Severe Weather Discussion 2007-13-3

Severe Weather Discussion for October 17, 2007.
Valid: 10/17/2007.

**Outbreak of Severe Thunderstorms and Tornadoes Today**

Highlights:

– Significant severe weather event is expected this afternoon across the eastern half of Oklahoma, all of Arkansas, and parts of northeast Texas. This is a Particularly Dangerous Situation with the potential for long-lived, long-track tornadoes. Additionally, large hail and damaging winds are possible.

Discussion:

Little change to prior forecast reasoning. Overnight convection did develop, but not as extensively forecast by the NAM-WRF. A blend of the GFS and NAM seemed to fit the morning convective evolution. As such, much of central and eastern Oklahoma is untouched by convection. The limiting factor is widespread cloud cover due to impressive moisture fetch from the Gulf. 12:20pm Mesonet observations show the best heating to be south of a line from Hobart to Fort Cobb to Norman to Tulsa. Temperatures continue to warm this afternoon and moisture values continue to increase. Current dewpoints are in the upper 60s across much of the region. CAPE values are above 1000 J/Kg with an area of 1500 J/Kg in south-central Oklahoma as of 12:00pm. This area of instability should increase during the afternoon hours. Finally, an outflow boundary is located in north-central Oklahoma just south of the early morning MCS. This boundary has huge potential to be a significant weather maker later
today. Current thinking is the boundary will separate warm/moist air to the south from cool/moist outflow air to the north. This boundary is expected be near I-44 from north of Oklahoma City to Tulsa by late this afternoon. Any storms that can move along this boundary will have an enhanced potential at producing a long track tornado. This is not to take away from the potential elsewhere in eastern Oklahoma into Arkansas as any areas untouched by convection this morning/early afternoon may experience significant severe weather this afternoon into the evening.

As is common with days like this I have little time to get into any more details than the above.

Chase Status:

Hanging close to home today, not sure I want to chase a storm moving at 45-50mph.

For more information, weather news, weather blog, and chase summaries go to http://www.hook-echo.com.

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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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