Another weather pattern change 

Posted: 6:58 am Tuesday, August 14th, 2018

By Kirk Mellish

We’ve enjoyed an extended spell of rain-free weather with lower than normal humidity.

Even though the humidity will gradually increase, MOST of us will stay dry the next few days with below-normal odds of a thundershower.

This is thanks to a ridge of high pressure over us with a fairly dry Northwest flow aloft:

Screen Shot 2018-08-14 at 5.55.56 AM

However, the flow aloft starts to switch around with the ridge shifting east and a trough of low pressure to our west, giving us a Southwest flow to begin to increase humidity levels Wednesday/Thursday and beyond:

Screen Shot 2018-08-14 at 6.00.29 AM

As that southwest upper-level flow continues into the weekend and beyond the rain odds will go up as the humidity goes up. There will be upper-level disturbances (vorticity) embedded within the flow aloft and that energy will help bring back scattered thunderstorms Friday through next Wednesday:

Screen Shot 2018-08-14 at 6.07.04 AM

(Pivotal weather images)

The total “precipitable water” in the atmosphere increases appreciably between today and the weekend (browns are dry air, greens are moist air) from 0.76 to almost 2 inches by Sunday into next week:

Screen Shot 2018-08-14 at 6.11.13 AMScreen Shot 2018-08-14 at 6.13.07 AMScreen Shot 2018-08-14 at 6.14.58 AM

(Tropical tidbits images)

At the same time surface “dew point” (another measure of how moist or dry the air is) will rise through the 60s into the 70s so the humidity will go back up returning the “sticky” muggy feel starting Thursday and beyond.

Dew Point:

Screen Shot 2018-08-14 at 7.06.24 AM

All these moisture variables increase the likelihood of a shower or thunderstorm and the higher they go the more clouds and the more intense the rain falls and the heavier the amounts.

No washout days are foreseen at this point, just scattered coverage, mostly afternoon or evening. But an early morning or late night stray thundershower can’t be ruled out Friday-Wednesday.

Again though, the majority of us will stay dry Tuesday-Thursday and hot.

I am on Jury Duty in Cobb so when I am at work is day to day based on the whims of the court.

Follow me on Twitter @MellishMeterWSB.