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.

April Fools Snowstorm

March was a bust of a moth if you live in New England and like snow. Boston only saw 0.1 inches when they'd normally have 7.8 inches, and Burlington only had 1.4 inches, much less than its normal 15.8.

April will look to rewrite that script right off the bat for parts of northern New England and upstate New York, as an April Fools Day snowstorm is forecast. Winter storm warnings and advisories are in effect for much of the Northeast from late Wednesday night into Thursday night.

(Pivotal Weather)

Here's what we should expect:

(Tropical Tidbits)

For the last day of March, southerly flow will cause temperatures to rise into the 60s. That will change after a low pressure system tracks up the Atlantic coast and a fold front moves through, causing temperatures to drop sharply and the wind direction to shift to from the north. See if you can pick out the cold front in this GIF.

(Tropical Tidbits)

Despite temperatures being around 60 °F, diurnal cooling and the cold front will enable temperatures to drop below freezing overnight. Precipitation will begin as rain and then change over to snow overnight on Thursday night, with higher elevation areas and places further west (that'll see the cold front move through earlier on) favored for snowfall.  Here is a NWS snowfall onset map.  Notice how western areas and high elevation areas will be favored for an earlier start-time of the snow.

(NWS Burlington)

The snow will end on Thursday evening with northern areas seeing snowfall stick around latest. Here is what the National Weather Service in Burlington thinks for snowfall totals.

(NWS Burlington)

Based on the models I've examined and the reading I've done, I think some of these number are a tad overdone, and I'd expect that snowfall will be slightly less. The March/April sun angle is quite high, causing the ground to heat up pretty easily. The ground is warm right now, and snow that does fall will have difficulty sticking. Also, temperatures will be in the 60s today, so the atmosphere needs to do some real work to cool down after the cold front moves through to enable snowflake production. For the most part, I'd bump the numbers in the above map down by an inch or two. I do think we'll see flakes, though.

Enjoy the April snow!

What Happened Yesterday

When I committed to attend Middlebury College, I did not expect that there would be a tornado in my college town during my time here. Especially in March. That happened yesterday.

A high CAPE, low shear setup spawned an EF-1 tornado just northeast of of downtown Middlebury.

(NWS Burlington)

Unfortunately, this one was not National Weather Service warned, and two injuries were suffered. Radar imagery showed a clear tornado debris signature, and fortunately the tornado was not more damaging. Here is the path of the tornado. We can see just how close it was to downtown.

The tornado started less than 1.5 miles from downtown and less than 2 miles from the Middlebury College campus. Per the National Weather Service storm survey, the width of the path was 75 yards, and the path length was one mile. This was an EF-1 tornado with a maximum wind speed of 110 mph, meaning that it had wind speeds just below the EF-2 category, which spans from 111 mph to 135 mph. The time of the event was estimated to be from 1:50 to 1:55 P.M.

The tornado damaged powerlines and ripped through numerous trees. On Painter Road, a house was almost completely destroyed, and 2 were injured.

(Tyler Jankoski)

I went over to Painter Road yesterday to examine some of the damage. Unfortunately, I wasn't allowed to proceed too far on the road since cleanup crews were busy at work. Here's some photos I took:

Thankfully, no lives were lost in this unwarned event.

Since 1950, there have been 47 tornados in Vermont, and only one occurred in March before this one. The last one was in 2019. In a future post, I plan to take a look at tornado climatology in Vermont.

Inversion Morning!

It was exciting to take a look at some of the observations this morning, as there was quite a temperature inversion in place. Without too much exciting weather to talk about in New England today, this was neat to take a look at. 

Take a look at this morning's observations for New Hampshire:

(NWS Gray)

You'll notice that Mt. Washington's summit was the warmest location in NH, with a temperature of 34 °F. Portsmouth, which is located on the Atlantic Ocean, was 6 °F colder than the summit of the Northeast's tallest mountain! I also found this temperature profile on the Mt. Washington Auto Road quite neat:

(Mt. Washington Observatory)

At an elevation of 1600', the temperature was 29.4 °F, and if you hiked up to 4000', the temperature would have jumped over 20 °F! Here's a beautiful sounding from the morning for Northern New Hampshire.

(Tropical Tidbits)

Notice how the red temperature line moves sharply to the right near the surface of the Earth, meaning that the temperature is warming quickly as elevation increases.

Because it was so clear and sunny last night, we had lots of radiational cooling from near the surface of the Earth, meaning that Earth's surface could emit heat more readily than higher locations. As a result, we had this inversion, which made for some neat weather this morning!

Vernal Equinox

In my book, spring started a few weeks ago on March 1, with the onset of Meteorological Spring. Many, however, would say that today is the first day of spring, as it is the Vernal Equinox.

The reason that we have equinoxes is because of Earth's tilt, which is a 23.5° tilt. As Earth orbits the sun, it receives direct sunlight at different portions of its sphere at different times of the year. At the Vernal Equinox (which can be thought of as a position on Earth's orbit), the equator receives direct sunlight at solar noon. Likewise, that is the case on the Autumnal Equinox.

(NWS)

In the above image, notice how the tilt of the Earth is responsible for why we have solstices and equinoxes (and season). Different latitudes receive the most direct sunlight at different time of the year.

Thankfully, the varying nature of the sunlight that we receive at different times of the year gives us exciting, variable weather to talk about.

Enjoy the warmer weather this weekend!

Warmup Soon

I haven't been able to post over the past week, as I've been quite busy with school and recovering from a dislocated shoulder in a ski crash. Aside from the arctic front that brought frigid temperatures and brisk winds earlier this week, the weather has remained mostly benign and spring-like. 

After high pressure from the north moves ushers in some cooler air for Friday, we're set to experience a major warmup for the weekend and the start of the next work week here in New England. Here is a look at 850 mb temperature anomalies for Monday morning.

(Tropical Tidbits)

While the South remains on the cooler side, we could be looking at temperatures in the 60s, which is about 10 °F above normal this year. That warmth sticks around for a bit. The CPC 6-10 day and 8-14 day temperature outlooks show high probabilities for above normal temperatures over these periods.

(NOAA/CPC)

(NOAA/CPC)

March seems to be leaving like a lamb this year, and winter weather seems complete.

BDL February Recap

Today will be an absolutely spectacular day here in New England - get out and enjoy it!

With not too much exciting weather to talk about in the next few days, I wanted to do one more February recap - this one for Bradley International Airport (BDL).

Temperatures

For February at BDL, the average maximum temperature was 35.2 °F, when the normal maximum is 38.5 °F, while the average minimum was 21.9 °F, when the normal minimum is 20.9 °F. So maximum temperatures were well below normal (3.3 °F) while minimum temperatures were a bit above normal (1.0 °F). I think this observation speaks to the fact that temperatures were fairly moderated this February, with no major heat waves or cold spells. The following temperature graph shows that daily temperatures mostly fell within the "normal" brown zone.

(NOAA Regional Climate Centers/xmACIS)

Overall, the mean daily temperature was 28.6 °F, giving a -1.1 °F temperature departure from the normal February value of 29.7 °F.

We saw 12 days where the maximum temperature was below 32 °F and 28 days where the minimum temperature was below 32 °F. These are both values above normal. The temperature never dipped below zero this February, which would happen on 0.6 days in a "normal" February at BDL.

Our highest temperature at BDL this February was 48 °F on the 24th - last year, we hit 63 °F. Overall, this was a cooler-than-normal month, without any crippling cold spells or drastic thaws.

Precipitation

BDL had 3.35 inches of total precipitation this February, which is more than the normal value of 2.89 inches by 0.46 inches. BDL's greatest total precipitation day was 1.23 inches, on February 1.

For snowfall, we saw 20.8 inches of snow with a 2.10 inch liquid equivalent. This was more total snowfall than an average February by 9.8 inches. Our largest storm came on the first of the month, when 11.7 inches fell. And on 13 days, there was at least a trace of snow at BDL.

Overall, it was nice to see a cooler and snowier than normal month for a change. We'll see what March has in store!

Major Changes to Come

Take a good look at the current snow depth and snow water equivalent (SWE) maps for the Northeast.

Snow Depth (NOAA/NOHRSC)

SWE (NOAA/NOHRSC)

By the weekend, these maps won't look very much like they do right now. Why is that? Well, a big change is set to come for our weather, and we can expect our first true spring-like weather later this week.

By Tuesday evening, a ridge will build in our region, causing flow from the south, which will bring warmer temperatures and air from the south. On Tuesday evening, we can see northerly flow on the GFS, but that takes a quick turn to southwest by Wednesday.

Tuesday Evening (Tropical Tidbits)

Wednesday (Tropical Tidbits)

As a result of the changing flow, temperatures will be much above normal by Thursday, and they'll stay that way until the weekend. Here's the GFS 850 mb temperature anomaly map for Thursday. Notice that temperatures at that level of the atmosphere will be much above normal.

(Tropical Tidbits)

What does this mean for what we can expect on the surface? I'd expect temperatures in the low 50s for northern New England and the 60s for the south. After a winter with few true thaws, that will certainly feel nice for those that are ready for spring.

(Tropical Tidbits)

Fortunately, for our snowpack, there doesn't look to be any substantial chances for precipitation associated with this warmer weather. Areas south and in the valleys where SWE and snowpack temperature are lower will certainly lose a significant amount of snow, but I'd imagine the deep snowpack and the cooler snowpack temperature in interior mountain areas will be able to withstand some of these high temperatures.

Enjoy the warm weather!