Tennessee Weather Forum

Weather News and Websites => Weather News and Research => Topic started by: Clay on May 09, 2021, 11:36:33 AM

Title: Updated NWS Climate Norms for TN (1991-2020)
Post by: Clay on May 09, 2021, 11:36:33 AM
The new NWS climate numbers are in. OHX prepared nice graphics denoting the changes but also included the rest of TN. You can look for yourself at the link at the bottom.   

(https://www.weather.gov/images/ohx/climate/BNA_19912020newclimatenormals.png)

Memphis 2020 climate data (vs 2010):
Avg. Annual High Temp: 73.0F (+.5F)
Avg. Annual Low Temp: 53.8F (+.2F)
Avg. Annual Temperature: 63.4F (+.4F)
Avg. Annual Precipitation: 54.94" (+1.26")
Avg. Annual Snowfall: 2.7" (-1.1")

Knoxville 2020 climate data (vs 2010):
Avg. Annual High Temp: 70.0F (+.4F)
Avg. Annual Low Temp: 49.1F (+.3F)
Avg. Annual Temperature: 59.6F (+.4F)
Avg. Annual Precipitation: 51.93" (+4.07")
Avg. Annual Snowfall: 4.6" (-1.9")

Chattanooga 2020 climate data (vs 2010):
Avg. Annual High Temp: 72.2F (+.5F)
Avg. Annual Low Temp: 51.5F (+1.4F)
Avg. Annual Temperature: 61.9F (+1.0F)
Avg. Annual Precipitation: 55.00" (+2.52")
Avg. Annual Snowfall: 3.6" (-.3")

(https://www.weather.gov/images/ohx/climate/CKV_19912020newclimatenormals.png)

(https://www.weather.gov/images/ohx/climate/CSV_19912020newclimatenormals.png)

I plan on adding more TN cities when I have time.
https://www.ncei.noaa.gov/access/us-climate-normals/ (https://www.ncei.noaa.gov/access/us-climate-normals/)
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: Flash on May 09, 2021, 12:10:03 PM
The new NWS climate numbers are in. OHX prepared nice graphics denoting the changes but also included the rest of TN. You can look for yourself at the link at the bottom.   

(https://www.weather.gov/images/ohx/climate/BNA_19912020newclimatenormals.png)

Memphis 2020 climate data (vs 2010):
Avg. Annual High Temp: 73.0F (+.5F)
Avg. Annual Low Temp: 53.8F (+.2F)
Avg. Annual Temperature: 63.4F (+.4F)
Avg. Annual Precipitation: 54.94" (+1.26")
Avg. Annual Snowfall: 2.7" (-1.1")

Knoxville 2020 climate data (vs 2010):
Avg. Annual High Temp: 70.0F (+.4F)
Avg. Annual Low Temp: 49.1F (+.3F)
Avg. Annual Temperature: 59.6F (+.4F)
Avg. Annual Precipitation: 51.93" (+4.07")
Avg. Annual Snowfall: 4.6" (-1.9")

Chattanooga 2020 climate data (vs 2010):
Avg. Annual High Temp: 72.2F (+.5F)
Avg. Annual Low Temp: 51.5F (+1.4F)
Avg. Annual Temperature: 61.9F (+1.0F)
Avg. Annual Precipitation: 55.00" (+2.52")
Avg. Annual Snowfall: 3.6" (-.3")

(https://www.weather.gov/images/ohx/climate/CKV_19912020newclimatenormals.png)

(https://www.weather.gov/images/ohx/climate/CSV_19912020newclimatenormals.png)

I plan on adding more TN cities when I have time.
https://www.ncei.noaa.gov/access/us-climate-normals/ (https://www.ncei.noaa.gov/access/us-climate-normals/)

Thanks for sharing this, Clay. You can definitely see that OBX UHI effect flexing its muscle in that graphic. As for secondary surprises...it's interesting the amount of snow days did not decrease as precip ops steadily increased. Additionally, I would have also assumed the greater max temp departure would have been reflected in the lows, not highs.
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: Clay on May 10, 2021, 06:43:43 AM
Thanks for sharing this, Clay. You can definitely see that OBX UHI effect flexing its muscle in that graphic. As for secondary surprises...it's interesting the amount of snow days did not decrease as precip ops steadily increased. Additionally, I would have also assumed the greater max temp departure would have been reflected in the lows, not highs.
For me, it's Knoxville's seasonal snowfall slipping behind Nashville.
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: Thundersnow on May 10, 2021, 08:10:29 AM
The numbers tell the picture.

So, Nashville has an annual snowfall average of 4.7" now.

I distinctly remember when it was 11" prior to adulthood. That's a pretty major drop in 30 years... on the order of we get less than half the snowfall we once did.
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: Bruce on May 10, 2021, 08:33:54 AM
The numbers tell the picture.

So, Nashville has an annual snowfall average of 4.7" now.

I distinctly remember when it was 11" prior to adulthood. That's a pretty major drop in 30 years... on the order of we get less than half the snowfall we once did.
i can remember Jackson average nearly 8 .5 yearly snowfall my childhood . Sadly it’s roughly just over four now ...
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: dwagner88 on May 11, 2021, 10:32:11 PM
Chattanooga’s snowfall drop doesn’t seem quite so bad on the surface, but barring some really amazing winters in the 2020’s, it’s going to fall off a cliff once the Superstorm drops off the averages in 2031. I won’t be surprised to see it drop below 2”.
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: Curt on May 12, 2021, 05:05:59 PM
Chattanooga’s snowfall drop doesn’t seem quite so bad on the surface, but barring some really amazing winters in the 2020’s, it’s going to fall off a cliff once the Superstorm drops off the averages in 2031. I won’t be surprised to see it drop below 2”.

Memphis Intl probably will start going up once the abysmal '90s drop off.

By decade:
1980's-->55 inches
1990's--> 12 inches
2000's--> 29 inches
2010's--> 27 inches
2020's-->10 inches and 9 more years to add! My guess is.. even with the new seasonal normals, this decade will be the best for Memphis since the 1980's. And also, Memphis Intl reports less snow than other reporting locations in the metro area, most notably MEG.

What's missing to me are having occasional blockbuster winters with large snowfall totals as in the 1980's. Without those, its just a bunch of nickle and dime events. But for here, the 1990's had the least amount of snowfall I could find of ANY decade. Even with a few dud winters, the trend here started upwards in the mid 2000's. And while February was a generational event in terms of cold and 3 legit winter storms within one week, it really wasn't over the top like Little Rock in terms of overall total snow. Don't get me wrong, having snow on the ground for a week and at times- a foot of it- was a trend setter. WE wont see that kind of prolonged cold in my lifetime anyways.

Why the sudden downturn in the 1990's and a slow re-build in snowfall? That's a loaded question BUT we do know the AMO and PDO flipped in the 1990's- and when both are positive, past records indicate less snowfall than when negative- esp the AMO. For now the PDO has flipped back negative and the AMO is still positive but most likely on borrowed time. When it does, I would gamble on more snow and cold that we have been accustomed to in the 1990-2020 period- even if you believe in global warming.
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: Clay on May 13, 2021, 12:20:41 PM
Is there a reason we don't use median snowfall rather than mean? Seems like a better predictor especially in subtropical climates with large yearly variation.
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: schneitzeit on July 27, 2021, 11:21:40 AM
Possible correlation between increasing precipitation and deceleration of temperature increase in the Southern U.S.

[attachimg=1]

[attachimg=2]
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: Thundersnow on July 27, 2021, 01:57:58 PM
I assume that shows how atmospheric moisture and precipitation are a limiting factor or offer "resistance" to temperature rises.
Title: Re: Updated NWS Climate Norms for TN (1991-2020)
Post by: StormNine on July 27, 2021, 06:04:29 PM
I assume that shows how atmospheric moisture and precipitation are a limiting factor or offer "resistance" to temperature rises.

I would say probably a combination of two things

1) Increased moisture that is preventing as much mixing especially in the summertime and therefore flatlining and in some places actually decreasing the amount of extremely hot summer days. 

2) The tendency for powerful ridges of high pressure out west (+PNA) ish patterns leading the heat to focus that way.

Also oceans are absorbing a large deal of the excess heat because of their surface area so we may be seeing that effect as we see areas along the coast like South Florida are much warmer than say Missouri.