Sunday, August 9, 2020

July 2020 Climate Data for Memphis, TN

July Climate Recap

A string of cooler than average months ended in July as temperatures crept back above normal. July's heat was not only above average, but very persistent. Every day during the month reached at least 89° and only two days failed to reach 90°, a feat only reached or eclipsed in three previous years (1954, 1993, 2010). In addition, there was little relief at night as the low temperature never dropped below 71°. This record has only been achieved in eight previous Julys. most recently 2016. Precipitation for the month totaled less than two inches despite some areas receiving much more rain due to the nature of scattered summertime thunderstorms.

Severe weather was very limited in July. As is typical, summertime thunderstorms occasionally produce limited reports of damaging wind gusts. Wind damage in the form of tree and power line damage was reported on July 1 in the Millington area and on the 16th in northern Crittenden County. Only a few Severe Thunderstorm and Flash Flood Warnings were issued over the course of the month.

Memphis International Airport, Memphis, TN

Average temperature: 84.1 degrees (1.4 degrees above average) 
Average high temperature: 93.0 degrees (1.4 degrees above average) 
Average low temperature: 75.3 degrees (1.5 degrees above average) 
Warmest temperature: 97 degrees (20th) 
Coolest temperature: 71 degrees (1st) 
Heating Degrees Days: 0
Cooling Degree Days: 603 (54 above average) 
Records set or tied: None 
Comments: July 2020 ended in the top 10% of hottest Julys on record in Memphis, ranking #18. The high temperature reached 90 degrees every day except two, and on those two the high was 89 degrees. Only five years in 146 years of record keeping had more 90-degree days in July.

Monthly total: 1.73" (2.86" below average) 
Days with measurable precipitation: 14 (5.2 days above average) 
Wettest 24-hour period: 0.44" (28th) 
Snowfall: None 
Records set or tied: None 
Comments: July 2020 ....

Peak wind: Northwest/47 mph (1st) 
Average wind: 6.2 mph 
Average relative humidity: 71% 
Average sky cover: 50% 

 Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions /, Bartlett, TN

Average temperature: 81.9 degrees 
Average high temperature: 93.7  degrees 
Average low temperature: 73.1 degrees 
Warmest temperature: 99.2 degrees (20th) 
Coolest temperature: 68.2 degrees (13th) 
Comments: None 

Monthly total: 2.18" (automated rain gauge), 2.07" (manual CoCoRaHS rain gauge) 
Days with measurable precipitation: 12 
Wettest date: 0.67" (1st) (via automated gauge) 
Snowfall: None 
Comments: None 

Peak wind: Northwest/27 mph (1st)
Average relative humidity: 81% 
Average barometric pressure: 29.94 in. Hg
Comments: None

Click here for a daily statistical recap for Bartlett, TN.

MWN Forecast Accuracy

MWN average temperature error: 1.32 degrees 
MWN forecast temperatures within 2 degrees of actual: 87% 
MWN average dewpoint error: 1.60 degrees 
MWN forecast dewpoints within 2 degrees of actual: 81% 

MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). Historical accuracy statistics can be found here.

Climate Outlook - August 2020

The August climate outlook for the United States from the Climate Prediction Center is shown below. Above average temperatures are forecast for areas west of the Rocky Mountains and the east coast and New England. Cooler than average temperatures are forecast for portions of the central Plains into the Mid-South. Odds favor below average temperatures for Memphis (42%) versus only a 25% chance of above average temperatures. Memphis' average temperatures for August is 82.0 degrees.

Wetter than normal weather is expected in the northern Plains, as well as the eastern U.S, particularly the Mid-Atlantic coast. Drier than average weather is forecast for the desert southwest and Rocky Mountains into the Pacific Northwest. For Memphis, odds favor average rainfall, which historically averages only 2.88 inches in August. 

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Saturday, August 1, 2020

Notes on July heat, plus a look ahead at pleasant August conditions!

Looking back

For those of you who thought July was hot - you're right! But July is climatologically the hottest month of the year (just barely edging out August). So what made July 2020 different? Was it just our continuing intolerance for more discouraging news, or is there something more to it? It may be a bit of both. Here are some facts.

While July 2020 was indeed hot (averaging about 1.5 degrees above a normal July), the main issue was the persistent heat. Check this out: Memphis hit 90° every day except two in July, and those two days it was 89°! How often does the high temperature reach at least 89° every day in July? Not often! There are only four years out of 146 in Memphis weather records in which every July day reached at least 89°. The last time was 2010. So the heat was persistent

How about the overnight lows? Well, as it turns out, we never dropped into the 60s in July overnight. In fact, all but one morning low was at or above 73° (and the one 71° low we had was on the 1st)! There have only been four years on record in which the low was at or above 73° every day or all but one day. So we also had very little relief from the heat at night.

Temperature anomaly (difference from average) for the U.S. in July. (WeatherBell)

With typical to slightly above average humidity during the month, heat indices eclipsed 100° almost every day as well and touched the danger level of 105° on several days. And while some lucky folks got several days of afternoon thunderstorms, many did not. The airport, and many other places, left the month with less than two inches of total rainfall and in "abnormally dry" condition. I'm OK putting July 2020 in the rearview mirror!

Looking ahead

If you were out last evening, you may have started to notice a change in the air. A pleasant breeze and slightly lower humidity made for a nice evening. This morning, clouds linger over the Mid-South with patchy light rain as low pressure spins over the region. In the wake of a cold front today, and with clouds lingering, we're set for our coolest day since June 26 with highs only near 80° and a pleasant breeze continuing! 

"Day cloud phase" satellite imagery from GOES-16 on Saturday morning shows a swirl of low clouds (in blues/greens) over the area, representative of low pressure. As long as low clouds stick around, temperatures remain in the 70s. (College of DuPage)

But is this one day of relief or a trend? Fortunately, the latter, though not quite to this extent. A large and persistent trough of low pressure will set up over the northeast U.S. but it's effects will cover a large portion of the eastern half of the country. With "northwest flow" set up over the Mid-South for the next week, we're in for less humid days, just spotty rainfall chances, and below average temperatures!

A trough of low pressure at the mid levels (~18,000 feet up) is indicated by the "valley" in the pressure lines over the Midwest and Mississippi Valley. The blue shading shows departure from normal for this time of year. Blue = cool! This map shows the average pressure pattern over the next 5 days from the European ensemble model. (WeatherBell)

This weekend will be a transition to that pattern with warmer weather, but still low humidity and some clouds, on Sunday as highs reach 87° following a morning low in the mid to upper 60s. A reinforcing cold front arrives Monday with a small chance of rain and similar temperatures to Sunday.  Another small rain chance moves in Tuesday with an upper level disturbance rotating around the parent trough. That will knock highs down a couple more degrees, perhaps only the lower 80s north of the city and mid 80s in Memphis and north MS. 

Similar to the map above, the 5-day average temperature anomalies from the European ensemble model shows well below average temperatures the next 5 days over the center of the country. For Memphis, the average temperature departure from normal is 5-6° F, enough to make for pleasant August days! (WeatherBell)

Partly cloudy conditions are expected the rest of the week with highs in the mid 80s, warming back towards 90 by the end of the week, but still pleasant humidity levels. I think you'll especially like the mid 60s every morning as you drink the first cup of coffee on the patio, as well as 70s in the late evenings for a nice walk!

Further into the future

Starting next weekend, it appears we return to a more average August setup with highs back in the low 90s, lows in the 70s, and rain chances re-emerging occasionally. Overall, though, it does not currently appear that the second week of August will see above average, or excessive, heat.

The temperature outlook from the Climate Prediction Center for the second week of August. Temperatures in the Mid-South should be near to slightly below normal. (via PivotalWx)

Erik Proseus
MWN Meteorologist

Follow MWN on Facebook and Twitter for routine updates and the latest info!
Complete MWN Forecast: on the mobile web or via the MWN mobile app
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!
MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder