For the first time in quite awhile, both the ECMWF and GFS long-range forecasts are indicating a possibility that precipitation could make an appearance in the far Southwest. It has been almost a month now since a light rain fell here at the house - a month of only cold morning low temperatures, wind, and dust!
Above is the ECMWF 500 mb forecast for 168-hours (valid 12 UTC Monday, March 19th) and below is the same forecast from the GFS (both of these are for the operational member). The GFS is actually a bit further west with the axis of the short-wave trough and also just a tad deeper, making this a bit of an unusual situation. Most of the GFS ensemble members forecast some precipitation over southeast Arizona from 168 to 180 hours out. So, finally something to watch.
The above graphic is the GFS 500 mb spaghetti chart (20 member ensemble) for 500 mb heights at 168 hours. The southern contours are 5760 m and the northern contours are 5340 m. At this time the model forecasts have a fairly large spread across the western US, meaning that, this far out, there is much uncertainty regarding what might actually happen, particularly in southern Arizona, 7 and 8 days from now. Will we eat more dust or welcome higher humidity - we'll watch closely as the situation evolves.
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