Coolest Low Temperature in Four Months

Posted Thursday, September 7th, covering September 6th:

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A heron enjoys a stroll at the Baker Wetlands just south of town Thursday evening.   All the images on this post were taken late Thursday, September 6th, 2017.

Yesterday, the morning low temperature at the Lawrence Airport was 43 degrees, 16 degrees below the normal low for the date and the coolest since May 13, or in more than 16 weeks.  The high temperature was 75, which was 10 degrees below the normal high for the date of 85.  This resulted in a mean temperature for the day of 59 (the average of the 24-hour high and low), which was 13 degrees below the normal mean temperature for September 6.

A year ago on September 6,  the high was 91 and the low 74 with a mean temperature for the day 11 degrees above normal.

This morning the temperature at the airport at 7 AM today (and the low so far) was almost as cool with a reading of 44.

At my residence in southwest Lawrence, the mean temperature yesterday was 63, some 4 degrees warmer than the airport, with a high of 78 and low of 48.  This morning my low temperature was 50.

This difference at least partially points to the cooler location of the airport than much of the city proper, as the airport lies on the lower-elevation and flat Kansas River floodplain.  On relatively calm nights with strong radiational cooling of boundary layer (or near-the-surface) air,  such as the last few nights, cooler air will drain into ravines and drainages and then flow downward like so much water and pool on the floodplain. This results in significantly cooler minimum temperatures at such lower elevation areas than surrounding but slightly higher elevations.  The high temperature will tend to be cooler out at the airport, especially on more or less calm days with less mixing of the boundary layer air, due to the rural surroundings versus the buildings, asphalt and concrete that predominate within the city.

The front that ushered in the cooler, drier air into the local area during the day on September 5th (and pushed southward the haze and layers of smoke aloft) has now pushed all the way to the Gulf of Mexico.  This morning, even Houston, Texas, is in the cooler and drier airmass with 7 AM temperatures in the Houston area in the mid 60s with dew points in the mid 50s.   No organized return flow of moist, gulf air is expected in Houston until the middle of next week.  This will keep tropical systems at bay along the Texas Gulf Coast and help allow the area to dry out.

As for our area, a slow warming trend will ensue over the next several days but humidity will remain low with temperatures remaining near to slightly below normal.   While there could be some clouds from time to time over the next several days, no chance of significant rainfall is seen in the local area until a possible pattern change late in the week next week, or even next weekend.

In the mean time, we will have some mild, dry and low-humidity early September weather conditions to contend with for at least the next week or so.

We must be living right.

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Just a fine day for a stroll on the wetlands.

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Wait, is that a fish?

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Nah, nothing to see there!

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Another heron takes a break.

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But I disturb him so he goes for a shoreline stroll.

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Some wild sunflowers are maturing.

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The marsh grass appears healthy..

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The wetlands plants appear to have had a good  year.

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A common silhouette this time of year.

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And the sun sets toward the western horizon..

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