Kirk Mellish's Weather Commentary 

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Break in weather action may be in sight

  • 10:08 am Monday, July 16th, 2018 by Kirk Mellish

The “precipitable water” content of the air mass over us is around 2 inches, so the muggy high humidity is air you can wear. It is also fuel for heavy showers and strong thunderstorms with strong gusty winds, small hail and lots of frequent dangerous and destructive lightning. Coverage should go up today and tomorrow as a front and upper-level disturbance move in from the Northwest.

Dew points are in the 70s so we have very high relative humidity.

But more clouds than normal and a higher than normal rain chance are keeping high temperatures under control at 90 or lower. But [More]

Looking ahead with models

  • 8:10 am Tuesday, July 10th, 2018 by Kirk Mellish

We are heading toward the heart of summer based on climatology:

As the heat and humidity build back from time to time remember some car notes: Steering wheel can hit 180F in sun. Interior air temp even in a car with all windows OPEN in sun hits 100 in just 7 min! Closed window cars in sun get over 125 and breach 100 in under 5 minutes. These were tests with an outside temp of just 84!

Here is how a couple of the models are showing the rest of summer and start of Fall.

The soil moisture based CAS model from CPC [More]

4th of July week not so bad

  • 8:18 am Tuesday, July 3rd, 2018 by Kirk Mellish

We’ve had much worse weather for Fourth of July week in the past, running the gamut from unusually cloudy and stormy to insane heat and even somewhat coolish.

This year the week features fairly benign conditions compared to what is possible this time of year, and especially given the extreme heat and humidity that has hit to our West and up North even into Canada.

While Atlanta will not get any extreme heat, we will be more muggy than usual through Saturday.

Weak upper level low pressure over the Northern Gulf Coast near New Orleans is drifting West and another wave of low [More]

The ring of fire

  • 3:52 pm Thursday, June 28th, 2018 by Kirk Mellish

It’s not just a great Johnny Cash song.

One of the classic weather patterns known in synoptic meteorology in the summertime is known as the “ring of fire” and Northwest Flow Aloft.

It can impact just about any part of the country and usually moves around from the South to the North as we move from Spring to late Summer as the jet stream migrates toward Canada, but it sometimes dips back south or oozes West and East from time to time.

It’s called the ring of fire because the worst storms occur along the outer ring of a big hot air mass [More]

Severe weather

  • 12:06 pm Thursday, June 28th, 2018 by Kirk Mellish

A Severe Thunderstorm Watch is in effect for most of the Metro Atlanta area until 8pm, that means conditions in the atmosphere are favorable for additional severe storms and warnings.

The threat of a tornado is not zero but it is very low. But thunderstorm wind gusts to 70mph are possible in a few storms, along with hail up to 1-inch in diameter in the stronger storms.

In addition to damaging winds there is also a risk of flooding.

Not all of the storms will be severe, many will be ordinary. The worst of it will be shifting South and West of Atlanta [More]

Bad forecast Monday

  • 4:40 am Tuesday, June 26th, 2018 by Kirk Mellish

I often observed that some of my worst forecasts are on Mondays. Perhaps its the weekend “hangover” even if not the alcohol type. It’s just being a little less in touch with data from partial down-time on weekend, and of course in this case a Monday after a week of vacation.

Yesterday was definitely a case in point. It was a busted forecast on my part, I didn’t anticipate an organized squall line to form based on the overnight data available at the start of the day. Storms were in my forecast, but only of the hit and miss variety.

An area [More]

New weather trend coming

  • 6:59 am Thursday, June 14th, 2018 by Kirk Mellish

We’ve returned to a tropical air mass with more than usual cloud cover and more than usual coverage of showers and storms, something we’ve done three times already here in the spring and early summer.

While I can’t issue the all clear on rain or storm odds or give a completely sunny forecast, it does look like the trend is our friend the next 5-7 days, and MAYBE beyond.

Higher than normal moisture in the air and upper level low pressure, surface fronts or troughs, and bits of energy aloft have all conspired to give us our latest bout of unsettled weather.

Notice [More]

Shifting storm odds

  • 9:43 am Tuesday, June 12th, 2018 by Kirk Mellish

It’s that time of year when it’s rare to get a day with zero chance of rain or a thunderstorm or even a very low chance.

Today it looks like the highest threat will be gradually shifting south by late afternoon and evening:

AFTERNOON THUNDERSTORM COVERAGE:

THUNDERSTORM COVERAGE AFTER 8PM:

5-day forecast.

Thunderstorm chances change from one day to the next, and as I’ve written so many times in the past, UNLIKE other types of forecasts, thunderstorm forecasts in some patterns have to be updated every 3 or 4 hours.

Looks like a little hotter, drier and sunnier as we get into the weekend but [More]

Forecasting without computer models

  • 12:15 pm Wednesday, June 6th, 2018 by Kirk Mellish

Meteorologists look at synoptic charts for the position of upper-level ridges of high pressure and troughs of low pressure in the jet stream, both analysis (current data) and forecast projections from models of the future.

Because upper-level ridges and troughs go a long way in determining wet/cool and warm/dry areas.

However, research has shown we don’t have to rely just on computers. Patterns of ocean sea surface temperatures can signal ahead of the models where troughs and ridges will be favored due to energy exchanges between ocean and atmosphere. The same is true of dry areas and wet areas on land due [More]

Hurricane season projections

  • 5:30 pm Tuesday, June 5th, 2018 by Kirk Mellish

Now that we are in June tropical cyclone season is here, generally just called “hurricane season” running from June through November reaching a peak September 10th:

The most active season was 2005, during which 28 tropical cyclones formed, of which a record 15 became hurricanes. The least active season was 1914, with only one known tropical cyclone developing during that year.

We are in a transition in the Pacific Ocean pattern to an expected El Nino. El Nino usually acts to suppress the tropical cyclone season. However, its predictability in the spring is not very good. Therefore, the speed at which the El [More]

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