There are some indications that the cold air now over the plains may mix out or pull away from the foothills by noon MST on Thursday (21st). If the cold air does retreat eastward or mix out, we are likely to get enough vertical mixing of momentum from aloft to give breezy conditions from the west to southwest by late morning and continuing till dusk Thursday evening. I give this a 50-50 chance of happening. If it does, extreme gust on M2 is likely to be in the 15-20 m/s range.
I think Thursday evening is likely to see light winds, but it is possible that winds will come up again toward Friday morning, and Friday daytime looks more likely than Thursday to have winds in excess of 15m/s (I'll say 70%, i.e., not that much more likely). These winds will be more synoptically driven than Thursday, as cyclogenesis is likely on the plains this day, though not with the strength we saw a week earlier. But, the Friday winds are also likely to be augmented and made more likely during the daytime by downward mixing of momentum within a fairly deep mixed layer.
Indications currently are for little wind over the Easter weekend, but with an active weather pattern (that is, with intermittent vigorous flow aloft with the passage of short-wave troughs and ridges, and changeable conditions at low levels) , this outlook could easily change. I will attempt another update tomorrow afternoon.
John B.
Cold air has mixed out and we are now getting some west winds on the flats and at bldg 33, gusting to 15m/s or so now. So, the windy 50% of last night's forecast is what is verifying. WIll provide a formal forecast update later this aftn.
ReplyDeletejohn b.