High Plains Drifter

Well the 00z and 12z runs of the GFS today show a similar pattern, which offers a little hope in terms of maybe some consistency beginning to show up for the 24th… that is until you look at the 18z run. The “off hour” runs of the NCEP models are usually quite suspect since they do not have the benefit of RAOB data (which are 12z and 00z). Anyway, both the 00z and 12z runs today (the 18th) show a nice shortwave trough over the northern Rockies entering the northern High Plains with a discrepency in timing.

GFS 500mb:

GFS Surface:

Here is today’s 12z GFS Ensemble graphic of 500mb heights and precipitation… Great uncertainty exists over the northern plains and midwest where it looks more like spaghetti. In looking at the 0.50″ QPF contour, it looks like there’s a storm track across the northern plains and midwest. There’s a huge timing issue… but keep in mind, this is still a day 6.5 forecast!!:

The 12z Canadian global model (not shown) also supports a storm system over the northern Rockies ejecting from the large Pacific trough. The problem is, it is about a day faster than the GFS…. which, if more correct, Wednesday the 24th could either be a) a down day, or b) much farther south along the front in the Central Plains.

The upshot is… who knows! That’s the key… it’s 6 days out, and the models continue to be all over the place… but this is expected…. we won’t be able to get reliable signals for a chase target “region” (or if we’ll be chasing at all the first day) until about 108 to 120 hours… if we are lucky… and more realistically 72 hours. But, to continue the game, the “GFS Deterministic dart” for today will be in the same general area as before: