Winter 2013-14 medium range discussion

[Srain]

For verification purposes regarding the Central/Western Region Winter Storm as mentioned in post 110, here are the official totals to date:

THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD

STORM SUMMARY MESSAGE

STORM SUMMARY NUMBER 10 FOR SOUTHWEST U.S. TO SOUTHERN PLAINS

WINTER STORM

NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

900 AM CST MON NOV 25 2013

...LIGHT SNOW CONTINUES TO FALL ACROSS THE CENTRAL AND SOUTHERN

ROCKIES...WITH LIGHT TO MODERATE FREEZING RAIN FALLING ACROSS EAST

TEXAS AND THE LOWER MISSISSIPPI VALLEY...

ISOLATED WINTER STORM WARNINGS ARE IN EFFECT FOR A SMALL AREA

AROUND THE TEXAS/OKLAHOMA/ARKANSAS BORDER.

WINTER WEATHER ADVISORIES ARE IN EFFECT FOR PARTS OF THE SOUTHERN

PLAINS AND INTO THE NORTHERN PORTION OF THE LOWER MISSISSIPPI

RIVER VALLEY.

FOR A DETAILED GRAPHICAL DEPICTION OF THE LATEST

WATCHES...WARNINGS AND ADVISORIES...PLEASE SEE WWW.WEATHER.GOV

AT 800 AM CST...AN UPPER LEVEL LOW WAS MOVING SLOWLY EASTWARD OVER

THE TEXAS PANHANDLE AND WAS TRIGGERING PRECIPITATION NORTH AND

EAST OF IT IN THE SOUTHERN PLAINS AND THE LOWER MISSISSIPPI

VALLEY. NATIONAL WEATHER SERVICE DOPPLER RADARS AND SURFACE

OBSERVATIONS INDICATED ONLY SPOTTY AREAS OF LIGHT SNOW IN THE

CENTRAL AND SOUTHERN ROCKIES. FARTHER EAST...SOME AREAS WERE

RECEIVING FREEZING RAIN IN NORTH TEXAS AND PORTIONS OF ARKANSAS.

LIGHT TO MODERATE RAIN WAS FALLING ACROSS SOUTHEAST

TEXAS...NORTHERN LOUISIANA...AND WAS BEGINNING TO FILTER INTO

MISSISSIPPI.

...SELECTED STORM TOTAL SNOWFALL IN INCHES FROM 200 AM CST THU NOV

21 THROUGH 800 AM CST MON NOV 25...

...COLORADO...

VALLECITO 9 NE 39.0

COAL BANK PASS 37.0

LA PLATA 3 NE 36.0

RIO GRANDE RSVR 14 SSW 35.0

CRESTONE 1 SSE 28.6

ELK PARK 9 ENE 27.0

WOLF CREEK PASS 1 SSE 24.0

COLUMBINE PASS 23.0

CRESTONE 9 ESE 23.0

GRAND MESA 22.0

CUCHARA 7 WSW 20.0

PLATORO 2 NNW 19.0

ST ELMO 8 NNW 17.4

WESTCLIFFE 9 S 16.0

SOUTH FORK 14.0

RYE 1 SSW 12.0

WALSENBURG 5 WSW 10.0

COLORADO CITY 1 WNW 8.0

...NEW MEXICO...

RED RIVER 8 SSW 17.0

PECOS 3 N 12.0

TERERRO 6 WNW 12.0

ARROYO SECO 8 NE 10.0

OCATE 1 NW 10.0

TESUQUE 1 SSW 9.5

EDGEWOOD 3 W 9.0

SAN MIGUEL 8 SSW 9.0

TIJERAS 9 SE 9.0

MOUNTAINAIR 1.0 S 8.5

CHUPADERO 7 ESE 8.0

CUBA 9 E 8.0

LOS ALAMOS 6 W 7.0

WAGON MOUND 7.0

...SELECTED STORM TOTAL FREEZING RAIN ICE AMOUNTS IN INCHES FROM

200 AM CST THU NOV 21 THROUGH 800 AM CST MON NOV 25...

...ARKANSAS...

ASHDOWN 0.10

DE QUEEN 0.10

TEXARKANA 10 SE 0.10

...TEXAS...

ODESSA 2.00

ANDREW 1.00

KERMIT 1.00

RANKIN 1.00

CRANE 0.50

DRYDEN 28 NE 0.50

MARFA 0.50

SNYDER 1 N 0.50

CROSBYTON 0.25

ELDORADO 0.25

GRAPE CREEK 0.25

DENISON 0.10

PARIS 3 SE 0.05

...SELECTED STORM TOTAL SLEET IN INCHES FROM 200 AM CST THU NOV 21

THROUGH 800 AM CST MON NOV 25...

...OKLAHOMA...

ASHLAND 0.50

...TEXAS...

JAYTON 1.00

BOWIE 0.10

BRYSON 0.10

GRAHAM 0.01

...SELECTED PEAK WIND GUSTS IN MILES PER HOUR EARLIER IN THE

EVENT...

...CALIFORNIA...

LAGUNA PEAK 76

CAMP NINE 57

WARM SPRINGS 57

FREMONT CANYON 53

TUSTIN FOOTHILLS 6 ENE 53

...KANSAS...

GOODLAND 4 S 53

BURLINGTON 4 S 52

SHARON SPRINGS 9 SSE 51

...NEW MEXICO...

RATON CREWS ARPT 60

SANTA TERESA 5 SW 54

DRIPPING SPRINGS 52

SAN AUGUSTIN PASS 52

ALBUQUERQUE 5 S 51

...TEXAS...

EL PASO 8 NNW 64

...SELECTED STORM TOTAL SNOWFALL IN INCHES WHERE THE EVENT HAS

ENDED...

...ARIZONA...

FOREST LAKES 12.0

GRAND CANYON RIM 11.5

FLAGSTAFF ARPT 11.4

ALPINE 2 E 8.0

KACHINA VILLAGE 2.8

...CALIFORNIA...

ASPENDELL 24.0

OWENS VALLEY 5 W 12.0

OWENS VALLEY RAWS 5 S 12.0

WRIGHTWOOD 12.0

IDYLLWILD-PINE 1 NW 9.0

...KANSAS...

RICHFIELD 11 ENE 7.0

HUGOTON 6.5

SUBLETTE 6.5

MOSCOW 10 W 6.0

ULYSSES 5.0

MEADE 3.0

DODGE CITY 2.0

...NEVADA...

MT. CHARLESTON 2 SW 19.0

COYOTE WASH RAWS 9 E 5.0

...OKLAHOMA...

VINSON 13.0

GRANITE 10.0

MANGUM 8.0

ROOSEVELT 8.0

ALTUS 4.0

ELK CITY 2.0

HOLLIS 2.0

LAWTON 3 E 2.0

QUANAN 2.0

ROCKY 2.0

...TEXAS...

HEDLEY 10.0

WELLINGTON 1 S 10.0

MULESHOE 1 N 8.3

DIMMIT 8.0

FRIONA 8.0

CLARENDON 7.0

MEMPHIS 7.0

TULIA 7.0

FARWELL 6.0

HEREFORD 6.0

HOWARDWICK 6.0

AMARILLO 5 N 4.0

...UTAH...

ABAJAO SNOTEL 1 SE 41.0

LA SOL SNOTEL 20.0

BLANDING 14 W 18.0

SAN JUAN CO ARPT 6 W 11.0

PARADOX 7 WSW 10.0

MONTICELLO 10 N 7.0

MOAB 3 S 5.5

...SELECTED STORM TOTAL RAINFALL IN INCHES WHERE THE EVENT HAS

ENDED...

...ARIZONA...

MT LEMMON ALERT 5.20

SAMANIEGO PEAK 4.40

DAN SADDLE 4.10

PLEASANT VALLEY 3.70

PROMONTORY 3.70

GISELA 3.50

CATALINA STATE PARK 3.40

ORO VALLEY 5 SSW 3.20

CLIFTON ALERT WEATHER STATION 3.10

PAYSON 3.10

...CALIFORNIA...

MID HILLS RAWS 2.34

...NEVADA...

MOUNTAIN SPRINGS RAWS 2.76

YUCCA GAP 1.91

BARSTOW-DAGGETT 1.76

LAS VEGAS 1.37

SOME ADDITIONAL ACCUMULATION OF LESS THAN A QUARTER INCH OF ICE IS

POSSIBLE FOR NORTHEAST TEXAS AND ARKANSAS ON MONDAY...HOWEVER THE

FREEZING RAIN WILL END BY TONIGHT. AS THE UPPER LOW CONTINUES TO

MOVE EAST...RAIN WILL SPREAD ACROSS THE LOWER MISSISSIPPI VALLEY

AND EVENTUALLY MOVE INTO THE SOUTHEAST BY MONDAY EVENING. RAINFALL

TOTALS UP TO 3 INCHES COULD BE POSSIBLE ACROSS THE LOWER

MISSISSIPPI VALLEY AND INTO THE SOUTHEAST FROM MONDAY NIGHT AND

INTO TUESDAY. THE RAIN IS FORECAST TO ADVANCE FURTHER ACROSS THE

SOUTHEASTERN STATES AND ENTERING INTO THE MID-ATLANTIC REGION ON

TUESDAY WITH AS MUCH AS 2 INCHES OR MORE POSSIBLE.

THE NEXT STORM SUMMARY WILL BE ISSUED BY THE WEATHER PREDICTION

CENTER AT 300 PM CST. PLEASE REFER TO YOUR LOCAL NATIONAL WEATHER

SERVICE OFFICE FOR ADDITIONAL INFORMATION ON THIS EVENT.

FANNING

Last Updated: 931 AM EST MON NOV 25 2013

[donsutherland1]

Verification:

 

From Message #103 (11/21):

 

For some time, the November 22-30 period has looked colder than normal in the eastern U.S. (#40) and the ensemble guidance has suggested an unusually strong shot of cold at some point during the timeframe (#87). As the event has drawn nearer, the cold shot appears even more impressive than earlier modeled. The cold air that will blast into the region later Saturday appears likely to produce near record low maximum readings on Sunday (11/24) and near record low temperatures on Monday morning (11/25). A few areas could see new records…

 

In terms of outcomes, it appears possible that Boston and New York City could experience a high temperature at or below 32° on Sunday. Philadelphia also has a shot at approaching its record low maximum temperature on Sunday. All of the above cities will likely see low temperatures in the low 20s on Monday. Many outlying areas will see low temperatures in the teens. The possibility of a temperature below 20°, particularly in Boston or Philadelphia exists. Philadelphia has perhaps the best shot at approaching or reaching its daily record low temperature for Monday.

 

November 24 High Temperatures:

Boston: 31°

New York City: 30° (tied daily low figure from 1880; lowest November high since 11/30/1976)

Philadelphia: 32° (broke daily low record of 34° from 1956)

Washington, DC: 34°

 

November 25 Low Temperatures:

Boston: 18°

New York City: 23°

Philadelphia: 20° (broke the daily record low of 21° from 1965)

Washington, DC: 24°

[Jonger]

Verification:

 

From Message #103 (11/21):

 

For some time, the November 22-30 period has looked colder than normal in the eastern U.S. (#40) and the ensemble guidance has suggested an unusually strong shot of cold at some point during the timeframe (#87). As the event has drawn nearer, the cold shot appears even more impressive than earlier modeled. The cold air that will blast into the region later Saturday appears likely to produce near record low maximum readings on Sunday (11/24) and near record low temperatures on Monday morning (11/25). A few areas could see new records…

 

In terms of outcomes, it appears possible that Boston and New York City could experience a high temperature at or below 32° on Sunday. Philadelphia also has a shot at approaching its record low maximum temperature on Sunday. All of the above cities will likely see low temperatures in the low 20s on Monday. Many outlying areas will see low temperatures in the teens. The possibility of a temperature below 20°, particularly in Boston or Philadelphia exists. Philadelphia has perhaps the best shot at approaching or reaching its daily record low temperature for Monday.

 

November 24 High Temperatures:

Boston: 31°

New York City: 30° (tied daily low figure from 1880; lowest November high since 11/30/1976)

Philadelphia: 32° (broke daily low record of 34° from 1956)

Washington, DC: 34°

 

November 25 Low Temperatures:

Boston: 18°

New York City: 23°

Philadelphia: 20° (broke the daily record low of 21° from 1965)

Washington, DC: 24°

 

That's amazing.

[donsutherland1]

That's amazing.

It was definitely a notable cold shot.

[tacoman25]

It was definitely a notable cold shot.

 

Coldest November high at NYC in almost 40 years? Yeah, I'd say so!

[The_Global_Warmer]

In Message #131, I posted my idea for December, which was that the eastern half of the U.S. with the exception of the Southeast and Gulf States is likely to be colder than normal for December. The Southeast and Gulf region will probably wind up with near normal readings. The western third of the U.S., including the Pacific Northwest could be warmer than normal. Most of Canada except for western/northwestern Canada will likely be colder than normal. The excepted areas could be warmer than normal. Alaska should wind up warmer than normal.

 

This morning's forecast shows a large split among the ensemble members as it relates to the evolution of the Arctic Oscillation (AO) in early December.

period.

 

 

 

I ran partial teleconnection cases, but in addition to taking an unusually wide spread for the AO members, I also ran two scenarios, one in which the AO reverts to predominantly positive values and the other in which the AO periodically returns to negative values in a back-and-forth fashion or sees the development of persistent blocking. The closest match to the first scenario was 2008. The closest matches to the second scenario were 1995, 1996, and 2010.

 

The composite maps for November and December for North America and Europe are posted below.

 

 

 

 

 

IMO, given the SAI and new OPI, something closer to the first scenario is still more likely than the second one. Hence, the idea that the Southeast and Gulf Coast likely wouldn't wind up cold, though I compromised with near normal temperatures in my December forecast, is probably not implausible. There is probably greater risk that those areas would wind up somewhat milder than normal rather than colder than normal.

 

Again, it's important to emphasize that the partial teleconnection cases do not incorporate ENSO. They are used primarily for trend analyses.

 

I don't have the ensembles or I would post them instead.

 

The GFS and Euro seem have to have strong agreement at the end of the medium range.

 

Are we going to see the trough that seems to have tucked itself under the big ridge in the GOA swing East?  Earlier model runs were pushing the cold quickly into the mid-west.  They seem to be trending towards a large trough hanging out over the PNW/California. 

 

Going further out into the GFS.  Which is highly unreliable the cold hits the brick wall and ends up scooting through the lakes.  While Western Canada reloads. 

 

 

 

 

 

[donsutherland1]

My Winter 2013-14 Idea:

 

In the wake of one of the strongest November cold shots in years, it might be tempting for one to embrace winters along the lines of 1976-77, 2000-01, and 2002-03. With the Arctic Oscillation (AO) having gone negative after one of the strongest November positive regimes, one might be anticipating the development of a blocky winter. With the East Pacific Oscillation (EPO) having brought a series of cold shots to the U.S. and southern Canada, in spite of the strongly positive AO, one might be tempted to believe that the AO won’t matter this winter.

 

However, strong November cold shots do not necessarily assure a cold winter in the affected areas. In fact, if the first week of December turns warm, that’s often an indication that a milder winter lies ahead. When it comes to the AO, both the Snow Advance Index (SAI) and the new October Pattern Index (OPI) are in agreement that the AO will very likely be predominantly positive for the December-February timeframe. At the same time, the EPO is likely to remain predominantly negative to neutral.

 

What happens during EPO-/AO+ winters might provide insight into winter 2013-14. While there is variation, the placement of the coldest anomalies (adjusted to take into consideration a share of the warming that has occurred since 1970—roughly 0.6°C per decade in the CONUS for the December-February period) suggest that December has the best chance to have the most widespread cold anomalies. Afterward, the coldest anomalies tend to lift northward, as the AO+ plays a stronger role. Below are the charts for the placement of the coldest anomalies from the analog cases alongside the latest monthly ensemble forecasts from the CFSv2. The charts are strictly aimed at showing the migration of the coldest anomalies, not the placement of warm anomalies or magnitude of the temperature anomalies. They bear some similarity to the latest CFSv2 forecasts. In short, those forecasts appear to be reasonable relative to EPO-/AO+ cases.

 

 

With the winter Pacific Decadal Oscillation (PDO) likely to average negative, albeit not as negative as last winter, along with neutral ENSO conditions, a predominantly neutral to negative Pacific North America (PNA) pattern is likely to predominate. Such a pattern favors the development of southeast ridging in the absence of a negative Arctic Oscillation.

 

Overall, that would likely translate into much of Canada winding up colder than normal and a large portion of the CONUS winding up milder than normal for the December-February period

 

 

Taking into consideration the likely state of ENSO and the teleconnections, as well as some of the modeled seasonal forecasts, I expect December-February to turn out as follows:

 

Alaska: Cold East/Warm West

 

Canada: Generally colder than normal except for southern Canada. Toronto and Montreal will likely wind up near normal to somewhat warmer than normal. Ottawa and Quebec City will likely be somewhat cooler than normal to near normal.

 

CONUS:Generally somewhat warmer than normal across the nation. The Southeast/Gulf Coast will likely have the warmest anomalies relative to normal. The Northern Plains could wind up somewhat cooler than normal.

[Jonger]

My Winter 2013-14 Idea:

 

In the wake of one of the strongest November cold shots in years, it might be tempting for one to embrace winters along the lines of 1976-77, 2000-01, and 2002-03. With the Arctic Oscillation (AO) having gone negative after one of the strongest November positive regimes, one might be anticipating the development of a blocky winter. With the East Pacific Oscillation (EPO) having brought a series of cold shots to the U.S. and southern Canada, in spite of the strongly positive AO, one might be tempted to believe that the AO won’t matter this winter.

 

However, strong November cold shots do not necessarily assure a cold winter in the affected areas. In fact, if the first week of December turns warm, that’s often an indication that a milder winter lies ahead. When it comes to the AO, both the Snow Advance Index (SAI) and the new October Pattern Index (OPI) are in agreement that the AO will very likely be predominantly positive for the December-February timeframe. At the same time, the EPO is likely to remain predominantly negative to neutral.

 

What happens during EPO-/AO+ winters might provide insight into winter 2013-14. While there is variation, the placement of the coldest anomalies (adjusted to take into consideration a share of the warming that has occurred since 1970—roughly 0.6°C per decade in the CONUS for the December-February period) suggest that December has the best chance to have the most widespread cold anomalies. Afterward, the coldest anomalies tend to lift northward, as the AO+ plays a stronger role. Below are the charts for the placement of the coldest anomalies from the analog cases alongside the latest monthly ensemble forecasts from the CFSv2. The charts are strictly aimed at showing the migration of the coldest anomalies, not the placement of warm anomalies or magnitude of the temperature anomalies. They bear some similarity to the latest CFSv2 forecasts. In short, those forecasts appear to be reasonable relative to EPO-/AO+ cases.

 

 

With the winter Pacific Decadal Oscillation (PDO) likely to average negative, albeit not as negative as last winter, along with neutral ENSO conditions, a predominantly neutral to negative Pacific North America (PNA) pattern is likely to predominate. Such a pattern favors the development of southeast ridging in the absence of a negative Arctic Oscillation.

 

Overall, that would likely translate into much of Canada winding up colder than normal and a large portion of the CONUS winding up milder than normal for the December-February period

 

 

Taking into consideration the likely state of ENSO and the teleconnections, as well as some of the modeled seasonal forecasts, I expect December-February to turn out as follows:

 

Alaska: Cold East/Warm West

 

Canada: Generally colder than normal except for southern Canada. Toronto and Montreal will likely wind up near normal to somewhat warmer than normal. Ottawa and Quebec City will likely be somewhat cooler than normal to near normal.

 

CONUS:Generally somewhat warmer than normal across the nation. The Southeast/Gulf Coast will likely have the warmest anomalies relative to normal. The Northern Plains could wind up somewhat cooler than normal.

I hope this verifies, I'm sure most of the east coasters don't.

[wisconsinwx]

I hope this verifies, I'm sure most of the east coasters don't.

 

It more or less describes the current look of the pattern at first glance for the first week of December.  Looks like too strong of a SE Ridge in fact for much of the Great Lakes, but perhaps this current cold shot can help temper the ridge just a tad.

[The_Global_Warmer]

My Winter 2013-14 Idea:

 

In the wake of one of the strongest November cold shots in years, it might be tempting for one to embrace winters along the lines of 1976-77, 2000-01, and 2002-03. With the Arctic Oscillation (AO) having gone negative after one of the strongest November positive regimes, one might be anticipating the development of a blocky winter. With the East Pacific Oscillation (EPO) having brought a series of cold shots to the U.S. and southern Canada, in spite of the strongly positive AO, one might be tempted to believe that the AO won’t matter this winter.

 

However, strong November cold shots do not necessarily assure a cold winter in the affected areas. In fact, if the first week of December turns warm, that’s often an indication that a milder winter lies ahead. When it comes to the AO, both the Snow Advance Index (SAI) and the new October Pattern Index (OPI) are in agreement that the AO will very likely be predominantly positive for the December-February timeframe. At the same time, the EPO is likely to remain predominantly negative to neutral.

 

What happens during EPO-/AO+ winters might provide insight into winter 2013-14. While there is variation, the placement of the coldest anomalies (adjusted to take into consideration a share of the warming that has occurred since 1970—roughly 0.6°C per decade in the CONUS for the December-February period) suggest that December has the best chance to have the most widespread cold anomalies. Afterward, the coldest anomalies tend to lift northward, as the AO+ plays a stronger role. Below are the charts for the placement of the coldest anomalies from the analog cases alongside the latest monthly ensemble forecasts from the CFSv2. The charts are strictly aimed at showing the migration of the coldest anomalies, not the placement of warm anomalies or magnitude of the temperature anomalies. They bear some similarity to the latest CFSv2 forecasts. In short, those forecasts appear to be reasonable relative to EPO-/AO+ cases.

 

 

Don, it seems almost every morning now for 3-4 days when I check the forecasted AO index.  It continues to show up more and more positive.  The models are now bleeding the cold back into a Western trough.  The PNA has started to show a slow march into negative territory as well. 

 

I thought an HP like that oozing into the arctic was surefire to dump the hammer on us.  Looks to me like a typical lakes cutters regime.

 

Now the GFS Ensmble members are in a majority agreement that the AO will be staying positive at least into the first third of December. 

 

 

 

 

 

[Amped]

GFS is pretty damn cold for the PACNW. Looks like Seattle and Portland have several shots at snow.

[SnowGoose69]

Funny how just a day or two back the SE ridge depicted on the GFS was much more massive in the Day 6-12 range than it is now, it seems thus far this is the complete opposite of the last 2 winters early on everthing that can possibly go right is while everything in the medium-long range last year and in 11-12 went wrong...remember that 2 weeks ago the GFS was showing a SE ridge at Days 14-16, the Euro was even showing it at Day 10 for awhile back in early November.

[donsutherland1]

Don, it seems almost every morning now for 3-4 days when I check the forecasted AO index.  It continues to show up more and more positive.  The models are now bleeding the cold back into a Western trough.  The PNA has started to show a slow march into negative territory as well. 

 

I thought an HP like that oozing into the arctic was surefire to dump the hammer on us.  Looks to me like a typical lakes cutters regime.

 

Now the GFS Ensmble members are in a majority agreement that the AO will be staying positive at least into the first third of December...

 

 

 

 

 

 

 

 

 

The kind of pattern that is typically associated with the forecast teleconnections has the cold focused from the Northen Plains westward. Often one sees the pattern evolve into a deep trough in the West and ridge in the East. With a deeply negative EPO, parts of the West could become quite cold.

[Jonger]

GFS is pretty damn cold for the PACNW. Looks like Seattle and Portland have several shots at snow.

 

That is a good indicator that the pacific has no influence on our pattern right now, its hard to keep cold pooled over the PNW for very long.

[donsutherland1]

GFS is pretty damn cold for the PACNW. Looks like Seattle and Portland have several shots at snow.

Yesterday, I noted that the applicable partial teleconnection case for a return to an AO+, considering the other teleconnections, was 2008. Today's ensemble data produced the same case. Once the trough pops in the West, it could get very cold there.

 

In 2008, one saw the trough develop on 12/13. The next two weeks were generally colder to much colder than normal in Seattle. 6 days had highs of 32° or less. The lowest high temperature was 26° on 12/20 (3rd coldest high for the date). The lowest temperature was 14° on 12/20, which tied the daily record that had been set in 1990.

 

Total snowfall during that two-week period came to 10.9". The biggest snowfall was 6.6", which fell on 12/20-22. From that storm, 3.0" fell on 12/20 (breaking the daily record of 1.7" from 1951) and 3.0" on 12/21 (breaking the daily record of 2.6" from 1967).

[ORH_wxman]

Yesterday, I noted that the applicable partial teleconnection case for a return to an AO+, considering the other teleconnections, was 2008. Today's ensemble data produced the same case. Once the trough pops in the West, it could get very cold there.

 

In 2008, one saw the trough develop on 12/13. The next two weeks were generally colder to much colder than normal in Seattle. 6 days had highs of 32° or less. The lowest high temperature was 26° on 12/20 (3rd coldest high for the date). The lowest temperature was 14° on 12/20, which tied the daily record that had been set in 1990.

 

Total snowfall during that two-week period came to 10.9". The biggest snowfall was 6.6", which fell on 12/20-22. From that storm, 3.0" fell on 12/20 (breaking the daily record of 1.7" from 1951) and 3.0" on 12/21 (breaking the daily record of 2.6" from 1967).

 

 

Spokane, WA saw 10 consecutive days with a high of 20F or lower from Dec 14 to Dec 23, 2008 including a high of 5F on Dec 20, 2008 which broke the old record of 6F in 1990. The low of -18F on Dec 20, 2008 also broke the previous record low of -6F in 1983. Spokane also had 61.5" of snow that December which broke the old record December snowfall of 42.0" in 1964 and the all time monthly snowfall record of 56.9" set previously in January 1950. As a reference, Spokane's average snowfall for the whole winter is about 41.5".

[donsutherland1]

The models are now bleeding the cold back into a Western trough.  The PNA has started to show a slow march into negative territory as well... 

 

 

 

 

 

 

 

 

 

 

The map you posted at the bottom of your message is consistent with what one would expect from a strongly negative PNA. Below are both the 500 mb height anomalies and surface temperature anomalies from all December dates when the PNA was -1 or below during the 1981-2010 climate reference period:

 

 

[donsutherland1]

Spokane, WA saw 10 consecutive days with a high of 20F or lower from Dec 14 to Dec 23, 2008 including a high of 5F on Dec 20, 2008 which broke the old record of 6F in 1990. The low of -18F on Dec 20, 2008 also broke the previous record low of -6F in 1983. Spokane also had 61.5" of snow that December which broke the old record December snowfall of 42.0" in 1964 and the all time monthly snowfall record of 56.9" set previously in January 1950. As a reference, Spokane's average snowfall for the whole winter is about 41.5".

December 2008 saw an epic stretch of winter weather in the Pacific Northwest. I don't think this winter will feature anything quite as extreme but perhaps the early December will wind up unseasonably cold some accumulating snowfall even in Seattle and possibly Portland.

[usedtobe]

The map you posted at the bottom of your message is consistent with what one would expect from a strongly negative PNA. Below are both the 500 mb height anomalies and surface temperature anomalies from all December dates when the PNA was -1 or below during the 1981-2010 climate reference period:

 

 

For the PHL south crowd it's not a good snow look.  I did a stupid guy composite of today's D+11 centered mean temp anomalies and posted them on the mid atlantic forum.  For he Dec5-9 period, it suggests temps will average warmer than normal for the southeast northward into the the dc area.  Sort of like the latest CPC outlook except the nortern extend of the warmer than normal extended at tad north of their forecast. 

[donsutherland1]

For the PHL south crowd it's not a good snow look.  I did a stupid guy composite of today's D+11 centered mean temp anomalies and posted them on the mid atlantic forum.  For he Dec5-9 period, it suggests temps will average warmer than normal for the southeast northward into the the dc area.  Sort of like the latest CPC outlook except the nortern extend of the warmer than normal extended at tad north of their forecast. 

 

I agree with your thinking, Wes. If a strong PNA- develops, I wouldn't be surprised if the southeast ridging isn't a little more robust than what is currently modeled. If so, the warm anomalies could be more expansive. 

[Wow]

Is it really possible to get 3 poor winter seasons in a row?  Thanks for the confidence!

[usedtobe]

I agree with your thinking, Wes. If a strong PNA- develops, I wouldn't be surprised if the southeast ridging isn't a little more robust than what is currently modeled. If so, the warm anomalies could be more expansive. 

Hopefully, any warmer than normal pattern for the mid atl will not last though if the big positive that keeps poking over AK (our neg EPO) shifts to just north of Kamchatka, I think that teleconnects to warmer than normal over the mid atlantic. I think that might be a problem going forward but that's way to far out to really care about.  I have enough trouble looking 10 to 14 day ahead. 

[donsutherland1]

Hopefully, any warmer than normal pattern for the mid atl will not last though if the big positive that keeps poking over AK (our neg EPO) shifts to just north of Kamchatka, I think that teleconnects to warmer than normal over the mid atlantic. I think that might be a problem going forward but that's way to far out to really care about.  I have enough trouble looking 10 to 14 day ahead. 

I agree. It's too soon to know with much confidence whether the ridge will migrate northward. For now, the NAEFS have an impressive PNA- look.

 

[GaWx]

Is it really possible to get 3 poor winter seasons in a row?  Thanks for the confidence!

 

 Three solidly warm winters in a row hasn't happened in Atlanta at least since records started in 1879. So, hopefully the SE US will at least have a more average winter in terms of temperatures (what I'm leaning toward) although the jury is still out. Actually, the back to back solidly warm winters just experienced are enough of a rarity as it is.

[Jonger]

Is it really possible to get 3 poor winter seasons in a row?  Thanks for the confidence!

 

 Three solidly warm winters in a row hasn't happened in Atlanta at least since records started in 1879. So, hopefully the SE US will at least have a more average winter in terms of temperatures (what I'm leaning toward) although the jury is still out. Actually, the back to back solidly warm winters just experienced are enough of a rarity as it is.

I don't mean to sound like a wet blanket, but what's the difference between normal and bad? Doesn't Atlanta average like 6 inches a year?

[ORH_wxman]

I don't mean to sound like a wet blanket, but what's the difference between normal and bad? Doesn't Atlanta average like 6 inches a year?

 

 

He didn't mention snowfall, he mentioned temperature.

[Jonger]

I don't mean to sound like a wet blanket, but what's the difference between normal and bad? Doesn't Atlanta average like 6 inches a year?

 

 

He didn't mention snowfall, he mentioned temperature.

Whoops.... Atlanta is one of the few regions to have a net cooling over the past 30 years, if I'm recalling correctly.

[GaWx]

I don't mean to sound like a wet blanket, but what's the difference between normal and bad? Doesn't Atlanta average like 6 inches a year?

 

 Actually, 6" would be a great winter because Atlanta actually averages only 2". Be that as it may, low averages make people like me really appreciate snow when it comes!

 

 Anyway, I was specifically referring to temperatures, not snowfall, as ORH just posted. However, I'll also mention that Atlanta has had two winters in a row of only trace amounts of snow. Since 1890, it has experienced three winters in a row of only a trace only once. So, hopefully this winter won't give us the 2nd such case of three in a row.

[tacoman25]

 Three solidly warm winters in a row hasn't happened in Atlanta at least since records started in 1879. So, hopefully the SE US will at least have a more average winter in terms of temperatures (what I'm leaning toward) although the jury is still out. Actually, the back to back solidly warm winters just experienced are enough of a rarity as it is.

 

Of course your area also had back to back solidly cold winters right before that.

 

 

[GaWx]

Of course your area also had back to back solidly cold winters right before that.

 

 

2009-11.png

 

 Not only were they cold, but 2009-10 and 2010-11 were very snowy (for Atlanta): 12.4" total! So, taken in total, the last four winters averaged fairly close to normal temperaturewise and still averaged above normal snowwise with 3"/winter vs. the 2" normal.