July 2015 Climate Data and Forecast Accuracy

July Recap

Temperatures and precipitation were above normal the past couple months and that trend continued in July. In fact, daily average temperatures were at or above normal on 16 consecutive, and 24 of 25, days after a cooler than normal week to start the month. Precipitation was well below normal with the exception of 2 days (the 3rd and 23rd) which produced  87% of the total monthly rainfall. Through July, Memphis International Airport has a year-to-date rainfall deficit of 2.64", or about 92% of normal.

On July 14th, a complex of severe thunderstorms swept through the metro, downing trees and power lines across southwest TN with wind speeds of 50-60 mph. An 87 mph peak gust was recorded in Atoka, TN. Over 30,000 MLGW utility customers lost power, which took over 3 days to fully restore. Earlier in the month, flash flooding occurred across the metro on the Independence Day weekend as rainfall totals of 3-5" were recorded across the area.

Precip totals for the period July 2-4, 2015. Flash flooding was common across the southern metro.

Memphis International Airport, Memphis, TN

Temperature
Average temperature: 84.5 degrees (1.8 degrees above average)
Average high temperature: 92.7 degrees (1.1 degrees above average)
Average low temperature: 76.4 degrees (2.6 degrees above average)
Warmest temperature: 99 degrees (20th, 29th)
Coolest temperature: 69 degrees (5th)
Records set or tied: 81 degrees (20th) - tied record for warmest minimum temp. 82 degrees (29th) - tied record for warmest minimum temp. The average minimum temperature for the month was 7th warmest on record. July 2015 was the 15th warmest July on record.
Comments: The first six days of the month were below average, then the rest of the month (except the 23rd which was 1 degree below average) featured above average temperatures. Only one day saw the low drop below 70 degrees (69 degrees on the 5th). Five days had low temperatures at or above 80 degrees.

Precipitation
Monthly total: 5.17" (0.58" above average)
Days with measurable precipitation: 9 (0.2 days above normal)
Wettest 24-hour period: 3.41" (2nd-3rd)
Total Snowfall: None
Records set or tied: 3.40" (3rd)
Comments: Over 4.5" of rain was recorded on just two days (3rd and 23rd). If those two days were discarded, it would have been the 7th driest July on record.

Miscellaneous
Peak wind: North/48 mph (14th)
Average wind: 6.6 mph
Average relative humidity: 69%
Average sky cover: 50%

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

Cirrus Weather Solutions / MemphisWeather.net, Bartlett, TN

Temperature
Average temperature: 83.0 degrees
Average high temperature: 92.3 degrees
Average low temperature: 74.0 degrees
Warmest temperature: 99.0 degrees (29th)
Coolest temperature: 65.1 degrees (31st)
Comments: None

Precipitation
Monthly total: 5.58" (automated rain gauge), 5.91" (manual CoCoRaHS rain gauge)
Days with measurable precipitation: 8
Wettest date: 3.04" (3rd) (via automated gauge)
Total Snowfall: None
Comments: None

Miscellaneous
Peak wind: West/35 mph (14th)
Average relative humidity: 79%

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

MWN Forecast Accuracy

MWN average temperature error: 1.58 degrees
MWN forecast temperatures within 2 degrees of actual: 80%
MWN average dewpoint error: 1.48 degrees
MWN forecast dewpoints within 2 degrees of actual: 80%

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

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Back to summer to start the week, then thunder arrives by mid-week

Although we enjoyed below average dewpoints to end last week, humidity levels are back near normal for summer with another hot day on tap tomorrow as highs reach the upper 90s. However, the oppressive heat will improve a bit as we head into Wednesday, with high pressure deteriorating and rain chances increasing. A pattern that favors chances for thunderstorms will persist through at least Friday before leading to a mainly dry and fairly comfortable weekend. Lets get into the details of the forecast below.

GFS modeled 500 mb (18,000') height anomalies, valid late Wednesday night. Lower than normal pressure (indicated by light blue) over the Mid-South indicates a low pressure disturbance over the area, which brings our t'storm chances.

As high pressure retreats on Wednesday, a mid-level shortwave (or area of lower pressure in the middle portions of the troposphere) and weak cold front will be the primary cause of rain chances for the latter portion of the work week. The mid-level feature in the atmosphere allows thunderstorms to more easily form during the heat of the day beginning Wednesday as it draws closer to the region. The strength of this shortwave will also lead to chances of thunderstorms at night (particularly on Wednesday night) providing enough lift to fuel some scattered storms even without the mid-day sun. The best chance of thunderstorms this week could be Wednesday night. Though severe weather is not expected to be widespread, a few strong storms are possible as the potent shortwave moves through.

A Marginal Risk (category 1/5) severe weather risk exists Wednesday into Wednesday night for the metro. Widespread severe weather is NOT anticipated at this time.

By Thursday, the disturbance will be exiting the region, but with the weak cold front near the area, scattered showers and thunderstorms will be possible Thursday and Friday before high pressure re-builds into the area heading into the weekend. The result will be slightly lower temperatures for the region from Thursday through Saturday. If you happen to get a thunderstorm during the daytime hours, you'll enjoy some relief from the heat, but also increased humidity.  Most of Saturday and Sunday look dry and fairly comfortable for early August, though temps start climbing again as we head into early next week.

You can check out the full MWN Forecast here or within the MWN mobile app which you can find links to below.

William Churchill
MWN Social Media Intern

Erik Proseus
MWN Meteorologist

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Follow MWN on Facebook, Twitter, and Google+
Visit MemphisWeather.net on the web or m.memphisweather.net on your mobile phone.
Download our iPhone or Android apps, featuring StormWatch+ severe weather alerts!