A look back at winter 2017-2018

This will discuss the major driving factors that made winter 2017-2018 what it was. It will also show the major events for each month.

A look back:

2017 was a warm year.  East of the Rockies saw heat records broken for March through October.  Here in the Northeast  October was  overall the warmest on Record.  November the pattern went back and forth between mild to cool. There was an arctic outbreak that started in the Midwest on November 9th. The air mass moved east over the Great Lakes and into the East Coast. Those downwind of Lake Ontario and Lake Erie saw a significant lake effect event. The area of low pressure brought a foot of snow southeast of Lake Erie. Downwind of Lake Ontario, parts of the Tug Hill saw upwards of two feet of snow. But overall November ended up being doggedly mild. Here are the top 10 years for warmest Autumn in the Northeast.......  1931, 1947, 1953, 1961, 1999, 2001, 2007, 2011, 2016, 2017.

Winter 2016-2017 saw two meter temperatures well above normal from November through February. There were a few very limited cold spells.  Because of the warmth snowfall was severely below average. It wasn't until March that winter like temperatures showed up.

Looking back at those warm Autumns most of the following winters ended up being lackluster with above average warmth and below average snowfall.  One of those winters was 2011-2012 one that many have dubbed "the year without a winter" The only winter that bucked the trend of mild winters was 2007-2008.  2017 was so warm it's no wonder that many winter outlets and Meteorologist were calling for a warm winter with below average snowfall. I wasn't one of them, nor were members of my weather team. Jamie Mahoney, Robbie Venditti, and Joe Karnik. We were calling for almost the exact opposite of most weather outlets.

Here is a link to my 2017-2018 winter outlook.     

 

Here is a look back at winter 2017-2018:

Teleconnections:

The El Nino-Southern Oscillation (ENSO) over the winter featured a east based weak to moderate La Nina. The  Quasi-Biennial Oscillation (QBO) was also east based. The QBO has a big influence on temperatures in North America. When the QBO is east based, the Northeast and Mid Atlantic is more prone to see high latitude blocking and ridging in the west. The East Pacific Oscillation (EPO)was predominately negative.  Winters with a negative EPO tend to be colder than average.   Over the winter we also had very low solar activity. Winters with low solar activity tend to end up colder on average.

December:

After a very warm Fall December started out mild. But by mid month arctic air plunged into the Northeast. By Christmas the Northeast was locked in a block of ice. Most locations saw record lows from Christmas to the end of the month.

January:

The record cold from December greeted those celebrating New Years Eve. Those who braved the cold in Times Square saw the coldest New Years ball drop in several decades. In fact it was so cold that many places canceled New Years Eve celebrations altogether.  On the 3rd -5th a Nor'easter brought heavy snow. Winter storm warnings stretched from Florida into New England.  New Jersey to Northern New England saw several inches of snow. By the 8th temperatures rose to well above average levels.  Over just a 4 days, the warm temperatures melted most of the snowpack in the Northeast. The entire Northeast saw huge ice jams that lead to significant flooding.  The warm up didn't last long and by the evening of the 12th arctic air once again had many of us in its grip. Most places in the Northeast saw a 45 to 60 degree drop in temperatures in only a few hours.   The arctic cold once again retreated north around the 17th. This 2nd thaw lasted to the last of January. The 2nd thaw didn't get anywhere near as warm as the 1st thaw. But lasting nearly two weeks it still melted a lot of snow and ice even on the Great Lakes.  Downwind of the Great Lakes, saw copiousness amounts of Lake Effect snow.

 

 

 

February:

La Nina's are often erratic.  During an La Nina, the Madden-Julian Oscillation (MJO) can be a big factor in influencing the pattern. We saw this happen in February. The record breaking warm temperatures cooled by February.  The first week of February it was cold enough for snow across northern New York State and northern New England.  The cooler and snowy start to February ended as we approached mid month. The pattern flipped back to above average warmth, allowing February to end as one of the warmest overall on record. The flip back to warm was a result of the MJO stalling in phase 7 for 21 days. During February phase 7 is a warm signal.  We had a historically strong area of high pressure off the Southeast Coast. This caused a heat dome over the East Coast. The Jet Stream was very wavy. The eastern ridge was well north into northern Canada, with a deep trough out west. The jet stream orientation allowed the clockwise motion of the air flow around the high pressure to drive record breaking warmth into the Mid Atlantic and Northeast. While the trough out west brought cold arctic air into the west and Rockies.   By the 28th of February all the cities in the Northeast were in the 80's.   The lake snow belts saw an abundance of lake snows for February as well.  

 

 

The 2nd half of February is when my winter outlook deviated from the actual pattern. I had not counted on the MJO stalling for a record 21 days.

 

March:

March came in as a lion. The pattern returning to below average cold and snowstorms brought my winter outlook back into focus. The warmth during the last half of February became history when the pattern changed back. The MJO finely went into the cold phases. The shift to the cold phases 8-2 allowed blocking to develop near Greenland.  We saw the ridge develop out west and the trough to develop over the East Coast.  The southern branch of the jet stayed active, which allowed the southeast ridge to interact with the northern jet stream. This was the perfect environment for Northeast snowstorms. March brought 4 nor'easters to the Mid Atlantic and Northeast. The 1st was March 1-3, 2018. The 2nd was March 6-8, 2018. the 3rd was March 12-14. and the 4th was March 20-22, 2018. The nor'easters brought feet of heavy wet snow to the Mid Atlantic and Northeast. The high winds and heavy snow led to hundreds of thousands of power outages due to downed trees and power lines. Coastal flooding was also a huge problem.

 

In retrospect:

When I issued my 2017-2018 winter outlook I Stated that Northern Pennsylvania New York State and New England  would see below average to well below average temperatures, with above average snowfall. I showed how the snow belts would end up with well above average snowfall. I outlined how Southern (especially southeast) Pennsylvania and the Mid Atlantic would see more in the way of seasonal to slightly above average snowfall and temperatures. Even with the warm spells we had, winter 2017-2018 saw overall below average temperatures. The major cities saw above average snowfall, with Northern New York and New England ending up with very ample snowfall.  There is time to even add to seasonal snowfall totals, as I always say from first flake to last flake.  April is going to be an overall colder than average month. The first half of April does have the chance to see more snow. The pattern does support the idea of the possibility of another coastal type storm during the first 10 days of April.

 

Here are some seasonal snowfall amounts for the winter so far.  They are a testament to the fact that winter 2017-2018 was stormy and not the lack luster winter many think it was.

 

 

All in all my winter outlook ended up being very close to what ended up happening.

 

 

 

Spring outlook 2018

Well it's March which is the beginning of Meteorological Spring. I've been dropping a lot of hints on how this spring will go during my Facebook post. I wanted to get this out a couple of weeks ago. But one thing or another prevented me from doing that.

This outlook will cover March through May. It will also touch on the spring severe season and my first thoughts on how this year's Atlantic Hurricane season go.

First a look back:

Winter 2017-2018 turned out much different than many thought it would. Many outlets winter outlooks, talked about warmth and a lack of snow.  But through pattern analysis a few like myself were able to come up with a forecast that worked and worked well. 

My 2017-2018 winter outlook and be found here.

But December into the first week of January saw temperatures that were well below average. Temperatures became extremely cold around Christmas into the first week of January.  January had two big thaws that ended up taking most of our snowpack. Pass the first week or so of February my outlook called for the cold to return for the rest of winter. But for the last 20 days of February the Madden Julian Oscillation (MJO) stayed in the cold phase 7. So the East Coast had to deal with that big ridge.  I said our winter was going to be a bookend style winter with cold on both ends. Even though February didn't go as expected. My ideas did become reality as we got into March. I had said March was going to see below average temperatures with several chances for snowstorms.  That turned out to be quite true. As of this writing we've had three March nor'easters with the possibility of another around the spring equinox. Most of New York State and New England has seen above too well above snowfall for the winter of 2017-2018.  And we still have time left to add even more snow to the seasonal totals. Parts of Pennsylvania and the Mid Atlantic didn't see much snow until March, so these areas are at average to below average snowfall amounts. Here are some reanalysis images that show how the temperature anomalies worked out. Why talk about a winter outlook, before I post one for Spring 2018? It is to show, that long range forecasting is possible, using a blend of the new and old way of doing meteorological forecasting approaches using analog and pattern analysis.

The Eastern Pacific Oscillation (EPO) was habitually negative this winter. This was one of the main reason winter 2017-2018 was as cold as it was.

The Pacific Decadal Oscillation (PDO) was mostly positive this winter. This helped to keep an active southern storm track.

Anyway enough about the winter. Let's take a look at Spring 2018.

Spring is harder to forecast than winter. But we can still use many of the same techniques to arrive at a general conclusion.

The El Nino-Southern Oscillation (ENSO), NOAA is still saying the La Nina conditions are still present in the equatorial Pacific. But, from the data I've seen, I think the weak La Nina has shifted into neutral, this is ahead of what NOAA had forecasted. ENSO neutral is called La Nada. The surface water temperatures (SST) in ENSO region 3.4 will continue to warm over the next few months. These warm SSTs  and subsurface temperatures will work east.  The other teleconnections are borderline, with some split one way, others are split the other way. The tropospheric (lowest level of the atmosphere) circumpolar vortex (polar vortex or PV) is weaker than normal for this time of year.

Temperatures:

Because the PV is weak, a lot of the late spring into early summer heat will be in the South especially in the Southeast US. The weak PV will still allow some of the cold air to our north to enter the northern contiguous United States (CONUS) from time to time over the next few months.

March:

The current pattern will make the rest of March colder than average. We even could see a few days where temperatures are similar to what we would expect for the end of December.

This march has been cold depending on the state you live in, this march has been the 5th-8th coldest on record so far this month.

The MJO isn't going to rotate into the warm phases anytime soon. With all that cold rebuilding in Canada. I think the pattern is going to stay widespread cold in the Great Lakes, Northeast,  and Middle Atlantic Right into the first weekend of April.

We've had a lot of snow this March, so we have a snowpack. The cool temperatures will lead to chances to add to the snowpack. The buildup of ice in the Great Lakes and the replenished snowpack will make it easier to hang on to the colder temperatures longer.  This will have implications as we move into April and even May.

April:

April will see a slow transition to spring like temperatures. But we will see some mild to warm days especially during the second half of April. But, because the large scale pattern is neutral. I am thinking that temperatures will end up being below average overall.  But by the last week of April  temperatures should be turning around.

May:

The same setup that leads to the coolness for March and April, will also be in play for May.  We will see several days where temperatures are seasonal to warm. But, with no real driving factors in play; the slide into Summer will be a slow process.  Overall I think May will be seasonal in temperatures. Temperatures could ratchet up a little toward the end of the Month. 

Precipitation:

I still expect to see an active storm track.  This should allow for above average precipitation for the Great Lakes into parts of the Northeast for the three month period. This should help keep any drought issues to a minimum into the early Summer. But we do run the risk for flooding; with the Gulf of Mexico (GOM) and Atlantic much warmer than average any storm systems that can tap into that moisture could bring heavy rainfall to the region.  

Severe (tornado) season:

There was a large severe weather outbreak on February 24th. But since then the United States in running below average in the number of tornadoes.  Active severe weather seasons typically occur when colder air hangs on across the northern tier of the CONUS. This is because we have the cool dry air to the north and the warm moist air to the south. When these two air masses interact results can be explosive.  Sometimes this setup can lead to major tornado outbreaks.

There is a coloration between ENSO phases and severe weather. During El Nino we normally see the Jet stream shifted to the south. This blocks moisture from the Gulf of Mexico from moving north. This cuts down on the number of severe weather outbreaks. During La Nina we tend to see more variation and a shift northward of the jet stream. Because the jet is to the north the moisture from the GOM is free to come north allowing for a better chance of a clash between the cold dry air and the warm moist air.  It appears that Spring years that followed a La Nina are at added risk of seeing severe tornado outbreaks; The super outbreaks of 1974, 2008, and 2011 occurred following a La Nina the previous winter. 1953 was a very deadly spring tornado season. 1953 followed a weak El Nino winter. So La Nada could be the culprit, because of the wild shifts in the jet we get during a La Nada phase of the ENSO. Since this Spring follows a weak La Nina we very well could see an uptick in severe weather events contributing to tornado outbreaks.  The PDO could help keep the 2018 severe season from being to explosive. The PDO was negative in 2008, which allowed the storms to dig into the southwest close to that Gulf moisture. If the PDO can stay mostly positive this Spring it would help counter the idea of being in a La Nada. But if it goes negative it would increase the odd that this Spring severe season could be like 2008 or 2011.

 

Above, Spatial impact of El Nino (left) and La Nina (right) conditions of subsequent March, April, May MAM tornado and hail. Units are number of tornadoes (top row) and number of hail events (bottom row; events as defined in Allen et al,2015) per 1x1 box.

For 2018, I think southern Pennsylvania and the Mid Atlantic will see above average severe weather activity, with the northern Pennsylvania and New York seeing slightly above average severe weather activity.  New England would see average to slightly below average severe weather activity.   

My first thoughts on the 2018 Atlantic Hurricane season:

This year will be active. But, not quite as active as 2017. Because we're in a La Nada, there is a better chance for hurricanes to stay east of the eastern CONUS. So the risk of US land falling tropical cyclones will be less than last season. This hurricane season should end up being slightly above average in the number of Atlantic hurricanes.  10-14 named storms look to be on the table based on what I'm seeing now.