[FRIAM] The Dry Line Report

[Prof David West]

couldn't find link for video, but saw an incredible "fog tsunami" on Lake Michigan on evening news. Worth looking, for weather nerds.

davew


On Mon, May 19, 2025, at 2:06 PM, Nicholas Thompson wrote:
> Because I have family near Desmoines this morning, I will focus first on the situation nearby in Northeastern KS. where there was very nasty night time tornado last night.   
> 
> image.png
> The dry line is very tight following the 100th meridian northward through TX with dew point drops of 40 degrees between, say,  Dallas and Lubbock.  It is less well defined in western KS where it meets a "triple point", a convergence of moist gulf air with hot (high theta) dry ;desert air, with cool canadian air. This arrangement will propagate eastward and makes for very complex layered atmospheres which are conducive to extreme thunderstorm development.  Lets see what the hazard map looks like this morning.
> 
> image.png
> The risk of all hazards is concentrated in OK ;as is the tornado risk.
> image.png
> Iowa is in the Canadian airmass just to the ne of the low pressure center. Risks are low but not impossible.  Needless to say, anybody leaving IA tonight would best travel west before they travel south. 
> 
> Upper air support seems to be displaced to the west
> image.png
> This is the wind pattern and height half way up in the atmosphere.  The filled triangles on the wind barbs indicate 50 mph, a modest jet stream.
> 
> Let's look at central OK skew T where the risk seems to be greatest.
> image.png
> Oh, my.   Saturated at the bottom, then the EML signature, the nose, the huge dry layer above the Convection Available Potential Energy where the blue line bulges to right of the redline.  At noon MDT,  strong storms are developing s of OK city  and developing north and eastward.  Here's the satellite.
>  https://www.star.nesdis.noaa.gov/GOES/conus_band.php?sat=G19&band=GEOCOLOR&length=24  
> 
> Not very dramatic, atm, but you can see the anvils developing and streaming ne-ward. 
> 
> Meanwhile, back in Santa Fe we are under an upper trough with a couple of unstable layers above but no CAPE.  Cloudy and cool with showers?
> 
> . Nick 
> Nicholas S. Thompson
> Emeritus Professor of Psychology and Ethology
> Clark University
> nthompson at clarku.edu
> https://wordpress.clarku.edu/nthompson
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