Severe Weather Discussion 2010-7-2

Severe Weather Discussion for May 19, 2010.
Valid: 05/18/2010.

Highlights:

– Active severe weather day is likely on Wednesday. Tornadoes,
destructive hail, and widespread damaging winds are likely.

– Severe thunderstorms are likely Thursday afternoon across eastern Oklahoma.

– Chase Readiness is increased to Level 3.

Discussion:

18z model data continues prior trends for Wednesday. Model agreement
is improving and so is confidence in a significant severe weather
episode. Current storms in the Texas panhandle are isolated with the
majority of activity north of I-40. Additional development is likely
later today as the low level jet strengthens across the region. How
long the storms survive, their intensity, and ultimate track are all
vital to determine the threats for Wednesday. Current thinking is
that the atmosphere across Oklahoma will recover by mid-afternoon from
morning convection. This may yield CAPE values AOA 3000 J/Kg with
ample speed and directional shear. The GFS has the dryline near HWY
81 at 00z while the NAM is farther west. We played this game a week
ago and the GFS won. I'll stick somewhere in the model and go with
that one.

Deep layer UVV's are again impressive with this system and convection
is likely by mid-afternoon on Wednesday. Models develop QFP up and
down the dryline, leading to confidence of storm development. Both
the GFS/NAM develop deep layer UVV's across the western parts of the
state which should be sufficient to initiate storms. Curved
hodographs and high instability should favor supercells. Any
boundaries left over from convection tonight will provide a favorable
environment for storms to anchor upon.

LCL's may be a little high initially for tornadoes, but this should
change with any southern storms providing lower LCL's and temperatures
cooling near sunset. This event may go well into the night hours as
the atmosphere remains very unstable and storms are driven by the
negative tilt shortwave trof rotating through the state.

Storms are again possible on Thursday in eastern Oklahoma. How
significant Thursday gets will be dependent on tomorrow.

Probabilities:

Risk area for any part of OK/TX (valid: 05/19 Day 1, Day 2):

Slight: 100%, 100%
Moderate: 100%, 75%
High: 20%, 0%

Chase Readiness:

Level 3 – looking at Snyder tomorrow.

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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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