11 Oct KBIL forecast

Post date: Oct 11, 2012 9:36:56 PM

today's challenge: min temp

cold air, low stratus, and easterly winds locked in place all day at KBIL, but things are expected to change considerably tomorrow as the surface anticyclone is predicted to rapidly move off to the east overnight. winds at the surface are predicted by NAM meteogram to switch from east to west right around 06Z tonight, southwest flow near the surface should pick up during the day as a weak cyclone approaches the area from the west. after staying stuck in the 30s all day, they should easily warm up into the 70s tomorrow with full sun and downslope flow. min temp tonight will be very tricky, their temps will likely stay stuck in the mid-upper 30s while the low cloud deck remains in place, but could warm up a bit overnight once the winds shift and some of the downslope flow taps into the warmer air above the surface. I think it will be an interesting meteogram to look at tomorrow morning. NAM meteogram has them cooling off to near 30 by sunrise, seems a bit wacky given the surface winds that it is predicting, and MOS guidance is well above that (more like mid 30s) not to mention the USL forecast of 42 for their min. My confidence is very low on the min temp, my thinking is that they'll stay around 35 all evening until midnight, the winds will shift and skies will clear and temps will hold steady if not increase a bit as the winds pick up. I've got more confidence in the max temps, full sun and downslope flow should allow them to develop a deep boundary layer tomorrow afternoon, allowing their temps to rapidly warm up into the mid 70s. Guidance values are in the 74-77 range, I'm leaning towards the upper end of that range, thinking we'll see a similar situation to Tuesday when they warmed up beyond most forecasted values. Winds will be somewhat of a challenge, the pressure gradient is not very strong once the current anticyclone moves away, but they will be well-mixed over a deep (2.5-3km) PBL, so some of the better momentum should mix down to the surface, similar to Wednesday when they saw gusts up to ~30kts and max sustained of 24kts. I will probably go a couple kts below that. Precip is not an issue.

So, for what it's worth (I'm better at predicting consensus than I am predicting the actual weather) I think consensus will be something like 75/35/20kt/0.00" with a large spread in the min temp, some potential for gaining ground if you do happen to be on the correct side of consensus

quick update: just read the AFD from Billings and they mention the possibility of fog...not sure if there ground condition is moist there, could see some ground fog developing which often makes the temps lower...just another tricky factor to consider for their min temp!