Weekly Severe Weather Discussion

Severe Weather Discussion for February 15 – 21, 2010.
Valid: 02/14/2010.

Highlights:

– Slight chance of rain Thursday night into Friday. Snow is possible
in northern Oklahoma on Friday and possibly central sections early
that evening.

– Temperatures will be in the low 40s on Monday, mid 40s Tuesday, mid
50s Wednesday, low 50s Thursday, upper 40s Friday, upper 30s Saturday,
mid 40s Sunday.

Probabilities:

– Severe Thunderstorms in Oklahoma: < 5%
– Storm Chase: < 5%
– Winter Precip: 15%

Discussion:

Large eastern U.S. longwave trof will continue through mid-week as the
southern jet amplifies. An amplified ridge will be located over the
far western U.S. with Oklahoma caught in northwest flow. GFS is the
preferred model and the 12z ECMWF has shifted to this viewpoint.
Weather impacts this week look to be on the low side, but there is the
seemingly endless threat of snow/ice. Given how easy snow has been
this year, I wouldn't be surprised to get a little on Friday into late
Friday even with current progs. We saw about 1/2 inches here this
morning, which actually stuck for a few hours.

Later in the week the models show a southern stream low being torn
apart over the northwest U.S. Part of the energy is wrapped back into
the high pressure system while the rest moves southeast into the
region. Models show dewpoints in the low 40s moving northward into
Oklahoma. This would be sufficient for light rain. Models also show
that 850mb temps go below freezing late Friday just as dry air is
advecting into the region. As such, have gone with snow chances for
northern and central Oklahoma.

12z GFS shows the Friday cold front to be a western Canada type front
with only cool air in the source region. Additionally, given the lack
of amplitude at the lower latitudes, the surface ridge center shifts
east through the Ohio Valley late in the weekend. This seems to limit
scouring of the Gulf with the GFS showing 65F depwoints just north of
the Yucatan late Sunday. Models note a southern stream closed low
approaching the SW U.S. early next week. This could certainly make
things interesting around the 24th. However, that is for later
discussions!

GFS numbers looked okay, except for Wednesday where southwest flow
should warm us up. I stayed a little warmer next weekend since we
should get some sun on Sunday. Albeit, forecasting mid 40s on Sunday
is still ten degrees below late-February averages.

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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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