, while past and
present trends back then held the foreboding of a "rough", "hard" or
simply "bad" winter as early as November; nothing as extreme as
experienced last winter could have been forecast unless one would be so
bold (and foolish in every instances except ONE) to use the headline
sentence "Worst Winter Ever to Hit Southeast Lower Michigan Since Records have Been Kept Expected This Winter 2013-14".
It's just not done when looking out several MONTHS ahead without being
called an alarmist, wish-casting or a plain winter weather nut. One
would have had to predict the coldest winter when combined with a record
amount of snow since 1880 to succeed totally.
First from LAST winter's season outlook;
In addition; winter analogues and resulting
final statistical data strongly suggest a colder than normal winter. I look for the final winter statistical departure to range between -1.0 to -4.0 across Southeast Lower Michigan when compared
to the 30 year 1981-2010 normals (also included on
analogue charts).
As mentioned later last winter/spring, 1880-81 and 1981-82 were very good analogues for the Winter of 2013-14. Not only did they contain the highest amounts of snow previously recorded in Detroit but they were in the top ten coldest...a feat hard to come by considering a century plus of records. The Winter of 1880-81 final winter statistics were almost a duplicate of this past winter's /2013-14/ snowfall in Detroit and close to the average temperature.
First from LAST winter's season outlook;
Temperatures:
In one of the strongest below normal signals I've seen in the 17 years of Outlooks; you'd think it'd be a slam dunk but not always. Granted most of the time when a temperature trend was even close to this strong, it turned out to be in the right direction.I can't go against a cold signal this strong and dominant nor from what I'm seeing this fall, therefore below normal it is.
In addition; winter analogues and resulting
final statistical data strongly suggest a colder than normal winter. I look for the final winter statistical departure to range between -1.0 to -4.0 across Southeast Lower Michigan when compared
to the 30 year 1981-2010 normals (also included on
analogue charts).
While the
analysis of my winter analogues show mainly below normal
(very similar to our recent summer analogues), it is felt the coldest
of analogues are too cold and
thus, skewing the average down
some. However, at the same time, some of the cold outbreaks seen this winter will rival some of the outbreaks seen in recent compared milder winters, leading to a normal to above normal amount of below zero days.
In hind-cast;
The analogues, some real time upper wind data, recent autumn trends along with long-term experience pointed to a notably cold winter. My Winter Outlook called for this strongly along with the cold being dominant trend through the winter - but not of the magnitude of what did occur. Forecasting up to -4.0 for the winter departure many months out, I deducted was a good "live-with" projection at the time... but still risky both ways! I will say, I did make the mistake in thinking the the coldest of analogues were "too cold"- not this time. No way was last winter's cold analogues too cold but still, I would have NOT forecast the worst winter ever in regards to a combination of temperatures and snowfall!
Snowfall:
As would be somewhat expected in a Neutral ENSO winter, snowfall amount ranges were more extreme in the analogue years with some of the snowiest to snow-less seasons included this season. Overall, however snowfall means in the analogue years tended to hug the lower end of the normal ranges. Southeast Michigan was clearly in the sweet spot for heavy snows in first analogue of 1880-81 (snowiest winter on record) and ironically about 100 years later for #3 snowiest in 1981-82.
On average, snowfall should average near to above normal (or near normal to 12"above of the normal) across the south half of the region and normal to 12” below across the northern sections.
In hind-cast;
As mentioned later last winter/spring, 1880-81 and 1981-82 were very good analogues for the Winter of 2013-14. Not only did they contain the highest amounts of snow previously recorded in Detroit but they were in the top ten coldest...a feat hard to come by considering a century plus of records. The Winter of 1880-81 final winter statistics were almost a duplicate of this past winter's /2013-14/ snowfall in Detroit and close to the average temperature.
In 1880-81 the average temperature at Detroit came in at 21.8 degrees and 93.6" of snow fell, while in 1981-82 the average temperature again came close at 21.9 and 74.0" of snow fell. However, clearly 2013-14 was a worst winter as much of the area around and south of I-69 to the Ohio border received record amounts of snow AND the entire region averaged the 7th coldest winter on record! As a side note, also remember there was a heat island affect at times at Detroit Metro Arpt which makes Detroit's average temperature that much more impressive! Here again are the impressive stats:
Winter 2013-14 Temperature Statistics
| Location | Winter 2013-14 | Coldest Winter Since |
2013-14 Ranking | All-time Coldest |
| Detroit | 20.9 | 1977-78 |
8th | 18.8 (1903-04) |
| Flint | 19.0 | 1978-79 | 5th | 16.7 (1976-77) |
| Saginaw | 18.2 | 1978-79 |
T-7th | 15.7 (1962-63) |
2013-14 Seasonal Snowfall Stats
| Seasonal Normal | Winter 2013-14 (through May 5th) |
Record (Year) | Seasonal Ranking | |
| Detroit Area | 42.5" | 94.9" |
93.6" (1880-81) | 1st |
| Flint Area | 47.4" | 83.9" |
82.9" (1974-75) | 1st |
| Saginaw | 45.5" | 59.4" |
87.2" (1966-67) | 15th |
To see a more complete listing of last winter's stats and winter review, go here.
Second,
we have the October Pattern Index, or OPI. The above image shows
anomalies of the October Pattern Index over the last several days, since
the start of October. The OPI, the concept of which was brought about
by a group of Italian scientists, says that monitoring of the atmosphere
during the month of October can yield great hints at what the coming
winter will bring. October is a month well-known for big
winter-predictors showing their cards for the coming cold season (i.e.
the LRC, and Judah Cohen's Snow Advance Index (SAI)), but it may
interest many to know what the OPI may be one the best, if not the best
predictor of the upcoming winter season out of the three mentioned
above.
The explanation page of the OPI tells of the index's incredible accuracy, around 90%, of being able to predict the December-January-February Arctic Oscillation. In the winter, a negative phase of the Arctic Oscillation (AO) means the polar vortex is weak and is more prone to sending cold outbreaks to the mid-latitudes, while a positive AO indicates a strong polar vortex, hence a warmer winter increases in probability.
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The explanation page of the OPI tells of the index's incredible accuracy, around 90%, of being able to predict the December-January-February Arctic Oscillation. In the winter, a negative phase of the Arctic Oscillation (AO) means the polar vortex is weak and is more prone to sending cold outbreaks to the mid-latitudes, while a positive AO indicates a strong polar vortex, hence a warmer winter increases in probability.
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion. - See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
OPI has been in sustained negative territory throughout the month, not
once touching positive marks. This tells us with overwhelming certainty
(or at least as much certainty as we can have at this point) that the
coming winter's Arctic Oscillation will be negative, and this is backed
up by the aforementioned SAI discussion. - See more at:
http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
explanation page of the OPI tells of the index's incredible accuracy,
around 90%, of being able to predict the December-January-February
Arctic Oscillation. In the winter, a negative phase of the Arctic
Oscillation (AO) means the polar vortex is weak and is more prone to
sending cold outbreaks to the mid-latitudes, while a positive AO
indicates a strong polar vortex, hence a warmer winter increases in
probability.
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion.
Lastly, let's go over the Lezak Recurring Cycle.
Something I've discussed on here more than a few times is the concept of
the Lezak Recurring Cycle, or LRC. The LRC was developed by
meteorologist Gary Lezak, and discusses the idea that weather patterns
which develop in October leave a 'footprint' of sorts that is repeated
in a regular interval, between 40-60 days through the winter and
following spring. In other words, the weather patterns that develop in
October repeat themselves for the better chunk of the next year.
Since mid-September, we've seen predominantly below-normal temperatures for large swaths of the Central and East US. One of the more impressive atmospheric set-ups came with this very strong upper level low positioned just north of the US/Canada border. Notice how the influence of this low extends all the way to the Gulf Coast, per the contour lines. My worry is that this upper level low will end up being another piece of the polar vortex, like we saw last winter, that might push south and bring intense cold back once or twice through the coming winter. I'm not going to speculate any further, but some sharp Arctic blasts may be in the works for the next few months.
As we dip into a warm period right now, this will likely reflect in the LRC with some warm periods in the coming winter, but I'll go into that further down the road when we know how long this warmth might last.
- See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion.
Lastly, let's go over the Lezak Recurring Cycle.
 |
| HPC/WPC |
Since mid-September, we've seen predominantly below-normal temperatures for large swaths of the Central and East US. One of the more impressive atmospheric set-ups came with this very strong upper level low positioned just north of the US/Canada border. Notice how the influence of this low extends all the way to the Gulf Coast, per the contour lines. My worry is that this upper level low will end up being another piece of the polar vortex, like we saw last winter, that might push south and bring intense cold back once or twice through the coming winter. I'm not going to speculate any further, but some sharp Arctic blasts may be in the works for the next few months.
As we dip into a warm period right now, this will likely reflect in the LRC with some warm periods in the coming winter, but I'll go into that further down the road when we know how long this warmth might last.
- See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
explanation page of the OPI tells of the index's incredible accuracy,
around 90%, of being able to predict the December-January-February
Arctic Oscillation. In the winter, a negative phase of the Arctic
Oscillation (AO) means the polar vortex is weak and is more prone to
sending cold outbreaks to the mid-latitudes, while a positive AO
indicates a strong polar vortex, hence a warmer winter increases in
probability.
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion.
Lastly, let's go over the Lezak Recurring Cycle.
Something I've discussed on here more than a few times is the concept of
the Lezak Recurring Cycle, or LRC. The LRC was developed by
meteorologist Gary Lezak, and discusses the idea that weather patterns
which develop in October leave a 'footprint' of sorts that is repeated
in a regular interval, between 40-60 days through the winter and
following spring. In other words, the weather patterns that develop in
October repeat themselves for the better chunk of the next year.
Since mid-September, we've seen predominantly below-normal temperatures for large swaths of the Central and East US. One of the more impressive atmospheric set-ups came with this very strong upper level low positioned just north of the US/Canada border. Notice how the influence of this low extends all the way to the Gulf Coast, per the contour lines. My worry is that this upper level low will end up being another piece of the polar vortex, like we saw last winter, that might push south and bring intense cold back once or twice through the coming winter. I'm not going to speculate any further, but some sharp Arctic blasts may be in the works for the next few months.
As we dip into a warm period right now, this will likely reflect in the LRC with some warm periods in the coming winter, but I'll go into that further down the road when we know how long this warmth might last.
- See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The OPI has been in sustained negative territory throughout the month, not once touching positive marks. This tells us with overwhelming certainty (or at least as much certainty as we can have at this point) that the coming winter's Arctic Oscillation will be negative, and this is backed up by the aforementioned SAI discussion.
Lastly, let's go over the Lezak Recurring Cycle.
|
| HPC/WPC |
Since mid-September, we've seen predominantly below-normal temperatures for large swaths of the Central and East US. One of the more impressive atmospheric set-ups came with this very strong upper level low positioned just north of the US/Canada border. Notice how the influence of this low extends all the way to the Gulf Coast, per the contour lines. My worry is that this upper level low will end up being another piece of the polar vortex, like we saw last winter, that might push south and bring intense cold back once or twice through the coming winter. I'm not going to speculate any further, but some sharp Arctic blasts may be in the works for the next few months.
As we dip into a warm period right now, this will likely reflect in the LRC with some warm periods in the coming winter, but I'll go into that further down the road when we know how long this warmth might last.
- See more at: http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
OPI has been in sustained negative territory throughout the month, not
once touching positive marks. This tells us with overwhelming certainty
(or at least as much certainty as we can have at this point) that the
coming winter's Arctic Oscillation will be negative, and this is backed
up by the aforementioned SAI discussion. - See more at:
http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
OPI has been in sustained negative territory throughout the month, not
once touching positive marks. This tells us with overwhelming certainty
(or at least as much certainty as we can have at this point) that the
coming winter's Arctic Oscillation will be negative, and this is backed
up by the aforementioned SAI discussion. - See more at:
http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
OPI has been in sustained negative territory throughout the month, not
once touching positive marks. This tells us with overwhelming certainty
(or at least as much certainty as we can have at this point) that the
coming winter's Arctic Oscillation will be negative, and this is backed
up by the aforementioned SAI discussion. - See more at:
http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
OPI has been in sustained negative territory throughout the month, not
once touching positive marks. This tells us with overwhelming certainty
(or at least as much certainty as we can have at this point) that the
coming winter's Arctic Oscillation will be negative, and this is backed
up by the aforementioned SAI discussion. - See more at:
http://theweathercentre.blogspot.com/#sthash.ZcF77jjp.dpuf
The
image above shows correlations with the Pacific Decadal Oscillation
(PDO) and surface temperatures during a December-January-February
period. What this chart is saying, is whenever the PDO is positive,
temperatures in the West US will be warm (due to the positive
correlation), and temperatures in the East US will be cold (due to the
negative correlation). Similarly, when the PDO is negative, temperatures
in the West US (East US) will be cold (warm), due to the positive
(negative) correlation. So long as the PDO
remains positive this winter, the risk of a cold winter would still be
maintained for most of the Central and all of the East US. It
remains to be seen if the cold waters will keep pushing east and erase
the positive PDO completely, but as of right now, this would be a
beneficial development for both cold weather fans in the East US, and
warm weather fans in the West US.
Interestingly enough, positive PDO winters tend to bring wetter than normal winters to the Northern Plains... - See more at: http://theweathercentre.blogspot.com/#sthash.7JVoR6Xe.dpuf
Interestingly enough, positive PDO winters tend to bring wetter than normal winters to the Northern Plains... - See more at: http://theweathercentre.blogspot.com/#sthash.7JVoR6Xe.dpuf
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