Sunday, January 16, 2011

Model Forecasts Still Vacillating At 96-Hours

The GFS and ECMWF are still vacillating some at the 96-hour period from last evening's 0000 UTC runs. The models' 500-mb forecasts are shown above. The GFS now has the vorticity maximum in the Southwest over southwestern Colorado; whereas, the ECMWF has returned to forecasting the maximum further to the west, i.e., over far southwest corner of Utah. The GFS spaghettis chart at 96-hours indicates that greatest uncertainty stretches from the Northeast to the Southwest and into the east Pacific, off the West coast. Note that the two models have height differences of 60 m or so over northwestern Arizona and southwest Utah at 96-hours. Primary impact of the model differences will likely affect northeastern Arizona (i.e., the Flagstaff NWS Office), where there may or may not be some snowfall as the short-wave approaches and moves by. Nice example of how scientifically unrealistic it is for the NWS to be doing small-scale, gridded, deterministic forecasts out to seven days.

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