Dry spells between heavy downpours 

Posted: 6:00 am Friday, May 18th, 2018

By Kirk Mellish

Rainfall the past two days has been highly variable, ranging from just a TRACE to 1.5 inches on average, with an isolated 4.6 inch total.

We will continue stuck in this soupy tropical air mass the next 5-10 days so no major change. Each day will be a little different in who gets the most sun and who gets the most rain or the strongest thunderstorm and who stays dry.

Due to the lack of an organized focusing mechanism that can be identified well in advance, the random nature of pop ups means there is no scientific basis to determine more than a few hours in advance where which area will be which on a given day. All the points I made in blogs the past two days still apply so read previous two posts if you haven’t already.

Unlike a typical forecast, in some cases for air mass thunderstorms they must be updated every 2-4 hours.

SURFACE WEATHER CHART FRIDAY:

Screen Shot 2018-05-18 at 5.32.40 AM

SURFACE WEATHER CHART SATURDAY:

Screen Shot 2018-05-18 at 5.33.44 AM

SURFACE WEATHER CHART SUNDAY:

Screen Shot 2018-05-18 at 5.34.04 AM

 

ESTIMATED RAINFALL AMOUNTS ON AVERAGE IN 24-HOUR INCREMENTS FRIDAY-SUNDAY:

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3-DAY ACCUMULATED RAIN AVERAGE ESTIMATE:

Screen Shot 2018-05-18 at 7.28.12 AM

This is not a situation for any day having the rain go on for hours. There is no way of knowing exactly when or where a shower or thunderstorm will pop up so there’s no way to give specific start and stop times for any given location.

There will be more dry hours than wet hours even where it rains. Some places will keep getting missed. Some areas will get a decent amount of sunshine at times, others just a little.

Like the past couple days amounts will not be even, some spots will get nothing other spots will get a deluge, this is why we forecast average amounts not amounts that apply to everyone across the Metro areas 12-18 counties, that’s NOT how weather works, but most people are smart enough to know that I hope.

On MOST days the chance of rain will go up starting with the lunch hour.

The heaviest rain and greatest coverage will come sometime in the window of 2pm to 11pm each day, although a shower before or after that time frame can’t be ruled out.

No widespread severe weather is expected but some place could get a strong gusty wind storm with small hail. As always all lightning is dangerous so if you hear thunder get inside a building or car.

I’ve explained in past blogs why thundershower forecasts of an “air mass” variety are different than other forecasts, I hope you were enlightened by them for ‘meteorology 101’. I am sure I’ll do a similar blog again in the future.

We also have to watch the Gulf and off the SE US coast this month as models keep suggesting a tropical system will try to form.

KATL_2018051800_min_max_16KATL_2018051800_eps_min_max_15

The GEFS looks too warm while the EPS looks too cool.

Follow me on Twitter @MellishMeterWSB for updates and more.

 

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