Weekly Severe Weather Discussion

Severe Weather Discussion for June 2 – 8, 2008.
Valid: 06/01/2008.

***Significant and widespread severe weather events likely across
large parts of the U.S. this week***

Highlights:

– Severe thunderstorms are possible Monday – Friday and again on
Sunday, with special emphasis on Wednesday – Friday.

– Temperatures will be well above normal all week.

– Hurricane season officially starts today, but we already have had Arthur.

Probabilities:

– Severe Thunderstorms in Oklahoma: > 75%
– Storm Chase: > 75%
– Winter Precip: < 5%

Probabilities:

Models are in good agreement through much of this forecast period with
some deviation towards next Sunday. For now, I'm not going to worry
about it as the high-impact weather appears to be Wednesday – Friday.
While Oklahoma may not see the coverage to warrant a high risk during
these days, it will likely see a few severe thunderstorms with
high-impacts.

588dm ridge was nosing northward across the state today and the
damaging MCS this morning traveled southeast along the 588dm
isoheight. This ridge will remain over the state through Tuesday.
The net impact will be well above average temperatures in the mid 90s
Monday and Tuesday. While severe thunderstorms cannot be ruled out in
northern Oklahoma, the threat should remain in the area of large hail
and damaging winds.

By late Tuesday the ridge dives south as the mid-level flow buckles in
response to a western U.S. trof. 12z models advertise this system
progressing rapidly into the central U.S. and amplifying. The 6-wave
pattern appears to have dissipated and we are in a 5-wave pattern and
may rapidly got to a 4-wave. Either way models have slowed the system
some and this seems to fit the change in the Northern Hemispheric
longwave pattern. SPC Day 4 has much of western/central KS
highlighted and this is good, although I think it should be dropped
into northwest Oklahoma. By Thursday the large upper system moves
into the central U.S. with very strong speed and directional shear
aloft. Temperatures warm into the upper 80s/low 90s with dewpoints in
the mid/upper 60s. GFS is up/down with CAPE values and I haven't
tracked this much recently. However, I'm not convinced of how low it
is going even though 500mb temperatures are progged to be around -8C.
SPC Day 5 appears a little too far east and I'd expect it to come back
some to the west.

Friday looks rather interesting to me at this point for parts of
Oklahoma. Now, it is strongly contingent on what happens Thursday.
Winds will remain strong across the region and a boundary should be in
the state. This would provide a favorable environment for severe
thunderstorms.

The 588dm ridge makes a reappearance on Sunday, so Sat/Sun may be
quiet. Tough call right now, but will continue to watch.

Special discussions will be needed and I'll probably get one out here
in a little bit.

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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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