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Forecast Discussion:
It is finally storm day! Figure 1 is the next 3 days at-a-glance. A chance of rain begins around 7am but really picks up after noon. The weatherunderground rainfall total (only a bit of snow possible Saturday AM - grassy surfaces and bridges might get a bit of slush) is about 2/3rds of an inch of liquid.
Figure 2 is the upper air cutoff low creating this storm. It is fairly far north from optimal (for large rainfall and or snowfall amounts) Friday morning.
Figure 3-6 shows the surface low and approximate frontal positions as the storm passes. Figure 3, Thursday PM, the low is near the Four Corners. Instead of moving slowly eastward, it shoots north into NE Utah (Figure 4). Rainfall and snowfall hits the mountains and western slopes first (Thursday into Friday midnight).
Figure 5 has the low back down where we want it, near Raton, and it is time for the mountain snows to really pick up and the Plains rain to begin (Friday 6am). I'm skipping the bulk of the storm (lots of rain down low and snow up high) and jumping to the end of the storm around noon Saturday (Figure 6). The low has continued southeast.
Precipitation forecasts by model:
The GFS puts a trace/coating of snow on Lamont (more to the west) - Figure 7.
For total water, the GFS gives us 1/2 to 3/4th inchs of water - Figure 8.
Figure 9 is the WPC 50th percentile confidence forecast - and we have a coating to an inch. It could happen that Longmont gets a slushy inch if heavier precipitation hits us (that would cool the air column a bit more).
Figure 10 is the NAM and it has us on the edge of nothing to an inch of snow.
Aside from Saturday AM slush and grass-snow, this should be a nice wet Spring storm.
The longer range forecast:
We warm right back up on Sunday (Figure 1 again). A Monday night storm may give us a bit of rain and a Tuesday cool down. Nothing notable. More later!
