Weekly Severe Weather Discussion

Severe Weather Discussion for November 15 – 21, 2010.
Valid: 11/14/2010.

Highlights:

– Rain is possible Monday afternoon into the evening hours.

– Temperatures will be in the low 60s on Monday-Wednesday, mid 60s
Thursday-Saturday, upper 60s Sunday. Wildfire danger looks to
increase late week into the weekend.

Probabilities:

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

Discussion:

Models in good agreement on keeping the current longwave trof across
the central U.S. a few more days. Shortwave trof will drop southeast
into the mean longwave position and amplify. This process occurs on
Monday and despite limited moisture, some rain is expected across the
area. NAM ensembles create a wide range of QPF with the max near 0.50
inches. Given dewpoints AOB 50F across much of Texas and lack of
return flow, overall QPF should remain low, AOB 0.2 inches.

Shortwave trof moves east into Louisiana on Tuesday as another
shortwave trof moves southeast out of Canada. ECMWF/GFS indicate dry
air below 700mb, such that limited impacts are expected as this system
moves over the state Wednesday. Longwave trof progresses eastward by
Thursday with shortwave ridging across the central U.S. This will be
short-lived as the 500mb flow buckles yet again along the west coast.
Models develop a broad closed low across the northwest U.S. with
trofing southward to Mexico. A lee side cyclone is progged to develop
in this pattern with south and southwest surface flow across the
state. ECMWF/GFS RH fields show very dry air at 700mb with some moist
850mb air in eastern OK. Wildfire concerns seem possible in western
Oklahoma but may be mitigated by recent 1-2 inch rainfall in this area.

Models have backed off on the cold air intrusion for this week but now
show it for the 23rd. Given good agreement among the GFS/ECMWF, I see
no reason to disagree at this point. If current progs verify, the
incoming airmass will easily be the coldest of the season and just
in-time for Thanksgiving!

I went with NAM temperatures through Wednesday as the GFS seems a
little too low. Given drought conditions in OKC, little to no
rainfall overall here last week, I think a little higher temperatures
are warranted. We managed to hit the upper 50s today even with
widespread cloud cover. I did undercut the GFS next Sunday, where I'm
probably wrong. I do have trouble going low 70s at D7, but I do think
it will verify.

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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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