April 14, 2004 Killer Tornado in Northern Bangladesh
On April
14, 2004, a tornado moved southeast across northern Bangladesh, killing
75 people. Daily news
reports
attest to the violence
of the tornado. A journalist from Sylhet visited the affected area and
reported the tornado damge
path was over a mile
wide in spots. My convective
outlook issued at 0100 UTC(700 am BST) discussed
the possibility
of tornadic storms near
the outflow boundary in northern Bangladesh. I updated the discussion
at 08 UTC and upgraded
from moderate to high
risk for parts of central and northern Bangladesh. It was not
clear from the sparse surface data
just how close the outflow
boundary was to the Khasi Hills. In retrospect, the outlook should have
been a hair further
north. The tornadoes
occurred in the moderate risk area. It sure would be nice if we had a surface
station at Mymensingh.
I issued a tornado
watch at 0820 UTC(220 pm BST). At the time, I only had access to global
view--5km res meteosat-5
data. After the fact,
I was given a glance of much higher resolution, half-hrly, meteosat-5 data
which is proprietary. At
6 pm, no more than a
large towering cu was visible on satellite near the affected area. The
tornadoes occurred in the
extreme northern part
of the tornado watch area between 1245 UTC and 14 UTC(645-8 pm BST)
In fact, part of the
tornado
paths were a few miles outside the watch area. But as the saying
goes in the United States, tornadoes may occur
in and close to the watch
area. It is still not clear whether there were one or two tornadoes. I
will be getting maps of each
district of Bangladesh
soon, with all the villages shown. I will then trace the path of the tornadoes,
which may shed some
light on this issue.
Here are surface charts, upper
air charts and model initializations for April 14:
surface maps: 06
UTC 09UTC
12
UTC
500mb: 00
UTC
500mband
300mbUKMET
initialization for 12 UTC April 14(obtained from
vortex.plymouth.edu)
300mb
GFS initialization for 18 UTC April 14(obtained from
vortex.plymouth.edu)
UKMET maps with terrain for 00 UTC April 15
500mb
wind barbs, height,
700mb
wind barbs, height, temp
850mb
wind barbs, temp
GFS maps with terrain for 12 UTC April 14
300mb
wind barbs, temp
New
Morning soundings from April
14 and April
15 were modified for conditions 12
hour later and 12
hours earlier.
The sounding were only modified below 900mb to reflect boundary layer changes.
Also, the April 15 sounding
was missing some upper level data and this was approximated. The
capping inversion was apparently weaker
across far northern Bangladesh near Meghalaya, India.