|Saturday 500 mb height|
|4 different models showing 500 mb heights for Saturday (upper left model did not come in fully)|
|500 mb maps for Sunday|
|500 mb maps for Monday|
So our confidence in this event is quite high. We are certain this low will form and move over portions of the Inland Northwest however how long it will remain over the area and where its precipitation band will set up is the big question. Looking at the GFS for the Saturday and Sunday yields a significant northwest to southeast orientated band of precipitation.
|48 hr precipitation amounts for Saturday-Sunday (latest model run )|
|Rainfall forecast for Saturday and Sunday (Monday's model run)|
|Another Saturday-Sunday 48 hr precipitation forecast|
So given these uncertainties it will be hard to pinpoint exactly where the band will take up residence. This is where ensemble model forecast can sometimes help to pinpoint the band (s) of heavy precipitation. So once again referring to the GEFS/NAEFS ensemble forecasts we see that it maintains a NW-SE oriented band of heavy precipitation as well. However the model has backed off from previous runs which suggested this would be a 99-99.9 percentile event for this time of year. Nonetheless the model still suggests this is potentially a 90-97 percentile event which is still significant.
|NAEFS/GEFS Ensemble 48 hr rainfall Sat-Sun|
So what about the temperature forecast? We are holding onto our thoughts of hitting near 70° each day in Spokane this weekend, however if the band hits our area what will our temperature be? To say there is some uncertainty in this forecast would be an understatement. The 12z run of the GFS (dark blue line) has our high hitting the mid-70s that day. How about the 18z run of the GFS? A chilly mid-50s! That is about as uncertain as things can get. Its pretty much the same story for other parts of the Inland Northwest including Moses Lake (bottom meteogram)
|Meteogram for Spokane|
|Meteogram for Moses Lake|
This forecast remains a problematic one. Suffice it to say a good portion of the Inland Northwest is going to see a soggy beginning to the holiday weekend. Specifically where that will be, we still can't say with good confidence. We expect the wettest day of the three-day weekend will be Saturday with a gradual improvement expected after that.