Weekly Severe Weather Discussion

Severe Weather Discussion for April 12 – 18, 2010.
Valid: 04/11/2010.


– Isolated thunderstorms are possible across western Oklahoma all
week. The remainder of Oklahoma stands a chance for thunderstorms
Friday-Sunday. There is a threat for severe thunderstorms Saturday
and Sunday, but currently very conditional.

– Temperatures will be near 80F Monday – Friday, upper 70s Saturday – Sunday.


– Severe Thunderstorms in Oklahoma: 20%
– Storm Chase: 20%
– Winter Precip: < 5%


Atmosphere has jumped right into summer with an eastern U.S. longwave
ridge this week. Models agree on the the development of this feature
and subsequent weakening by the end of this week as it shifts a little
west. There is little confidence in the dailies as the models are in
poor agreement. There is some general agreement that weak
perturbations will influence the area during the week and this is the
reason for POPs each day. Given the lack of a ridge over Oklahoma,
showers and thunderstorms are certainly possible. Organized severe
weather is expected to remain limited much of the week due to limited
winds. Moisture is flowing back into the region, but is limited due
to Gulf ridging. This is not expected to change during much of the
weak. GFS and ECMWF show a weak system impacting the region around
Saturday. There seems to be some potential for this system to
interact with increasing moisture and winds aloft for severe
thunderstorms. I have gone 20% on the chase and severe weather
probabilities for this reason. Additionally, there is some limited
chance for severe thunderstorms each day, but activity is expected to
remain isolated or poorly organized.

Potential for a medium-end event or greater remains below climatology
again this week as the eastern U.S. ridge dominates. Just beyond this
week, the models hint at an Omega Block in the northern jet with a
continued weak southern jet across this region. Since the ensembles
diverge significantly by 168 hours, there is no confidence in what
will happen beyond the 18th or potential for severe thunderstorms.
Latest El Nino update indicates it has weakened to a moderate El Nino
with further weakening expected into May. Some models forecast
ENSO-neutral conditions in May. The atmospheric response so far in
April may indeed be in response to the weakening El Nino.

Lack of significant shortwave trofs/closed lows across the region
should negate airmass changes. As such, temperatures are set for
current readings throughout much of the week. I didn't mess too much
with the models on these. I did bring highs down a little next
weekend due to increased moisture and clouds if the expected shortwave
trof/possible closed low does develop.

I will hold out some hope that parameters will combine to warrant a
chase on Saturday.

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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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