New Climate Normals Released Today

It has been a while since I last posted, as I've been quite busy with school, and I'm trying to make the most of my last few weeks of college.

Today will mark the release of the highly-anticipated new NOAA U.S. Climate Normals.

What are these "Normals"?

The NOAA Climate Normals are a 30-year average of all types of weather data for locations all across the country. If you go to this database you can see how any given month compares to these normals at any location in the country. The Climate Normals are developed by NOAA scientists by analyzing data at nearly 10,000 weather stations around the country. Whenever I write my monthly or seasonal recaps, the data that I compare to are these climate normals. For instance, if a given month is 1.4 °F warmer than normal, what we are comparing to is the 30-year NOAA Climate Normals.

What's Happening Today?

Today NOAA will release the new climate normals for the period 1991-2020. Of course, it would be an incredibly laborious process to update the climate normals annually or semi-annually. They're updated every decade. The previous period that we were comparing to was 19981-2010. This update will provide a newer, more current picture of the state of U.S. climate. Many areas will see an increase in "normal" temperatures.

Some Thoughts on the Term "Normal"

I have some gripes about the use of the term "normal" to describe the statistical averages in weather data for locations throughout the U.S. In a changing climate and an extremely variable climate system, there is nothing that is truly normal, and there are massive fluctuations from the statistical "normals".

How Unusual is Late April Snow?

Wow! Yesterday was a wild weather day here in New England. Unfortunately, I didn't get a chance to post a forecast beforehand, but if I did, it certainly would have been a tricky one. We saw summer-like convective thunderstorms, hail, a tornado warning, and accumulating snow, and a freeze warning in one day! Here in Vermont, where I'm located, the big story was the snow. 

Unlike last week's elevation-dependent snowfall, this one brought accumulating snow to valley locations as well. 

(NWS Burlington)

You may be thinking, it's April 22, should we still be seeing accumulating snow? To answer your question, I'll look at the climatology behind late-season snow in Vermont.

To begin, let's take a look at a map of April snowfall climate normals for 1981-2010.

(Northeast Regional Climate Center)

Clearly, we can see that April is not a very snowy month in New England. Much of Vermont falls in the 3-5" range, with a few areas at elevation receiving more snow in a normal year. Yesterday, Burlington International Airport officially received 2.8 inches of snow. The monthly total is 3.5 inches so far, which falls just short of the April normal of 3.9 inches to date. So while April snow may feel like a surprise, it is certainly not unprecedented to see it, and we've actually seen less snow this year than in a normal April.

Last year, Burlington only saw 0.1 inches of snow in April, whereas in 1983 21.3 inches fell.

It does not look like we'll see any more snow this month.

Fascinating Elevation-Dependent Storm

As was forecast, Friday's storm had really impressive elevation-dependence. Here's a quick post documenting what I saw.

At Middlebury College in Middlebury, VT (elevation 470 ft.) it poured rain all day, a welcome sight for the parched ground in this dry April.

I drove into the mountains with the hope of finding some deep snow for skiing. As I drove up route 125, Rikert Nordic Center (elevation 1,400 ft.) had absolutely no snow on the ground. The snowfall line was at approximately 1,600 ft. and when I arrived at the Middlebury College Snow Bowl base (elevation 1,720 ft.) it was absolutely dumping snow. Here's a photo from the summit of the mountain (2,720 ft.) where about 8-10 inches of heavy, wet snow fell from Thursday night into Friday.

The contrast in the amount of snow over just a few miles was fascinating to me.

Storms with elevation-dependence like this are quite common in the Cascade mountains of the Pacific Northwest, where the mountains get pummeled with snow and the lowlands get drenched with rain.

Wild Weather to come

Get ready for a wild stretch of weather over the next few days. Given what we'll be seeing, it's crazy to think that last weekend we had three days of temperatures in the 70s and sunny skies. Here's what we're looking at.

Here is the current surface analysis for our region:

(NWS/WPC)

You're reading that right - temperatures are in the 50s in many spots, but we're tracking a snowstorm! The National Weather Service has issued winter storm watches and warnings for many areas at elevations above 1500 feet, as temperatures will drop throughout the day. In valley locations, we're looking at an entirely liquid precipitation event.

(Pivotal Weather)

Here's what radar looks like currently. Rain has begun in western New England, and it will become more widespread throughout the day. To examine the storm track, let's take a look at the GFS:

(Tropical Tidbits)

This one is taking a classic Nor'easter track, moving northeast up the Atlantic Coast, and stalling for a few days near Nantucket. 

For precipitation type, things will be very elevation dependent. Valley locations will likely see all rain, where the mountains of Vermont and New Hampshire could see 1+ feet of snow. Here's what the National Weather Service is thinking, and I think these numbers are reasonable.

(NWS Burlington)

Regardless of precipitation type, there is lots of moisture associated with this system. The National Weather Service's quantitative precipitation forecast (QPF) indicates that some areas will be receiving 3+ inches of total precipitation. This will not be a drought-buster given how dry we've been, but it will certainly be helpful. Here's where things stand now.

(NOAA/National Drought Mitigation Center)

Enjoy the storm!

Winter 2020-2021 Recap Part 1

Today and the past two days brought temperatures well into the 70s, with yesterday setting a new April 9 record of 76 °F. Based on 30 year climate normals, that is a high temperature that we should be seeing on June 15, not April 9. Entering the middle of April, it feels safe to say that winter weather in New England is complete. That is not to say that we may see another round of cold temperatures or some more snow, but any substantial winter-like weather has pretty much ended for the year. With that, I'd like to take a look at the weather that we saw this past winter. In part one of this multi-series post, I'll take a look at notable events in the first half of the winter.

Notable Events

December Nor'easter - From December 15-17, a crippling nor'easter impacted much of the Mid-Atlantic and Northeast. As a result of low pressure moving up the Atlantic coast, many areas saw over a foot of snow.

(NWS Eastern Region)

In the above figure, you can see where snow totals were most notable, in a stretch extending from Central Pennsylvania, through Central New York, and into Southern Vermont and New Hampshire. This was due to mesoscale banding that caused snowfall rates to reach >3 inches per hour at times. In each of those states, some regions observed over 40 inches of snow.

Christmas Day Rain and Warmth - After an impressive taste of winter the previous week with the aforementioned nor'easter, Christmas Day brought rain and record high temperatures to many locations in New England, destroying the snowpack that had built the previous week. Burlington, VT had a high temperature of 65 °F, surpassing the previous Christmas Day high temperature of 62 °F, set back in 1964.

Map for December 25, 2020 (NOAA)

As shown in the above map, the bulk of the precipitation occurred in areas west, with some locations seeing 2+ inches of rain.

At the start of the New Year, things became quiet. Here's a look at the January 4, 2021 snow depth in the Northeast, showing not much snow throughout the region.

(NOAA/NOHRSC)

Mid-January Snowstorm

After things were quiet for the start of 2021, we had a nice snowstorm on January 16. This one was fairly elevation dependent, with areas in the mountains seeing up to 20 inches of snow, and valley locations seeing virtually no snow.

Thank you for all of your reports! We were able to come up with a storm total snow map through 2 PM this afternoon. Additional accumulations will be possible across northern Vermont this afternoon. Visit https://t.co/bWrAqA6WUF for more info. #nywx #vtwx pic.twitter.com/2tZ1FVLdGx

— NWS Burlington (@NWSBurlington) January 17, 2021

On the back end of that storm, frigid air closed out the month of January, with temperatures in the single digits on most days and highs only surpassing 32 °F once.

(NOAA Regional Climate Centers/xmACIS)

That's it for the first post in a series of posts about winter 2020-2021 in New England. I'll have more in a future post.

 

BDL March Recap

I previously took a look at the March 2021 weather at BTV in Vermont. Now, let's examine what we saw at Bradley International Airport (BDL) in CT.

Temperatures

Like Vermont, Connecticut experienced much above normal temperatures this March. The average maximum temperature was 52.8 °F and the average minimum was 29.0 °F, 5.1 °F and 1.1 °F above the respective normal values. March's mean temperature was 40.9 °F, which is 3.1 °F above the normal value of 37.8 °F. March 2021 was the 19th warmest March on record at BTV, and it was actually cooler than March 2020, when the mean temperature was 42.8 °F and much cooler than 2012, when the mean average temperature was 47.7 °F.

(NOAA Regional Climate Centers/xmACIS)

We started the month on a cold note, reaching our lowest temperature of the month (13 °F) on the second day. After a normal to below normal stretch to start the moth, temperatures quickly took an upward trajectory, topping out at 77 °F on March 26, which was a record for that date.

The story is not much different for the rest of Connecticut, as above normal tempeatures were felt throughout the state.

(High Planes Regional Climate Center)

Precipitation

We fared a bit better for March precipitation at BDL than we did at BTV, though it was still a dry month. In total, we had 2.50 inches of precipitation, which is 1.12 inches less than the normal value of 3.62 inches and 69.06% of normal.

(NOAA Regional Climate Centers/xmACIS)

The above image shows how dry it was to start the month, and we didn't see any significant rainfall until the month's end.

As for snow, in a month where we'd normally see 6.4 inches of snow, we only received 0.1 inches this month.

April has been off to a warm start, and it's looking like it'll continue that way.

BTV March Recap

March brought us some pretty interesting weather here in Vermont - let's take a look at what we saw, focusing on Burlington International Airport (BTV).

Temperatures

March was much warmer than normal at BTV, with average maximum temperatures running 6.3 °F above normal (40.0 °F) and average minimum temperatures 2.0 °F above normal (22.0 °F). This left the mean average temperature of 35.1 °F to be 4.1 °F above the normal March mean temperature of 31.0 °F.

(NOAA Regional Climate Centers/xmACIS)

Although this month's warmth paled in comparison to the scorching March of 2012 (the highest point in the above figure), March 2021 was the 19th warmest March on record at BTV when considering mean daily temperatures. And when we consider mean maximum temperatures, it was the sixth warmest March

(NOAA Regional Climate Centers/xmACIS)

On a daily basis, March 2021was a bit of a roller-coaster month for temperatures at BTV. Our warmest day (the 25th) had a high temperature of 73 °F, and the temperature dropped down to 4 °F on the coldest day (the 2nd). The above figure shows how March temperatures this year took a very upward trajectory throughout the month. On March 11 and March 25, we set daily record high temperatures, at 64 °F and 73 °F, respectively. Also of note is that the temperature never dropped below 0 °F this March. In a normal BTV March, that would occur on 1.3 days.

While the much-above-normal temperatures were most apparent in Northwest Vermont (BTV's location) this March, almost the entire state saw above normal temperatures. The one exception was the Northeast Kingdom, which saw slightly below-normal temperatures.

(High Planes Regional Climate Center)

Precipitation

March 2021 was drier than normal at BTV, as less than half the normal precipitation fell. We received a total of 1.02 inches, when a normal March would have 2.22 inches of precipitation. The figure below gives you a sense of just how dry it was this March. For practically the first 25 days, we saw no rain or snow.

(NOAA Regional Climate Centers/xmACIS)

This March ranked as the 16th driest on record at BTV, and the lack of rain was not only noticed near Vermont's capital - if we look at a map of departure from normal precipitation, a similar story gets told, with the center of the state being the recipients of the least rain and snow when compared to normal.

(High Planes Regional Climate Center)

Snow

Based on the 1981-2010 climate normals, March is BTV's 4th snowiest month, and a normal March would bring 15.8 inches of snow. That certainly was not the case this year, as a measly 1.4 inches of snow fell.

(NOAA Regional Climate Centers/xmACIS)

The above plot shows just how poor the snowfall was when compared to a normal March (brown line) March 2018 (cyan) and March (2017). 

The little snow that we did see came at the start of the month. March 3 saw the largest snowfall, with 1.0 inches falling. That brought the BTV snow depth to 9 inches. However, the warm temperatures that we experienced this month quickly decimated the snow pack, and from March 12 onwards, there was no snow on the ground, although we did see a few flakes on March 29.

Recap

This March was characterized by warmth, dryness, and little snow at BTV. The weather put a quick end to winter conditions in Vermont. As we progress further into a the warmer months from a climatological standpoint, it'll be neat to see what the weather has in store.