Hey, Its Humid!

A novel thing happened the other morning. I stepped outside to get the newspaper and to check on the neighbor, and wow! I could smell dirt and moisture! We had humidity for the first time in a month or two. Whee! And then a low-pressure trough set up to the west, raced east, and we got “dry lined.” All that lovely moisture ended up in Oklahoma. And the Okies failed to send it back, prompting a few discouraging words and unhappy glares eastward.

I suspect most of my readers live in places where a dry-line means, oh, the bus route that does not go near any bars, or is shorthand for what your grandmother hung clothing on after she washed it. Here, it means a wind shift line, changing from southeast or south to west-south-west. As the dry-line passes, the southwesterly fetch pushes the moisture away, the dew-point drops, and the temperature usually climbs. I will admit, in late April and May, I am not always sad to watch the dry-line sweep through, because that means someone else will get tornadoed, usually Oklahoma and eastern Texas.

Wave good-by to the rain! From: http://media.twnmm.com/storage/22681501/1085

Wave good-by to the rain! From: http://media.twnmm.com/storage/22681501/1085

The lumpy bit in teh corner is an overshooting top, probably a supercell making someone's evening . . . interesting. http://usercontent1.hubimg.com/7231682_f520.jpg

The lumpy bit in the corner is an overshooting top, probably a supercell making someone’s evening . . . interesting. http://usercontent1.hubimg.com/7231682_f520.jpg

First I noticed that the sky had clouds, and that it was still in the 50s. Since the forecast was for the low 40s, that suggested humidity had come on overnight. The clouds undershot, with brilliant pink bits below the blue-purple, then generalized salmon, then grey and blue and white. The air felt warm and fat, rich with water. Most people open the house to let moisture out, but I had the windows open to let it in. I left to go do some things around 0900 and stopped to watch the clouds. They travelled from west to east at a brisk pace, warning that the winds aloft had already shifted.

The morning stayed pretty moist, with dew-points in the upper 40s until 1030 or so. Then the shift began, the air grew noticeably drier. Although high clouds remained, and some mid-level clouds dropped virga that looked impressive but never reached the ground, the moisture had departed. The air temperature and dew-point moved farther and farther apart, alas. What stings is that on radar, it looks like light rain. That light rain gets within a few thousand feet of the ground and evaporates, going right back home.

Today there was no severe weather expected. When it gets exciting is the combination of a low pressure center (a Low), a trailing cold front, and the dry-line. Where the three meet is called a triple-point, and that’s usually where you get strong, long-lived, rotating thunderstorms. You do not want to be there. For a few years I lived and worked in a small city just west of the dry-line, and the airport bums and my medical staff and I would sit outside on summer evenings, watching the storms form, turn dramatic gold and pink with sunset, and drop tornadoes to the east of us. Not that we lacked for storms, but the heavy-duty monsters just couldn’t get enough moisture to do large amounts of damage where we were. Most of the time. There was that memorable night when the regional AM farm radio station’s DJ started reading the warning list, stopped, and said, “If you can hear me, you are under a warning. Take cover.” He wasn’t kidding, either.

But not that morning. No, that morning I enjoyed smelling the scent of moisture, opened the house to air, and waved by-by to all that humidity as the dry-line swept through. Win some, lose some.


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