Winter 2015-2016 Medium-Term Discussion

[donsutherland1]

Incorporating today's weekly ENSO region data, the change in the mean January ENSO Region 1+2 anomaly has been approximately 0.50°C cooler than the change in the ENSO Region 3.4 anomaly. ENSO Region 1+2 has seen its average anomaly fall from near +2.15°C to about +1.40°C (OISST weekly data). In contrast, Region 3.4 has seen its average anomaly drop from approximately +2.80°C to near +2.55°C.

 

Given the tendency of some Central Pacific-oriented El Niño events to produce widespread cold across North America in February, one might be tempted to expect a much more widespread cold relative to normal than the preceding January.

 

In fact, the evolution of ENSO anomalies that has occurred suggests that the spatial distribution of temperature anomalies and, to a lesser extent, their magnitude should be pretty similar to January.

 

Since 1950, there have been four cases with moderate or strong El Niño events that saw the January Region 1.2 anomaly cool by 0.30°C or more than the Region 3.4 anomaly from their December averages.

 

If one looks at the outcomes, one finds that the subtropical jet tends to have a somewhat larger impact on temperature anomalies in the southern tier than January, but the overall distribution of anomalies is not much different overall across North America. In other words, the kind of evolution that is underway is a sort of “preserver” of the January anomalies.

 

 

With the exception of the circled region, the 1/31 CFSv2 forecast for February was quite similar to the January outcome. Moreover, if one looks at the latest ensemble guidance, the first 10 days of February appears likely to build up an impressive warm anomaly in some of the areas that wound up with warm anomalies during January. The 10-15-day EPS outlook favors a large cold shot to eastern North America that would then dent but not erase those warm anomalies. What happens afterward will depend largely on whether blocking can be sustained.

 

The February 1 Arctic Oscillation (AO) value was +2.186. As a result, the AO average for meteorological winter to date has swung back to slightly positive values (+0.034). However, strong blocking is forecast to develop over the next 7-10 days. Back in January, blocking predominated during the January 2-22 period with the strongest blocking present during the January 9-19 timeframe. If the GFS ensembles are reasonably accurate, the strongest blocking could again be present during a similar period in February as was the case in January.

 

As Yogi Berra once suggested, perhaps February will prove to be “déjà vu all over again.” Certainly, the ENSO evolution temperature anomalies lend some weight to such an outcome and the timing of the forecast blocking may, as well.

[donsutherland1]

The storm that brought a swath of snow across the Plains States is moving into Canada. Its associated warm front will bring a large area of moderate to heavy rainfall across the U.S. East Coast today.

 

In the larger scheme of things, the Arctic Oscillation, currently at +0.467 is forecast to go negative to possibly strongly negative in 3-5 days. During the last period of strong blocking, a blizzard brought near record to record snowfall amounts across parts of the Middle Atlantic region. Some of the guidance suggests that parts of the East could again be impacted by an appreciable to possibly significant snowfall during the forecast round of blocking.

 

The ensemble guidance has been consistent and in agreement that an Arctic outbreak will likely occur near February 10 +/- 1-2 days and then spread eastward from the Plains States to the East Coast. That cold air should be sufficient to dent the impressive warm anomalies that have been accumulating in the early part of February. For example, in New York City, through 10 am today, the February anomaly is running at 14.2° above normal. To put this anomaly into context, if the remaining 26 days of February had normal temperatures, the monthly anomaly would wind up +1.5°. An average anomaly of 1.6° below normal for the 2/4-29 period would be required to produce a normal monthly mean temperature. So far, similar warmth has prevailed across much of the eastern half of the United States.

 

This raises the question as to whether the groundhogs that failed to see their shadow yesterday (a forecast of an early spring) were looking ahead or whether they were reacting to the exceptionally warm start to February.

 

As that the cold moves into the eastern half of the U.S., the western third of the United States and British Columbia, which have started off very cold should experience a warming trend.

 

After mid-February, the blocking is forecast to dissipate with a positive to possibly strongly positive AO returning. As a result, a warming trend could develop from the Plains States and then expand eastward during or just after mid-February. What happens beyond that will depend on whether blocking returns. The forecast MJO suggests that the forecast AO+ might last at least 5-10 days, but that’s speculative right now.

 

Nevertheless, at this point in time, it appears that the AO will wind up slightly positive overall for meteorological winter. In addition, somewhere around 55% +/- 5% of days will likely have seen a positive AO.

 

Finally, if one takes the trimmed GFS analog pool and rolls them ahead to February 20, milder than normal readings seem somewhat more likely than cooler ones for such cities as Chicago and Washington. That kind of outcome would be consistent with a positive AO during that date. A few of the cases did produce a cold shot from the Upper Plains into the Midwest, so there is still a fairly large degree of uncertainty regarding the evolution of events after the forecast Arctic shot.

[raindancewx]

ONI for NDJ isn't out yet, but based on the raw monthly SSTA for January in Nino 3.4, I think NDJ is a higher/warmer ONI value than OND. January had slightly warmer waters and a warmer SSTA than October. This is likely the ONI peak for this event.

 

 

https://www.ncdc.noaa.gov/teleconnections/enso/indicators/sst.php

 

MONTH NIÑO 1+2 NIÑO 3 NIÑO 4 NIÑO 3.4 TEMP ANOM TEMP ANOM TEMP ANOM TEMP ANOM

 

[donsutherland1]

Some daily record temperatures for 2/3:

 

Albany: 57° (old record: 56°, 2006)

Bridgeport: 56° (old record: 54°, 2006)

New Haven: 54° (old record: 53°, 2006)

Poughkeepsie: 63° (old record: 60°, 1991)

Westhampton: 55° (old record: 53°, 2006)

[Isotherm]

Earlier today I wrote a post in the New England forum explaining why I thought model guidance was largely incorrect in collapsing the Pacific pattern. This afternoon's 12z EPS has initiated that correction process with improved heights upstream. Post can be found here:

 

http://www.americanwx.com/bb/index.php/topic/47634-february-pattern-disco/page-19?

[donsutherland1]

With the GFS showing continued cold after mid-month, the ECMWF continues to oscillate wildly between cold and warm anomalies in its extended range. The ECMWF is highlighting uncertainty and the continued cold following mid-month appears very much to be on the proverbial table.

 

 

it's still premature to assume that the very warm weekly guidance for the period beyond mid-February will necessarily verify. Odds increasingly appear that it won't.

 

A lot will depend on whether blocking is sustained or redevelops. The most recent GFS ensembles suggest more blockiness than had been shown even a few days ago. Hence, any warm up after mid-month relative to normal, if it occurs, may be delayed or even short-lived. Should the blocking break down as had previously been indicated, then the prospects of a sustained warmer period would increase.

 

Right now, perhaps the safest route is to assume that there will be sufficient and sustained cold to bring the exceptionally warm anomalies across much of the eastern two-thirds of the country down toward levels closer to January's figures given the evolution of the strong El Niño (post #211).  Put another way, the very warm weekly guidance from a few days ago increasingly appears to have been overdone and perhaps substantially overdone.

[donsutherland1]

If one examines the forecast 500 mb pattern at 48 hours and compares it with the 500 mb pattern of February 10, 2015 (both cases featured an AO+), one finds some similarities and also some differences:

 

Similarities:

• Deep trough in the Southeast

• Positive to very positive 500 mb height anomalies over the top of the trough

 

Differences:

• The trough is centered west-northwest of its 2015 position

• There is a weakness in the positive 500 mb height anomalies close to where the most positive anomalies were centered in 2015

• The trough is also forecast to be deeper than it was in 2015

 

 

These differences are somewhat subtle, but they imply an area of snowfall that would be more southwest-northeast oriented than the largely east-west orientation of 2015. They also imply that appreciable snows will likely fall farther to the south and west than those in 2015. Southeast Massachusetts will still very likely feature the heaviest accumulations. But significant accumulations (6” or more) might well extend into southern Connecticut and parts of Long Island. New York City (0.1” in 2015) and Newark (0.2”) might still have the potential to pick up several inches of snow.

 

Finally, a quick look at snowstorms that commenced in the 2/8-10/1950-2015 period with a positive AO as high as +2 provided the following distribution of outcomes for Boston and New York City:

 

Boston:

1” or more: 43%

2” or more: 29%

4” or more: 14%

6” or more: 14%

10” or more: 14%

15” or more: 7%

 

New York City:

1” or more: 43%

2” or more: 29%

4” or more: 7%

6” or more: 7%

10” or more: 7%

15” or more: 0%

[donsutherland1]

The GFS ensembles have been forecasting a shot of Arctic air with readings 1.5 to 2.5 standard deviations below normal across parts of the Midwest and 2.0 to 3.0 standard deviations below normal in parts of the northern Middle Atlantic and New England areas in recent days. Select data for Boston, Chicago, Detroit, New York City, Philadelphia, and Washington, DC is below:

 

[donsutherland1]

With the calendar now approaching mid-February and meteorological winter nearing an end (that does not mean that winter weather will be finished), it's a good time to look at how the Arctic Oscillation (AO) has fared this winter. As noted on repeated occasions, the AO cannot accurately be forecast for more than a few weeks in advance. Even the leading effort based on the Snow Advance Index (SAI) falls short.

 

At this point in time, it is now likely that the Snow Advance Index (SAI) forecast of a negative winter AO, the third consecutive such forecast, will again be incorrect. That does not mean that it does not add value, as there was a period of severe blocking that occurred in January and another period of blocking that has just commenced. The overall outcome that appears likely suggests that the SAI has some predictive value, but other variables outside the index also have predictive value and those other variables may explain more of what happens, at least in some winters.

 

Through today, here's where things stand:

 

AO Average: +0.072

 

% Days AO > 0: 58%

% Days AO  +1.000 or above: 41%

% Days AO +2.000 or above: 18%

% Days AO +3.000 or above: 8%

 

% Days AO < 0: 42%

% Days AO -1.000 or below: 30%

% Days AO -2.000 or below: 22%

% Days AO -3.000 or below: 14%

 

Lowest AO Value: -4.898, 1/16/2016

Highest AO Value: +4.503, 12/22/2015

 

Maximum % Days AO- (if February 12-29 all have AO- values): 54%

Maximum % Days AO+ (if February 12-29 all have AO+ values): 66%

 

In order for the winter AO to average 0.000, the AO would need to average -0.292 for the February 12-29 period. Right now, the ensemble forecast favors a return to AO+ values just after mid-February. In turn, that outcome suggests that a positive AO average is very likely for meteorological winter and a majority of days during that period will wind up featuring AO+ values.

 

 

If the AO winds up with a positive average for the December-February period, winter 2015-16 would be the 4th out of the last 5 winters to feature an AO+ average:

 

2011-12: +0.670

2012-13: -1.126

2013-14: +0.188

2014-15: +0.843

2015-16: Near +0.100 (?)

 

In terms of extreme AO values (-3.000 or below or +3.000 or above), winter 2015-16 featured a return of severe negative values for the first time since winter 2012-13. It also saw a higher percentage of days with such negative or positive values than any of the preceding four winters.

 

[raindancewx]

PDO and AMO both jumped a lot in January by JISAO and ESRL respectively.

[donsutherland1]

A few quick thoughts...

 

Today's AO value was -1.807. The current period of blocking coincides very closely with the severe cold that will be unfolding from today into the weekend.

 

Afterward, the AO is forecast to rebound rapidly to positive values at a time a storm is forecast to impact parts of the eastern U.S. and Canada. During the second half of February, AO- values typically correspond with significant (6" or greater) snowfalls on the coastal plain. For example, 75% of such storms that brought 6" or more snow to two or more of the major cities in the Middle Atlantic region northward (Washington, DC, Philadelphia, New York, and Boston) occurred when the AO was negative. In this case, it is forecast to have returned to positive values.

 

As a result, the more typical outcome would be an interior storm that brings significant snowfall amounts well inland. A blend of the latest ECMWF, GFS, and CMC snowfall forecasts is very consistent with that more typical scenario. Some snow could still accumulate in the major East Coast cities with Washington and Baltimore more favored than New York or Boston for a few inches, but the major snows will likely fall well west of the coastal plain.

 

It should be noted that the 2/12 12z run of the NAM offers a snowier "second opinion" about that storm.

 

Finally, in the extended range near the end of February, the AO is forecast to go negative. If that forecast verifies, the eastern half of the U.S. and southern Canada could again see more cold return. Whether or not such a pattern change might create the opportunity for a stormy March, as has occurred on some occasions during waning El Niño events will need to be watched if the AO heads negative.

 

[donsutherland1]

Record Heat Likely in the Plains…

 

What has been a winter of extremes continues. So far highlights include:

 

• An historically warm December in large parts of eastern North America equivalent to among the 10 warmest Novembers on record.
• A late December blizzard that buried parts of New Mexico under more than 20” snow along with extensive flooding along the Mississippi and Missouri Rivers.
• A late January blizzard that brought record snowfall to Baltimore and the 2^nd biggest snowfall on record to New York City
• A Valentine’s Day Arctic outbreak that produced some of the coldest readings in nearly 50 years in parts of southern New England and New York City’s first subzero reading since January 19, 1994
• An exceptionally warm Arctic winter that has seen record low Arctic sea ice extent figures on more than half the days during the January 1-February 15 period.

 

The latest GFS ensembles indicate that 2σ or greater positive height anomalies will move through the Plains states Tuesday through Thursday producing an area of temperature anomalies of 2.0σ to 3.0σ above normal.

 

 

 

Record high temperatures for February 18:

Albuquerque: 71°, 1981

Denver: 71°, 1930

Lincoln: 70°, 1930

Rapid City: 66°, 1983

Wichita: 74°, 1930

 

Another round of excessive warm anomalies is forecast to develop in the western third of the U.S. for the February 22-25 period. That region will likely continue to experience above to much above normal readings through the remainder of February.

 

Finally, the Arctic Oscillation is forecast to dive to negative and perhaps strongly negative values in the extended range. The latest ensemble forecasts take it negative around 2/24 +/- 1 day. This could have implications as the closing week of February and perhaps the opening week of March could be stormy. A negative AO could have the largest implications for the Middle Atlantic region, as more than two-thirds of that region’s significant (6” or greater) snowstorms have occurred with an AO-.

 

 

Courtesy of the continuing strong PDO+, the PNA is likely to remain positive to strongly positive for the remainder of February and likely into at least the start of March. This situation could also favor a trough in the East, though shortening wavelengths could lead to the trough’s migration toward the Midwest over time.

[donsutherland1]

To illustrate the potential extremes of the upcoming warmth in parts of the Plains States, the 2/17 0z GFS MOS forecasts a high temperature of 81° for Rapid City on February 18. That would smash the existing record of 66°, which was set in 1983. It would also be the earliest 80° reading on record by 3 weeks, if it verifies.

[Chambana]

To illustrate the potential extremes of the upcoming warmth in parts of the Plains States, the 2/17 0z GFS MOS forecasts a high temperature of 81° for Rapid City on February 18. That would smash the existing record of 66°, which was set in 1983. It would also be the earliest 80° reading on record by 3 weeks, if it verifies.

Interesting that would smash the old record from 1983, as 82-83 was a very strong Nino as well. Very impressive warmth expanding eastward across the conus. Winter 15-16 is gasping it's last few breaths I believe.

[donsutherland1]

Interesting that would smash the old record from 1983, as 82-83 was a very strong Nino as well. Very impressive warmth expanding eastward across the conus. Winter 15-16 is gasping it's last few breaths I believe.

A lot can still happen between now and the end of the winter. Winter 1982-83 featured an unseasonable shot of cold after mid-April. It will be interesting to see how things evolve.

[donsutherland1]

Some temperature forecasts for today (2/17):

 

If Phoenix hits 90°, that would be the earliest 90° reading on record there. The earliest is 91°, which occurred on 2/24/1904. If Tucson hits 90°, that would be the second earliest 90° temperature on record there.Tucson's earliest 90° reading is the 92° that occurred on 2/14/1957.

[donsutherland1]

Select high temperatures for 2/17:

 

Albuquerque: 72° (old record: 70°, 1970 and 1996)

Las Vegas: 81° (tied record set in 1996)

Phoenix: 90° (old record: 88°, 2014) -- earliest 90° reading on record

Santa Fe: 65° (old record: 61°, 2014)

Tucson: 90° (old record: 86°, 2014) -- 2nd earliest 90° reading on record

[raindancewx]

I don't know if it will happen this year or next year, or in two years...but Albuquerque is way way overdue for a wet March. We've had eight dry Marches in a row. With our current heat wave and possibly record setting February warmth (after excellent snow and cold from Oct-mid Jan no less) March 2016 would be a great time to break the streak. We just missed last year - the last week of Feb was like 15F below average with 10" of snow here in Albuquerque, and up to 100" fell in the mountains Feb 22-Mar 5 2015.

 

Pretty sure the MJO in phase 1,2,3 in March would make us cold/wet but it's not looking like it gets past phase 8 right now. 

[donsutherland1]

I don't know if it will happen this year or next year, or in two years...but Albuquerque is way way overdue for a wet March. We've had eight dry Marches in a row. With our current heat wave and possibly record setting February warmth (after excellent snow and cold from Oct-mid Jan no less) March 2016 would be a great time to break the streak. We just missed last year - the last week of Feb was like 15F below average with 10" of snow here in Albuquerque, and up to 100" fell in the mountains Feb 22-Mar 5 2015.

 

Pretty sure the MJO in phase 1,2,3 in March would make us cold/wet but it's not looking like it gets past phase 8 right now. 

Precipitation in New Mexico is positively correlated with the PDO and ENSO. So, the ongoing El Niño and PDO+ could result in above normal precipitation. The CFSv2 seems to like that idea right now.

[donsutherland1]

Some temperature forecasts for today (2/18):

 

 

Yesterday saw the GFS MOS fare much better than the NAM MOS in areas that experienced record warmth. Finally, the GFS MOS forecasts St. Louis to have a high temperature of 78° tomorrow. That city's daily record is 76°, which was set in 1930.

[raindancewx]

Precipitation in New Mexico is positively correlated with the PDO and ENSO. So, the ongoing El Niño and PDO+ could result in above normal precipitation. The CFSv2 seems to like that idea right now.

 

It's been wetter than normal here overall since mid-2014, it just hasn't materialized in March - including March 2015/2010 which were El Nino years. Bastardi seems to think the storminess comes back West at some point in March, which I would take. It just missed last year, good last week of February, good second half of April and May, but dry as a bone in March...and warm.

[donsutherland1]

The February 19 preliminary Arctic Oscillation figure was +1.609 bringing the winter-to-date AO average to +0.057. With today's being the 46th AO+ day, winter 2015-16 is assured to have more than 50% of days with AO+ values. Even as the ensembles take the AO negative next week, somewhere close to 55% of days during winter 2015-16 will wind up with AO+ values. It remains likely that the winter AO average will also be somewhat positive unless the ensemble members showing the deeper blocking verify.

 

At present the AO will likely be shifting negative around the 2/24-25 timeframe. About half of ensemble members are negative at that time and around half are positive.

 

 

As that is happening, the computer guidance is in good agreement about the development of a potentially significant storm. Assuming the AO forecast is reasonably accurate, the timing of the development of the blocking will probably be a little late to promote the kind of storm that could bring a significant snowfall from Washington, DC to Boston. Instead, interior sections with perhaps those somewhat to the south and east of the heaviest snowfall during the February 15-16 storm would more likely be favored. Some snow could not be ruled out for the coastal plain, but the focus of heavier snows would be inland.

 

With March approaching, it makes sense to examine how the AO has evolved relative to past strong El Niño winters. The closest match for the 15-day period ending February 25 is 1998.

 

 

March 1998 featured a persistent trough in eastern North America that gradually shifted south and westward after mid-month. The closing portion of March saw the development of a ridge over the eastern CONUS and trough along the West Coast.

 

There was also a close match with respect to the PNA. February 1998 saw 26 of 28 days with a PNA+. So far, February 2016 has had 17/19 days with PNA+ values and, if the ensemble forecasts are correct, would wind up with 27/29 days of PNA+ values. Both winters featured a strong and persistent PDO+, which favors the PNA+. March 1998 featured predominantly PNA+ values, with 27 of 31 days having such values. The closing 10 days of March saw the only PNA- values.

 

Some differences should be noted, as well.

 

1. The current strong El Niño is basinwide and experiencing the strongest cooling in the eastern ENSO regions; 1997-98 was an East-based ENSO event. During that event, Regions 3.4 and 4 were cooling faster than Region 1+2.

2. The current guidance forecasts somewhat earlier development of blocking than during late February 1998.

3. The current guidance forecasts that the blocking will be stronger than that which occurred from the end of February into March of 1998.

4. Much higher amplitude MJO during February

 

So, at this point in time, one can cautiously argue for the development of a trough in eastern North America and possibly a fairly deep one. This trough could persist through at least the first 10-15 days of March. Then, at some point, it could weaken and/or migrate westward. Much will depend on the strength of the forecast blocking and its evolution.

 

For now, it's still a little soon to be sure, but there would be a risk of a dramatic pattern change late in the month. Before then, the active subtropical jet should provide periodic opportunities for frozen precipitation from the Plains States eastward to the Middle Atlantic and New England regions.

 

It should be noted that the latest CFSv2 begins to develop ridging in the East during week 4. That could be premature, but something that would be plausible during Week 5 or 6 if the evolution of blocking is reasonably similar to what took place in 1998 while allowing for stronger and somewhat longer-lasting blocking. The biggest uncertainty concerns the MJO. During March 1998, the big change to ridging occurred when the MJO moved in Phases 1 and then 2. Phase 2 closed the month and it was the only high-amplitude MJO during March. Assuming the MJO remains at predominantly high amplitudes as has been the tendency this winter (average amplitude through 2/17: 1.747 vs. DJF 1997-98 figure of 1.113), MJO forcing will play a larger role in shaping the outcomes.

[donsutherland1]

During the November 19-22, 2015 period, a significant early season storm brought heavy snow across parts of the Midwest into the Great Lakes region. Chicago picked up 11.2” and Detroit received 6.0”. Howell, MI was buried under 15.5”.

 

An even stronger storm will bring heavy snow to the south and east of the November storm’s axis of heaviest snows. As a result, parts of northwestern Indiana into Michigan will likely see the biggest accumulations. The 12z run of the RGEM suggests the potential for 10” or more snow exists in parts of that region.

 

 

 

At the same time, unseasonably warm air appears very likely to surge up the Eastern Seaboard. During the November storm, temperatures rose into the 50s as far north as southern New England with middle 50s reported in such cities as New York and Philadelphia. The push of warm air could be stronger this time around on account of the greater forecast intensity of the storm. As a result, it still appears likely that Baltimore, Richmond, and Washington could see temperatures reach or exceed 60°. Readings of 70° or above are possible from parts of Virginia southward. Temperatures in the 50s could reach as far north as Portland, Maine. Moreover, parts of the Coastal Plain could pick up 1.50”-3.00” precipitation over the next 60 hours.

 

The 12z GFS MOS forecast highest temperatures for the 2/24-25 period for select cities are:

Baltimore: 60°

Boston: 52°

Bridgeport: 51°

Charleston, SC: 77°

New York City: 57°

Newark: 56°

Norfolk: 70°

Philadelphia: 58°

Portland: 51°

Providence: 51°

Raleigh: 72°

Richmond: 71°

Savannah: 78°

Washington, DC: 62°

[donsutherland1]

Select readings in the warm sector of the storm at 3 pm were:

 

Baltimore: 61°

Charleston: 76°

Norfolk: 68°

Philadelphia: 64°

Raleigh: 72°

Richmond: 66°

Savannah: 82°

Washington, DC: 65°

[donsutherland1]

Today's AO figure was -0.378. Based on the final December and January values and preliminary February values, the AO was neutral to slightly positive for Winter 2015-16. The preliminary average is +0.007.

 

The distribution of values is below:

 

 

With the wave lengths continuing to shorten courtesy of the seasonal evolution, one needs stronger blocking, all other variables being equal, to produce the cold anomalies similar to those in February. For example, for New York City, the March 1-10 temperature anomalies for an AO of -2.999 to -0.001 is similar to those for an AO > 0. An AO of -3.000 or below is decidedly cooler (nearly 6° cooler).

 

 

 

One variable that could offset a positive AO is the EPO. Last March, the EPO was negative to strongly negative for much of the first 20 days of the month. This March, it is forecast to be positive through at least the first 10 days of the month. At the same time, the AO is forecast to bottom near -2.000 before rising toward possible positive values by March 10.

 

Just looking at the state of those two indices and typical 500 mb patterns associated with them would argue for a warming trend to roll across the CONUS near March 7 +/- a few days with the potential for a bout of much above normal readings. There remains a risk that the second half of the month could witness the development of sustained ridging covering parts of eastern North America including Ontario, Quebec, the Midwest, Mid-Atlantic, and New England areas. If so, the second half of the month could be very warm relative to normal. Such ridging developed in late March in 1998 as a super El Niño was winding down. For now, it's a little soon to be sure about such an outcome this March, but the potential is there, especially if blocking dissipates and does not rebuild.

 

For now, my guess is that a large part of the Midwest and eastward will probably wind up experiencing a much warmer than normal month (anomalies of 3° or more above normal). The PDO+ will likely continue to promote a PNA+ pattern, which would bring continued warmer than normal readings to the Pacific Northwest.

[donsutherland1]

Last night into today, a storm moving off the lower Mid-Atlantic coast deposited a swath of snow across the Middle Atlantic region. For the most part, snowfall amounts were fairly light (2" or less). However, a few locations saw greater amounts including Cape May, NJ: 6.5"; Milton, DE: 5.8"; and, Princess Anne, MD: 6.7".

 

Big changes lie ahead on account of the expected development of an extreme trough centered near Mexico's Pacific Coastline (more than 5 standard deviations below normal) and a ridge with positive height anomalies of 1-2 standard deviations above normal in the East during the 3/8-10 period. The result should be the warmest readings so far this year in parts of the Great Lakes Region to the Middle Atlantic and New England areas.

 

[donsutherland1]

3/5 0z MOS (highest readings for the 3/8-10/2016 period):

 

Boston: 65°

Chicago: 63°

Detroit: 63°

New York City: 68°

Washington, DC: 76°

[donsutherland1]

The forecast below normal height anomalies off Mexico are 7.5σ below normal.

 

[wxmx]

<558mb dm  heights forecasted here...unheard of. Snow in the Sierra Madre (west and east) for altitudes>2300m is going to be pretty extensive and in the order of near 2 feet in places (> 3000m).

[donsutherland1]

<558mb dm heights forecasted here...unheard of. Snow in the Sierra Madre (west and east) for altitudes>2300m is going to be pretty extensive and in the order of near 2 feet in places (> 3000m).

The GFS ensembles last forecast a 9 standard deviation trough. This almost certainly is an historic event.