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Monday, March 7th 2011, 5:10 am
By: News On 6


Here we go with another storm system for Tuesday.  This one will also bring a threat for some strong to severe storms across the area, and once again, the higher chances will be across the far eastern and southeastern part of the state.  The dynamics with the upper level system will be extremely strong and if low level moisture can return, the severe weather chances will be increasing.  This is the normal dilemma for late winter and early spring:  strong dynamics but limited moisture.  In weather speak we term these events as high shear and low cape.  CAPE stands for convective and potential energy and is measured in joules per kilogram.  Higher CAPE values range from 3000 to 5000 j/kg with low cape values usually around 700 to 1000 j/kg.  CAPE can also be found not only at the surface but also in the mid levels of the atmosphere.  

Instability in the atmosphere can be measured by something called the lifting index.   Generally, positive lifted index values indicate a stable atmosphere and negative index values indicate instability.  Extreme instability would be on the order of -7 to -12, with limited instability from 0 to -3.  Moderate instability would be from -3 to -7. 

There are a number of other severe weather parameters one may use to determine the state of the atmosphere.  I'll try to post some additional information about these various products over then next few days.  Almost any individual measure is limited in scope by itself, but combined with over parameters can offer great insight into the convective ability of the atmosphere. 

 The fire danger will be high today and tomorrow due to strong winds and dry vegetation.  Please use extreme caution.  Wild fire spread will be rapid today and tomorrow.

We expect mostly cloudy and windy conditions today with a high in the upper 50s and lower to mid 60s.  South winds around 15 to 30 mph will be common.  Relative humidity values this afternoon will be in the 40% range. 

 The front that moved across the area Friday effectively scoured out the atmosphere of low level moisture which is suppressed into the Texas gulf coastal region this morning.  But our incoming upper level system is very dynamic and will cause a rapid increase of moisture later today and more so tonight.  Late tonight or tomorrow morning we may have some warm air advection showers forming as the moisture is returning over the area.  These would be scattered showers and storms should be non severe.  The higher location for these showers would be across northern OK and east of I-35.

 Tuesday afternoon a strong dry line will develop and move east during the afternoon.  A surface area of low pressure may form along the southwest OK vicinity before lifting northeast Tuesday evening.  Thunderstorms will form Tuesday afternoon or evening to the east and then march eastward with time Tuesday evening.  The shear profile supports the development of a line of thunderstorm activity (squall line) during maturity.  These type systems usually produce wind damage in some locations and this will be the main threat as the storms form these lines or line segments late Tuesday night.

 Before this process occurs, discrete storms may form with large hail the main threat.  A tornado threat will remain low, but is not zero at this point in the life cycle of the system.  If moisture can increase, the tornado threat may also increase across southeastern OK.

 After the system passes, we're looking at decent weather.  Another system may enter the area either Friday night or Saturday morning, but may arrive with no precipitation due to the lack of low level moisture.  

 The next shot would occur Sunday evening into Monday of next week.

 My friend David Whitlock was our guest speaker at our church Sunday.  David is the president of Oklahoma Baptist University in Shawnee and is a wonderful leader for the university.  More importantly, he is a good man and a super friend.  Do you have those friends who you haven't seen in a while, but when you get together, its like you haven't missed a beat?  What a blessing. 

 Forecast Confidence for entire 7 day:  7

Issues:  severe potential for Tuesday and exact location for higher chances.

 10 is highest- 1 is lowest.