Severe Weather Discussion for May 10-12, 2010.
– Active severe weather day will occur on Monday across much of
Oklahoma. Significant impacts are possible, including damaging
tornadoes. Additionally, destructive hail is likely along with
isolated damaging winds.
– Severe thunderstorms are possible Tuesday afternoon across southern
Oklahoma. Primary threats will be large hail and isolated tornadoes.
– Another active severe weather day is possible on Wednesday. Threats
are quite difficult to discern this far out and mesoscale features
will play a significant rule along with prior convection.
Models agree that the stage is set for widespread severe thunderstorms
on Monday. There are two questions remaining at this juncture: 1)
dryline location at convection initiation and 2) impacts of convection
prior to the main show Monday afternoon/evening. 18z models are in
general agreement regarding the evolution of this event with the NAM's
dryline position near Clinton and the GFS slightly east at
mid-afternoon. GFS is much lower on CAPE than the NAM and likely due
to lack of warming behind the initial wave of convection Monday
morning. NAM's temperature field looks more realistic given time of
year. As is common this time of year, the models are having a
difficult time with convective initiation tomorrow afternoon. This is
seen in the NAM/GFS/SREF/high resolution models. There is no doubt in
my mind that the cap will be breached across Kansas/Oklahoma/NW Texas.
In fact, I'd think there will be numerous supercells clustered near
HWY 412 in Oklahoma and northward into Kansas. Farther south, storms
will be more isolated but there should still be 3-4 south of HWY 412.
This is my rationale for staying south and that model UVV fields focus
near Anadarko to Hinton to Watonga. Some of this is fluid based on
the ultimate location of the dryline. At this point there is no need
to review all the other parameters that are more than favorable for
significant severe weather including long-track tornadoes. SPC's Day
2 product looks good and if overnight convection doesn't materialize
or limit heating tomorrow, I think a high risk is still possible.
For Hook-echo, we're looking at leaving around 14:30 CDT and heading
west to Hinton. I've explained some of my thinking above. My main
goal is to be about 50 miles east of the dryline to allow positioning.
I definitely prefer to stay south on this one due to storm motion up
north and how crowded things will be in the higher risk area. Storms
at I-40 and south will be just as likely to produce significant severe
weather as activity to the north.
Severe thunderstorms are possible on Tuesday along a frontal boundary
in southern Oklahoma. Winds will still be strong across the state but
the surface flow will be much weaker. As such, higher-end storms are
not expected, but supercells should be likely with any storm that
anchors on the warm front.
Wednesday has potential to be another active severe weather day as
another piece of the western U.S. longwave trof ejects northeast.
Models are slightly weaker with surface flow but still show a cold
front in Kansas with a dryline in western Oklahoma. Models are likely
not handling expected thermodynamics very well, so I expect CAPE
values to higher than progged. NAM develops QPF across parts of
Oklahoma Wednesday afternoon and this appears reasonable. I've spent
much of my forecast time on Monday, but Wednesday will be monitored
given that moisture will remain nearby along with favorable winds aloft.
Risk area for any part of OK/TX (valid: 05/10 Day 1, Day 2, Day 3):
Slight: 100%, 100%, 100%
Moderate: 100%, 0%, 50%
High: 40%, 0%, N/A
Level 3 – Looking to head out tomorrow. Target area is Hinton to
Watonga. While northern OK/southern KS is the sure thing, I'm not up
for 40mph moving storms. Certainly not to ignore the chaser
convergence. I'd rather sit near I-40 and catch a stray.
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