11 May 2011: Initial Area Forecast Discussion


  • A closed low will move from the Four Corners area to the north-northeast through the afternoon and evening.  A short wave trough rounding the base of the closed low will track from southern NM into the OK/TX panhandles this afternoon.  The largest height falls are forecast from the panhandles into western KS, with weaker forcing extending farther east.
  • RUC forecasts MLCAPE in the 2000-3000 J/kg range east of the dryline.  Sufficient deep layer shear to support severe thunderstorm development should be in place by early afternoon.  Via a combination of surface heating and increasing large scale forcing for lift, the cap is expected to weaken enough to allow for thunderstorm formation.
  • Our area of focus was chosen considering not only the potential for severe convective storms, but also the availability of lightning data and OUN WRF data over Oklahoma.
  • Afternoon thunderstorm development is conditional, depending to a large extent on the evolution of ongoing thunderstorms over central OK and north TX.  Further thunderstorms developing in between these two areas could decrease instability by limiting moisture advection and surface heating.
  • Top four choices for CWAs of focus:
  1. OUN
  2. ICT
  3. DDC
  4. FWD


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2011-05-10: Initial Area Forecast Discussion

  • Focus today through this evening over the MAF and SJT CWAs.
  • Ongoing convection initiated on lead wave this morning extending from the western Hill Country northeast into Oklahoma complicating matters.
  • Dryline initially from 30 W KCDS south to near KSWW then southwest to KFST will mix/advect west about 30-40 miles before stalling and retreating westward in advance of shortwave rounding the base of the longwave trough over the western CONUS.
  • OUN WRF indicates weak convection firing along and ahead of dryline/differential heating boundary from near KSNK south to near KJCT.
  • Initial activity should move northeast…high res models suggest activity will decay a bit after 23z.
  • Well defined wave on WV and short term model guidance expected to move out of northern Mexico after 00z.
  • Convergence along retreating dryline with MLCAPEs over 2500 J/kg.
  • RUC SBCAPE indicates significant increase in instability retreating west with the dryline after 00z.
  • Another round of CI expected to occur between 00z and 03z invof MAF.  Deep moisture over western Hill Country southeast should not mix much owing to cloud cover and attenuated insolation.
  • NAM and HRRR hints at robust convection between MAF and SJT around sunset.
  • Potential for supercellular structure with large hail (aoa baseballs) with second round.  Tornado and high wind threat somewhat less owing to stabilization of PBL.

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