The dog days have arrived! Rain chances heading into the weekend

Summer has definitely arrived in the Mid-South as temperatures are now consistently rising into the 90s each day. We’ve also seen dewpoints rise to mid-summer levels, pushing the heat index above 100 degrees each afternoon. Be sure you are taking precautions against the heat – drinking water, checking on the young and old, and avoiding it if possible!

(A side note: today is the 37th anniversary of the hottest day on record in Memphis! July 13, 1980 saw the mercury rise to 108 degrees and was smack in the middle of the longest stretch of 100-degree days the city has ever seen, reaching 15 days!)

With the increased heat and humidity came a few popcorn showers the past couple of days. Unfortunately (if you want dry weather a little longer), rain chances will increase even further heading into the weekend as a front sags south. An upper level trough develops over the eastern U.S. in response to a building ridge of high pressure to the west, placing the region in northwest flow that promotes the passage of upper level disturbances. All of this adds up to: 1) slightly cooler temps due to increased cloud cover, 2) continuing high humidity, 3) higher rain chances, but 4) “marginal” severe weather chances.

The surface map for Friday evening shows high pressure over the Midwest and a front separating that airmass from warm, humid air to the south. The front will move south this weekend then wash out over the area by Sunday. (NOAA/NWS)
The upper level weather pattern this weekend features a strong ridge of high pressure over the western U.S. and a trough over the east, which places the Mid-South in northwest flow (wind following the arrows from northwest to southeast), meaning increased rain chances. (NOAA/NWS)

A Marginal Risk of a few severe storms exists on Friday across west TN and northern AR, according to the Storm Prediction Center. A few storms late in the day could contain strong wind gusts. (NOAA/SPC)

For those trying to plan outdoor events, I believe the best chance of thunderstorms, when a few could contain gusty wind as represented by the level 1 “Marginal Risk” of severe weather donated above, will be late Friday afternoon into the evening, and mainly north of the city. As shown by the afternoon run of the high-resolution NAM model below, an area of storms may fire up to our north and head towards the Memphis area late in the afternoon, but this model believes it could quickly fall apart heading into the evening.

The afternoon run of the NAM3 model from 1pm Friday to 1am Saturday shows a potential line of storms dropping towards the metro but falling apart as it gets close. Have a backup plan for any outdoor activities during the PM hours Friday.

Saturday could also see scattered showers and thunderstorms, but the highest likelihood will be during peak heating roughly south of I-40, or mainly north MS. Don’t plan any outdoor activities the next couple of days without a “plan B” however. By Sunday, we should see a more northerly component to the wind as the front washes out just to our south, resulting in a low chance of precipitation and perhaps SLIGHTLY lower dewpoints. Temperatures this weekend will likely peak near 90 degrees each day.

As we head into next week, indications are that the ridge to our west shown in the upper level map above will build east, suppressing precipitation chances and causing temperatures to rise once again, back into the lower to mid 90s. More summertime weather as we work our way through the “dog days!” For the routinely updated, human-generated MWN Forecast, check out our mobile apps linked below or click here.

Erik Proseus
MWN Meteorologist

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

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