Severe Weather Discussion for May 21 – 27, 2012

Severe Weather Discussion for May 21 – 27, 2012.
Issued:  05/20/2012.
Highlights:
–  A few showers and thunderstorms are possible tomorrow in southern Oklahoma.
–  Thunderstorms, a few severe, are possible in the panhandle on Saturday.  Thunderstorms are again possible on Sunday in the panhandle and northwest Oklahoma.
–  Temperatures will be in the upper 70s Monday, low 80s Tuesday, and upper 80s Wednesday – Sunday.
–  Tropical Storm Alberto is located off the Georgia Coast and is expected to move northeast into the Atlantic.
Probabilities:
–  Severe Thunderstorms in Oklahoma:  15%
–  Storm Chase:  < 5%
–  Tropical Development:  10%
Discussion:
Atypical minimum in severe weather will continue this week across Oklahoma and in many ways much of the U.S.  While a rather significant trof is expected to develop in the western U.S. a strong ridge is expected to the east.  The latter feature will serve to continue disrupting Gulf moisture and subsequent return to Oklahoma.  GFS indicates stronger flow aloft moving across Oklahoma on Tuesday and Wednesday but storm potential appears nil due to nuclear cap.  By Thursday, the upper ridge develops in earnest and the remaining energy retrogrades southwest over southern California.  The GFS and EC are in good agreement on this but diverge beyond that point, which covers D6/7 of the forecast.  The GFS brings stronger flow across Oklahoma and also part of the trailing trof by Memorial Day.  However, it keeps instability parameters unseasonably low, due in part to warm mid-level temperatures (@5C/500mb).  I went with low pops Sat/Sun as the GFS has been somewhat consistent on this.  Severe weather chances look low at this time but will continue to monitor.  Certainly a surprising change to the high-end threat we faced a year ago.
I gave Alberto 10% just for being there and that’s about it.  No impacts to the U.S. should occur due to Alberto.
Temperatures don’t appear too tough this week.  Cold front south of Oklahoma City should shift northward on Monday and washout.  As such, Monday will be cool with a warming trend throughout the week.  Upper ridge builds into the area on Wednesday with warming occurring in earnest.  The ridge does weaken somewhat by the weekend, but don’t think lowering temperatures is a good idea.  I could nudge temperatures a little higher on Friday when the ridge should be maximized, but upper 80s gets the point across.
25 more days of storm season, we’ll see what happens.  Two tornadoes for the month of May, even those those occurred in the early morning hours of May 1st.  So, best put 20 days without a tornado in Oklahoma in May.  Very reminiscent of May 2005.
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