Joe’s Weather Blog: 2 Fronts…one weak and one strong (FRI-9/17)

Weather

It’s going to be another hot and somewhat humid day in the area with dew points well into the 60s and plenty of sunshine. A weak front…more or less a wind shift really…will move into the area this evening and that may create some scattered storms in parts of the area. There is a stronger front that I’ve written about all week that will move in later Monday and that front has much better potential of creating at least some widespread rain with various amounts expected.

We’re coming to the time of the year where more fronts come through the Plains. As the jet stream starts it’s seasonal strengthening thanks to stronger temperature gradients developing aloft. The weakening sun and fewer daylight hours expand from the northern hemisphere southwards…while at the same time the warmth persists down towards the equator. As the contrasts strengthen…the jet stream strengthens too and gets more wavy. This creates fronts and storms…and voila we get more active weather.

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Forecast:

Today: Turning partly cloudy with scattered storms possible after 4PM or so. The chances persist through 9PM. Not for all. Highs in the upper 80s

Tonight: Variable clouds and mild with lows in the upper 60s

Saturday: Clearing out and warm with highs in the mid 80s

Sunday: Hotter with highs in the upper 80s

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Discussion:

As the seasons transition from summer to fall…our weather changes. The fronts get stronger and the air masses undergo bigger changes. In my opinion the best time of the year for weather is roughly now through mid October.

Rain can vary, as it usually does from not getting much to getting a lot. It can be very haphazard in terms of amounts. We’ve had wet falls and dry falls. These last 30 days or so have been generally dry though, punctuated by some decent rains.

Drought conditions are expending and developing across the southern/western Plains to some extent.

The front today is that is in the Plains is actually a decent front. Temperatures behind it have dropped into the 40s while ahead of it it’s near 70.

The push to the front though will weaken as the day moves along but it should still be enough to get towards I-70 by later today. So a front coming into the dew points in the mid 60s or so and temperatures in the upper 80s…there should be some decent instability building.

Model data shows this…especially north and west of the I-35 corridor.

Notice the waning instability S/E of KC. Sort of a tell that whatever storms develop may struggle to make it to areas farther south of US 50. The morning run of the HRRR model shows this.

For timing…18Z is 1PM…21Z is 4PM…0Z is 7PM and 3Z is 10PM

The animation above goes from 1PM to 10PM.

So some activity is expected but not a ton at this point. We’ll watch this as things develop this afternoon. As mentioned yesterday this may affect some of the high school games tonight.

The cooler air mass this morning across the Plains…where Nebraska is in the 40s this morning will struggle though to push southwards…but it is a sign of things to come down the road. Below are the 8:30 temperatures.

So tomorrow is another warmish day with above average highs. Average during this time of the year is close to 79° or so. We’ll be above that. Then in Sunday with more of a south wind developing we go right back into the “hotter” air.

Monday we start in the hotter air…but a seasonably strong cold front will come into the area Monday night. That changes the air mass because the push to this cooler air mass will be stronger.

So we go from this air mass at around 3000 feet (temperatures are in °C)…

4PM Monday

To this…

10AM Tuesday.

That’s a drop from the upper 70s (at that level) to the lower 50s at that level.

Good drop there and a good drop at the surface…plus add in some rain cooled air from Monday night…and voila…a cooler more fall-like day for Tuesday (the last day of summer).

The 1st day of fall looks to be cool in the morning. Near 50 with 40s in spots…and mild in the afternoon as some really nice weather settles in.

The cool shot of air coming though only lasts for about 48 hours before a moderating/warming trend settles back in heading into next weekend.

There aren’t a lot of signals for rain after Monday night. So hopefully we get 1/4-1″ of moisture from this because after that…not looking so great heading into early October as a matter of fact the 10 day rainfall anomaly ending on 10/2 shows this.

That’s dry. In late September and October we also see decreasing monthly rain totals on average heading into the winter season. During that span we average about 1.1″ every 10 days or so…

OK that’s it for today. I’ll be taking some time off next week but will get a blog or two out for you.

The feature photo comes from William Johnson of the moon from last night.

-Waxing Gibbous Phase-(83.3% Illuminated)
The current moon phase for today is the Waxing Gibbous phase. This is the phase where the moon is more than 50% illuminated but has not yet reached 100% illumination (which would be a Full Moon).
-Bates City, Missouri-
9-16-2021

Joe

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