Discussion

Your forecast will depend on the extent to which you believe the GFS solution and its associated GFS MEX MOS product. The TLH ZFP’s from 23 October 2003 are largely consistent with this input, forecasting partly cloudy to clear skies and temperatures that are below the climatological mean for the date. The ZFP temperatures are adjusted upward from the MOS product by about 5 degrees (5 p.m. update), making the forecasted temperatures for the day around 9 degrees below normal. This adjustment is in agreement with the practice of trending longer range forecasts toward the climatological mean. All in all, the ZFP’s look to be a very good forecast for 28 October 2003, assuming the GFS verifies.

If the upper air flow pattern does not evolve in a manner consistent with the GFS 120 hour forecast of a major full latitude long wave trough over the eastern U. S., then the forecast of clear, cool, dry conditions for TLH may be in jeopardy. In particular, if the UKMET 72 hour forecast of significant vorticity “digging” into Texas persists into 28 October 2003, then TLH may experience much milder temperatures and greater cloud cover. If the residual moisture from Patricia does indeed propagate northeastward into the Gulf coast region as suggested by the UKMET solution, TLH may receive significant rainfall, as well. See the loops for the GFS and UKMET forecasts in Part I, Section2.