The extreme heat in the western Corn Belt Tuesday, May 14 2013 bears some examination. Was it just atmospheric activity or was there some drought effect as well?
We talked about this event during our DTN-Schneider long range forecast conference call Wednesday. My colleague Mike Palmerino made a strong case for the atmospheric dynamics alone being responsible for the quick and intense heat event. I also checked with a few climatologists in the region about this subject. That atmospheric forcing angle was also supported by Nebraska state climatologist Al Dutcher, northern South Dakota regional climatologist Laura Edwards, and South Dakota state climatologist Dennis Todey. Both Mike Palmerino and Laura Edwards noted as well that in the immediate western Corn Belt there are actually moist soils.
But there was also possibly a drought component--and believe it or not, a freeze component, to this heat outbreak as well. Here's how Dennis Todey described it:
"(There was) certainly at least some of a drought component. And I think there are two related parts that helped lead to this in addition to the dynamic considerations.
P[L1] D[0x0] M[300x250] OOP[F] ADUNIT T
One – obviously, overall conditions over the area are dry leading to limited evaporation/Evapotranspiration (ET). Solar radiation is going to heating and not to ET.
Two is interesting but somewhat related--The colder temperatures have put rangeland and crop growth behind where they would be at this time of year. Any greenness map shows you that. Part is drought. Part is delayed greening even where there is moisture from the cold.
So what you had yesterday in addition to the dynamic issues was a large part of the Plains which is much browner than usual at this time of year. (There is) little ET to partition the solar radiation to latent heat. Thus, the solar (radiation) was focused on sensible heating much more that we would expect at this time of year."
And, Nebraska's Al Dutcher offered this description:
"Probably a little of both. (There was) some compressional heating and a long southwest surface fetch bringing in the low relative humidity values from drought-plagued southern High Plains areas of New Mexico, Texas, Kansas, and Oklahoma."
And, Al Dutcher also made this observation: "(It's) kind of interesting that the same type of pattern happened in 1967 also (early May snow, highs of 100+ two weeks later). Sometimes history does repeat itself."
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