Severe Weather Discussion for May 10 – 12, 2010.
– Active severe weather day is expected on Monday across much of
Oklahoma. A significant severe weather event may be in the offering,
but much too early to know.
– Isolated severe thunderstorms are possible in eastern Oklahoma
Tuesday morning and potentially again in southern Oklahoma late Tuesday.
– Severe thunderstorms are possible on Wednesday across parts of Oklahoma.
12z NAM is significantly different than prior runs with respects to
moisture return. It is tough this far out to know if this is a trend
or a bad run. And, this has implications for the severe weather on
Monday. 12z NAM is rather slow with moisture return and as of Monday
morning hangs 65F dewpoints along the Red River. The slow pace of
moisture return is rather odd and not sure the model is handling it
correctly. By Monday late afternoon the NAM does have mid/upper 60s
dewpoints in northern Oklahoma with a tight gradient leading into
Kansas. The slow motion of the warm front appears due to the
widespread precipitation the NAM develops across Oklahoma. The NAM
has a history of way overdoing QPF at 84 hours, so I'm not going to
change my thinking based on this one run. This is also a departure
from prior runs and the other models.
Other forecast elements remain the same and assuming the NAM returns
to prior runs, a significant severe weather event looks possible on
Monday. NAM does show a westward shift in the dryline location, which
is also different than the ECMWF/GFS. There is still some
consideration for this to change as the system enters the upper air
network in a few days. Given the unusual model agreement regarding
this system, it really isn't a shocker the NAM went a completely
different direction. Confidence remains high enough to warrant
discussions for Monday.
Risk area for any part of OK/TX (valid: 05/11 Day 3):
Level 1 – Normal – watching Monday, will up it tomorrow if necessary.
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