Winter 2013-14 medium range discussion

[donsutherland1]

Don, I was talking to Ryan Maue on Twitter from WxBell, He literally said some of the model runs as of late had a -7 sigma EPO value, which is just quite crazy.

Some of the earlier runs were quite impressive. It will be interesting to see how this plays out in terms of the actual weather, especially if the current AO- regime can be sustained.

[donsutherland1]

Morning Thoughts...

 

1. The signal that appeared on yesterday's operational GFS for a more sustained AO- regime that would persist through January into at least the start of February has been maintained overnight.

 

Below is a chart that compares the 1/16 and 1/17 6z runs of the GFS (yesterday's 6z run provided the first strong signal for a more sustained AO-) using the 11-day objective analogs:

 

 

 

2. The strong shot of cold for the 1/21-23 period is a high confidence event.

 

3. The cold shot will produce a large area of readings 1.5 to 2.0 standard deviations below normal and a smaller area up to 2.5 standard deviations below normal from southern Canada across the Great Lakes Region, Ohio Valley and eastward.

 

4. The idea that the Great Lakes Region eastward to the northern Mid-Atlantic and southern New England regions will likely see above normal snowfall during the 1/25-2/15 period still looks good given the pattern evolution. Models may vary on a run-to-run basis in terms of identifying specific opportunities, but the pattern has potential.

[uncle W]

Morning Thoughts...

 

1. The signal that appeared on yesterday's operational GFS for a more sustained AO- regime that would persist through January into at least the start of February has been maintained overnight.

 

Below is a chart that compares the 1/16 and 1/17 6z runs of the GFS (yesterday's 6z run provided the first strong signal for a more sustained AO-) using the 11-day objective analogs:

 

 

 

2. The strong shot of cold for the 1/21-23 period is a high confidence event.

 

3. The cold shot will produce a large area of readings 1.5 to 2.0 standard deviations below normal and a smaller area up to 2.5 standard deviations below normal from southern Canada across the Great Lakes Region, Ohio Valley and eastward.

 

4. The idea that the Great Lakes Region eastward to the northern Mid-Atlantic and southern New England regions will likely see above normal snowfall during the 1/25-2/15 period still looks good given the pattern evolution. Models may vary on a run-to-run basis in terms of identifying specific opportunities, but the pattern has potential.

the negative ao is a good sign for the northeast...I've showed when the AO is at its lowest point of the season NYC usually has a cold wave, snowstorm or both around the date of the AO's winter minimum...last year it came in March and NYC had a snowstorm on that date...If the AO gets lower later on in the winter and bottoms out in February it will be a long cold/snowy winter into March...

[donsutherland1]

the negative ao is a good sign for the northeast...I've showed when the AO is at its lowest point of the season NYC usually has a cold wave, snowstorm or both around the date of the AO's winter minimum...last year it came in March and NYC had a snowstorm on that date...If the AO gets lower later on in the winter and bottoms out in February it will be a long cold/snowy winter into March...

The AO has a good correlation with snowfall, so the growing guidance in favor of a more sustained AO- regime is quite encouraging. It will be interesting to see if things work out as they did last year during the blocking. I'm optimistic about the 1/25-2/15 period. Whether there is some relaxation and then another bout of cold/opportunities for snowfall afterward remains to be seen.

[Snowman99]

Love your write-ups Don. What's your crystal ball telling you for the Midwest region snow wise? Looks cold for sure, but would like to see some southern storms try to get into the act around here.

[donsutherland1]

Love your write-ups Don. What's your crystal ball telling you for the Midwest region snow wise? Looks cold for sure, but would like to see some southern storms try to get into the act around here.

 

 

Thanks for the kind words, Snowman99.

 

The cold certainly looks highly likely for St. Louis for next week through at least the end of January.

 

In addition, St. Louis appears to have a much above climatological probability of reaching 30" in seasonal snowfall. For the 122 seasons in which St. Louis has seasonal figures, 16 (13%) received 30" or more seasonal snowfall.

 

The current winter saw St. Louis pick up 5.6" snow in December. For seasons for which monthly and seasonal snowfall are available, there were 23 cases that saw St. Louis receive 5"-10" snowfall in December. 4/6 (67%) cases that picked up 8" or more snowfall in January wound up receiving 30" or more seasonal snowfall. In contrast, 15/17 (88%) of those cases that received less than 8" snowfall in January received less than 30" seasonal snowfall. St. Louis has already received 15.2" snow this month and has 20.8" for the season.

[Ottawa Blizzard]

My benchmark for this cold wave is another "zero day" in Toronto. We managed it on the 7th, which is quite the feat for Toronto. I think it is possible to do it again so long as we don't get a rip-off midnight daytime high.

[Snowman99]

Thanks Don..keep up the great work!

[N. OF PIKE]

Don as far as the AO blocking goes (pardon my ignorance) is this a text book block (positioning) for slowing down flow in n atlantic or more of a Quasi block in a less favorable position

[donsutherland1]

Don as far as the AO blocking goes (pardon my ignorance) is this a text book block (positioning) for slowing down flow in n atlantic or more of a Quasi block in a less favorable position

Right now, it does not appear to be a textbook block on the guidance, but it is better than nothing. Hopefully the models will continue to evolve into an even better blocking pattern over the next few days. 

[donsutherland1]

Some morning thoughts...

 

1. The 1/21-23 cold shot is now a high confidence event. The possibility exists and New York City could have another single-digit low temperature and numerous cities across the Great Lakes into New England could have some subzero lows.

 

2. The pattern still has potential. However, northern branch disturbances are not always well-modeled very far in advance. The potential has been hinted at in occasional runs showing moderate snowfalls.

 

3. The 0z GFS aggressively broke the cold after about 240 hours. The 6z GFS has not. More than likely the pattern will ease after the January 26-28 Arctic shot. However, it does not right now look like a very warm period should unfold shortly thereafter.

 

4. Recently, the SOI reached +50. This is yet another hint that the cooling that has occurred in ENSO Region 3.4 will likely be sustained for some time. In short, February is not likely to see anything close to borderline El Niño conditions and cool ENSO anomalies are probably more likely than warm ones for most or all of the month.

[donsutherland1]

Cold Pattern Now Evolving...

 

1. Today saw an area of precipitation bring snow across parts of southeast and central New York State into New England. In areas, qpf was double what had been modeled. For example, both the 1/18 0z and 6z runs of the GFS forecast 0.12" precipitation for White Plains, NY. The actual amount was 0.27". The important point is that the guidance can have some difficulties with northern branch disturbances. This is something to keep in mind when dealing with prolonged periods showing almost no meaningful qpf.

 

2. It is a high confidence idea that the 1/21-23 period will see a strong Arctic shot delivered to the Midwest and East. It won't be quite as cold as the January 6-7 Arctic shot, but could be cold enough to bring a single-digit low to New York City and some subzero lows in the larger area running from the Midwest to New England.

 

3. There is a growing probability of another strong Arctic shot around the 1/25-28 timeframe. That Arctic shot might be preceded by a period of snow in parts of the East, as a clipper ushers in the air mass. Were the clipper to have similar dynamics to today's event, the system could produce a widespread swath of 2"-4" of snow with locally higher amounts. Details concerning the clipper won't be pinned down until the middle or even latter part of next week.

 

4. The European Model hints at another shot of cold to follow closely on the heels of the 1/25-28 cold shot. It may be comparable to the 1/21-23 cold shot. There is some potential it could be a little stronger, but its magnitude is not fully certain. It is also too soon to tell, especially as that idea is not supported by its ensembles. The 12z GFS had a different idea.

 

Overall, the idea of above normal snowfall from the Great Lakes to northern Mid-Atlantic/southern New England for the January 25-February 15 timeframe still seems reasonable. If one examines the objective analogs from the 1/15 6z GFS and 1/15 0z GFS ensembles, one finds dates close to snowy periods: 1/20/1961, 2/4/2003, 2/12/2006, and 1/22/2009, among others. While the pattern provides no guarantees, it is similar to patterns that have produced in the past.

 

Finally, the guidance points to the development of a PNA- toward the close of January. However, some recent forecasts toward that end didn't verify. The pattern evolution might be slower than what the guidance currently shows, especially if historic experience is representative. Since 1950, there were 6 PNA+ ridges that developed in the 1/1-1/20 timeframe and peaked at +1.3 or higher. The median duration was 25 days and the mean duration was 22.7 days. The shortest was 18 days (2009) and the longest was 39 days (1961). The current PNA+ ridge developed January 13, so odds probably favor the PNA's remaining positive through the rest of January. That outcome would be consistent with the ECMWF, which is slower to bring moderation than the GFS.

[donsutherland1]

Morning Thoughts...

 

1. Through mid-February, snowfall events likely will be of the smaller to moderate variety, with locally significant amounts. Given the guidance's having retreated on an AO- for the extended range, a KU-type snowstorm appears unlikely. This does not mean that there can't be above normal snowfall. It does limit prospects for excessive snowfall.

 

2. The AO is the most important teleconnection when it comes to KU snowstorms in February. Since 1950, 78% of such snowstorms commenced when the AO was negative. 50% of February KU snowstorms commenced with an AO-/PNA+ combination.

 

 

3. In terms of the MJO, 67% of the February KU snowstorms that occurred since the MJO was recorded, commenced when the MJO is in Phases 7, 8, or 1. None occurred when the MJO was in Phases 4 or 5.

 

4. At present, there still appears no prospect of a sudden stratospheric warming (SSW) event.

 

5. A blend of the ECMWF, ECMWF ensembles, GFS, and GFS ensembles suggest that moderation will likely occur to start February. Depending on the evolution of the EPO, the moderation might yield to renewed cold., But that's too far out for much confidence. For now, the 1/21-23 and 1/26-28 cold shots will assure January closes on a cold note for its final 10 days.

[N. OF PIKE]

Don your updates have been great, it seems some keep trying too hard and bite on any meaningful blocking potential , maybe they are trying to pole holes (at some level) in OPI , but i think that meaningful blocking is most likely off the table until mid-late feb (not that its likely then) if it does return in any textbook fashion by late march.

Id be very interested to see in years where the OPI was 1.50 or > how much classic blocking took place, during DJF and also how March faired in those years wrt the same

[donsutherland1]

Don your updates have been great, it seems some keep trying too hard and bite on any meaningful blocking potential , maybe they are trying to pole holes (at some level) in OPI , but i think that meaningful blocking is most likely off the table until mid-late feb (not that its likely then) if it does return in any textbook fashion by late march.

Id be very interested to see in years where the OPI was 1.50 or > how much classic blocking took place, during DJF and also how March faired in those years wrt the same

FWIW, the AO is -2.36 right now. One of these clippers could blow up into something more meaningful. The 1/21-22 seems to favor eastern New England, particularly the Cape. The 1/25-26 might have a wider impact, but we'll have to see how it develops.

 

I am also interested in the data concerning the OPI, but I haven't seen the draft paper and don't have a table of the values.

[GaWx]

 The 1/19 12Z GFS has come in much colder for the 11 to 15 day period vs. the prior three runs. The prior three runs had suggested a torch during the same period. With this sudden change to colder, one has to wonder if the warmth on these three 11 to 15 day runs is going to bust as badly as the 1/9/14 runs' day 11 to 15's. Here's something that clearly illustrates the 1/9 run 11-15 day busts: 

 

First, compliments of Earthsat, here is the very toasty 1/9/14 12Z GFS 11-15 day 850 mb anomaly in degrees C:

 

 Now, from Earthsat again, here is the very cold 1/19/14 12Z GFS 1-5 day 850 mb anomaly, which covers the exact same period:

 

 The 1/9 run warm busts were a result of the western ridging breaking down when in fact it will be very strong for the period! The greatest busts were in the Midwest and NE US. Examples: Chicago and NYC are now 19/17 C degrees (34/31 F) colder, respectively, than they were on that 1/9 run! The 0Z 1/9/14 run was very similarly warm.

 

 Any comments? Is the GFS not taking into account that very warm water in the NE Pacific?

[donsutherland1]

Snowfall followed by Severe Cold On The Way...

 

In the near-term, perhaps aided somewhat by the currently negative Arctic Oscillation, a system now looks increasingly likely to produce a moderate snowfall across parts of the Mid-Atlantic and southern New England regions. Parts of Long Island and southeastern New England look to receive the highest accumulations. In those areas, the potential does exist for 6" or more of powdery snow.

 

The upcoming cold shot looks formidable. The GFS ensembles now bring cold anomalies to 2.0-2.5 sigma at its height. This likely means that NYC will see its third day this winter with a maximum temperature in the teens and at least 5th or 6th days with lows in the single digits. The MEX MOS already shows lows of 10° during the peak of the cold.

 

The GFS, which had been prematurely breaking the cold, has now moved into better agreement with the ECMWF and the ECMWF ensembles. This development leads me to believe that my thinking that the Great Lakes Region eastward to the northern Mid-Atlantic and southern New England regions will likely see above normal snowfall during the 1/25-2/15 period has not derailed. Models may vary on a run-to-run basis in terms of identifying specific opportunities, but the pattern has potential. The recent trends with respect to tomorrow's system offers some evidence of that. That system precedes the snowy period I have outlined and is a sort of bonus. Overall, given December snowfall outcomes, NYC and Philadelphia appear on course for 30" or more seasonal snowfall and Boston appears on track for 50" or more seasonal snowfall. In the Midwest, St. Louis appears on track for 30" or more seasonal snowfall.

[Srain]

Don, while those of us along the NW Gulf will escape the brunt of this Arctic intrusion we are certainly no out of the woods for a classic NW Gulf Coast Winter Weather Event. The 00Z Euro and GFS are in better agreement that a strong short wave dropping S from British Columbia will tap into a piece of the cold Arctic air and allow a 1040mb Arctic high to settle across Texas and extend ENE. The Arctic boundary appears to stall along Coastal Texas/Louisiana as a Coastal trough forms allowing over running conditions to develop Thursday afternoon after the cold air at the surface is in place. Past experience suggests this is a solution that tends to favor a freezing rain/sleet event that may extend as far S as Metro Houston, Beaumont and Lake Charles. The MOS guidance has trended colder with each run and it is not out of the question that Winter Weather Advisories or even Winter Storm Watches may be needed along portions of the I-10 Corridor for Thursday and possibly extending in Saturday if the guidance does indeed verify.

[donsutherland1]

Don, while those of us along the NW Gulf will escape the brunt of this Arctic intrusion we are certainly no out of the woods for a classic NW Gulf Coast Winter Weather Event. The 00Z Euro and GFS are in better agreement that a strong short wave dropping S from British Columbia will tap into a piece of the cold Arctic air and allow a 1040mb Arctic high to settle across Texas and extend ENE. The Arctic boundary appears to stall along Coastal Texas/Louisiana as a Coastal trough forms allowing over running conditions to develop Thursday afternoon after the cold air at the surface is in place. Past experience suggests this is a solution that tends to favor a freezing rain/sleet event that may extend as far S as Metro Houston, Beaumont and Lake Charles. The MOS guidance has trended colder with each run and it is not out of the question that Winter Weather Advisories or even Winter Storm Watches may be needed along portions of the I-10 Corridor for Thursday and possibly extending in Saturday if the guidance does indeed verify.

Very good discussion, Steve. I agree that prospects for frozen precipitation are increasing. Even Florida should have some rare, for this winter, cold anomalies.

[donsutherland1]

With respect to the cold anomalies of 2.0 to 2.5 standard deviations below normal for the Middle Atlantic region, below is a chart showing highs and lows that are 1-3 sigma below normal for the 1/22-25 timeframe:

 

[donsutherland1]

ENSO Region 3.4 Cools Some More...

 

For the week centered around 1/15, ENSO Region 3.4 saw its anomaly decline to -0.7°C. A week earlier, it had been -0.5°C. In contrast, warming continued in Region 1+2, with the anomaly reaching +0.6°C.

[snowfallower]

ENSO Region 3.4 Cools Some More...

 

For the week centered around 1/15, ENSO Region 3.4 saw its anomaly decline to -0.7°C. A week earlier, it had been -0.5°C. In contrast, warming continued in Region 1+2, with the anomaly reaching +0.6°C.

Thanks Don for all of your incredible and insightful posts. I've always enjoyed reading what you have to say and of course more so when you tell me the pattern is favorable for winter weather.What does region 3.4 cools some more mean for the rest of winter? I hope it's not bad news! Thanks in advance.

[donsutherland1]

Thanks Don for all of your incredible and insightful posts. I've always enjoyed reading what you have to say and of course more so when you tell me the pattern is favorable for winter weather.What does region 3.4 cools some more mean for the rest of winter? I hope it's not bad news! Thanks in advance.

Thanks for the kind words.

 

This cooling may suggest that February might wind up cooler than normal across a large area of the CONUS. Winters that preceded the development of an El Niño that had a January-March ENSO Region 3.4 anomaly of > 0°C typically featured a lot of warmth in February (1957 and 2002). Those that had an anomaly of < 0° often featured a lot of cool anomalies in February (1965 and 1968). 1997 was an exception to the rule, but 1997 preceded the development of a super El Niño. The statistical models do not indicate the development of a strong El Niño at this time. Hence, I'm cautiously optimistic that the recent cooling of ENSO Region 3.4 is another argument pointing to a generally cold February and it would fit the idea should the EPO generally remain negative.

[Ji]

Thanks for the kind words.

 

This cooling may suggest that February might wind up cooler than normal across a large area of the CONUS. Winters that preceded the development of an El Niño that had a January-March ENSO Region 3.4 anomaly of > 0°C typically featured a lot of warmth in February (1957 and 2002). Those that had an anomaly of < 0° often featured a lot of cool anomalies in February (1965 and 1968). 1997 was an exception to the rule, but 1997 preceded the development of a super El Niño. The statistical models do not indicate the development of a strong El Niño at this time. Hence, I'm cautiously optimistic that the recent cooling of ENSO Region 3.4 is another argument pointing to a generally cold February and it would fit the idea should the EPO generally remain negative.

don...check this out

 

http://www.americanwx.com/bb/index.php/topic/42406-late-january-early-february-pattern-discussion/?p=2668934

[Cold Rain]

 

don...check this out

 

http://www.americanwx.com/bb/index.php/topic/42406-late-january-early-february-pattern-discussion/?p=2668934

 

The 1/22 run is even colder for areas in the south and east than the 1/21 runs that you posted, although they're not quite as wet. It's hard to put a lot of stock in the CFS, but the trend is definitely for a colder Feb, as we get closer. To me, that's the most important take-away from this model.

[donsutherland1]

Morning Thoughts on Snowfall:

 

The recent storm that is now departing New England brought 3.8" snow to Washington, DC (a city in which some residents seemingly wondered whether it could ever snow there), 13.5" to Philadelphia, and 11.5" to New York City. Seasonal snowfall has now reached 33.1" at Boston, 26.5" in New York City, and 33.7" in Philadelphia. In addition, Boston, New York City, and Philadelphia have all received 15" or more snow this month.

 

In message #448, I posted revised table of climatological occurrences following December snowfall of 8" or more snow in Boston, New York City, and Philadelphia in which at least a trace of snow fell during the first half of January. The table confirmed the idea (#359) that the northern Mid-Atlantic region and southern New England area appeared in line for above normal seasonal snowfall. That table is below:

 

 

As I have noted in a number of earlier messages, I believe the pattern will likely be conducive to above normal snowfall from the Great Lakes region eastward to the northern Mid-Atlantic and southern New England areas for the January 25-February 15 timeframe. Given the January snowfall data, odds favor above normal February snowfall. Washington, DC should also receive some snowfall and if things work out there were two very snowy cases.

 

 

Finally, given where things currently stand, I continue to believe Boston is on track for 50" or more seasonal snowfall, New York City is on track for 30" or more snowfall. Philadelphia has already reached 30" snowfall. Both New York City and Philadelphia have a reasonable shot at 40" or more seasonal snowfall.

 

Farther south, Baltimore has received 12.4" snowfall to date and Dulles International Airport has picked up 16.5". Seasonal norms for those areas are 20.1" and 22.0" respectively. Both locations will probably wind up with above normal snowfall by the time winter is finished.

 

Washington, DC (DCA) is a more difficult call with respect to reaching its normal figure of 15.4" given its current figure of 7.2". Interestingly enough the three cases in which the December-February ENSO Region 3.4 anomaly averaged between -1.0°C and 0.0°C (1934-35, 1960-61, and 1995-96), as appears very likely for winter 2013-14, saw Washington, DC pick up 4.0", 18.0", and 20.4" for the February-March period. The sample size is very small, however, so a lot of caution is required. Therefore, I would use the "dreaded term" of "equal chances" with respect to its prospects of reaching or exceeding its seasonal norm by the end of the winter.

[donsutherland1]

Afternoon thoughts...

 

1. Today saw more widespread single-digit low temperatures in parts of the East. Washington, DC saw its second such reading this winter. For that city, that is the most since winter 1995-96 when there were also two such low temperatures.

 

 

In the Great Lakes region, Detroit had a morning low temperature of -6°. That was Detroit's 6th such reading, the most since winter 2008-09 when there were also 6 subzero readings.

 

2. The GFS ensembles are indicating that the a large part of the Great Lakes region, Ohio Valley, and eastward into the Mid-Atlantic and New England States could see cold anomalies of 1.5 standard deviations below normal, with some areas in excess of 2 sigma below normal. The 12z ECMWF is consistent with that idea with potentially even colder readings.

 

It should be noted that as the current Arctic outbreak drew closer, the ensemble mean anomalies grew colder by 0.5 to 1.0 standard deviations. The recurrence of that outcome would fit what the ECMWF is currently showing.

[donsutherland1]

January 22, 2014 saw numerous cities set or tie record low maximum temperatures. Some examples follow.

 

[donsutherland1]

February 1-7, 2014 Thoughts...

 

The cold that developed following the thaw that dominated the second week of January appears likely to persist through much of the first week of February in a large part of the eastern U.S. and Canada. The notable exception will likely be western Canada and the western United States.

 

The GFS Ensemble 11-day objective analogs rolled forward to 2/4 and teleconnection cases that have had the best fit to January both hint at the development of a February 1994-type gradient pattern. Whether such a pattern emerges during the latter part of the first week of February or shortly thereafter remains to be seen. Nevertheless, I suspect that the first week of February will have the potential for storminess to coincide with general cold.

 

Below are the teleconnection, teleconnection cases with the best fit for January, and 11-day objective analogs rolled forward two days:

 

 

At this time, given the persistence of the EPO- and recent cold east-warm west pattern, I favor a compromise between the kind of pattern depicted on the GFS ensembles and best-fit teleconnection cases and the ECMWF ensembles. That outcome would lead to the following idea:

 

Western Canada and western third of the U.S.: Warmer to perhaps much warmer than normal, but cold could begin to seep westerward late in the period.

 

Eastern half of the U.S., except for Florida: Colder than normal. The Great Lakes Region and Ohio Valley could be much colder than normal.

 

Eastern two-thirds of Canada: Colder than normal.

[donsutherland1]

Arctic Blast of 1/26-29/2014:

 

The GFS ensembles, with strong support from the ECMWF ensembles, are indicating that a very cold air mass will plunge into CONUS, with the coldest anomalies impacting the Midwestern and portion of the Southern states. The peak standardized anomalies could be 2-3 standard deviations below normal.

 

 

This would translate into near record or possibly even record cold for a number of cities. Below are some high and low temperatures associated with the standardized anomalies for select cities, along with the coldest readings so far this winter and daily record low minimum and maximum readings for 1/28-29: