00Z W 4 May 2011 Forecast Discussion

Today's "event" appears to have been pretty much of a dud from my perspective, in part due to the thick wave cloud that limited vertical mixing of stronger westerly momentum from aloft. The more interesting winds occurred before dawn.

The front that I have been anticipating tonight is currently still in northern WY, having passed Gillette at 2255Z. This means it will not get here till the wee hours at the earliest; the HRRR and RR suggest passage about 5am. This will not be a strong frontal passage. Prior to then, I anticipate some west to north winds on the flats. These will likely be intermittent at 10m, with low-level stability and weak winds alternating with periods of breezy conditions.

Wednesday looks to be partly to mostly cloudy with a chance of a little drizzle in the morning, and a slight chance of a shower in the afternoon. Winds will be < 10m/s and likely from the NE quadrant in the morning, and E to SE in the afternoon.

The Wednesday night outlook is for light winds, dominated by drainage flows if cloud cover dissipates, which I anticipate it will. By Thursday the cool air of Wednesday will be displaced by weak downslope and the likelihood of a deep mixed layer developing. This will be sufficient to mix westerly or northwesterly momentum aloft down to the surface, but no strong winds are expected. It appears likely that the possibilities for stronger winds become larger as we approach Friday night into Saturday, but no repeat of the winds of last Friday is anticipated.

Probability of gusts on M2 exceeding 15m/s ................25m/s

00-06Z W 4 Feb ............................... 30% .................near 0%

06-12Z W 4 Feb ............................... 40% .................near 0%

12-18Z W 4 Feb ............................... 10% .................near 0%

18Z W 4 through 06Z Th 5 Feb ......... near 0% ..........near 0%