Winter Forecast 2016-2017 Review

I think it goes without saying that this past winter was far from what was expected – and that holds true whether a cold/snow or warm/snow-less winter was forecasted. From what I have seen, no one nailed the winter forecast, however, I must tip my hat to those who forecasted a warmer winter and were closer to reality than me. So let’s dive in to how it turned out and look at some possible reasons why.

Winter 2016 – 2017: The CONUS

The Contiguous United States (or all but Hawaii/Alaska) had the 6th warmest December – February period on record.  Most of the eastern 2/3rds of the country saw above normal temperatures, and parts of the southern US saw their record warmest winter. Not to mention numerous record highs were set across the country.

Oddly enough, we actually got warmer as the winter progressed. December was pretty average across the county, but the warmth quickly built in January, and exploded in February.

And just for fun, here’s the season snowfall analysis for the country.

Winter 2016 – 2017: Locally

We were no exception to the incredible warmth. All three winter months ended up above average – though December was closer to normal in most areas.  I do include March in the winter forecast, but temperature data isn’t available yet, but we’re on track to finish about normal.

Maryland, and Virginia had their 3rd warmest winters on record, and Delaware their 5th warmest. All three states saw drier than normal conditions, which has contributed to the abnormal dryness across much of the area, including drought conditions in northern Virginia, DC Metro and through central Maryland.

Maryland:

Delaware: 

Virginia:

 

  Reagan National BWI Salisbury
1st 70° Day

(climo since 1940)

Jan 12 (7th earliest)

Avg: Feb 19

Jan 12 (5th earliest)

Avg. Feb 28

Feb 8 (16th earliest)

Avg. Feb 25

# of 70+ days so far in 2017 70+: 11

80+: 1

70+: 13

80°+: 1

70+: 6

80+: 0

December 2016 Avg. Temp: +2.1°

Snow: Trace

Avg. Temp: +1.6°

Snow: Trace

Avg. Temp: +0.7°

Snow: Trace

January 2017 Avg. Temp: +6.1°

Snow: 1.4”

Avg. Temp: +6.1°

Snow: 0.7”

Avg. Temp: +4.8°

Snow: 9.6”

February 2017 Avg. Temp: +8.7°

Snow: Trace

Avg. Temp: +8.4°

Snow: Trace

Avg. Temp: +7.5°

Snow: Trace

March 2017 Avg. Temp: n/a

Snow: 2.0”

Avg. Temp: n/a

Snow: 2.3”

Avg. Temp: n/a

Snow: Trace

Season Snow
(Dec-Mar)
3.4”

(15.4 normal)

3.0”

(20.1” normal)

7.1”

(9.3 normal)

Reviewing the Forecast

I was fully expecting a colder than normal with above average snowfall – about as far from what actually happened as I could get. My forecast for December was near normal with little snowfall, and that worked out well. Then we took a wrong turn. If you ask me, Mother Nature had too much fun on New Years and forgot about winter. 🙂

I forecasted January to be colder than normal with slightly above normal snowfall. The above normal snow worked out for areas S&E where that one winter storm hit, but most areas saw below normal snow.

I expected February to be the worst month with frequent storms, and bitter cold. Instead we got plenty of warmth and almost no snowfall. By the end of February, we also had our first day of severe weather, including numerous hail reports and an EF-1 tornado in Charles County that touched down about 2 miles north of where I live.

I expected the stormy trend to continue into March, though not as bad, and expected it to be colder than normal. In reality, it was our snowiest month for all areas that missed out in January.

On the plus side, I didn’t think we’d see any crippling significant snowstorms or blizzards, and that turned out to be correct!

I also expected winter to try to hold on and we’d have a delayed start to spring. While March has been cooler, spring weather came way early this year and winter isn’t putting up too much of a fight against it.

Here’s my snowfall forecast, vs what fell.

What Went Wrong?

At the end of my winter forecast I included a section titled ‘What Could Go Wrong?’ and listed a few things that could cause the forecast to not pan out as I expected.

I want to call your attention to numbers 2 and 3. Number 2 should sound familiar because I’ve mentioned the Pacific Jet several times this winter. To get a winter weather pattern for the Eastern US, we need a Ridge in the Jet Stream over the west coast with a trough in the east (since troughs are associated with colder/stormier conditions). To help reinforce that ridge, we also need warmer waters in the eastern Pacific, which we call a positive PDO. There’s a lot more than this, but I want to specifically focus on these two items.

The Jet Stream over the Pacific Ocean since last Autumn has been abnormally strong and relentless. This abnormal strength of the Pacific Jet does a couple things. First, it keeps the pattern very progressive, or constantly moving. By the time storm systems reach the east coast, they’re already being kicked out to sea by the next incoming system – so nothing can really stall or develop into a major system. The constant influx of energy on the west coast also keeps the necessary ridge from developing, and actually has resulted in a mean trough over the west coast, and ridge over the east (exact opposite of what we need). It did help California, however, where the consistently wet pattern completely erased their severe drought.

The other thing the strong Pacific Jet does is mix up the Pacific Ocean. Take a look at the two maps below. The one on the left is from early November, and the one on the right is valid today (March 30).  In November, notice the warm pool of water in the Gulf of Alaska and along the west coast. This was our positive PDO, albeit weak. But, also notice the trail of cool water across the Pacific, which lines up with the Pacific Jet track. Because the Pacific Jet was so relentless, it pushed all that cool water to the east and completely erased the warm water in the Gulf of Alaska and off the west coast, and turned the PDO negative.

Where did all that cooler water come from? There was an incredible buildup of cold air and snow over Eurasia/Siberia during October. Research from a guy named Judah Cohen has linked this with colder US east coast winters. But, that was not the case this year. Essentially, the overall flow, took all that cold air and pushed it east, which contributed to the cooling of the northern Pacific. Because the Jet Stream sets up over temperature contrasts, the Pacific Jet essentially fed itself. It pushed the colder air out over the warm pacific, creating a strong temperature gradient that persisted all winter. And that has been our driving factor into why it was so warm this winter.

So there you have it, the review of my forecast, and why winter didn’t work out as I expected it. The forecast itself gets an ‘F’, but I’m going to give it a ‘D’ because I at least anticipated the things that could go wrong.

By the way, the Pacific Jet still shows no signs of weakening, and has contributed to an early and active start to the severe weather season. March 30 marks day 8 of consecutive severe weather days across the central and southern US – with more in the coming days. This pattern I expect will continue into April. I don’t normally do a spring forecast, but I’m leaning on a mild (but not incredibly warm) spring, with wetter than normal conditions.

-Andrew