Weekly Severe Weather Discussion

Severe Weather Discussion for August 11 – 17, 2008.
Valid: 08/10/2008.

Highlights:

– Temperatures in the low/mid 90s through Thursday. Cooling off to
the mid/upper 80s through Sunday. Texas will lag by a few days,
especially depending on location. But it does look like below normal
temperatures for the region by next weekend.

– Isolated thunderstorms are possible on Monday with little chance of
precip until Thursday and Friday when a much better chance occurs.
Slight chance for storms on Sunday.

– NHC is watching two areas in the Atlantic.

Probabilities:

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

Discussion:

12z/18z models are in decent agreement concerning the pattern this
week. The 12z ECMWF is slightly farther west with the longwave trof
and subsequent shortwave features by Thursday. However, will stick
with the GFS, since the NWS has done the same. It could mean for a
temperature problem on Thursday should the ECMWF verify as we'd get
southwest flow.

12z GFS/ECMWF advertise that the eastern U.S. closed low will exit the
lower 48 with the longwave trof remaining in-place. By mid-week a
shortwave trof dives south out of Canada and reloads the longwave trof
as it retrogrades to the west. The GFS centers over Oklahoma and just
east with the ECMWF farther west. This does seem to have pretty big
temperature implications for the region. The NWS has gone with the
GFS and see no reason to disagree. I'll take the hit on temps if the
ECMWF verifies.

GFS creates CAPE values around 1500 J/Kg on Thursday and this combined
with a front and strengthening winds aloft should be enough for some
isolated severe storms. Isolated general thunderstorms are possible
next Sunday. Storm chances continue southward into Texas on Friday
and near the coast on Saturday. However, severe thunderstorms are not
expected.

Overall it appears that we're going for a very nice mid-August week.
I'll take anything other than the 100F temperatures.

NHC is watching two areas in the Atlantic right now. 12z GFS took a
hurricane into North Carolina while the 18z recurved it in the
Atlantic. While the former would be exciting, I don't think the
subtropical ridge is strong enough for it to occur. Of course the
system has to develop first.

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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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