Weekly Severe Weather Discussion

Severe Weather Discussion for March 23 – 29, 2009.
Valid: 03/22/2009.

Highlights:

– Severe thunderstorms are likely Monday afternoon and evening, into
Tuesday morning.

– Severe thunderstorms are again possible on Thursday and Friday.

– Temperatures will be in the upper 70s Monday, upper 60s
Tuesday-Wednesday, mid 70s Thursday-Friday, mid 50s Saturday, and low
60s Sunday.

– Light snow is possible late Friday into Saturday, little impacts
are expected.

Probabilities:

– Severe Thunderstorms in Oklahoma: 50%
– Storm Chase: 40%
– Winter Precip: 10%

Discussion:

Sensible weather will be maximized this week as two storms systems
impact Oklahoma and a strong cold front at the end of the week. The
majority of my forecasting effort has been targeted towards Monday's
expected severe weather event and likely tornado chase. See
discussion 2009-3-3 for more details.

GFS and NAM are blended Monday and Tuesday, with the GFS used
Wednesday-Thursday. ECMWF is used for Friday-Sunday, although I don't
get temperatures, so will have to guess a little.

Forecast for Tuesday-Wednesday is straight forward as the incoming
upper system is kicked northeast and the longwave trof remains over
the western U.S. Differences come into play for the Thursday/Friday
time period which have huge implications on the forecast. The GFS is
much less amplified with the next system and ejects the longwave trof
with it on Friday. If this model were followed, there would be a
chance of thunderstorms on Thursday, turning cooler on Friday. ECMWF
digs the next system southward along the California coast and then
ejects it eastward into the central U.S. A surface low develops in
Texas Friday morning and moves rapidly northeast to Kansas City by
Saturday morning. While I have to infer what would happen, strong
flow aloft would be present over the region and thus a chance for
severe thunderstorms. My pick is the ECMWF for the latter part of the
forecast as it seems to fit better with what is evolving and has been
consistent. HPC has sided mostly with the ECMWF, but have some GFS
thrown in for good measure. Given my pick of the ECMWF, I've spread
severe chances across Thursday and Friday, cooling off things for the
weekend. If the GFS verifies, I'll bust the temperatures
Friday-Saturday, but that's why I forecast!

This is a rather short discussion, but I'll make up for it in the
special discussions. Also, fire danger will be extreme in western
Oklahoma on Tuesday.

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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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