Severe Weather Discussion – 2008-12-2

Severe Weather Discussion for May 22 – 23, 2008.
Valid: 05/22/2008.

Highlights:

– Isolated severe thunderstorms are expected late this afternoon into
the evening hours, generally across the western half of Oklahoma. The
primary threats are tornadoes and destructive hail. A greater
concentration of severe thunderstorms is possible in far northwest
Oklahoma northward into Kansas.

– Storm development is expected between 5-7pm along a dryline near the
TX/OK border. Storms will initially produce large hail. As the
storms mature and move eastward into Oklahoma they may become better
organized with an increasing tornado threat. Only a few storms are
expected in Oklahoma this afternoon, but there is potential for strong
tornadoes and hail to baseball size.

– Isolated severe thunderstorms are again possible on Friday in
western Oklahoma, but the overall threat appears to be less than today.

Discussion:

Tornado watch being issued for the panhandle and parts of western Oklahoma.

Latest surface analysis shows a dryline along I-27 in the Texas
panhandle. To the east of this boundary, temperatures are in the
upper 70s to low 80s with dewpoints in the low/mid 60s. This is
creating an unstable atmosphere with 100mb MLCAPEs of 2000-2500J/Kg
across western Oklahoma, surface based CAPE values are in the
3000-3500J/Kg range. Continued diurnal heating will provide a very
unstable atmosphere later this afternoon and long and just east of the
dryline. The dryline should be located near the TX/OK border by late
this afternoon. Wind fields aloft are quite favorable for organized
thunderstorms as they veer with height and increase, especially
across western Oklahoma.

A strong cap is currently preventing thunderstorm development with CIN
values around 75 J/Kg across much of the threat area. This indicates
that severe thunderstorm initiation is still several hours away. By
late this afternoon a combination of continued surface heating along
with increasing winds aloft should be able to breach the cap in a few
locations. Explosive thunderstorm development will occur once the cap
is breached. Storms will initially struggle due to lower moisture
depths near the dryline. This will result in large hail being the
primary threat. As storms move east into better moisture they should
organize and will develop a tornado threat along with destructive
hail. Storms should move northeast, with deviant movers more
eastward. Storm coverage should decrease by late evening as the cap
re-strengthens.

Isolated severe thunderstorms are possible on Friday, but weakening
flow should keep the threat lower than today.

As much as I'd like to chase today, it is not in the offering.

Probabilities:

– Risk area for any part of OK/TX (valid: 03/23 Day 1):

Slight: 100%
Moderate: 5%
High: 0%

Chase Status:

Level 1 – Normal

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About Putnam Reiter

Putnam has been storm chasing since 1990 and is a co-founder of Hook-Echo.com. For his day job, Putnam works in emergency management for information technology.
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