250 hPa Analysis
850 hPa AnalysisThe animation on the previous page contains a
850 hPa analysis, which has the parameters of geopotential heights,
Precipitable Water and wind. The 850 hPa conditions that day were
actually rather remarkable with regards to the formation of severe
weather. First and foremost, the magnitude of the low level jet was
incredible, with winds between 45 and 50 kts. In addition, the
winds were roughly out of the south-southwest. This, like the
intense 700 hPa winds, allowed for long, looping hodographs
necessary for low level rotation within storms. In addition, as the
850 hPa low consolidates and moves eastward throughout the period,
it catches and strong plume of moisture that comes off the Gulf of
Mexico. Given the intensity of the low, and in consequence the
magnitude of the low level jet, this plume of moisture actually
wraps around the top of the low, causing very deep moisture to be
ushered into eastern lower Michigan. Needless to say, this created
very favorable thermodynamic conditions for the formation of strong
to violent tornadoes throughout the entire region.Surface (1000
hPa) AnalysisSurface Analysis
Surface AnalysisThe animation on the previous page contains a
1000 hPa surface analysis, which has the parameters of geopotential
heights, equivalent potential temperature and wind. Similar to the
850 hPa analysis, the parameters in the animation are rather
remarkable when it comes to the formation of severe weather. First,
winds are still strong, 25 kts, and now out of the southeast.
Again, the winds helped in hodograph length and size, and were
tremendously favorable for the formation of strong to violent
tornadoes. There was more than 90 of turning between the surface
and 500 hPa pressure surface over eastern Michigan, which allowed
for tremendous bulk shear and helicity values to be in place.
Additionally, equivalent potential temperature (theta-e) values are
a big key here. Theta-e values were exceptionally high that day,
implying a very warm, moist air mass was being advected into the
area. This tells us that the airmass was also very unstable, and
parcels probably had very little trouble rising rapidly. Finally,
theta-e, as well as the placement of the winds, tell us that the
storms formed near or on a warm front. This, like many of the other
parameters in place, allowed for a very favorable environment for
strong to violent tornadoes. The warm front undoubtedly added more
helicity to any storm that could form on or near it.Moisture
Analysis (Surface)
Moisture Analysis (Surface)The animation on the previous page
simply shows how dewpoint temperatures were also advected northward
by the surface low. Dewpoint is a good absolute indicator of
atmospheric moisture content, as higher values imply higher
moisture. It is also a good indicator of LCL height, as a good
first guess for LCL is to subtract the dewpoint in Fahrenheit from
the temperature, also in Fahrenheit, and divide by 4.5. Lower LCLs
allow for tornadoes to form more easily, as the storm-scale
rotation is more easily transferred to the ground. On that day,
dewpoints were very high, and as such, storms had a lot of moisture
to use as fuel, in addition to probably what were very low
LCLs.Sourceshttp://en.wikipedia.org/wiki/1953_Flint_%E2%80%93_Beecher_tornadowww.topinspired.com/top-10-most-devastating-tornadoes-in-history/
(picture)IDV