Long-range forecast discussions seem to involve a mild degree of embarrassment for many of us. We know that beyond day three we're entering into the realm of prestidigitation and reading animal entrails, so we shuffle our feet awkwardly, gaze at the floor, and mumble some kind of caveat when we talk about long-range: "Well, it's a long way out, and the models are going to change." Don't want anyone to think we're naive, after all. Nevertheless, a lot of us--I'll bet most of us--still look out all the way to the end of the road at 384 hours, if not always then at least some of the time. Why? Certainly not to forecast with any degree of certainty. We just want to get a sense of what may be coming down the pike and to start looking for a general consistency. We're particularly likely to do so when the short term looks bleak. What we're really looking for is hope, right? Plus, of course, people who have got to nail down a time frame for their chasecation need at least some sense that they're choosing a potentially productive time, not a death ridge.
Patterns often crash and burn as they move from far out to near in. That's understood. But the fact is, some of them verify. The burlier systems seem to broadcast themselves well in advance of day three. So it pays to watch the GFS and Euro. The big question is, what's going on with the 500 mb chart. For me, I also like to get a sense of how mid-levels
may interact with instability, so I check out moisture, too, and CAPE on the GFS. I'm not looking for anything resembling detail or accuracy, but for shapes and possibilities. Last night's 00z GFS for May 23 looked horrible; this morning's 6z makes the northern plains look awesome. What can I extrapolate from that--a forecast? Heck no, just a sense of what to keep an eye on farther down the pike. Particularly on May 22, which, as I've said before, is my "lucky date."
And a lucky date is reason enough to keep an eye on things and watch how they evolve as long-term moves into NAM territory, and from there into days 3-2-1.
