Severe Storms Possible Thursday


Wednesday, April 13th 2011, 5:19 am
By: News On 6


We expect mostly sunny conditions along with gusty south winds and highs in the 80s today.  Storms will be possible across eastern OK Thursday late afternoon into early evening.  Some will be severe.  Large hail and tornadoes will be possible in some thunderstorm activity.  A tornado watch will almost certainly be needed for late Thursday into pre dawn Friday across Eastern OK and portions of Western Arkansas as well as locations across eastern Kansas.  As this system moves eastward with time, additional severe storms are likely across the Midwest and the Deep South. A regional severe weather outbreak will be possible Thursday.

 

The wind is already picking up from the south in response to falling surface pressures to the west.  This is happening because of a major upper level system that is approaching the southern and central plains states.  This system will drag a cold front into the region early Friday morning and a dry line into the eastern sections of the state Thursday evening. 

  We continue to be concerned about the severe thunderstorm potential for Thursday evening regarding super cell development with large hail and possibly a few tornadoes.   The upper air dynamics of the incoming system will be very strong.  Low level moisture is expected to surge into eastern OK Thursday afternoon and evening just as the forcing from the system arrives. Unlike the last few events, southeast surface winds Thursday afternoon may increase convergence along the dry line just west of Tulsa by 5pm.  This may provide a window for super cell development Thursday afternoon and evening along the dry line before storms move into Arkansas late Thursday evening as a squall line or broken line of storms.  The dry line position is expected to be near a Ponca City to OKC to Ardmore line by 5pm.  Please remain aware of this weather situation Thursday afternoon and evening across eastern OK. We'll try to offer more timing information tomorrow regarding start and stop time predictions for storm formation.  Locations west of the dry line will quickly see strong west wind and very low relative humidity values.  This will enhance the fire danger Thursday afternoon across western and central OK.  If the dry line is faster and moves across the Tulsa metro before 6pm, the fire danger will also be very high in Tulsa.  The deeper moisture east of the dry line may reside across the extreme eastern section of the state with the Tulsa metro on the western edge of the moisture surge. 

 The upper air system may "close off" and spread some showers back around southeastern Kansas and northeastern Ok Friday afternoon.  I mentioned this possibility yesterday but we'll keep the mention off the graphics portion of the forecast at this point.

 NAM model data supports more of a westerly wind Friday with very strong wind speeds from 25 to 35 mph.  A wind advisory may be needed Friday if the data continues to support this solution.  Friday fire weather conditions may also be very high due to the dry air and strong environmental winds.

 The next system may not appear until Sunday evening into early next week, but another round of strong to near severe storms will be possible early next week. Details of this system will be forthcoming tomorrow and Friday, but I'll continue to focus on the Thursday system.